Voice Browser Call Control: CCXML Version 1.0

Abstract

This document describes CCXML, or the Call Control eXtensible Markup Language. CCXML is designed to provide telephony call control support for dialog systems, such as VoiceXML [VOICEXML]. While CCXML can be used with any dialog systems capable of handling media, CCXML has been designed to complement and integrate with a VoiceXML interpreter. Because of this there are many references to VoiceXML's capabilities and limitations. There are also details on how VoiceXML and CCXML can be integrated. However, it should be noted that the two languages are separate and are not REQUIRED in an implementation of either language. For example, CCXML could be integrated with a more traditional Interactive Voice Response (IVR) system or a 3GPP Media Resource Function (MRF), and VoiceXML or other dialog systems could be integrated with other call control systems.

Status of this Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This specification describes the Call Control XML (CCXML) markup language that is designed to provide telephony call control support for VoiceXML or other dialog systems. This document has been produced as part of the W3C Voice Browser Activity, following the procedures set out for the W3C Process. The authors of this document are members of the Voice Browser Working Group (W3C Members only).

This third last call working draft addresses many of the comments that came up during the last call review and a number of minor changes that came up during the implementation report. We also added definitions for external Event I/O Processors to the specification.

For a detailed list please see Changes in Last Call Working Draft 3.

This is a W3C Last Call Working Draft for review by W3C Members and other interested parties. Last Call means that the Working Group believes that this specification is technically sound and therefore wishes this to be the Last Call for comments. If the feedback is positive, the Working Group plans to submit it for consideration as a W3C Candidate Recommendation. Comments can be sent until 29 July 2005.

A Implementation Report Plan is currently being developed for this specification. The Working Group currently expects to require at least two independently developed interoperable implementations of each required feature, and at least one implementation of each feature, in order to exit the next phase of this document, the Candidate Recommendation phase. To help the Voice Browser Working Group build such a report, reviewers are encouraged to implement this specification and to indicate to W3C which features have been implemented, and any problems that arose.

This document is for public review. Comments and discussion are welcomed on the public mailing list < www-voice@w3.org >. To subscribe, send an email to <www-voice-request@w3. org> with the word subscribe in the subject line (include the word unsubscribe if you want to unsubscribe). The archive for the list is accessible on-line.

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced under the 5 February 2004 W3C Patent Policy. The Working Group maintains a public list of patent disclosures relevant to this document; that page also includes instructions for disclosing [and excluding] a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) with respect to this specification should disclose the information in accordance with section 6 of the W3C Patent Policy.

Per section 4 of the W3C Patent Policy, Working Group participants have 150 days from the title page date of this document to exclude essential claims from the W3C RF licensing requirements with respect to this document series. Exclusions are with respect to the exclusion reference document, defined by the W3C Patent Policy to be the latest version of a document in this series that is published no later than 90 days after the title page date of this document.

Conventions of this Document

In this document, the key words "must", "must not", "required", "shall", "shall not", "should", "should not", "recommended", "may", and "optional" are to be interpreted as described in [RFC2119] and indicate requirement levels for compliant VoiceXML implementations.

Table of Contents

• 1: Introduction
• 2: Motivation (Informative)
• 3: Concepts and Architecture
• • 3.1: Event Processing
  • 3.2: Conferencing
  • 3.3: Scripting
  • 3.4: Definitions
  • 3.5: Session Life-Cycle
  • • 3.5.1: Startup
    • 3.5.2: Shutdown
    • 3.5.3: Session Life-Cycle Diagrams
• 4: Simple Examples
  • 4.1: Hello World
  • 4.2: Accept or Reject a Call
  • 4.3: Simple Dialog
• 5: CCXML Elements Listing
• 6: Document Control Flow and Execution
• • 6.1: Overview
  • 6.2: Elements
  • • 6.2.1: <ccxml>
    • 6.2.2: <meta>
    • 6.2.3: <metadata>
    • 6.2.4: <if>
    • 6.2.5: <elseif>
    • 6.2.6: <else>
    • 6.2.7: <fetch>
    • 6.2.8: <goto>
    • 6.2.9: <createccxml>
    • 6.2.10: <exit>
    • 6.2.11: <log>
  • 6.3: Events
  • • 6.3.1: Overview
    • 6.3.2: fetch.done
    • 6.3.3: error.fetch
    • 6.3.4: ccxml.exit
    • 6.3.5: ccxml.loaded
    • 6.3.6: ccxml.kill
    • 6.3.7: ccxml.created
    • 6.3.8: error.createccxml
    • 6.3.9: error.unsupported
• 7: Dialogs
• • 7.1: Overview
  • 7.2: Elements
  • • 7.2.1: <dialogprepare>
    • 7.2.2: <dialogstart>
    • 7.2.3: <dialogterminate>
  • 7.3: Events
  • • 7.3.1: Overview
    • 7.3.2: dialog.started
    • 7.3.3: dialog.exit
    • 7.3.4: dialog.disconnect
    • 7.3.5: dialog.transfer
    • 7.3.6: dialog.terminatetransfer
    • 7.3.7: error.dialog
    • 7.3.8: error.dialog.notstarted
    • 7.3.9: error.dialog.wrongstate
    • 7.3.10: dialog.user.*
    • 7.3.11: dialog.prepared
    • 7.3.12: error.dialog.notprepared
    • 7.3.13: dialog.transfer.complete
  • 7.4: Dialog Object Properties
• 8: Variables and Expressions
• • 8.1: Overview
  • 8.2: Elements
  • • 8.2.1: <assign> and <var>
    • 8.2.2: <script>
  • 8.3: Session Variables
  • 8.4: Application Variables
• 9: Event Handling
• • 9.1: Overview
  • 9.2: Elements
  • • 9.2.1: <eventprocessor>
    • 9.2.2: <transition>
    • 9.2.3: <send>
    • 9.2.4: <move>
    • 9.2.5: <cancel>
  • 9.3: Events
  • • 9.3.1: error.notallowed
    • 9.3.2: error.semantic
    • 9.3.3: error.send.targetunavailable
    • 9.3.4: error.send.targettypeinvalid
    • 9.3.5: error.send.failed
    • 9.3.6: send.successful
    • 9.3.7: move.successful
    • 9.3.8: cancel.successful
    • 9.3.9: error.move
  • 9.4: Standard Events
  • • 9.4.1: Overview
    • 9.4.2: Standard Event Attributes
    • • 9.4.2.1: Overview
      • 9.4.2.2: Standard Event Attribute Table
    • 9.4.3: Connection Events
    • 9.4.4: Language Events
    • 9.4.5: Error Events
  • 9.5: Error Handling
• 10: Telephony Operations and Resources
• • 10.1: Overview
  • • 10.1.1: Concepts Background (INFORMATIVE)
  • 10.2: Connections
  • • 10.2.1: Connection State
    • 10.2.2: Connection Object
    • 10.2.3: Connection Events
  • 10.3: Conferences
  • • 10.3.1: Conference Object Properties
  • 10.4: Bridges
  • • 10.4.1: <join> Outcomes
    • 10.4.2: Invariant Examples
  • 10.5: Elements
  • • 10.5.1: <accept>
    • 10.5.2: <redirect>
    • 10.5.3: <reject>
    • 10.5.4: <createcall>
    • 10.5.5: <createconference>
    • 10.5.6: <destroyconference>
    • 10.5.7: <join>
    • 10.5.8: <unjoin>
    • 10.5.9: <disconnect>
    • 10.5.10: <merge>
  • 10.6: Events
  • • 10.6.1: Overview
    • 10.6.2: connection.alerting
    • 10.6.3: connection.progressing
    • 10.6.4: connection.connected
    • 10.6.5: connection.disconnected
    • 10.6.6: connection.redirected
    • 10.6.7: connection.merged
    • 10.6.8: connection.failed
    • 10.6.9: error.connection
    • 10.6.10: connection.signal
    • 10.6.11: conference.created
    • 10.6.12: conference.destroyed
    • 10.6.13: conference.joined
    • 10.6.14: conference.unjoined
    • 10.6.15: error.conference.create
    • 10.6.16: error.conference.destroy
    • 10.6.17: error.conference.join
    • 10.6.18: error.conference.unjoin
    • 10.6.19: error.merge
    • 10.6.20: error.connection.wrongstate
• 11: Complex Examples
• • 11.1: Calling Card Application
  • 11.2: Conferencing application
  • 11.3: Personal Assistant
• Appendix A - Related Work
• Appendix B - CCXML DTD
• Appendix C - CCXML Schema
• Appendix D - VoiceXML 2.0 Integration Details
• Appendix E - Recommended Telephony Protocol Names
• Appendix F - Changes
• Appendix G - Acknowledgments
• Appendix H - References
• Appendix I - CCXML Media Type
• Appendix J - Conformance
• Appendix K - Basic HTTP Event I/O Processor
• Appendix L - Session Creation Event I/O Processor

1: Introduction

This document describes CCXML, the Call Control eXtensible Markup Language. CCXML provides declarative markup to describe telephony call control. CCXML is a language that can be used with a dialog system such as VoiceXML [VOICEXML].

CCXML can provide a complete telephony service application, comprised of Web server CGI compliant application logic, one or more CCXML documents to declare and perform call control actions, and to control one or more dialog applications that perform user media interactions

Since platforms implementing CCXML MAY choose to use one of many telephony call control definitions (JAIN Call Control [JSR021], ECMA CSTA [CSTA], S.100 [S.100], etc.), the call control model in CCXML has been designed to be sufficiently abstract so that it can accommodate all major definitions. For relatively simple types of call control, this abstraction is straightforward. The philosophy in this regard has been to "make simple things simple to do." Outdial, transfer (redirect), two-party bridging, and many forms of multi-party conferences fall within this classification.

Figure 1 shows the architecture of a telephony implementation consisting of three primary components:

• a caller (along with the telephone network),
• a dialog system (e.g. a VoiceXML implementation),
• and the CCXML implementation which manages the Connections between the first two components.

The Telephony Web Application may or may not be integrated with the Voice Web Application.

The Telephony Control and Dialog Control Interfaces may be implemented as an API or protocol.

The components as shown in the figure below represent logical functions, and are not meant to imply any particular architecture.

Figure 1

2: Motivation (Informative)

CCXML is designed to complement dialog systems such as VoiceXML by providing advanced telephony functions. It also can be used as a third-party call control manager in any telephony system. This document contains references to VoiceXML's capabilities and limitations, as well as details on how VoiceXML and CCXML can be integrated.

The CCXML specification originated from the desire to handle call control requirements that were beyond the scope of the VoiceXML specification. The following requirements are addressed by this specification:

• Support for multi-party conferencing, with advanced conference and audio control. A conferencing application involves multiple participants, and is dependent upon call control to establish relationships between those participants.
• The ability to give each active call leg its own dedicated VoiceXML interpreter. For example, in VoiceXML, the second leg of a transferred call lacks a VoiceXML interpreter of its own, limiting the scope of possible applications.
• Sophisticated multiple-call handling and control, including the ability to place outgoing calls.
• Handling for a richer class of asynchronous events. Advanced telephony operations involve substantial amounts of signals, status events, and message-passing. VoiceXML 2.0 does not integrate asynchronous "external" events into its event-processing model.
• The ability to receive events and messages from external computational entities. Interacting with an outside call queue, or placing calls on behalf of a document server, means that VoiceXML must have additional external interfaces.

CCXML and VoiceXML implementations are not mutually dependent. A CCXML implementation may or may not support voice dialogs, or may support dialog languages other than VoiceXML.

3: Concepts and Architecture

A CCXML application consists of a collection of CCXML documents that control and manage the objects listed below:

• CCXML Session: A CCXML session is comprised of an executing CCXML document, or sequence of CCXML documents; each concurrently executing CCXML document is a separate session, and can be uniquely identified and referenced.
• Connection: Connections can be "call legs" (real-world phone connections) or system resources to facilitate interaction with a voice dialog. Media streams between Connections, or between Connections and Conference objects, need to be tracked by the CCXML interpreter and will take real system resources, but do not need a dedicated identifier because they are identified by their endpoints. Ownership of Connections can be moved from one session to another using <move>.
• Conference object: A Conference Object models a resource for mixing media streams. In order to accommodate the widest range of underlying telephony call control definitions, CCXML assumes a separate Conference Object, realizing that this abstraction may not have a direct counterpart in all telephony platforms. See <createconference> and <destroyconference> for further information.
• Voice Dialog: When active, a Voice Dialog is associated with a specific Connection by which the Voice Dialog may interact with one-way or two-way media streams from other Connections or a Conference Object.

CCXML programs manipulate these entities through elements defined in the CCXML language. They can also send and/or receive asynchronous events (mentioned above) associated with these entities.

CCXML programs directly manipulate Connection Objects and Conference Objects with various elements in the language, such as <accept>, <createconference>, and <join>. CCXML may also receive events from Connection and Conference Objects, in the case of line signaling, line-status informational messages, or error and failure scenarios. Connections and Conference Objects do not accept events; CCXML must use the builtin elements to direct them.

CCXML programs can start and kill Voice Dialogs using language elements. It can receive events from Voice Dialogs, which may be standardized events such as dialog.exit, or application-specific ones. CCXML can support sending of an event to a Voice Dialog.

CCXML programs can create other CCXML sessions using <createccxml>. This is the only guaranteed control mechanism a CCXML Session ever wields over another. Any other interaction takes place through the event mechanism. CCXML Sessions can both send and receive events between one another.

3.1: Event Processing

Telephone applications need to receive and process large numbers of events in real-time. These events arrive from outside the program itself - either the underlying telephony platform, or from other sources of events.

A CCXML program includes event handlers which are executed when certain events arrive. There are mechanisms for passing information back and forth between Voice Dialogs (such as VoiceXML) and CCXML, but the important points are that CCXML:

• lives on its own thread, and
• carries the burden of rapid asynchronous event handling

Note: References to threads are meant as logical threads and do not imply any specific platform implementation.

3.2: Conferencing

CCXML provides a powerful and flexible method of creating multi-party calls based on the following concepts:

• Call legs are audio sinks and sources which can be combined to form arbitrary networks.
• A conference is an audio stream that mixes together all the speakers' audio outputs. CCXML conference networks allow for conference objects, which mix inputs into a single output channel.
• A conference can include splitters, which take a single input channel and emit it over several outputs.
• A conference's architecture may be modified dynamically, thus allowing for moderation, floor control, mute, etc.
• Conferencing technology is implementation-dependent. CCXML implementations may not support all conferencing features mentioned above.

3.3: Scripting

The computational semantics of CCXML language is based on the ECMAScript Compact Profile (ES-CP, also known as ECMA-327) [ECMA327]. ES-CP is a strict subset of the third edition of ECMA-262 [ECMASCRIPT]. Execution efficiency is a primary goal of CCXML implementations, and ES-CP was chosen to ensure that CCXML implementations can operate in a variety of execution environments and without excessive execution overhead.

The ES-CP document specification states:

'ECMAScript Compact Profile is a subset of ECMAScript 3rd Edition tailored to resource-constrained devices such as battery powered embedded devices. Therefore, special attention is paid to constraining ECMAScript features that require proportionately large amounts of system memory (both for storing and executing the ECMAScript language features) and continuous or proportionately large amounts of processing power.'

While CCXML implementations are not necessarily intended for battery powered embedded devices, it is intended to be used in large, real-time telephony platforms managing thousands of lines. The constraints of ES-CP emphasize CCXML's ongoing concern for execution efficiency.

Even though ES-CP tends to be implemented using interpreters, CCXML does not require an interpretive implementation. ES-CP can be compiled to a target language such as C, and thus in turn to machine code, so that CCXML documents which are static can be rendered once in machine code. For example, a CCXML implementation, for optimization purposes, could translate and compile frequently used CCXML documents on their way from the document server to the CCXML execution environment in order to avoid multiplying interpretive overhead by the number of lines that execute the same document.

The emphasis on efficiency in CCXML language is also shown by the avoidance of requirements which can only be implemented either by interpretation or by run-time evaluation.

The choice of an implementation strategy is up to the CCXML implementer and CCXML language is aimed to allow a range of design choices in order to accommodate implementations on a wide variety of platforms.

A CCXML implementation MUST support the ECMAScript Compact Profile.

3.4: Definitions

The following terms, which are used throughout this specification, are defined as:

• ECMAScript left-hand-side expression - defined in ECMA-262 [ECMASCRIPT] 11.2; this is an expression which produces a result to which a value can be assigned; an expression which is valid as the left hand operand of an assignment (=) operator;

  Several examples of left-hand-side expressions are as follows (left-hand-side expression in red):

  <?xml version="1.0" encoding="UTF-8"?>
  <ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  
  <script>
  simpleVar            = 'Simple Expr';
  arrayVar[0]          = 'Simple Expr';
  arrayVar['arrayKey'] = 'Simple Expr';
  arrayVar             = {callingDevice: 'notSpecified', callCharacteristics: 'voiceUnitCall'};
  </script>
  
  </ccxml>
  

• ECMAScript expression - defined in ECMA-262 [ECMASCRIPT] 11.1; this is an expression which produces a value; an expression which is valid on the right hand side of an assignment operator;

  Several examples of ECMAScript expressions are as follows (ECMAScript expression in red):

  <?xml version="1.0" encoding="UTF-8"?>
  <ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  
  <script>
  simpleVar = 'hello world'; // simple string expression
  simpleVar = 'hello world'.length; // Calling a method that returns a 
                                    // number on the simple string object
  simpleVar = 5; // Simple number expression
  simpleVar = array[0]; // Array position expression
  simpleVar = array['key']; // Array named value expression
  simpleVar = myCoolFunction(); // Function return expression
  </script>
  
  </ccxml>
  

• ECMAScript variable name - defined in ECMA-262 [ECMASCRIPT] 7.6; this is any valid sequence of characters, known as an identifier, which can be used as a variable name, a property name, or a function name; this does not include any qualifiers, such as array or property accessors;

  Several examples of ECMAScript variable names are as follows (ECMAScript variable name in red):

  <?xml version="1.0" encoding="UTF-8"?>
  <ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  
  <script>
  simpleVar            = 'Simple Expr';
  arrayVar[0]          = 'Simple Expr';
  arrayVar['arrayKey'] = 'Simple Expr';
  arrayVar             = {callingDevice: 'notSpecified', callCharacteristics: 'voiceUnitCall'};
  </script>
  
  </ccxml>
  

• Empty ECMAScript object - an object returned by the new Object() ECMAScript expression; an object with no properties.
• CCXML variable name - a variable name, with optional dot separated qualification, declared in a CCXML <var> element or defined within ECMAScript code using the var keyword.
• Scope element - a CCXML variable name which defines a variable scope; <ccxml> and <transition> are CCXML scope elements. Variables which are defined within a scope element are not visible to variables defined in other scope elements.
• Time interval - CCXML uses the Cascading Style Sheets, Level 2 [ CSS2 ] time format. Time designations consist of a non-negative real number followed by a time unit identifier. The time unit identifiers are:
  • ms : milliseconds
  • s : seconds
  Examples include: "3s", "850ms", "0.7s", ".5s" and "+1.5s".
• CCXML Application/Program - A collection of CCXML documents that together create a complete application/program.
• CCXML Interpreter - The software that processes CCXML documents, executes commands and dispatches events. Also referred to as the "CCXML Platform".
• CCXML Session - A single instance of a CCXML application. Can span multiple documents and phone calls. See Section 3.5 Session Life-Cycle for details.
• CCXML Parent Session - The CCXML session that created the currently running session using the <createccxml> element.
• Event - An action or occurrence to which an application can respond. Examples of events are incoming phone calls, dialog actions or user defined events. Events in CCXML are modeled as ECMAScript objects and can contain complex values.

3.5: Session Life-Cycle

3.5.1: Startup

A CCXML session can be started for the following reasons:

• A new incoming phone call coming into the platform.
• A CCXML application executing a <createccxml>.
• An external session launch request coming into the platform.

When a session is started due to an incoming call it has ownership of the event endpoint associated with the new Connection. The new CCXML session will be responsible for processing the Connection state events and performing the Connection actions. If the session was started because of a <createccxml>, it will start without ownership of any event endpoints. In the case of an external session launch the session will not own any event endpoints.

A CCXML application can determine the reason its session was started by evaluating the contents of the session.startupmode session variable that is defined in the Session Variables section.

3.5.2: Shutdown

A CCXML session can end in one of the following ways:

• The CCXML application executes an <exit>.
• An unhandled "error.*" event.
• An unhandled "ccxml.kill" event.
• A "ccxml.kill.unconditional" event.

When a CCXML session ends, all active connections, conferences and dialogs that are owned by that session are automatically terminated by the platform.

3.5.3: Session Life-Cycle Diagrams

The following diagrams illustrate the session life-cycle of several different scenarios. These diagrams do not show all possible scenarios but rather show some of the most common ones that CCXML applications may encounter.

3.5.3.1: session can live before and after active connections (or no connections at all)

A CCXML session does not necessarily need to have any connections associated with it. After starting, a session may acquire connections as a result of <createcall> or <move> requests.

3.5.3.2: connection life shorter than session

In this example, the session is started due to an incoming call. A connection is typically shorter than a session. A session does not end when a connection terminates.

3.5.3.3: session ends, kills all active connections

When a session ends, any resources, including connections owned by that session are terminated.

3.5.3.4: session can have multiple sequential connections

A session can have multiple sequential connections

3.5.3.5: session can have multiple sequential connections and multiple concurrent connections

In addition to having multiple sequential connections, a session can have multiple concurrent connections.

3.5.3.5: move a connection to a newly created session

A connection can be moved from one CCXML session to another session. In the figure below, CCXML session (1) creates a new CCXML session (2) via <createccxml>. Then, the connection is moved from the original CCXML session to the new session.

3.5.3.7: move a connection to a "master" session

A connection can be moved from one CCXML session to another session, such as a "master" session.

3.5.3.8: optional "master" session for inbound call handling

Implementations MAY, as a platform-specific optimization, choose to deliver more than one inbound call to a single "master" session. This is can be viewed as equivalent to several sessions performing a <move>, as described in 3.5.3.7, of the connection.alerting event to a single CCXML session.

The default inbound call handling behavior for CCXML implementations is to create a new CCXML session and deliver the connection.alerting event to it. If a platform supports delivery of multiple inbound calls to a single session, the way this is configured is implementation specific.

3.5.3.9: ccxml.kill.unconditional event raised

If at anytime a ccxml.kill.unconditional event is raised by the underlying implementation, the CCXML session is immediately terminated and all active connections, conferences and dialogs that are owned by that session are automatically terminated by the platform.

3.5.3.10: Normal session shutdown requested by the platform

If at anytime the platform wishes to terminate a CCXML session it MUST raise a ccxml.kill event to inform the CCXML application. The normal response to this event is for the CCXML application to perform any clear up and termination of current active connections, conferences or dialogs and then execute an <exit> element.

If the CCXML application does not respond to the ccml.kill event in a timely manner the platform MAY then raise a ccxml.kill.unconditional event to immediately terminate the CCXML session and all active connections, conferences, and dialogs that are owned by the session.

4: Simple Examples

4.1: Hello World

This simple CCXML document shows an example of a "hello world" application that is started due to an incoming call where the application simply assigns a value to a variable, prints a message to the platform log and exits:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  <eventprocessor>  
    <transition event="connection.alerting" name="evt">
      <var name="MyVariable" expr="'This is a CCXML Variable'"/>
      <log expr="'Hello World. I just made a variable: ' + MyVariable"/>
      <log expr="'Lets hang up on this incoming call.'"/>
      <exit/>
    </transition>    
  </eventprocessor>
</ccxml>

4.2: Accept or Reject a Call

This CCXML document shows an example of how to process a incoming call event and answer or reject the call based on the phone number of the calling party:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  <eventprocessor>
  
    <transition event="connection.alerting" name="evt">
      <log expr="'The number called is' + evt.connection.remote + '.'"/>
      <if cond="evt.connection.remote == 'tel:+18315551234'">
        <log expr="'Go away! we do not want to answer the phone.'"/>
        <reject/>
      <else/>
        <log expr="'We like you! We are going to answer the call.'"/>
        <accept/>
      </if>
    </transition>
    <transition event="connection.connected">
      <log expr="'Call was answered,Time to disconnect it.'"/>
      <disconnect/>
    </transition>
    <transition event="connection.disconnected">
      <log expr="'Call has been disconnected. Ending CCXML Session.'"/>
      <exit/>
    </transition>
    
  </eventprocessor>
</ccxml>

4.3: Simple Dialog

This is an example of running a simple VoiceXML dialog from CCXML. The application answers an incoming phone call and then connects it to a VoiceXML dialog that returns a value that is then logged to the platform:

dialog.ccxml:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  <!-- Lets declare our state var -->
  <var name="state0" expr="'init'"/>
  
  <eventprocessor statevariable="state0">
    <!-- Process the incoming call -->  
    <transition state="init" event="connection.alerting">
      <accept/>      
    </transition>
    <!-- Call has been answered -->  
    <transition state="init" event="connection.connected" name="evt">
      <log expr="'Houston, we have liftoff.'"/>
      <dialogstart src="'dialog.vxml'"/>
      <assign name="state0" expr="'dialogActive'" />
   
    </transition>
    <!-- Process the incoming call -->  
    <transition state="dialogActive" event="dialog.exit" name="evt">
      <log expr="'Houston, the dialog returned [' + evt.values.input + ']'" />
      <exit /> 
    </transition>
    <!-- Caller hung up. Lets just go on and end the session -->
    <transition event="connection.disconnected" name="evt">
      <exit/>
    </transition>
    <!-- Something went wrong. Lets go on and log some info and end the call -->
    <transition event="error.*" name="evt">
      <log expr="'Houston, we have a problem: (' + evt.reason + ')'"/>
      <exit/>
    </transition>
  </eventprocessor>    
</ccxml>

dialog.vxml:

<?xml version="1.0"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
  <form id="Form">
    <field name="input" type="digits">
      <prompt>
        Please say some numbers ...
      </prompt>
      <filled>                            
        <exit namelist="input"/>
      </filled>
    </field>
  </form>
</vxml>

5: CCXML Elements Listing

6: Document Control Flow and Execution

6.1: Overview

A CCXML session begins with the execution of a CCXML document. The flow of the execution can be changed with the help of <if>, <elseif>, <else>, <fetch>, and <goto>. Most of a CCXML session's execution will take place within an <eventprocessor>, which processes a stream of incoming events.

A CCXML session can consist of multiple CCXML documents, traversed by use of <goto> and <fetch>.

A new CCXML session has a new session object (session.*), where initially the length of the connection array is 0. A CCXML session can contain multiple active connections.

A CCXML session may launch a new CCXML session using <createccxml>. The new CCXML session executes in an independent context and variable space from the original CCXML session, completely independent of the lifetime of the original session. Sessions can communicate by sending messages via <send>.

The media type application/ccxml+xml will be registered for CCXML documents.

The proposed definition of the media type is located in Appendix J: The CCXML Media Type.

This media type should be used for a XML document containing CCXML content.

6.2: Elements

This section details the CCXML elements for control flow and execution.

6.2.1: <ccxml>

6.2.1.1: Overview

This is the parent element of a CCXML document and encloses the entire CCXML script in a document. When a <ccxml> is executed, its child elements are collected logically together at the beginning of the document and executed in document order before the target <eventprocessor>. This is called document initialization.

The <ccxml> can designate the CCXML namespace. This can be achieved by declaring an xmlns attribute or an attribute with an " xmlns " prefix. See [XMLNS] for details. Note that when the xmlns attribute is used alone, it sets the default namespace for the element on which it appears and for any child elements. The namespace URI for CCXML is "http://www.w3.org/2002/09/ccxml".

6.2.1.2: <ccxml> Attribute Details

6.2.2: <meta>

6.2.2.1: Overview

The <metadata> and <meta> are containers in which information about the document can be placed. The <metadata> provides more general and powerful treatment of metadata information than <meta> by using a metadata schema.

A <meta> declaration associates a string to a declared meta property or declares " http-equiv " content. Either a name or http-equiv attribute is REQUIRED. It is an error to provide both name and http-equiv attributes. A content attribute is REQUIRED. The seeAlso property is the only defined <meta> property name. It is used to specify a resource that might provide additional metadata information about the content. This property is modelled on the rdfs:seeAlso property of Resource Description Framework (RDF) Schema Specification 1.0 [RDF-SCHEMA §2.3.4]. The http-equiv attribute has a special significance when documents are retrieved via HTTP. Although the preferred method of providing HTTP header information is by using HTTP header fields, the " http-equiv " content MAY be used in situations where the CCXML document author is unable to configure HTTP header fields associated with their document on the origin server, for example, cache control information. Note that, as with <meta> in HTML documents [HTML], HTTP servers and caches are not REQUIRED to introspect the contents of <meta> in CCXML documents and thereby override the header values they would send otherwise.

Informative: This is an example of how <meta> can be included in a CCXML document to specify a resource that provides additional metadata information and also indicate that the document MUST NOT be cached.

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0"
       xmlns="http://www.w3.org/2002/09/ccxml">
       <meta name="seeAlso"
content="http://example.com/my-ccxml-metadata.xml"/>
       <meta http-equiv="Cache-Control" content="no-cache"/>
</ccxml>

<meta> is an empty element.

6.2.2.2: <meta> Attribute Details

6.2.3: <metadata>

6.2.3.1: Overview

<metadata> is a container in which information about the document can be placed using a metadata language. Although any metadata language can be used within <metadata>, it is recommended that the Resource Description Format [RDF] be used in conjunction with the general metadata properties defined by the Dublin Core Metadata Initiative [DC].

RDF [RDF-SYNTAX] is a declarative language and provides a standard way for using XML to represent metadata in the form of statements about properties and relationships of items on the Web. A recommended set of generally applicable metadata properties (e.g., " title ", " creator ", " subject ", " description ", " copyrights ", etc.) is the Dublin Core Metadata Element Set [DC], used in the example below.

Document properties declared with <metadata> can use any metadata schema.

Informative: This is an example of how <metadata> can be included in a CCXML document using the Dublin Core version 1.0 RDF schema [DC] describing general document information such as title, description, date, and so on:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0"
       xmlns="http://www.w3.org/2002/09/ccxml">
  <metadata>
   <rdf:RDF
       xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
       xmlns:dc = "http://purl.org/dc/elements/1.1/">
   <!-- Metadata about CCXML document -->
   <rdf:Description rdf:about="http://www.example.com/meta.ccxml"
       dc:title="Hamlet-like Soliloquy"
       dc:description="Aldine's Soliloquy in the style of Hamlet"
       dc:publisher="W3C"
       dc:language="en"
       dc:date="2002-11-29"
       dc:rights="Copyright 2002 Aldine Turnbet"
       dc:format="application/ccxml+xml" >
       <dc:creator>William Shakespeare</dc:creator>
       <dc:creator>Aldine Turnbet</dc:creator>
   </rdf:Description>
  </rdf:RDF>
 </metadata>
</ccxml>

The following CCXML elements can occur within the content of <metadata> : none .

6.2.3.2: <metadata> Attribute Details

6.2.4: <if>

6.2.4.1: Overview

<if> is a container for conditionally executed elements. <else> and <elseif> can optionally appear within an <if> as immediate children, and serve to partition the elements within an <if>. <else> and <elseif> have no content. <else/> is a synonym for <elseif cond="true"/>.

Each partition within an <if> is preceded by an element having a cond attribute. The initial partition is preceded by the <if> and subsequent partitions by <elseif>s (or <else>s). The first partition in document order with a cond that evaluates to true is selected. <else> always evaluate to true. A partition MAY be empty.

If an <if> has no immediate <elseif> or <else> children, the full contents of the <if> will be selected when the cond attribute is true.

<else> was chosen to match similar concepts in other languages, and supports examples such as

<if cond="...">
  <!-- selected when <if cond> is true -->
  <else/>
    <!-- selected when <if cond> is false -->
  </if>.

However, <else> is a synonym for <elseif cond="true"/>, so an example such as

<if cond="...">
  <!-- selected when <if cond> is true -->
<else/>
  <!-- selected when <if cond> is false -->
<else/>
  <!-- never selected -->
</if>

<if cond="...">
  <!-- selected when <if cond> is true -->
<elseif cond="true"/>
  <!-- selected when <if cond> is false -->
<elseif cond="true"/>
  <!-- never selected -->
</if>.

6.2.4.2: <if> Attribute Details

6.2.5: <elseif>

6.2.5.1: Overview

An <elseif> partitions the content of an <if>, and provides a condition that determines the selection of the partition it begins. <elseif> can appear optionally as an immediate child of an <if>.

6.2.5.2: <elseif> Attribute Details

6.2.6: <else>

6.2.6.1: Overview

<else> is a synonym for <elseif cond="true"/>.

6.2.6.2: <else> Attribute Details

6.2.7: <fetch>

6.2.7.1: Overview

<fetch> is used to asynchronously fetch content identified by the attributes of the <fetch>. The fetched content may either be a CCXML document, or script content. Content that has been acquired using <fetch> is accessible through other elements defined by CCXML. Execution returns from the element immediately, and the CCXML application can continue on while the platform works to fetch the identified resource. When the fetch request has been completed, an event is generated against the session that initiated the fetch. The event is one of fetch.done, which indicates that the identified content was fetched successfully, or error.fetch, indicative of a failure to fetch the requested content. Note that even if content is successfully fetched, errors in processing fetched content (for instance, a CCXML document with a syntax error) may result in an error.fetch being thrown.

The fetch request is local to the session that initiated the <fetch>, and is referenced through a unique identifier generated by the CCXML platform. The application may obtain the unique identifier for a fetch request by providing an ECMAScript left-hand-side expression in the fetchid attribute when the fetch is performed. The fetch identifier can also be obtained as a property of the fetch.done event. The application uses the fetch identifier in any CCXML elements that reference fetched content, currently <goto> and <script>.

Fetched content has a lifetime that is limited to that of the document in which it is fetched. Therefore, following a transition to a new CCXML document using <goto>, content fetched in the scope of the current document is no longer accessible. Note that this should not be taken to preclude platform-level optimizations or caching of resources that are fetched multiple times.

The use of <fetch> to obtain content does not compel the application to make use of that content. However, it is wasteful of system resources to fetch resources that are not used. Platforms are responsible for clearing out unused fetch resources, and may impose limits on the resources that can be fetched by a single session.

The "http" URI scheme MUST be supported by CCXML platforms, the "https" protocol should be supported and other URI protocols may be supported.

6.2.7.2: <fetch> Attribute Details

6.2.8: <goto>

6.2.8.1: Overview

<fetch>, in conjunction with <goto>, is used to transfer execution to a different CCXML document in a multi-document CCXML application. The <fetch> tells the platform to find, load, and parse a given CCXML document. After the fetch completes, the CCXML application can then issue a <goto> to execute the now-fetched document.

Below is a small snippet of code from the CCXML application's event handler. We execute a <fetch> operation, and continue on to assign to a state variable, and maybe handle more events. Eventually, the fetch completes, the CCXML platform services the event, and the application performs the <goto>.

<fetch next="'http://www.web.com/control.ccxml'"/>
<--control continues here->
<assign name="state_var" expr="'fetch_wait'"/>
</transition>
<!-- ……… -->
<transition state="fetch_wait" event="fetch.done" name="evt"/>
<goto fetchid="evt.fetchid"/>
</transition>

A <goto> transfers control to the document obtained through a fetch request, using the platform-generated unique identifier associated with that fetch request. The fetch completion event MUST have arrived before the <goto> is executed, otherwise, an error.semantic event is generated. If the fetched content referenced by the fetch identifier is not a CCXML document, or the fetch identifier is invalid and does not correspond to any fetch request, this also results in an error.semantic event.

When a <goto> is executed, the target document replaces the current document in its session. Event sources associated with this session are inherited by the target document. Execution of the current document terminates.

6.2.8.2: <goto> Attribute Details

6.2.8.3: <fetch> and <goto> Example

The following code shows the use of the <fetch> and <goto> elements along with the fetchid attribute to handle more complex fetching situations:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">

  <!-- var to hold the value of the fetch 
          identifier that we care about -->
  <var name="myGoodFetchID"/>

  <eventprocessor>  
    <transition event="ccxml.loaded">
       <!-- stick the value of the fetch 
               identifier in the myGoodFetchID var -->
       <fetch fetchid="myGoodFetchID" 
                 next="'http://www.example.com/goodfetch.ccxml'"/>

       <!-- do not bother saving the fetch id's for these, 
               we would just ingore them anyway -->
       <fetch next="'http://www.example.com/fakefetch1.ccxml'"/>
       <fetch next="'http://www.example.com/fakefetch2.ccxml'"/>
    </transition>

    <transition event="fetch.done" name="evt">
       <if cond="myGoodFetchID == evt.fetchid">
          <!-- only matched if we have fetched 
                  http://www.example.com/goodfetch.ccxml -->
          <goto fetchid="evt.fetchid"/>
       </if>
    </transition>

  </eventprocessor>
</ccxml>

6.2.9: <createccxml>

6.2.9.1: Overview

<createccxml> is used to create another CCXML session, which begins execution with the document identified by this element. The term "session" is not meant to imply a particular form of implementation. A CCXML session exists for each concurrently executing CCXML document. A session provides independent execution and a separate variable space for the CCXML documents it executes. A session is associated with one or more event sources and will receive events only from those endpoints. The execution of a CCXML document MAY add or subtract event sources from a session. The new CCXML session has no relation to its creator once spawned, and has a wholly separate lifetime and address space.

Execution returns from the <createccxml> element immediately, and the CCXML interpreter can continue on while the new CCXML session is established and loads its initial document. If the new session is successfully established or a failure occurs an event is generated and is delivered to the session that executed the <createccxml> element.

6.2.9.2 <createccxml> Attribute Details

6.2.10: <exit>

6.2.10.1: Overview

<exit> ends execution of the CCXML session. All pending events are discarded, and there is no way to restart CCXML execution.

6.2.10.2 <exit> Attribute Details

A CCXML document executing the <exit> will generate a ccxml.exit event to the parent session. The exiting document will be identified on the exit event by its session ID.

6.2.11: <log>

6.2.11.1: Overview

<log> allows an application to generate a logging or debug message which a developer can use to help in application development or post-execution analysis of application performance. The manner in which the message is displayed or logged is platform-dependent. The usage of label is platform-dependent. The use of <log> SHOULD have no other side-effects on interpretation. <log>is an empty element.

6.2.11.2 <log> Attribute Details

6.3: Events

6.3.1: Overview

CCXML allows operations such as document fetching, startup and shutdown to execute independently. CCXML events that describe these operations are defined below:

6.3.2: fetch.done - Fetch Completion Event

This event is generated when a fetch request completes. It is delivered to the document which issued the request.

The fields of this event are:

6.3.3: error.fetch - Fetch Error Event

This event is generated when a fetch request does not successfully complete. It is delivered to the document which issued the request.

The fields of this event are:

6.3.4: ccxml.exit - CCXML Document Exit Event

This event is generated when a CCXML document executes an <exit>. This event is only generated when the session executing the <exit/> has a parent session. This event is sent to the parent session and not the session executing the <exit/>.

The fields of this event are:

6.3.5: ccxml.loaded - CCXML Document Loaded Event

This event is thrown once the document is parsed and ready for execution (document initialization occurs between the fetched and loaded events). The CCXML platform SHOULD generate this event when the CCXML document is first loaded, both at session startup and after transferring control to a new document with the <goto>. This event would be processed after the platform had executed the document initialization including executing any elements under the <ccxml> .

The fields of this event are:

6.3.6: ccxml.kill - CCXML kill Event

The kill event can be used by the platform to terminate a session without an explicit <exit>. There are two versions of this event: catchable, and non-catchable.

The ccxml.kill event can be caught, typically to perform a clean-up operation at the end of a session. If the event is caught the session will not be terminated unless the an <exit> element is processed. If the event is not caught the session will be terminated and all active connections, conferences and dialogs that are owned by that session will be automatically terminated by the platform.

Unlike other events, the ccxml.kill.unconditional event is the only event that cannot be caught by an application; it will unconditionally terminate the session and all active connections, conferences and dialogs that are owned by that session will be automatically terminated by the platform.

Note that while the normal cause of a ccxml.kill or ccxml.kill.unconditional event being queued to a session is that the platform wishes to terminate the session, it is legal for any event I/O processor to generate a ccxml.kill or ccxml.kill.unconditional event. For instance, it is legal for one CCXML session to unconditionally kill another session by sending a ccxml.kill.unconditional event using <send>. Note, however, that platforms may impose rules that prevent one session from arbitrarily killing another (to prevent malicious applications, for instance).

The fields of this event are:

6.3.7: ccxml.created - CCXML Session Create Completion Event

This event is generated when a <createccxml> request completes successfully. It is delivered to the document which issued the request and indicates that the new session has retrieved the specified initial CCXML document and has begun execution of it.

The fields of this event are:

6.3.8: error.createccxml - CCXML Session Create Failed Event

This event is generated when a <createccxml> request fails to complete. It is delivered to the document which issued the request and indicates that the new session has not been created.

The fields of this event are:

6.3.9: error.unsupported - CCXML Unsupported Operation

This event is generated when an OPTIONAL operation that is not supported by the platform is executed.

The fields of this event are:

7: Dialogs

7.1: Overview

CCXML does not provide any mechanism for interacting with callers but relies on separate dialog environments such as VoiceXML [ VOICEXML ]. Whenever interaction with a caller is required a CCXML session can initiate a separate dialog provided by a VoiceXML capability or some other technology. After the dialog interaction is complete, an asynchronous event is sent to the CCXML session which can use any results returned by the dialog environment to decide what should happen next.

Dialogs initiated by CCXML sessions are not tied to any single dialog language or technology. Any dialog system which fulfils CCXML's requirements MAY be used for interaction with the caller. Examples of dialog systems include VoiceXML, SALT [ SALT ], traditional IVR, 3GPP MRF as well as simple media handling systems for fax, media playback and recording, DTMF detection, answer-machine detectors, etc. A CCXML platform MAY support interaction with several dialog systems with the selection of the particular technology being based on the MIME type specified when the dialog is initiated.

All CCXML elements that manipulate dialogs are asynchronous with control returning immediately to the CCXML session after the operation is initiated. The CCXML session is notified when the dialog operation successfully completes, or fails, by an asynchronous event.

A CCXML program initiates a dialog using the <dialogstart> element. Execution of this element connects a dialog environment to a connection and instructs it to start interacting with the caller. For some dialog environments it may take some time to initialize the dialog environment and thus the use of the <dialogstart> element alone may cause the caller to hear silence, or "dead air". To avoid this situation CCXML provides an ability to ready a dialog environment prior to connecting and starting it, this is done using the <dialogprepare> element. Any dialog that has been either started with <dialogstart>, or prepared with <dialogprepare> can be terminated using the <dialogterminate> element. CCXML implementations MUST support the <dialogprepare>, <dialogstart>, and <dialogterminate> elements though the exact behaviour may vary depending on the dialog environments supported.

The following examples illustrate the valid use patterns for these three elements. Firstly the normal case of preparing a dialog, starting it, then optionally terminating it before normal completion. This example illustrates the use of <dialogprepare> to ready a dialog while the call is left in alerting state. When the alerting notification arrives the script executes a <dialogprepare> to prepare a dialog and associate it with the connection. When the dialog is prepared the script executes an <accept> to connect the call and then when the connection transitions to connected state, a <dialogstart> element is used to execute the previously prepared dialog.

<transition event="connection.alerting" name="evt">
    <dialogprepare src="..." connectionid="evt.connectionid"/>
</transition>
<transition event="dialog.prepared" name="evt">
    <accept connectionid="session.dialogs[evt.dialogid].connectionid"/>
</transition>
    
<transition event="connection.connected" name="evt">
    <dialogstart prepareddialogid="evt.dialogid" 
                    connectionid="evt.connectionid"/>
</transition>
    
(optionally)
<transition event="???">
    <dialogterminate dialogid="..." />
</transition>

The next example shows a single step dialog invocation without dialog preparation. In this case a connection in alerting state is accepted and, when the transition to connected state occurs, a <dialogstart> element is used to start the dialog.

<transition event="connection.alerting" name="evt">
    <accept connectionid="evt.connectionid"/>
</transition>
    
<transition event="connection.connected" name="evt">
    <dialogstart src="..." connectionid="evt.connectionid"/>
</transition>
    
(optionally)
<transition event="???">
    <dialogterminate dialogid="..." />
</transition>

The final example shows the case where a dialog which has been previously prepared is cancelled before a <dialogstart> has been issued. A dialog may be terminated when it is in the prepared state or while it is being prepared such as might be the case if the caller hangs up at some arbitrary point. In this case the <dialogterminate> may be executed before or after the dialog.prepared event is processed.

<transition event="connection.connected"> name="evt">
    <dialogprepare src="..." connectionid="evt.connectionid"/>
</transition>
<transition event="connection.disconnected" name="evt">
    <dialogterminate dialogid="evt.connection.dialogid" />
</transition>

It is possible for Dialogs to exist that are not joined to a Connection. For example this could be due to a Connection disconnecting or the user performing an <unjoin/> operation.

7.2: Elements

7.2.1: <dialogprepare>

7.2.1.1: Overview

<dialogprepare> is used to get an appropriate dialog handler ready to process, it is used as the precursor to a <dialogstart> request. The element includes a URI reference to the initial document for the dialog. The new dialog is prepared on a separate logical execution thread (this MAY be a thread, process, or system depending upon platform implementation) and does not block the processing of further events by the CCXML session. The use of the <dialogprepare> element is entirely optional, applications may choose to simply use <dialogstart> without prior preparation.

Optionally the new dialog may be associated with a connection by specifying the connectionid attribute.

When preparation of the dialog completes successfully a dialog.prepared event is posted to the event queue of the CCXML session. If however the dialog cannot be prepared for any reason, an error.dialog.notprepared event is posted.

CCXML implementations MUST support dialog preparation though the processing carried out as part of a <dialogprepare> request is dialog manager specific. In the case of a dialog manager that does not support preparation, the CCXML implementation MUST as a minimum, note the values provided via the src, namelist, and connectionid attributes, create a Dialog object, and return a new unique value to the location defined by the dialogid attribute and throw a dialog.prepared event.

The CCXML session selects what it believes to be the appropriate dialog manager based on the MIME type specified by the type attribute without retrieving the resource specified by the src URI. If, when the dialog manager retrieves the content, it finds the MIME type, as specified by the HTTP headers, differs from that specifed by the type attribute, it SHOULD raise an error.dialog.notprepared event with a reason indicating the type mismatch. The dialog manager MUST NOT ignore the type mismatch or render the resource as a different type based on the HTTP headers or on inspection of the document data. Refer to the W3C guidelines for client handling of MIME types [MIME-TAG] for further information.

7.2.1.2: <dialogprepare> Attribute Details

7.2.2: <dialogstart>

7.2.2.1: Overview

<dialogstart> is used to start a dialog and associate the dialog with a connection or conference. (See Section 10 for a discussion of connections and bridges). The element includes either a URI reference to the initial document for the dialog or the identity of a previously prepared dialog. The dialog executes on a separate logical execution thread (this MAY be a thread, process, or system depending upon platform implementation) and does not block the processing of further events by the CCXML session.

If the dialog cannot be started for any reason, an error.dialog.notstarted event is posted to the event queue of the CCXML session that processed the <dialogstart> request. When the dialog completes, a dialog.exit event is posted to the event queue of the CCXML session that started it.

If the connectionid attribute of <dialogstart> is specified, and if the dialog language allows access to telephony variables such as ANI, DNIS and UUI, values of these variables will be propagated from the specified connection to the dialog application.

If the prepareddialogid attribute is specified and a connectionid or conferenceid attribute was specified on the prior <dialogprepare> element, specifying a different connectionid or conferenceid on the <dialogstart> element WILL result in the throwing of an error.dialog.notstarted event.

The CCXML session selects the appropriate dialog manager based on the MIME type specified by the type attribute without retrieving the resource specified by the src URI. If, when the dialog manager retrieves the content, it finds the MIME type, as specified by the HTTP headers, differs from that specifed by the type attribute, it SHOULD raise an error.dialog.notstarted event with a reason indicating the type mismatch. The dialog manager MUST NOT ignore the type mismatch or render the resource as a different type based on the HTTP headers or on inspection of the document data. Refer to the W3C guidelines for client handling of MIME types [MIME-TAG] for further information.

7.2.2.2: <dialogstart> Attribute Details

7.2.3: <dialogterminate>

7.2.3.1: Overview

A CCXML document may decide that it wants to terminate a currently executing dialog, to throw away a previously prepared dialog, or to terminate the preparation of a dialog. This is accomplished using the <dialogterminate> element. When the CCXML interpreter encounters a <dialogterminate> element, it sends a terminate request to the specified dialog.

A dialog terminated due to the processing of a <dialogterminate> element MAY still return data to the CCXML application using a dialog.exit event if the value of the immediate attribute is false or unspecified. The details of the data returned are dialog environment specific.

If the immediate attribute is set to true the dialog does not return data to the CCXML application and the CCXML interpreter SHALL post a dialog.exit event immediately.

7.2.3.2: <dialogterminate> Attribute Details

7.3: Events

7.3.1: Overview

The majority of communication between CCXML interpreter sessions and dialogs is by way of events. Dialog environments post events to the CCXML interpreter event queue and a CCXML application MAY send an event to a dialog. How this is handled on the dialog side is dialog manager and CCXML interpreter dependent. On the CCXML side it is done by using <send> and passing in the dialogid that was received as a result of processing a <dialogstart>.

The following are the CCXML events related to dialogs:

7.3.2: dialog.started

The dialog.started event MUST be thrown when a dialog is successfully started. The fields available in the event are:

7.3.3: dialog.exit

The dialog.exit event MUST be thrown when a dialog terminates either normally or following a <dialogterminate> request. The fields available in the event are:

7.3.4: dialog.disconnect

The dialog.disconnect event MUST be thrown when a dialog requests it be disconnected from its current call. The dialog MUST NOT be not terminated, but simply requests the CCXML application end the call. The fields available in the event are:

7.3.5: dialog.transfer

The dialog.transfer event MUST be thrown when a dialog requests a transfer of its current call. The fields available in the event are:

7.3.6: dialog.terminatetransfer

The dialog.terminatetransfer event MUST be thrown when a ongoing transfer must be terminated, for example due to a "hotword" recognition. As part of handling of the dialog.terminatetransfer event, the CCXML Application should terminate the outgoing call leg and return the media stream of the original call to the dialog using the <join> tag. The fields available in the event are:

7.3.7: error.dialog

The error.dialog event MUST be thrown when there was an unspecified error with the dialog (for example the dialog server crashed). The fields available in the event are:

7.3.8: error.dialog.notstarted

The error.dialog.notstarted event MUST be thrown when the processing of a <dialogstart> element fails because the dialog cannot be started for some reason. The fields available in the event are:

7.3.9: error.dialog.wrongstate

The error.dialog.wrongstate event MUST be thrown when a dialog request such as <dialogterminate> has been received by the dialog environment but it cannot be completed because the dialog is not in a suitable state. The fields available in the event are:

7.3.10: dialog.user.*

The dialog.user.* (where * is the name of the user defined event) MUST be thrown when a dialog sends a user event to the CCXML session that initiated it. The fields available in the event are:

7.3.11: dialog.prepared

The dialog.prepared event MUST be thrown when a dialog has been successfully prepared following the execution of a <dialogprepare> element. The fields available in the event are:

7.3.12: error.dialog.notprepared

The error.dialog.notprepared event MUST be thrown when the processing of a <dialogprepare> element fails. The fields available in the event are:

7.3.13: dialog.transfer.complete

This event MUST be sent from the CCXML application to the Dialog which uses this to fill transfer results (i.e. for VoiceXML platforms to fill field item results). The fields of this event are:

For a complete source code example of how to support transfer please see the section below titled VoiceXML 2.0 Example.

7.4: Dialog Object Properties

An instance of the Dialog object is associated with each dialog created by <dialogstart> or <dialogprepare> and referenced in the session.dialogs array.

8: Variables and Expressions

8.1: Overview

CCXML expressions are valid ECMAScript [ ECMASCRIPT ] expressions, assignable to variables with valid ECMAScript names. For further details please see section 3.4.

8.2: Elements

8.2.1: <assign> and <var>

8.2.1.1: Overview

Variables are declared using the <var> element and are initialized with the results of evaluating the OPTIONAL expr attribute as an ECMAScript expression. If the expr attribute is not present in the <var> declaration, the variable is initialized to ECMAScript undefined. The values of variables MAY be subsequently changed with <assign>.

Variables are declared explicitly by <var> :

<var name="sessionid" />
<var name="currentstate" expr="'initial'" />

Variables declared without an explicit initial value MUST be initialized to the ECMAScript value undefined by the implementation.

It is illegal to make an assignment to a variable that has not been explicitly declared using <var> or a var statement within a <script>. Attempting to assign to an undeclared variable causes an error.semantic event to be thrown. Please see Section 9.5 for a detailed description of error events.

Note that when an ECMAScript object, e.g. "obj", has been properly initialized then its properties, for instance "obj.prop1", can be assigned without explicit declaration. An attempt to declare ECMAScript object properties such as "obj.prop1" results in an error.semantic event being thrown.

CCXML uses an ECMAScript scope chain (please see section 3.4.2) to allow variables to be declared at different levels of hierarchy in an application. For instance, a variable declared at ccxml (document) scope can be referenced anywhere within that document, whereas a local variable declared in a <transition> is only available within that element.

The implementation MUST define four scopes - session, application, ccxml and transition. The relationship between these scopes is shown below.

Variable Scoping

A description of the scopes is provided in the table below.

The implementation MUST instantiate a variable within the scope of the closest containing scope element. The fully-qualified name of a variable is the name of the variable's scope object prepended with a dot to the name of the variable. The implementation MUST allow reference to variables by their fully qualified names. The implementation MUST allow reference to variables without requiring use of their fully qualified names. In the case of like-named variables declared in different scopes, the implementation MUST reference the variable in the closest containing scope, unless the fully-qualified variable name is used.

The implementation MUST resolve variables by searching the enclosing transition scope first (if applicable) followed by the ccxml scope, the application scope and then the session scope, unless the variable reference is qualified with a scope prefix.

If the variable includes a scope prefix, the implementation MUST resolve the variable by searching the named scope.

If a variable is declared more than once, the implementation MUST evaluate the expr attribute of each subsequent declaration, and assign the result to the variable declared by the first <var>.

Variables can be assigned new values using <assign> :

        <assign name="currentstate" expr="'cleanup'" />

The implementation MUST evaluate the ECMAScript expression contained in the expr attribute of <assign>, and assign the results to the variable referenced in the name attribute.

8.2.1.2: <var> Attribute Details

8.2.1.3: <assign> Attribute Details

8.2.2: <script>

8.2.2.1: Overview

<script> encloses computations written in the ECMAScript Compact Profile [ECMA327] scripting language. The ECMAScript Compact Profile is a strict subset of the third edition of ECMA-262 [ECMASCRIPT]. It has been designed to meet the needs of resource-constrained environments. Special attention has been paid to constraining ECMAScript features that require proportionately large amounts of system memory, and continuous or proportionately large amounts of processing power. In particular, it is designed to facilitate prior compilation for execution in a lightweight environment. For specific details on what ECMAScript functions are not supported please take a look at ECMA-327 specification.

An implementation MUST support the ECMAScript Compact Profile and MAY support the full ECMA-262 ECMAScript specification.

The example <script> below defines a function that computes the greatest common factor of two integers:

<script>
<![CDATA[
function gcd(a, b)
{
 var t;
 if (a < 1 || b < 1)
   return -1;
 do
  {
   t = a % b;
   a = b;
   b = t;
  }
 while (b > 1);
 return (b == 0) ? a : b;
}
]]>
</script>

An implementation MUST support <script> within the <ccxml> element and in executable content. <transition> and <if> contain executable content. The implementation MUST evaluate script in a <ccxml> immediately after the document is loaded, along with any <var> and <assign> elements, in document order. When used as a child of the <ccxml> element, <script> cannot be used to execute dynamically fetched content obtained using <fetch>. The implementation MUST evaluate <script> in executable content as it is processed.

The ECMAScript contained within the <script> can declare variables with the ECMAScript var statement. Variables declared in this manner are declared in the scope of the closest containing scope CCXML element. They are known from the point of declaration to the end of the containing scope. The implementation MUST allow reference to these variables from CCXML and from ECMAScript, using either the fully-qualified variable name, or the declared name.

If the implementation is unable to run the script referenced it MUST throw an error.semantic event.

8.2.2.2: <script> Attribute Details

8.3: Session Variables

Every CCXML session has a set of standard ECMAScript variables that are available to the program during execution called session variables. The session variables are defined by the CCXML implementation when the CCXML session is created and are read-only to the running script and cannot be modified by the CCXML program. New session variables cannot be declared by CCXML programs.

Session variable values are modified by the CCXML implementation during execution time of the script as the state of the executing CCXML session changes. For example, when the state of a Connection changes within a CCXML session, the value of the state property of the session Connection object will be updated by the CCXML implementation so that if the CCXML program's event handler evaluates the state variable, it will reflect the current state of the Connection object. It is the responsibility of the CCXML implementation to control and update the session changes as they occur in the CCXML session. It is assumed that session changes are visible to the CCXML program as they occur. However, it is permissible for a CCXML implementation to optimize session changes by "lazy-binding" values as they are accessed or evaluated by a CCXML program, so as to minimize processing time. For example, an implementation might only update the current Connection states when a CCXML program evaluates the variable during execution time versus continually updating the Connection states inside ECMAScript scope as state changes. Regardless of when session variables are updated to reflect changes, the CCXML implementation is REQUIRED to provide the correct values when accessed by a CCXML program.

Variables defined in the session scope are subject to the parent scope chain delegation model but do not have a parent scope defined.

The following are the list of standard session variables:

session.startupmode

String that indicates the startup mode that the script was started as:

Value	Details
newcall	Session was started due to a new incoming call.
external	Session was started due to a external session launch request.
createccxml	Session was started due to a <createccxml> request.

session.id

A globally unique string that indicates the session identifier of the executing CCXML session.

session.uri

URI that was used when creating the current CCXML session.

session.parentid

String that indicates the session identifier of the parent of the CCXML session that created this session. In the case the current session has no parent, the value of the variable will be ECMAScript undefined. Once a new CCXML session is created, the new session and its parent are completely independent.

session.connections

Array which contains a list of the Connection objects that the session is currently using. The array is associative and each key in the array is the connection identifier for the Connection. For example, session.connections["1234"] would return the Connection object for connection id 1234. The following example demonstrates the use of the session.connections variable:

<transition state="in_vxml_session" event="connection.disconnected"
name="evt">
  <if cond="session.connections['1234'].id==evt.connid">
    <--  if the disconnect is on the first connection, do something -->
  <else/>
    <exit/>
  </if>
</transition>

session.conferences

Array which contains a list of the Conference objects that the session is currently using. The array is associative and each key in the array is the conference identifier for the Conference. For example, session.conferences["1234"] would return the Conference object for conference id 1234.

session.dialogs

Array which contains a list of the Dialog objects that the session is currently using. The array is associative and each key in the array is the dialog identifier for the Dialog. For example, session.dialogs["1234"] would return the Dialog object for dialog id 1234.

session.ioprocessors

Array which contains a list of external event I/O access URIs which are available to the current session. The array is associative and each key in the array is the type of the event I/O processor. For example, session.ioprocessors["basichttp"] would return the access URI (e.g. http://www.example.com/ccxml/basichttp) for the "basichttp" type event I/O processor.

8.4: Application Variables

CCXML provides application variables which, like session variables, persists across the CCXML application. Application variables differ from session variables in that they can be modified by CCXML programs.

Application variables are not explicitly declared since they are properties of the application object initialized by the CCXML implementation. By default, application variables have the value ECMAScript undefined. Variables in the application scope are subject to the parent scope chain delegation model and have session as their parent scope.

It is the responsibility of the CCXML implementation to properly initialize the application object.

Application variables are visible within documents which form the CCXML application. For example, a document in a CCXML application could assign an application variable a value using <assign name="application.userid" expr="'user001'"/>, and a later document in the CCXML application could reference application.userid to retrieve the value 'user001'.

Application developer should be careful in their use of application variables since they are visible to all CCXML documents within a CCXML application.

9: Event Handling

This section contains information on <eventprocessor>, <send>, <cancel>, <transition> and <move>.

9.1: Overview

Event Handling is one of the most powerful features of CCXML. CCXML events can be delivered at any time and from a variety of sources. This flexible event-handling mechanism is essential for many telephony applications.

Every CCXML session can send and receive events. These might be in response to a previous action by the CCXML session (e.g., an outbound-call request, which generates an event to indicate when the call goes off-hook), or on the initiative of some external source (e.g., an incoming call to be answered). Events can be generated by the telephony system (as in the two previous examples), other CCXML sessions (which emit events via <send>), Dialogs, or CCXML sessions can send events to themselves.

There is a core set of telephony-related events (derived from the JCC event model for connection objects. See the JAIN Call Control API (JCC) [JSR021] for more information) that a browser MUST support. Implementers are otherwise free to define and support any platform-specific events they like. In addition, users/programmers may use <send> to send arbitrary events to external destinations, or may send arbitrary events to CCXML documents from internal or external sources and may specify transition handlers to handle these events.

The transmission and reception of events both external and internal is controlled by a logical component in the platform called the "Event I/O Processor". A platform may support more than one type of Event I/O Processor and each of them may support a different format of external events (For example: SOAP, JMS, SIP, Simple HTTP or any other event transmission approaches). For incoming events the Event I/O Processor is responsible for accepting the incoming event and transforming it into an ECMAScript event object that can be accessed by CCXML. For outgoing events the Event I/O Processor is responsible for deciding the serialization and transport formats. The operation and behavior of the Event I/O Processor component is currently platform dependent but may be standardized at some point in the future by some other W3C specification.

Each running CCXML interpreter has a queue, into which it places incoming events, and sorts them by arrival time. A CCXML programmer can only gain access to these queued events by using the <eventprocessor> element with associated <transition> elements.

The CCXML session event queue generally operates in a First In, First Out (FIFO) manner with events to be processed being removed from the head and new events being placed at the tail. There are two exceptions to this behaviour: events where a time delay has been specified, and certain special events that are always placed at the head of the queue.

An event can be delivered to a CCXML session using a <send> element in which case an optional delay may be specified. When a delay is specified the event is delivered to the target CCXML session but it is not placed on to the event queue until the delay time has elapsed. When the delay has elapsed the event is placed at the tail of the queue.

There are two types of event that, when delivered to a CCXML session, are handled differently. All ccxml.kill.* events are placed at the head of the event queue rather than the tail so that they are processed in preference to all other events. All error.* events are placed at the head of the queue but behind any error.* or ccxml.kill.* events that are already on the queue.

An <eventprocessor> is interpreted by an implicit Event Handler Interpretation Algorithm (EHIA). The EHIA's main loop removes the first event from the CCXML session's event queue, and then selects from the set of <transition>s contained in the <eventprocessor>. A <transition> always indicates a set of accepted event types, and MAY indicate a further ECMAScript conditional expression to be evaluated. The <transition> that accepts the type for the just-removed event, has a satisfied conditional expression, and appears first in the <eventprocessor> in document order, is the selected <transition>.

Once selected, the elements inside a <transition> are executed in document order. At most, one <transition> will be chosen. If no <transition> meets all the criteria, none are selected and the event is simply dropped; the EHIA loop then starts over again, removing the event at the head of the queue. The only exception to this rule is when a ccxml.kill event is received. In this case, the CCXML interpreter will end the session if there are no <transition>s that match the ccxml.kill event explicitly.

Any events that arrive while an event is already being processed are just placed on the queue for later. If the event queue is empty, and the EHIA wants to process an event, execution pauses until an event arrives.

During the processing of an event by the EHIA, the state of any ECMAScript objects exposed by a platform, such as the Connection object, must reflect the state of the CCXML session immediately following the occurrence of the event. For instance, if a 'connection.alerting' event is being processed against a connection with ID 1234, then session.connections['1234'].state would have a value of 'ALERTING'. This is true even if the actual connection has already been terminated, with a 'connection.disconnected' event queued (but not yet processed) against the session. It is required that the ECMAScript state for the session is updated prior to the selection of a matching <transition>, since the <transition> might contain an ECMAScript conditional expression the value of which depends on the state changes caused by the event.

Code inside an <eventprocessor> SHOULD run "instantaneously", without blocking execution. This will allow events to be rapidly processed. CCXML applications should be aware of this and should keep calculations such as large ECMAScript functions within a transition to a minimum.

The only way for CCXML execution to leave an <eventprocessor> is via an explicit <goto> or <exit> inside a <transition>.

An <eventprocessor> MAY also declare a state variable attribute. An <eventprocessor>'s state variable must be declared in the ccxml scope using a <var> or a <script>. The <eventprocessor> can be considered, and programmed as, a finite-state-automaton, with the state variable indicating the automaton's current state or node, and the <transition>s, driven by incoming events, moving the machine to a new state and creating side effects along the way.

If an event is not selected by any <transition> within the <eventprocessor>, the CCXML platform SHOULD log the event using the "missed" label. The CCXML platform can configure the "missed" label for any desired disposition. This SHOULD be equivalent to the transition:

<transition event="*" name="ev">
   <log label="'missed'" expr="ev.toString()"/>
</transition>

9.2: Elements

9.2.1: <eventprocessor>

9.2.1.1: Overview

The <eventprocessor> acts as a container for <transition>s. A valid CCXML document MUST only have a single <eventprocessor>.

9.2.1.2: <eventprocessor> Attribute Details

<eventprocessor> can contain only <transition>s .

9.2.2: <transition>

9.2.2.1: Overview

1. the statevariable specified by the parent <eventprocessor> MUST be currently set to one of the values listed in the <transition>'s state attribute, if that attribute is present
2. the expression specified by the <transition> 's cond attribute MUST evaluate to true, if that attribute is present
3. the current event's name property MUST match the pattern specified by the <transition>'s event attribute, if that attribute is present

9.2.2.2: <transition> Attribute Details

9.2.2.3: <transition> Event Matching

The event attribute of a <transition> specifies a pattern used to match event names. If the state matches the current state and the cond attribute expression is true, the <transition> will be selected if the event pattern matches the event name. Event names are case-insensitive.

Pattern match examples

9.2.3: <send>

9.2.3.1: Overview

<send> is used to send messages containing events or other information directly to another CCXML Interpreter or other external systems using an Event I/O Processor.

The event target of <send/> is specified using the target and targettype attributes. These attributes control how the platform should dispatch the event to its final destination.

The target attribute specifies the unique identifier of the event target that the Event I/O Processor should send the event to. This can be the value of a CCXML Session ID or a Dialog ID if you wish to send an event to one of these respective targets. In the case where you are using some other Event I/O Processor this attribute should be able to describe how to connect to the event destination (For example a SIP URL for SIP-INFO messages or a HTTP URL for Web Services). If the value of the target attribute is not supported, invalid or unreachable by the Event I/O Processor the Platform MUST throw a error.send.targetunavailable event.

The targettype attribute controls what Event I/O Processor the event should be sent to. The default value of this attribute is 'ccxml'. If the event targettype specified is not supported the platform MUST throw a error.send.targettypeinvalid event.

A platform must support the following values for the targettype attribute:

Platforms may support other types of Event I/O Processors, for example: Web-services, SIP or basic HTTP GET. However, platforms SHOULD name the Event I/O Processor beginning with "x-" to signify that they are platform dependent.

<send> also specifies the content of the message to be sent. <send> may specify message content in one of two ways (the following mechanisms are mutually exclusive):

• data attribute with an OPTIONAL namelist
  • The data attribute specifies an ECMAScript expression that returns the name of the event.
  • The namelist attribute specifies a space separated list of CCXML ECMAScript variables to be included with the message.

  <var name="target" expr="'tel:+18005551212'"/>
  <var name="content" expr="'http://www.example.com/mycontent.txt'"/>
  <send target="target" 
           targettype="'x-messaging'" 
           data="'fax.SEND'" 
           namelist="content"/>
  

• Inline XML content that explicitly specifies the message to be sent.

  <send target="'csta://csta-server.example.com/'" targettype="'x-csta'"
  xmlns:csta="http://www.ecma-international.org/standards/ecma-323/csta/ed3">
   <csta:MakeCall>
    <csta:callingDevice>22343</callingDevice>
   
  <csta:calledDirectoryNumber>18005551212</csta:calledDirectoryNumber>
   </csta:MakeCall>
  </send>
  

When inline XML is specified, the content of the <send> is parsed but MUST be ignored by the sending CCXML Interpreter until the <send> is executed. XML namespace binding within the <send> element MUST be preserved in the message sent to the <send> target. This may result in XML namespace declarations being added to the message contents in order to resolve XML namespace prefixes whose associated namespace declarations were not contained in the message contents in the original CCXML document. It is the responsibility of the Event I/O Processor responsible for forwarding events to the <send> target to parse the incoming message and remove the namespace bindings, if required by the <send> target.

The sending CCXML Interpreter MUST NOT alter the content of the <send> other than by adding namespace declarations for unresolved namespace bindings. The data contained within a <send> MUST be sent to the destination specified in the target attribute of <send> using the Event I/O Processor specified by the targettype attribute. When <send> is used with inline XML content, and the target is a CCXML session, the mapping of that XML content to event object properties is implementation-specific, and outside the scope of this specification. Although the full set of requirements for the Event I/O Processor is not within the scope of this specification, an event processor sending an event to a CCXML Interpreter is required to generate an event which can be processed in a CCXML Session. See Section 9.1 for details regarding the processing of incoming events by an CCXML Interpreter.

When a message is successfully sent to the target, a send.successful event will be thrown. Note that this does not mean that the target processed the message successfully. It is up to the target to generate events specific to the message. These events are application specific.

If the send request fails, an event signifying the error will be returned to the CCXML Session. The failure events are documented at the end of this section.

9.2.3.2: <send> Attribute Details

9.2.3.3: <send> Examples

In this example we send the current CCXML session a hello.jack event that contains a single field. We catch the event, log the field and exit:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  <eventprocessor>  
    <transition event="ccxml.loaded">
      <var name="jacksvar" 
              expr="'I am Jack\'s complete lack of surprise.'"/>
      <send target="session.id" targettype="'ccxml'"
       data="'hello.jack'" namelist="jacksvar"/>
    </transition>
    <transition event="hello.jack" name="evt">
      <log expr="evt.jacksvar"/>
      <exit/>
    </transition>    
  </eventprocessor>
</ccxml>

In this example we send a event to our parent and then exit:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  <eventprocessor>  
    <transition event="ccxml.loaded">
      <var name="jacksvar" 
              expr="'I am Jack\'s inflamed sense of rejection.'"/>
      <send target="session.parentid" data="'hello.jack'"
       targettype="'ccxml'" namelist="jacksvar"/>
      <exit/>
    </transition>
  </eventprocessor>
</ccxml>

In this example we catch a dialog.transfer request and just return a error event back to the dialog:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  <eventprocessor>  
    <transition event="dialog.transfer" name="evt">
      <var name="reason" expr="'I am a jack's unsupported transfer.'"/>
      <send target="evt.dialogid" data="error.unsupported.transfer"
       targettype="'dialog'" namelist="reason"/>
      <exit/>
    </transition>
  </eventprocessor>
</ccxml>

9.2.4: <move>

9.2.4.1: Overview

<move> is used to move an event source (such as a Connection object) to an executing CCXML session. When an event source is moved to a session, events originating from that source will be delivered to that session's currently executing CCXML document. The event OR the source attribute MUST be specified. If neither attribute is specified or both attributes are specified, an error.fetch event will be thrown.

A <move> attempt may fail for a number of reasons. These reasons include:

• The referenced event source does not exist, or does not belong to the session executing the <move>;
• The referenced event source is immovable - the CCXML session itself and various external event I/O processors are examples of this;
• The referenced event source is currently bridged in a way that prevents it from being moved (as described below) ;
• The session to which the event source is being moved does not exist, or cannot accept the event source that is being moved;
• Other causes, which may be platform specific.

A <move> is not allowed once an event source is associated with another object through an implicit or explicit <join>. Moving event sources that are joined would disassociate the objects connected through the join. For example the result of moving connection that has an active dialog would be two CCXML sessions, one owning the connection, the other owning the dialog.

In the event of a <move> failure, an error.move event will be generated to indicate that the <move> attempt was unsuccessful. Otherwise, a move.successful event will be generated against the session that performed the <move> to indicate that the request has completed successfully.

Since each CCXML session has an event queue, it is possible that a session executing a <move> will already have events in its queue from the event source that is being moved. As an example, this situation could easily occur with connection.alerting and connection.disconnected if the incoming connection is abandoned before a CCXML platform initiates processing. Any such events will be removed from the queue of the session performing the <move>, and placed into the queue of the session that the event source is being moved to. Each event moved in this manner will be inserted into the queue of the target session as if it was a new event occuring in the context of that session. The order in which events are queued is the order in which they appear in the event queue of the session performing the <move>. If the event attribute is specified, then the referenced event is placed into the queue of the target session before other queued events from the event source are inserted. Note that queueing rules governing the order in which the inserted events will be processed continue to apply.

Like all CCXML elements, <move> executes asynchronously. As such, there is a period of time during which events generated by the event source being moved cannot be processed either by the session performing the <move>, or by the target session. If the <move> fails, then these events remain in the queue of the session that attempted the <move>, and will be processed normally. However, while the <move> is being performed, events from event sources other than the one being moved will continue to be processed according to the EHIA. As such, a failed <move> request may result in events being processed in a different order than if no <move> operation was performed. Note that the relative ordering of events from the event source being moved is not changed even as a result of such a failure.

9.2.4.2: <move> Attribute Details

9.2.5: <cancel>

9.2.5.1: Overview

When a CCXML program uses <send> to send an event and includes a delay attribute, the <cancel> command will cancel the pending event, if possible.

The cancel operation will cancel a pending event by removing it from the event queue of the CCXML session from which it has been sent. If the delay has expired and the event has already been removed from the event queue, the <cancel> request will fail and an error.notallowed event will be delivered to the event queue of the CCXML session that executed the <cancel>.

The <cancel> element may be used to cancel events delivered to local or remote CCXML sessions. Compliant CCXML implementations are REQUIRED to support the cancellation of local events but may choose not to support the cancellation of remote events in which case an error.notallowed event should be thrown for such requests. The format of the event identifier returned by a <send> request, and specified in the sendid attribute of <cancel>, is implementation specific but is expected to uniquely define events across CCXML sessions.

9.2.5.2: <cancel> Attribute Details

9.3: Events

9.3.1: error.notallowed

This error event is thrown when the execution of an element causes an invalid operation to be performed on a session and/or connection. The fields available in this event are:

9.3.2: error.semantic

This error event is thrown when there is a semantic error in a CCXML element (ie. passing an incorrect value for an attribute, etc.).

The fields of this event are:

9.3.3: error.send.targetunavailable

Could not connect to the target listed in <send>. The fields available in this event are:

9.3.4: error.send.targettypeinvalid

Could not connect to the Event I/O Processor listed in <send>. The fields available in this event are:

9.3.5: error.send.failed

Message in the <send> could not be sent for an unknown reason. The fields available in this event are:

9.3.6: send.successful

This event is thrown when an event is successfully sent to a CCXML session. Receipt of the event does not imply the event has been processed by the receiver but simply that it has been sent without error. The fields available in this event are:

9.3.7: move.successful

This event is thrown when an event source is successfully moved to a CCXML session. The fields available in this event are:

9.3.8: cancel.successful

This event is thrown when the sending of an event has been successfully cancelled. The fields available in this event are:

9.3.9: error.move

This event is thrown when a move request performed by a session fails to complete successfully. The fields available in this event are:

9.4: Standard Events

9.4.1: Overview

CCXML can generate arbitrarily-named events. While any event name is possible, there is a small set of well-known events that are generated as a matter of course, and which any telephone application SHOULD handle. There are three kinds of these events: connection events, language events and error events.

The first, and larger set, is present so a CCXML session can keep abreast of events happening with the telephone network. CCXML is designed to be neutral with respect to the telephony layer, so the event set MUST be very generic and capable of describing the behavior of a wide variety of systems (e.g., [Q931], [SS7], VoIP, etc).

9.4.2: Standard Event Attributes

9.4.2.1: Overview

All events received in a CCXML session must have a number of standard fields. It is the responsibility of the Event I/O Processor that delivered the event to make sure that they are present.

9.4.2.2: Standard Event Attribute Table

9.4.3: Connection Events

9.4.3.1: Overview

CCXML applications are notified of Connection activities by events, which often reflect Connection state changes. Applications MAY also take actions which change the state of a Connection and which cause other events to be generated.

9.4.4: Language Events

Language Events are a general class of responses that occur as a result of the execution of elements within a CCXML document. These events may be further categorized as follows:

• Document Control: These events are detailed in section 6.3
• Dialog Control: These events are detailed in section 7.3

• Event Handling Control: These events are detailed in section 9.3

• Call Control: These events are detailed in section 10

9.4.5: Error Events

9.4.5.1: Overview

CCXML uses its event handling mechanism to notify a CCXML document of errors that occur during execution. An error notification takes the form of an error event that is added to the event queue of the CCXML document where the error occurred. All error events are named with the prefix "error.*" so that a properly defined <transition> can filter out error events.

Here is an example of a <transition> that can be used to filter out and report error events:

<transition event="error.*" name="evt">
  <log expr="'an error has occurred (' + evt.reason+ ')'" />
  <exit/>
</transition>

All error events have a set of properties in common, shown in the following table:

9.5: Error Handling

In general, when an error occurs in a CCXML document, the corresponding error event is added to the front of the CCXML document's event queue. This causes the CCXML document to process the error event immediately after the current event.

A CCXML interpreter MAY provide the attributelist property on the error event. The attributelist object MAY have just the attribute and value in error, or MAY provide all the attributes and values.

Due to the nature of CCXML's event handling mechanism, some error scenarios are treated differently. These scenarios are described below.

9.5.1: Document Initialization Errors

Errors that occur during documentation initialization (elements that occur in the CCXML document before <eventprocessor>) occur outside of CCXML's event handling mechanism. These errors SHOULD cause the CCXML thread of execution to terminate and notify the platform of the document error.

9.5.2: Error In <eventprocessor> attributes

An <eventprocessor> contains <transition>s that comprise CCXML's event handling mechanism. Since errors in <eventprocessor> attribute evaluation could keep the EHIA from correctly processing an event, these errors SHOULD cause the CCXML thread of execution to terminate and notify the platform of the document error.

9.5.3: Error in <transition> attributes

<transition> attributes specify when the elements contained by the <transition> SHOULD be executed. Since errors in <transition> attribute evaluation could keep the <transition> from correctly handling the error event, these errors SHOULD cause the CCXML thread of execution to terminate and notify the platform of the document error.

9.5.4: Errors While Handling Error Events

If an error occurs during the handling of an error event another error event will be raised and posted to the front of the event queue. In many cases this may be perfectly acceptable and the CCXML application may be able to successfully recover from the error. In some situations however this can lead to an infinite loop in the CCXML session. Implementations MAY choose to include some form of loop detection and to terminate the CCXML session when a loop is detected.

10: Telephony Operations and Resources

This section contains information on <accept>, <createcall>, <createconference>, <destroyconference>, <disconnect>, <join>, <merge>, <redirect>, <reject>, and <unjoin> .

10.1: Overview

The primary goal of CCXML is to provide call control throughout the duration of a call. Call control includes handling incoming calls, placing outgoing calls, bridging (or conferencing) multiple call legs, and ultimately disconnecting calls.

In CCXML call control occurs through three major concepts: Connections, Conferences and Bridges.

A Connection is an object modeling a resource by which two independent unidirectional media streams, and optionally any associated network signaling traffic, can be controlled by a CCXML session. This corresponds roughly to a "call leg" as the term is used informally. The picture below illustrates the media streams associated with the Connection c1.

A Bridge occurs when the input and/or output media streams of Connections or Conferences are linked or "joined" together. The picture below depicts the result of a full duplex <join> between the connections c1 and c2.

A Conference is an object that controls the mixing of media streams for two or more Connections through Bridges.In the picture below, the connections c1 and c2 are joined in a full duplex mode to the conference C1.

These concepts are discussed in greater detail in the sections below.

10.1.1 Concepts Background (INFORMATIVE)

The goals of the CCXML call model are to focus on relatively simple types of call control and to be sufficiently abstract so that the call model can be implemented using all major telephony definitions such as JAIN Call Control(JCC) [JSR021], [CSTA], and [S.100]. The JCC call model meets these requirements by providing an event model for connections which abstracts away many of the differences between telephone networks (e.g., [Q931], [SS7], VoIP, etc). Additionally, this call model is small and easily-understood so that concrete example programs can be written.

JCC was designed to be a cross-platform high-level event set to describe as generic a phone model as possible. The JCC call model consists of Addresses, Calls, Connections, and Providers. In the context of CCXML, it was felt that the Address, Call, and Provider objects would add more complexity than value, so these were omitted as explicitly visible objects. Instead the behavior of Connections became the focus.

The CCXML call model therefore is based on the behavior of Connections. A call is received or initiated under control of a CCXML session through the properties of a Connection.

Note that the JCC model is designed for endpoint devices only.

10.2 Connections

The CCXML call model is based on the behavior of Connections. A network call is received or initiated under control of a CCXML session through properties of a Connection.

Each Connection has one input by which it receives a media stream from another Connection or Conference.

Each Connection has one output media stream that can be directed to the inputs of multiple Connections and/or Conferences.

If a network call is active on a Connection, the media stream received from the network is the Connection output, and the Connection input media stream is transmitted to the network.

Dialogs are also modeled internally as a Connection for the purposes of media interaction. The Dialog object behaves as if it was a Connection object and can be joined to other resources in the same way as any other Connection. A Dialog will not however be listed in the session.connections session variable.

<dialogstart connectionid="c1" src="'example.vxml'" duplex="'full'">

For a Connection created by <dialogstart> , the Connection input media stream is available to a recognizer under control of the CCXML session, and the Connection output media stream can be sourced from a resource (such as a Text To Speech engine) under control of the CCXML session.

10.2.1: Connection State

The state of a Connection object reflects events occurring at the telephony source it represents and actions taken by the CCXML document. The following state diagram shows the major aspects of Connection behavior, but omits some detail in favor of clarity (e.g. The ERROR state).

The list of valid states that a connection can be in is:

• ALERTING
• PROGRESSING
• CONNECTED
• FAILED
• DISCONNECTED
• ERROR

Connection Objects are created when a incoming call arrives to the platform via a connection.alerting event or via the execution of <createcall>.

If a platform operational error occurs, the Connection will emit a error.connection event.

Connection Objects are automatically destroyed by the platform after they have reached the DISCONNECTED, FAILED or ERROR states. Platforms are responsible for deciding when to remove unused Connection Objects, however platforms MUST maintain a Connection Object at least through the <transition> for the corresponding connection.disconnected, connection.failed, connection.redirected, connection.merged or error.connection event

The PROGRESSING and ALERTING states have reflexive transitions. This is intended to model protocols which have additional states at these points, and which MAY exchange messages such as PROCEEDING, ALERTING, FACILITY, or NOTIFY. Platforms MAY choose to implement additional states which MAY be reflected in the substate property of the Connection object. Additional messages can be implemented with <send>.

Initial Transitions

Transitions from ALERTING

Transitions from PROGRESSING

Transitions from CONNECTED

10.2.2: Connection Object

An instance of the Connection Object is associated with each telephony event source. Each instance is uniquely identified by its connection identifier. All Connection instances have a set of properties in common, shown in the following table. Properties marked optional only appear on an instance of the Connection object if they have a value. Other properties will always be present.

Platforms MAY choose to add properties to Connection instances. By convention, the properties MUST begin with an underscore, "_", to identify them as platform-dependent.

10.2.3: Connection Events

CCXML applications are notified of Connection activities by events, which often reflect Connection state changes. Applications may also take actions which change the state of a Connection and which cause other events to be generated.

All Connection events have a set of properties in common, shown in the following table. Fields marked optional only appear on the event object if they have a value. Other fields will always be present.

Platforms MAY choose to add properties to events. By convention, the properties MUST begin with an underscore, "_", to identify them as platform-dependent.

10.3: Conferences

CCXML applications can use <createconference> to create a new conference, or to attach to an existing conference. The CCXML application can then connect or disconnect existing connections/conferences/dialogs to the new conference using <join> and <unjoin> (as described in Section 10.4). When a session no longer requires the use of a conference, it uses <destroyconference> to detach from the conference. Asynchronous events will be sent to the CCXML document upon completion of each of these operations.

Each Conference Object has one logical output and multiple inputs. The actual output streams of a Conference Object are derived by mixing all its input streams, less any contributed audio of an individual Connection, Conference Object who receives that output. The output of a Conference Object can be directed to the inputs of multiple Connections and/or Conference Object (as a result of bridging).

Some telephony call control definitions do not define a separate Conference Object, instead defining a conference simply as a call with more than two parties. In order to accommodate the widest range of underlying telephony API's, CCXML requires explicit use of a Conference Object whenever two or more audio streams are mixed.

Unlike connections and dialogs, which are local to a single session (but can be moved between sessions using <move>), conferences are global across all sessions, and can be bridged with the connections/conferences/dialogs of any session. Conferences can be named in order to facilitate the use of that conference in other sessions. Assigning a name using the confname attribute allows other sessions to access the created conference by performing a <createconference> with the same value for confname. Conferences are 'reference counted' and continue to exist so long as at least one session exists that has attached to the conference using <createconference> without a corresponding <destroyconference>. When a session terminates, it implicitly detaches from any conferences to which it is still attached. Note that it is not necessary for a session to share a conference by assigning it a name in order for other sessions to make use of that conference. Other sessions may still establish bridges to a conference using <join> and <unjoin>, regardless of whether or not they have accessed the conference using <createconference>; only the conference ID is required for this. Because conferences are global, it is not legal to perform a <move> against a conference.

NOTE: A simple two-party call does not require the use of a conference object. This is discussed in Section 10.4.

10.3.1: Conference Object Properties

An instance of the Conference class is associated with each Conference Object created by <createconference> and referenced in the session.conferences array.

10.4: Bridges

A "bridge" is a relationship between the input and/or output streams of Connections or Conference Objects. The bridge concept and the details of its behavior are fundamental to CCXML. Bridges may also involve Dialogs, which are equivalent to Connections with respect to establishing and terminating bridges. Connections and Dialogs are therefore not distinguished below.

There are two main ways in which CCXML applications can manipulate bridges:

• Implicitly, using the <createcall> (with 'joinid') and <dialogprepare>/<dialogstart> (with 'connectionid'/'conferenceid') elements;
• Explicitly, via the <join> and <unjoin> elements.

Even in the simplest case of a network party interacting with a dialog, two Connections are REQUIRED, and a bridge is established between them implicitly by the action of <dialogstart>. More complex situations, such as two-party calls, two-party calls with "hot" word recognition, conference control, and "coaching" scenarios, all involve the use of multiple Connections and explicit control of one or more bridges between them by using <join> and <unjoin>.

The nature of bridges, and the behavior of <join> and <unjoin>, is concerned with the mapping between the media stream inputs and outputs of Connections and Conferences:

• Each Connection has one input, and one output. If a network call is active on a Connection, the media stream received from the network is the Connection output, and the Connection input media stream is transmitted to the network. For a Connection created by <dialogstart>, the Connection input media stream is available to a recognizer under control of the CCXML session, and the Connection output media stream can be sourced from a resource (such as a Text To Speech engine) under control of the CCXML session.
• The output of a Connection or Conference can be directed to the inputs of one or more Connections and/or Conferences. This is sometimes called "splitting" media streams. Not all environments/implementations will necessarily support "splitting" a media stream in this manner. In such environments, a request to establish a bridge that requires the presence of splitting may fail.
• A Connection or Conference input can come from the output of only one Connection or Conference.
• If a new bridge requires a Connection to "listen", and the Connection is already listening to a different source, this existing stream relationship is torn down automatically.

Bridges can be either one-way, in which the media stream flows only from party A to party B (such that A can hear B, but B cannot hear A), or two-way, in which the media stream flows in both directions between the parties invovled. <join> has a duplex attribute to distinguish between two-way bridges and one-way bridges. For example, <join> ing Connection A to Connection B with duplex=full will direct the A output to the B input, and the B output to the A input, creating a simple two-party call. If instead the same <join> is done with duplex=half, it will direct the B output to the A input, and will not have any effect on the B input. Similarly, <dialogprepare>/<dialogstart> have the 'mediadirection' attribute and <createcall> has the 'joindirection' attribute for controlling what kind of bridge is established.

For "hot word" recognition on a two-party call, a two-way (full duplex) bridge MUST be established between two network Connections, and a one-way (half duplex) bridge MUST be established from one of the network Connections to a third Connection that is associated with a dialog. There are several ways this arrangement can be achieved, depending on the initial states of the three Connections. For example, if the network party on Connection A is initially interacting with a dialog on Connection D (i.e., a full duplex bridge exists between them), all that is needed then is to do a <join> of Connection A to Connection B (the other network party) with duplex=full. This example highlights an important and subtle aspect of the behavior of <join> when one, or both, of the Connections being joined is already in one or more established bridges:

Note that <join> cannot be used to add a Connection to an existing two-party bridge in order to create a 3-way Conference. Instead, this functionality can be achieved by first using <createconference> to create a Conference object and then <join> ing all three Connections to this Conference. If a two-way bridge exists between A and B, and A is then <join> ed full duplex to C, the result will be a two-party bridge between A and C and a one-way bridge from A to B.

CCXML applications can only establishes bridges on Connections (and Dialogs) that are owned by the session running that application. As such, a session cannot bridge a Connection that it owns to a Connection that is owned by another session, nor can it establish a bridge between two Connections owned by another session. Since Conferences are global, however, a session can bridge a Connection that it owns to any Conference.

Asynchronous events are used to notify the CCXML application upon the completion of bridging operations performed by that application. Such events are also used to notify the application of changes to existing bridges that were not requested by the application - such as a <destroyconference> terminating a conference that a local connection has a bridge to. However, the execution of bridging operations and completion notification varies depending on how the bridging operation was performed:

• Implicit bridges created using <dialogprepare>/<dialogstart> (by specifing 'connectionid' or 'conferenceid') are established when the dialog is started. No bridging events are generated; the 'dialog.started' event indicates that the dialog was started and the bridge is in place. If the specified bridge cannot be established, then the dialog will not be started, and a 'dialog.notstarted' event is generated.
• Implicit bridges created using <createcall> (with 'joinid') are physically realized as soon as a platform is capable of doing so; however, the inability to establish the bridge immediately upon execution of a <createcall> does not constitute an error. Prior to the point in time at which the call enters the CONNECTED state, it may not be possible to establish the requested bridge, or it may only be possible to establish the bridge one direction. As a result, when using <createcall> with 'joinid', an event will be generated when the requested bridge operation is completed. This event is independent of connection-related events such as 'connection.connected', and may occur before or after such events depending on when the bridge is actually realized. If the bridge is established successfully, the 'conference.joined' event is generated. If the requested bridge cannot be established even after the connection reaches the CONNECTED state, or if some other issue prevents the bridge from being established, an 'error.conference.join' event will be generated. Referencing a dialog that has been prepared but not started in 'joinid' always result in an error, and thus an 'error.conference.join' event. Note that the call itself will proceed independently of whether or not the bridge can be established; for instance, it is possible to receive both an 'error.conference.join' event and a 'connection.connected' event for a single call initiated using <createcall>.
• Explicit bridges creation requests using <join> are performed immediately independently, of the state of the underlying resource. Requests to terminate existing bridges using <unjoin> are also performed immediately. CCXML applications can use <join> and <unjoin> at any time, except in the case of dialogs, where <join> and <unjoin> can only be used on dialogs that have been started. For instance, a CCXML application can join two connections where one (or even both) of the connections is in the ALERTING state, providing early media on the ALERTING connection. If the CCXML implementation does not support a requested <join> due to the current state of an underlying entity, then this will result in an error.conference.join event with the 'reason' field set appropriately.

10.4.1: <join> Outcomes

As an aid to understanding, the outcomes of all possible <join> operations are shown diagrammatically below for three different initial conditions:

1. a single Connection A, that is not currently in a bridge, represented graphically as: (A)
2. two Connections A and B, with a half duplex bridge (A output to B input), represented graphically as: A -----> B
3. two Connections A and B, with a full duplex bridge (A output to B input & B output to A input), represented graphically as: A <====> B

In summary, <join> behavior always respects three invariants:

1. The media stream relationship specified in the <join> is established between the two Connections/Conferences referenced in the <join>. In particular, any existing stream relationship between these two Connections/Conferences is torn down automatically if it conflicts with the specified relationship.
2. If the relationship specified in the <join> requires a Connection to "listen" and the Connection is already listening to a different source, this existing stream relationship is torn down automatically.
3. Any existing stream relationship that does not present a conflict according to invariant #1 or invariant #2 is preserved.

10.4.2: Invariant Examples

To illustrate some typical invocations of <join> invariants a few example scenarios are presented below. In the first scenario, connection c1 is bridged to a conference C1, via a <join> where the duplex mode is full.

After <join id1="'C1'" id2="'c1'" duplex="'full'">

Session object properties
session.connections['c1'].endpoint == 'C1'
session.connections['c1'].duplex == 'full'
session.conferences['C1'].bridges['c1'] == 'c1'

If c1 then became a participant in a <dialogstart> where d1 represents a connection to a dialog and the duplex mode is full, the original picture would change as follows:

After <dialogstart connectionid="'c1'" src="'example.vxml'" duplex="'full'">

session.connections['c1'].endpoint == 'd1'
session.connections['c1'].duplex == 'full'
session.connections['c1'].dialogid == 'd1'
session.conferences['C1'].bridges['c1'] == 'c1'
session.dialogs['d1'].connectionid == 'c1'
session.dialogs['d1'].duplex == 'full'

The <dialogstart> required c1 to "listen" to d1, however, c1 was already in an established bridge listening to C1. Consequently, the full duplex bridge between c1 and C1 is changed to a half duplex, where c1 is not allowed to "listen" to C1 and a full duplex bridge is established between c1 and d1.

In this second scenario, c1 and c2 have been joined into a conference, C1.

After <join id1="'C1'" id2="'c1'" duplex="'full'"> 
and:  <join id1="'C1'" id2="'c2'" duplex="'full'">

session.connections['c1'].endpoint == 'C1'
session.connections['c1'].duplex == 'full'
session.connections['c2'].endpoint == 'C1'
session.connections['c2'].duplex == 'full'
session.conferences['C1'].bridges['c1'] == 'c1'
session.conferences['C1'].bridges['c2'] == 'c2'

If a <join> is then executed that specifies c2 and C1 as participants and the duplex mode is half, the bridge between c2 and C1 will be re-established with C1 able to "listen" to c2, but c2 no longer able to "listen" to C1.

After <join id1="C1" id2="c2" duplex="'half'">

session.connections['c1'].endpoint == 'C1'
session.connections['c1'].duplex == 'full'
session.connections['c2'].endpoint == undefined
session.connections['c2'].duplex == undefined
session.conferences['C1'].bridges['c1'] == 'c1'
session.conferences['C1'].bridges['c2'] == 'c2'

Note connection c2 does not have a source therefore the endpoint and duplex properties are undefined

In this third scenario, there are three connections c1, c2 and c3. Connections c1 and c2 are connected with a half duplex bridge, connection 3 is not bridged at this point.

After <join id1="'c1'" id2="'c2'" duplex="'half'">
Session object properties
session.connections['c1'].endpoint == 'c2'
session.connections['c1'].duplex == 'half'
session.connections['c2'].endpoint == undefined
session.connections['c2'].duplex == undefined
session.connections['c3'].endpoint == undefined
session.connections['c3'].duplex == undefined

Connections c2 and c3 do not have a media source therefore the endpoint and duplex properties are undefined.

A full bridge is established between connections c2 and c3, connection c1 is still receiving from c2.

After <join id1="'c2'" id2="'c3'" duplex="'full'">
session.connections['c1'].endpoint == 'c2'
session.connections['c1'].duplex == 'half'
session.connections['c2'].endpoint == 'c3'
session.connections['c2'].duplex == 'full'
session.connections['c3'].endpoint == 'c2'
session.connections['c3'].duplex == 'full'

10.5: Elements

10.5.1: <accept>

10.5.1.1: Overview

When a CCXML document receives a connection.alerting event within an <eventprocessor>, the execution of an <accept> within the <transition> block will cause the underlying platform to signal the telephony system to connect the call. The CCXML document MAY then initiate interactive dialog sessions with the incoming caller, or perform other telephony operations (e.g., place outgoing calls, join calls, etc).

10.5.1.2: <accept> Attribute Details

An accepted incoming call will result in the generation of a connection.connected event.

10.5.2: <redirect>

10.5.2.1: Overview

When a CCXML document executes a <redirect> within the <transition> block, this will cause the underlying platform to signal the telephony system to send the call to a specified destination. The use of <redirect> is only valid when a call is in the ALERTING and CONNECTED states.

10.5.2.2: <redirect> Attribute Details

A redirected incoming call will result in the generation of a connection.redirected event.

10.5.3: <reject>

10.5.3.1: Overview

When a CCXML document receives a connection.alerting event within an <eventprocessor>, the execution of a <reject> within the <transition> block will cause the underlying platform to signal the telephony system to reject the call.

10.5.3.2: <reject> Attribute Details

A rejected incoming call will result in the generation of a connection.failed event.

10.5.4: <createcall>

10.5.4.1: Overview

A CCXML document can attempt to place an outgoing call with <createcall>. This element will instruct the platform to allocate a Connection and attempt to place an outgoing call to a specified address. The CCXML interpreter will receive an asynchronous event when the call attempt is completed. An <eventprocessor> <transition> block can handle this event and perform further call control, such as conferencing. If the call was successfully placed, the transition block can also initiate a dialog interaction with the called party.

10.5.4.2: <createcall> Attribute Details

The execution of <createcall> will result in the generation of one or more connection.progressing events (depending on platform support for call progress) and a connection.connected event on success and a connection.failed event on failure.

10.5.4.3: <createcall> examples

The following example illustrates the simplest use of <createcall> .

<createcall dest="'tel:1235551234'"/>

This example illustrates the use of several attributes of <createcall>. A SIP URI is provided as the originators caller id, a selection of protocol specific parameters are provided (callingDevice and callCharacteristics) and a string of application specific data is provided to be presented to the remote endpoint. The connection id for the new connection is returned in the variable "myConidVar".

<var name="myConidVar"/>
<createcall
 dest="'sip:+1-212-555-1212:1234@gateway.com;'"
 callerid="'sip:j.doe@big.com'"
 connectionid="myConidVar"
 aai="'This is application specific data'"
 hints="{callingDevice: 'notSpecified', callCharacteristics: 'voiceUnitCall'}" />

10.5.5: <createconference>

10.5.5.1: Overview

A CCXML document can attempt to create or attach to a Conference Object using <createconference>. This element will instruct the implementation to allocate a Conference Object using the specified options. The successful execution of <createconference> will result in the generation of a conference.created event. If for any reason the implementation is unable to create the Conference Object using the specified options it MUST fail with a error.conference.create event.

Since conferences are global in scope, it is possible that other sessions will establish or terminate bridges to a Conference created by an application. Sessions that have created or attached to a Conference using <createconference> receive notifications of any bridges that are created or destroyed, through the 'conference.joined' and 'conference.unjoined' events. However, if a session establishes or terminates a bridge between a Connection that it owns and a Conference that it has created/attached to, it will only receive one such event - not one event each for the Connection and for the Conference.

It is legal for a session to perform a <createconference> multiple times with the same value for the 'confname' parameter. The same conference ID will be returned in each case, allowing this to be used as a mechanism for looking up conference IDs. It must be noted, however, that no 'reference counting' is performed - a single <destroyconference> will detach the session from the conference no matter how many times <createconference> was used.

10.5.5.2: <createconference> Attribute Details

10.5.6: <destroyconference>

10.5.6.1: Overview

A CCXML document can attempt to detach from an existing Conference Object using <destroyconference>. This destroys the conference if no other sessions are attached to it. The target Conference Object is identified using the conferenceid attribute. The successful execution of <destroyconference> will result in the generation of a conference.destroyed event. If for any reason the implementation is unable to deallocate the Conference Object it MUST fail with a error.conference.destroy event.

Since other sessions may have created bridges to a conference using the conference's ID, but without performing a <createconference>, destroying a conference can affect the bridges established by other sessions. If any bridges are terminated in this fashion, a 'conference.unjoined' event will be posted to indicate to the session that its Connection is no longer bridged to the Conference.

10.5.6.2: <destroyconference> Attribute Details

10.5.7: <join>

10.5.7.1: Overview

A CCXML document can attempt to create a bridge between two connections, conferences, or dialogs using <join>. This element instructs the implementation to bridge the connections, conferences, or dialogs specified using the id1 and id2 attributes in accordance with media options specified by the other attributes of <join>. The successful execution of<join> will result in the generation of a conference.joined event. If for any reason the implementation is unable to create the bridge using the specified options it MUST fail with a error.conference.join event.

Any Connections or Dialogs referenced by the 'id1' and 'id2' attributes of <join> MUST be owned by the session performing the <join>. If 'id1' or 'id2' refer to Conferences, then it is not necessary that the session has performed a <createconference> to create/attach to that conference; it is sufficient that it has a valid conference ID.

When joining a Connection or Dialog to a Conference, or when joining two Conferences, the 'conference.joined' event will be posted to all sessions that are attached to the affected Conference(s). This will not result in multiple 'conference.joined' events if the session performing the <join> is attached to the conference, nor if any session owns both conferences when two conferences are joined together. If the implementation is unable to join the objects an error.conference.join will only be sent to the session that issued the <join>.

10.5.7.2: <join> Attribute Details

10.5.8: <unjoin>

10.5.8.1: Overview

A CCXML document can attempt to tear down a bridge between two existing connections, conferences, or dialogs using <unjoin>. This element will instruct the implementation to tear down the bridge between two connections/conferences/dialogs specified using the id1 and id2 attributes. The successful execution of<unjoin> will result in the generation of a conference.unjoined event. If for any reason the implementation is unable to terminate the bridge between the specified connections/conferences/dialogs, or if no such bridge exists, it MUST fail with a error.conference.unjoin event.

Any Connections or Dialogs referenced by the 'id1' and 'id2' attributes of <unjoin> MUST be owned by the session performing the <unjoin>.

When 'id1', 'id2', or both reference to a Conference, the 'conference.unjoined' event will be posted to all session that are attached to the affected Conference(s). This will not result in multiple 'conferene.unjoined' events if the session performing the <unjoin> is attached to the conference, or if any session owns both conferences when two conferences are being unjoined. If the implementation is unable to unjoin the objects an error.conference.unjoin will only be sent to the session that issued the <unjoin>.

10.5.8.2: <unjoin> Attribute Details

10.5.9: <disconnect>

10.5.9.1: Overview

A CCXML document MAY disconnect a Connection by using <disconnect> . The underlying platform will send the appropriate protocol messages to perform the disconnect, and send an asynchronous event to the CCXML document when the disconnect operation completes. A CCXML document may use <disconnect> to abandon an outbound connection created using <createcall> which has not yet entered the CONNECTED state. If <disconnect> is used to abandon an outbound call, it results in the generation of a 'connection.failed' event.

If the connection had been bridged when the <disconnect> request was made, the platform will tear down all bridges to the connection and send a conference.unjoined to the CCXML document once the media paths have been freed.

Note the platform is not required to generate the connection.disconnected /connection.failed or conference.unjoined in any particular order, unless an outbound call was abandoned in which case a connection.failed event will be generated.

10.5.9.2: <disconnect> Attribute Details

A disconnected call will result in the generation of a connection.disconnected event.

10.5.10: <merge>

10.5.10.1: Background

Many of the network environments in which a CCXML implementation may be expected to operate provide facilities by which two existing calls can be merged into a single call at the network level. The following diagram illustrates this for the case where user A has two independent calls with users B and C, and utilizes this functionality to merge the calls together:

Figure 1: Initial Call State

Figure 2: State Following Merge

The diagram illustrates the call control connections, or sessions, that exist between users A, B, C and the network that connects them; the media streams between users is not shown on the above diagram and may differ from the path for call control that is shown. The media path between users may or may not be affected as a result of the merge, depending on the properties of the underlying network; typically any media streams to user A would be terminated since call control sessions between user A and the network are terminated.

There are many different implementations of the merging capabilities described above, across both PSTN and Voice-over-IP networks. Known implementations include the following:

• Release Link Trunk (RLT) [ISDN, SS7 ISUP]
• Two B-Channel Transfer (TBCT) [ISDN, SS7 ISUP]
• Explicit Call Transfer (ECT) [ISDN, SS7 ISUP]
• AT&T Transfer Connect (some variants) [ISDN]
• Q.SIG Path Replacement [ISDN]
• SIP REFER with Replaces [SIP]
• H.450.2 Consultative Transfer [H.323]
• CSTA and other interfaces to PSTN switches
• Hook-flash Transfers [Analog, T-1 RBS, E-1 CAS]

Different implementations may also have different restrictions on when and how merge functionality can be used. Some implementations might allow calls that are alerting to be merged, whereas others might only operate on calls that are already in the connected state. In addition, some implementations might only be able to merge calls in which one of the calls is an outbound call that specifically identifies the associated inbound call when that outbound call is placed (via hints on <createcall>).

10.5.10.2: Overview

The <merge> element allows two calls being handled by a particular CCXML session to be merged together at the network level, if supported by the underlying network and CCXML platform.

If successful, the two referenced calls will be merged at the network level, and the connections to the CCXML platform associated with those calls will be terminated. A connection.merged event will be generated on each of the two calls affected by a merge. If the merge fails, then a single error.merge event will be thrown which identifies both of the connections against which the merge was performed.

10.5.10.3: <merge> Attribute Details

10.6: Events

10.6.1: Overview

This section defines the events related to telephony operations including events related to the call state, success and failure events for the various telephony operations.

10.6.2: connection.alerting

This event is emitted when a Connection transitions to the ALERTING state, or is notified of call progress in the ALERTING state.

The fields of this event are:

Information provided by the protocol prior to connection is accumulated and stored with the identified Connection object. This information will be available when the connection.alerting event is delivered to the application. Any further information provided by the protocol prior to connection MAY be provided in subsequent connection.alerting events, and made available in the updated Connection object. Alternatively, this data MAY be delivered in connection.signal events, and made available in the updated Connection object. This behavior is platform dependent.

Call related information provided after connection will result in connection.signal events.

10.6.3: connection.progressing

This event is emitted when a Connection transitions to the PROGRESSING state as a result of <createcall>, or is notified of call progress in the PROGRESSING state.

The fields of this event are:

Subsequent connection.progressing events MAY be generated to support protocols which exchange multiple messages during the PROGRESSING state.

10.6.4: connection.connected

This event is emitted when a Connection transitions to the CONNECTED state as a result of <accept>.

The fields of this event are:

10.6.5: connection.disconnected

This event is emitted when a Connection transitions to the DISCONNECTED state, as a result of either CCXML action or off-platform events.

The fields of this event are:

10.6.6: connection.redirected

This event is emitted when a Connection transitions to the DISCONNECTED state as a result of <redirect>.

The fields of this event are:

10.6.7: connection.merged

This event is emitted when a Connection transitions to the DISCONNECTED state as a result of a successful <merge>. A CCXML application will always receive two connection.merged events, one for each affected connection. The fields of this event are:

10.6.8: connection.failed

This event is emitted when a Connection transitions to the FAILED state, when an incoming or outgoing call fails to complete its connection.

The fields of this event are:

10.6.9: error.connection

This event is emitted when a Connection transitions to the ERROR state.

The fields of this event are:

10.6.10: connection.signal

This event is emitted when a Connection is notified of new data available when in the CONNECTED, PROGRESSING or ALERTING state. The fields of this event are:

Examples where connection.signal could be generated include:

• DTMF received on the media stream after connection, perhaps identifying call setup information such as DNIS;
• Messaging received by the protocol after connection, such as that delivered by SIP INFO or ISDN FACILITY messages;
• Call analysis results indicating the results of answering machine, FAX, TDD or modem detection attempts.

The data provided within the connection.signal event is protocol dependent. This data MAY be used to initiate a dialog (for example, if all REQUIRED information is now available), or to message other platform components.

Signalling delivered on the media stream after a successful <dialogstart> MAY not be available to the CCXML application. This behavior is platform dependent.

All available call setup information is provided in the Connection object when the first connection.alerting event is generated. Any further information provided by the protocol prior to connection MAY be provided in subsequent connection.alerting events, and made available in the updated Connection object. Alternatively, this data MAY be delivered in connection.signal events, and made available in the updated Connection object. This behavior is platform dependent.

Call related information provided after connection will result in connection.signal events.

The Connection Object MAY be updated with new or changed information as the result of a connection.signal event.

Section 10.6.11: conference.created

This event is emitted when a conference has been successfully established using <createconference>. The fields of this event are:

Section 10.6.12: conference.destroyed

This event is emitted when a session detaches from a conference using <destroyconference>. Note that this does not imply that the underlying conference has necessarily been destroyed, since there may be other sessions attached to that conference. The fields of this event are:

Section 10.6.13: conference.joined

This event is emitted when two resources (which are connections or conferences) have been bridged using <join>. The fields of this event are shown below.

If a session receives a 'conference.joined' event because it is attached to a Conference, either 'id1' or 'id2' may refer to a Connection/Dialog owned by another session. Such identifiers are not locally meaningful to the session receiving the event (although they can still be used for logging or other purposes).

Section 10.6.14: conference.unjoined

This event is emitted when a bridge is torn down between two resources using <unjoin>.

A conference.unjoined may also be emitted when the platform unjoins a connection due to processing a <disconnect> request or asynchronous connection.disconnected event.

If a session receives a 'conference.unjoined' event because it is attached to a Conference, either 'id1' or 'id2' may refer to a Connection/Dialog owned by another session. Such identifiers are not locally meaningful to the session receiving the event (although they can still be used for logging or other purposes).

The fields of this event are:

Section 10.6.15: error.conference.create

The processing associated with the <createconference> failed. The fields in this event are:

Section 10.6.16: error.conference.destroy

The processing associated with the <destroyconference> failed. The fields in this event are:

Section 10.6.17: error.conference.join

The processing associated with the <join> failed. The fields in this event are:

Section 10.6.18: error.conference.unjoin

The processing associated with the <unjoin> failed. The fields in this event are:

10.6.19: error.merge

This event is emitted when a <merge> attempt fails.. Only one event will be generated, which references both connections. The fields of this event are:

10.6.20: error.connection.wrongstate

This event is emitted when an application attempts a telephony operation that is not legal for the current state:

11: Complex Examples

11.1: Calling Card Application

Caller calls an 800 number and after some interaction with an IVR system places an outbound call to a friend.

calling_card.ccxml

<?xml version="1.0" encoding="UTF-8"?>

<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">

  <!-- Create our ccxml level vars -->
  <var name="in_connectionid" expr="''" />
  <var name="out_connectionid" expr="''" />

  <!-- Set our initial state -->
  <assign name="currentstate" expr="'initial'" />

  <eventprocessor statevariable="currentstate">
    <!-- Deal with the incoming call -->
    <transition state="initial" event="connection.alerting" name="evt">
      <assign name="in_connectionid" expr="evt.connectionid" />
      <accept connectionid="in_connectionid" />
    </transition>

    <transition state="initial" event="connection.connected" name="evt">
      <assign name="currentstate" expr="'in_vxml_session'" />
      <!-- VoiceXML dialog is started on a separate thread - see pin.vxml -->
      <dialogstart namelist="session.id" connectionid="in_connectionid" src="'pin.vxml'" />
    </transition>

    <!-- happens when pin.vxml VoiceXML dialog thread exits -->
    <transition state="in_vxml_session" event="dialog.exit" name="evt">
      <createcall dest="evt.values.telnum" name="out_connectionid" />
      <assign name="currentstate" expr="'calling'" />
    </transition>

    <transition state="calling" event="connection.failed" name="evt">
      <!-- tell the caller there was a error -->
      <dialogstart namelist="session.id" connectionid="in_connectionid" src="'error.vxml'" />
      <assign name="currentstate" expr="'outb_failed'" />
    </transition>

    <!-- happens when called party picks up the phone -->
    <transition state="calling" event="connection.connected" name="evt">
      <assign name="out_connectionid" expr="evt.connectionid" />
      <!-- tell the callee he is receiving a call -->
      <dialogstart namelist="session.id" connectionid="out_connectionid" src="'callee.vxml'" />
      <assign name="currentstate" expr="'outb_ready_to_join'" />
    </transition>

    <transition state="outb_failed" event="dialog.exit" name="evt">
      <exit />
    </transition>

    <!-- happens when callee's vxml dialog (callee.vxml exits) -->
    <transition state="outb_ready_to_join" event="dialog.exit" name="evt">
      <join id1="in_connectionid" id2="out_connectionid" />
      <assign name="currentstate" expr="'wtg_for_joined'" />
    </transition>

    <transition state="wtg_for_joined" event="ccxml.joined" name="evt">
      <assign name="currentstate" expr="'active'" />
    </transition>

    <!-- Lets clean up the call  -->
    <transition state="active" event="connection.disconnected" name="evt">
      <if cond="evt.connectionid == in_connectionid">
        <disconnect connectionid="out_connectionid"/>
        <exit />
      </if>
      <assign name="currentstate" expr="'in_vxml_session'" />
      <!-- start VoiceXML dialog again to see
        if caller wants to make another call -->
      <dialogstart namelist="session.id" connectionid="in_connectionid" src="'pin.vxml'" />
    </transition>

    <!-- Catch disconnects in unexpected states -->
    <transition event="connection.disconnected">
      <exit />
    </transition>
  </eventprocessor>
</ccxml>

pin.vxml

<?xml version="1.0" encoding="UTF-8"?>

<vxml xmlns="http://www.w3.org/2001/vxml" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xsi:schemaLocation="http://www.w3.org/2001/vxml 
   http://www.w3.org/TR/voicexml20/vxml.xsd"
   version="2.0">
  <form id="pin">
    <block> Welcome to Acme's Calling Card </block>
    <field name="pin" type="digits">
      <prompt> Please say your PIN number </prompt>
      <filled>
        <if cond="pin.length != 8">
          <clear namelist="pin"/>
        <else/>
          <submit next="checktime.asp" namelist="pin"/>
        </if>
      </filled>
    </field>
  </form>
</vxml>

error.vxml

<?xml version="1.0" encoding="UTF-8"?>

<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
  <form>
    <block> 
       Sorry. The Party you are trying to call
       is unavailble. 
       <exit/>
    </block>
  </form>
</vxml>

callee.vxml

<?xml version="1.0" encoding="UTF-8"?>

<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
  <form>
    <block>You have a call. Connecting</block>
  </form>
</vxml>

VXML page returned by checktime.asp

<?xml version="1.0" encoding="UTF-8"?>

<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
  <form id="form2">
    <!--.asp consults back-end database before filling this value-->
    <assign name="timeleft" expr="600"/>  
    <block> Time remaining is <value expr="timeleft"/> seconds </block>
    <field name="telnum" type="digits" >
      <prompt> Please speak the telephone number you want to call </prompt>
      <filled>
        <if cond="telnum.length != 7">
          <clear namelist="telnum"/>
        <else/>
          <exit namelist="telnum"/>
        </if>
      </filled>
    </field>
  </form>
</vxml>

11.2: Conferencing application

Different callers call into a conference through an agreed upon telephone number. When each one of them joins the conference he is told how many people are there in the conference and those already in the conference are informed about a new entrant to the conference. Similarly when someone hangs up, the fact that a conference participant has exited is announced. A conference object is created at the beginning of the conference and is destroyed when all the participants have hung up.

First page to all callers

<?xml version="1.0" encoding="UTF-8"?>
<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">
        <var name="in_connectionid" expr="''" />
        <var name="currentstate" expr="'initial'" />

        <eventprocessor statevariable="currentstate">
                <transition state="initial" event="connection.alerting" name="evt">
                        <assign name="currentstate" expr="'alerting'" />
                        <assign name="in_connectionid" expr="evt.connectionid" />
                        <accept connectionid="in_connectionid" />
                </transition>
                <transition state="alerting" event="connection.connected" name="evt">
                        <assign name="currentstate" expr="'fetching'" />
                        <fetch next="'http://example.com/conference.asp'" namelist="in_connectionid" />
                </transition>
                <transition state="fetching" event="fetch.done" name="evt">
                        <goto fetchid="evt.fetchid" />
                </transition>
        </eventprocessor>
</ccxml>

CCXML page returned by conference.asp to first callers browser

<?xml version="1.0" encoding="UTF-8"?>
<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">
        <var name="conf_id" expr="''" />
        <var name="currentstate" expr="'starting'" />
        <var name="in_connectionid" expr="'0f0c0d@host1.com'" />
        <!-- above value is the value submitted to conference.asp-->

        <eventprocessor statevariable="currentstate">
                <transition state="starting" event="ccxml.loaded" name="evt">
                        <createconference conferenceid="conf_id" />
                </transition>
                <transition state="starting" event="conference.created" name="evt">
                        <assign name="currentstate" expr="'fetching'" />
                        <fetch next="'http://example.com/conference.asp'" namelist="in_connectionid conf_id" />
                </transition>
                <transition state="fetching" event="fetch.done" name="evt">
                        <goto fetchid="evt.fetchid" />
                </transition>
        </eventprocessor>
</ccxml>

CCXML page returned by conference.asp to all subsequent callers

<?xml version="1.0" encoding="UTF-8"?>
<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">

        <var name="currentstate" expr="'ready_to_conf'" />
        <var name="in_connectionid" expr="'ff0d01@host2.com'" />
        <var name="conf_id" expr="'0a4602@host1.com'" />
        <!-- above values are the values submitted to conference.asp-->

        <eventprocessor statevariable="currentstate">
                <transition event="ccxml.loaded" name="evt">
                        <dialogstart connectionid="in_connectionid" src="'vconference.asp'" />
                        <assign name="currentstate" expr="'announcing'" />
                </transition>
                <transition state="announcing" event="dialog.exit" name="evt">
                        <join entertone="false" exittone="false" id1="conf_id" id2="in_connectionid" />
                </transition>
                <transition state="announcing" event="conference.joined" name="evt">
                        <assign name="currentstate" expr="'active'" />
                        <dialogstart conferenceid="conf_id" src="'newcaller.vxml'" />
                </transition>
                <transition state="active" event="connection.disconnected" name="evt">
                        <dialogstart conferenceid="conf_id" src="'leave.vxml'" />
                        <assign name="currentstate" expr="'fetching'" />
                        <fetch next="'http://example.com/teardown.asp'" namelist="in_connectionid conf_id" />
                </transition>
                <transition state="fetching" event="fetch.done" name="evt">
                        <goto fetchid="evt.fetchid" />
                </transition>
        </eventprocessor>
</ccxml>

vconference.asp

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <form>
                <block>
                        Welcome to the W3C conference. There are already 
                        <value expr="'3'" />
                        participants in the conference. 
                        <!--above value is based on count kept by vconference.asp-->
                </block>
        </form>
</vxml>

newcaller.vxml

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <form>
                <block>
                        A new participant has entered the conference. 
                </block>
        </form>
</vxml>

leave.vxml

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <form>
                <block>
                        Someone just left the conference. 
                </block>
        </form>
</vxml>

CCXML page returned by teardown.asp to all but the last participant

<?xml version="1.0" encoding="UTF-8"?>
<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">
        <var name="currentstate" expr="'destroying'" />
        <var name="conf_id" expr="'0a4602@host1.com'" />
        <var name="in_connectionid" expr="'ff0d01@host2.com'" />
        <!-- above values are the values submitted to teardown.asp-->

        <eventprocessor statevariable="currentstate">
                <transition event="ccxml.loaded" name="evt">
                        <exit />
                        <!-- just exit and destroy the session -->
                </transition>
        </eventprocessor>
</ccxml>

CCXML page returned by teardown.asp to last participant

<?xml version="1.0" encoding="UTF-8"?>
<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">

        <assign name="currentstate" expr="'destroying'" />
        <assign name="conf_id" expr="'0a4602@host1.com'" />
        <assign name="in_connectionid" expr="'ff0d01@host2.com'" />
        <!-- above values are the values submitted to teardown.asp -->
        
        <eventprocessor statevariable="currentstate">
                <transition event="ccxml.loaded" name="evt">
                        <destroyconference conferenceid="conf_id" />
                        <exit />
                </transition>
        </eventprocessor>
</ccxml>

11.3: Personal Assistant

This program is a Personal Assistant that operates as an automated answering service.

A subscriber to this service would receive a phone number to the automated service. When a caller wants to talk to the subscriber, he calls the given number. This automated system asks who the caller is, and records the audio. Then the system calls the current number of the target person, and asks if the call should be connected.

If so, the calls are bridged. If not, then the original caller is warned and disconnected.

main.ccxml

<?xml version="1.0" encoding="UTF-8"?>
<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">
        <var expr="'initial'" name="currentstate" />
        <var name="in_connectionid" />
        <var name="dlg_onhold" />
        <var name="out_connectionid" />
        <var name="accepted" />
        
        <eventprocessor statevariable="currentstate">
        
                <transition event="connection.alerting" name="evt" state="initial">
                        <assign expr="evt.connectionid" name="in_connectionid" />
                        <accept />
                </transition>
                
                <transition event="connection.connected" name="evt" state="initial">
                        <assign expr="'welcoming_caller'" name="currentstate" />
                        <dialogstart src="'welcome_message.vxml'" />
                </transition>
                
                <transition event="dialog.exit" state="welcoming_caller">
                        <!-- place the caller on hold -->
                        <dialogstart dialogid="dlg_onhold" connectionid="in_connectionid" src="'holdmusic.vxml'" />
                        <!-- Contact the target.  The number here is server-generated -->
                        <assign expr="'contacting_target'" name="currentstate" />
                        <createcall dest="'tel:+1-555-555-6666'" connectionid="out_connectionid" />
                </transition>

                <transition event="connection.connected" name="evt" state="contacting_target">
                        <!-- Ask the target if (s)he would like to accept the call -->
                        <assign expr="'waiting_for_target_answer'" name="currentstate" />
                        <dialogstart src="'outbound_greetings.vxml'" />
                </transition>
                
                <transition event="dialog.exit" name="evt" state="waiting_for_target_answer">
                        <assign expr="evt.accepted" name="accepted" />
                        <if cond="accepted == 'false'">
                                <!-- disconnect the called party (but still notify the other one) -->
                                <disconnect connectionid="out_connectionid" />
                        </if>
                        <assign expr="'stop_hold'" name="currentstate" />
                        <dialogterminate dialogid="dlg_onhold" />
                </transition>
                
                <transition event="dialog.exit" name="evt" state="stop_hold">
                        <if cond="accepted == 'false'">
                                <assign expr="'voice_mail'" name="currentstate" />
                                <dialogstart connectionid="in_connectionid" src="'vm.vxml'" />
                        <else />
                                <assign expr="'playing_connecting'" name="currentstate" />
                                <dialogstart connectionid="in_connectionid" src="'connecting.vxml'" />
                        </if>
                </transition>
                
                <transition event="dialog.exit" name="evt" state="playing_connecting">
                        <join id1="in_connectionid" id2="out_connectionid" />
                        <assign expr="'talking'" name="currentstate" />
                </transition>
                
                <transition event="connection.disconnected" name="evt">
                        <if cond="evt.connectionid == in_connectionid">
                                <exit />
                        </if>
                </transition>
        </eventprocessor>
</ccxml>

welcome_message.vxml

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <form>
                <record name="recording">
                        <prompt>
                                You have reached the personal assistant for Bill Lumbergh of InnoTech. 
                                If is about the new TPS format please call Dom Portwood to get the new cover sheet. 

                                If this is for any other reason go on and state your name 
                                and I will decide if I want to take your call.
                                
                                Oh ya, if this is Milt, we're gonna need to go ahead and 
                                move you downstairs into storage B. We have some new people 
                                coming in, and we need all the space we can get. So if you 
                                could go ahead and pack up your stuff and move it down there, 
                                that would be terrific, OK

                        </prompt>
                        <filled>
                                OK, thanks. 
                                <submit next="postRecordingAndExit.vxml" namelist="recording" />
                        </filled>
                </record>
        </form>
</vxml>

outbound_greetings.vxml

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <var name="willaccept"/>
        <form>
                <field id="answer">
                        <grammar src="yesnogrammar.grxml" />
                        <prompt>
                                Hi bill, you have a message from
                                <audio src="dynamicallyRecordedName.wav" />
                                Would you like to take it? Say Yes, or No.
                        </prompt>
                        <filled>
                                <if cond="answer=='yes'">
                                        Just a moment, please hold.
                                        <assign name="willaccept" value="true" />
                                        <exit namelist="willaccept" />
                                <elseif cond="answer==no" />
                                        OK, goodbye. 
                                        <assign name="willaccept" value="false" />
                                        <exit namelist="willaccept" />
                                </if>
                        </filled>
                </field>
        </form>
</vxml>

vm.vxml

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <form>
                <prompt>
                        Transferring you to voice mail hell. 
                </prompt>
                <block>
                        <goto next="voicemail.vxml" />
                </block>
        </form>
</vxml>

connecting.vxml

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <form>
                <prompt>
                        Just a moment, please hold... 
                </prompt>
                <block>
                        <exit />
                </block>
        </form>
</vxml>

holdmusic.vxml

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" version="2.0">
        <form id="Form">
                <block>
                        <prompt bargin="false">
                                When a man loves a woman
                                Can't keep his mind on nothin' else
                                He'd trade the world
                                For a good thing he's found
                                If she is bad, he can't see it
                                She can do no wrong
                                Turn his back on his best friend
                                If he puts her down.
                        </prompt>
                        <goto next="holdmusic.vxml" />
                </block>
        </form>
</vxml>

Appendix A - Related Work

CPL

The Call Processing Language (CPL) is an XML based language that can be used to describe and control Internet telephony services. Its focus is user scripting of call handling behavior for incoming calls. It is designed to be suitable for running on a server where users may not be allowed to execute arbitrary programs, and so is not Turing-complete.

The latest version of CPL can be found linked from the IETF IP Telephony (IPTEL) Working Group charter page.

CallXML

CallXML [CALLXML] is a markup language created by Voxeo Corporation that includes both voice and call-control functionality. CallXML is an XML based markup language used to describe the user interface of a telephone, voice over IP, or multi-media call application to a CallXML browser.

CallXML was designed to make it easy for Web developers to create applications that can interact with and control any number or type of calls, including:

• Telephone or Voice over IP call applications which can control the initiation and routing of a phone call itself, supporting such features as outbound dialing, conferencing, and multi-call interactions (e.g., conference bridges, Internet call waiting, follow-me/find-me, etc)
• Telephone or Voice over IP call applications which can easily interact and respond to touch-tone based entry and selection (e.g., voicemail, interactive voice response)
• Call Applications which include support for additional media, such as faxes and video (e.g., unified messaging, video conferencing, etc.)

For more information please see http://community.voxeo.com .

ECMA-CSTA

The description of CSTA [CSTA] from http://www.ecma-international.org/ is as follows:

"CSTA specifies an Applications Interface and Protocols for monitoring and controlling calls and devices in a communications network.

These calls and devices may support various media and can reside in various network environments such as IP, Switched Circuit Networks and mobile networks. CSTA however, abstracts various details of underlying signalling protocols (e.g. SIP/H.323) and networks for the applications."

The architecture of CCXML would allow a platform to be based on CSTA for the underlying telephony protocol while still providing the CCXML execution environment for ease of integration with voice browsers.

TXML

TXML (Telera's Extensible Markup Language) [TXML] is an XML based language designed by Genesys (formerly Telera) for remotely controlling the behavior of Point of Presence (POP) servers.

TXML provides the syntax for the XML Pages, which are generated at the customer's application at the premises and used by a POP server to execute actions on behalf of the customer's application. The XML Pages are simple ASCII text files that are either stored in a Web server's directory at the premises or generated by scripts at the premises server. The XMLPages are requested from the premises server via HTTP requests made by a client on the POP gateway.

The language includes elements for

• Media Control
• Call Control and Telephony
• Call Router Integration

Go here for more documentation.

SIP

SIP, the Session Initiation Protocol, [RFC3261] is a signaling protocol for Internet conferencing, telephony, presence, events notification and instant messaging. As a signaling protocol, SIP sits "below" the application description level of VoiceXML and CCXML. We expect many CCXML and VoiceXML browsers to support SIP signaling.

Appendix B - CCXML DTD

This section is Normative.

The CCXML DTD is located at http://www.w3.org/TR/ccxml/ccxml.dtd.

Appendix C - CCXML XML Schema

This section is Normative.

This appendix defines a normative XML Schema for CCXML. The CCXML schema is located at http://www.w3.org/TR/ccxml/ccxml.xsd.

Appendix D - VoiceXML 2.0 Integration Details

This section is Normative.

D.1 Overview

This section describes the details of how CCXML and VoiceXML 2.0 work together to provide dialog functionality in CCXML.

The CCXML application behaviors described below are guidelines and applications are not required to support the full set of VoiceXML interactions. Platforms however should support the events and methods specified below to allow CCXML applications to implement the behaviors documented in this Appendix.

Since HTTP is a stateless protocol, application servers typically use cookie-based and/or URL rewriting techniques to enable stateful interactions with the server. Authors should be aware that application servers employing cookie-based management techniques will view concurrently executing CCXML and VoiceXML applications as independent (the CCXML and VoiceXML cookie stores are independent). Authors wishing to correlate CCXML and VoiceXML data at the server can use URL rewriting or alternatively employ the CCXML sessionid variable together with the connectionid or conferenceid as a common, unique key across the CCXML and VoiceXML applications.

D.2 Events

CCXML and VoiceXML 2.0 need to be able to exchange events between the browsers. The method of the message passing is up to the platform but it is assumed that there is some basic capacity in place.

Each running CCXML session has an event queue used to process CCXML events, independently of VoiceXML event processing by the dialogs created by that CCXML session. The execution of certain CCXML elements, such as <dialogterminate> and <send>, may cause events to be sent to the VoiceXML browser; similar, certain VoiceXML elements such as <transfer> will result in the generation of dialog events delivered to the CCXML session that owns the dialog in question. The sections below define the eventing relationship between the CCXML and VoiceXML environments.

VoiceXML 2.0 provides limited capabilities for handling asynchronous or unexpected events. Since CCXML is designed around a robust event processing mechanism, and since the CCXML session manages connections to the underlying network, processing of asynchronous events - which may be delivered through externally accessible event I/O processors - typically occurs primarily within the CCXML application, which can then control the VoiceXML session as appropriate. The VoiceXML dialog can therefore focus exclusively on interaction with the user.

D.3 VoiceXML Session Variables

When a VoiceXML dialog is bridged to a connection with an associated call leg, the standard VoiceXML session variables obtain their values from the call leg. Otherwise, these variables are undefined. VoiceXML Session variables are updated whenever there is a update to the associated connection or conference. CCXML defines an additional read-only VoiceXML session variable called session.connection.ccxml with the following sub-properties:

session.connection.ccxml.sessionid

This variable evaluates to the CCXML Session ID to which the VoiceXML dialog is currently associated.

session.connection.ccxml.dialogid

This variable evaluates to the CCXML Dialog ID for the current dialog.

session.connection.ccxml.connectionid

This variable evaluates to the CCXML Connection ID to which the VoiceXML dialog is currently bridged. This variable is undefined if the dialog is not bridged to a connection.

session.connection.ccxml.conferenceid

This variable evaluates to the CCXML Conference ID to which the VoiceXML dialog is currently bridged. This variable is undefined if the dialog is not bridged to a conference.

session.connection.ccxml.namelist

The variable is a string valued array of names corresponding to the namelist supplied in a CCXML <dialogprepare> or <dialogstart> invocation. The length of the array is equal to the number of names in the namelist. The actual values are stored in the session.connection.ccxml.values variable.

session.connection.ccxml.values

Each name in the session.connection.ccxml.namelist array is a sub-property of this variable which evaluates to the value of the name at the time <dialogprepare> or <dialogstart> was executed.

D.4 CCXML <dialogprepare>

When a CCXML application processes a <dialogprepare> element it prepares a VoiceXML application with the URI that is passed in on the <dialogprepare> element.

Normally it is expected that a VoiceXML dialog environment will use the <dialogprepare> request as an opportunity to fetch the initial document indicated by the src and namelist attributes along with any referenced resources such as <audio>, <script>, and <grammar> elements marked as prefetchable.

Even if a VoiceXML dialog environment is unable to perform any useful preparation the CCXML implementation MUST support the <dialogprepare> element and deliver a dialog.prepared event in response. The implementation MUST as a minimum, note the values provided via the src, namelist, and connectionid attributes, create a Dialog object, and return a new unique value to the location defined by the dialogid attribute.

D.5 CCXML <dialogstart>

When a CCXML application processes a <dialogstart> element it starts up a VoiceXML application on the connection with the URI that is passed in on the <dialogstart> element or to the dialog that was prepared using <dialogprepare> and specified using the prepareddialogid attribute.

D.6 CCXML <dialogterminate>

When a CCXML application processes a <dialogterminate> it causes a "connection.disconnect.hangup" event to be thrown to the VoiceXML application. As far as the VoiceXML application knows the call was just disconnected. The VoiceXML application still has a chance to return data to the CCXML application by using <exit> in its <catch> statement.

D.7 VoiceXML <exit>

When a VoiceXML application processes a VoiceXML <exit> it will cause the VoiceXML application to exit and return the contents of the namelist attribute to the CCXML application in the "dialog.exit" event in the following form:

<exit namelist="foo bar jar"/>

maps into an event that looks like the following:

dialog.exit
           values.foo
           values.bar
           values.jar

and could be accessed in a CCXML Application like this:

<!-- Process the incoming call -->  
<transition state="dialogActive" event="dialog.exit" name="evt">
  <log expr="'Houston, the dialog foo: [' + evt.values.foo + ']'" />
  <log expr="'Houston, the dialog bar: [' + evt.values['bar'] + ']'" />
  <var name="xxx" expr="'jar'/>
  <log expr="'Houston, the dialog jar: [' + evt.values[xxx] + ']'" />
  <exit /> 
</transition>

If the VoiceXML application is returning data using the expr attribute the data will be stored in "values".

<!-- Process the incoming call -->  
<transition state="dialogActive" event="dialog.exit" name="evt">
  <log expr="'Houston, the dialog using expr [' + evt.values + ']'" />
  <exit /> 
</transition>

D.8 VoiceXML <disconnect>

When the VoiceXML application processes a <disconnect> element it causes a "dialog.disconnect" event to be thrown in the CCXML application. It is then up to the CCXML application to disconnect the call and sends back a "connection.disconnect.hangup" event by using the <dialogterminate> element. The following is an example of what would happen:

1. The VoiceXML application executes a <disconnect>.
2. As a result, the VoiceXML interpreter sends a disconnect event to CCXML.
3. CCXML receives a "dialog.disconnect" event from the VoiceXML application. It interprets this as a request from the VoiceXML application to "please disconnect me".
4. An eventprocessor in the CCXML document SHOULD have a <transition> element intended to handle the "dialog.disconnect" event.
5. The CCXML application would have a <disconnect> element as the child of the transition event. This would disconnect the call.
6. An eventprocessor in the CCXML document should have a <transition> element intended to handle the "connection.disconnected" event.
7. The <transition> element has a child element which performs a <dialogterminate> on the dialog.

Here is the example CCXML code that completes the disconnect and returns the "connection.disconnect.hangup" event back to VoiceXML:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">
  <var name="dialogid"/>
        
  <eventprocessor statevariable="mystate">
    <transition event="dialog.disconnect" name="myevent">
      <assign name="dialogid" expr="myevent.dialogid"/>
      <disconnect connectionid="myevent.connectionid" />
    </transition>
                
    <transition event="connection.disconnected" >
     <dialogterminate dialogid="dialogid"/>
    </transition>
  </eventprocessor>
</ccxml>

D.9 VoiceXML <transfer>

When a VoiceXML application processes a <transfer> element it is handled within CCXML via series of events between the VoiceXML platform and the CCXML application. The type of transfer is controlled in VoiceXML 2.0 by the bridge attribute. If the value of bridge is "true" this will come in with a transfer type of "bridge" and if the value is "false" it will have a type of "blind". Here is an example of the logic to support the VoiceXML 2.0 transfer types:

• The VoiceXML application executes a <transfer> causing a dialog.transfer event to be sent to the CCXML Session.
• The CCXML document should have a <transition> to handle the dialog.transfer event. This transition should implement the logic in the following steps.
• If the type attribute of the dialog.transfer event is "blind" perform the following:
  • Execute a <redirect> to move the call to URI specified in the dialog.transfer event
  • The CCXML Application sends a telephone.disconnect.transfer event to inform the VoiceXML session that the <transfer> is complete.
• If the type attribute of the dialog.transfer event is "bridge" perform the following:
  • Invoke a <createcall> to create an outgoing call leg.
  • If the <createcall> completes with a connection.connected event then do the following:
    • Join the two call leg together as full duplex and if needed start a maxtime timer.
    • If a connection.disconnected event comes in for the original party:
      • Disconnect the new party
      • Return a connection.disconnect.hangup to the VoiceXML session.
    • If a connection.disconnected event comes in for the new party:
      • <join> the original connection back to the dialog full dupex
      • return a dialog.transfer.complete event to the dialog with a reason of far_end_disconnect.
    • If a maxtime event comes in:
      • Disconnect the new party
      • <join> the original connection back to the dialog full dupex
      • send a dialog.transfer.complete event to the dialog with a reason of maxtime_disconnect
    • If a dialog.terminatetransfer event comes in:
      • Disconnect the new party
      • <join> the original connection back to the dialog full dupex
      • send a dialog.transfer.complete event to the dialog with a reason of near_end_disconnect
  • If the <createcall> fails with a connection.failed event then do the following:
    • Send a dialog.transfer.complete event to the VoiceXML dialog with the failure reason.
• If the type attribute of the dialog.transfer event is bridge, and if early media is desired/permissible, then the above steps should be performed with the following exceptions:
  • When invoking <createcall> to create the outgoing call leg, the joinid attribute should be specified and should refer to the connection ID of the inbound leg associated with the dialog performing the <transfer>;
  • If the <createcall> completes with a connection.connected event, start a maxtime timer (if needed), but do not perform a <join> (since the calls are already joined).

dialog.terminatetransfer

The VoiceXML interpreter is responsible for throwing this event when a "hotword" grammar is matched while performing a bridged transfer.

D.10 User Disconnect

When a caller hangs up on one of the connections the VoiceXML dialog is not automatically disconnected. The CCXML application then needs to send a "connection.disconnect.hangup" event to the VoiceXML application by using the <dialogterminate> element so it can complete any cleanup that is required. The VoiceXML application can then still return data to the CCXML application by using the VoiceXML <exit> element.

D.11 VoiceXML 2.0 Example

The following example code shows how you would duplicate the standard VoiceXML 2.0 Interpreter Context in a CCXML Application. This example is not meant to be a complete application and does not handle all error events but is rather meant to give an overview of what such an application may look like.

You may also download the source of this application.

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0">

    <!-- Declare the vars we are going to use -->
    <var name="in_connectionid" />
    <var name="out_connectionid" />
    <var name="dialogid" /> 
    <var name="vxml_maxtime"/>
    
    <!-- Set an initial state -->
    <var name="mystate" expr="init"/>
    
    <eventprocessor statevariable="mystate">

        <!--
           - Deal with an incoming call 
         -->
        <transition state="init" event="connection.alerting" name="evt">
            <!-- Save off the connection id -->
            <assign name="in_connectionid" expr="evt.connectionid" />
            <accept connectionid="evt.connectionid"/>
        </transition>

        <!--
           - Call is connected so lets start the dialog 
         -->
        <transition state="init" event="connection.connected" name="evt">
            <dialogstart connectionid="evt.connectionid" 
                src="http://www.example.com/dialog.vxml" 
                dialogid="dialogid"/>
            <assign name="mystate" expr="'connected'" />
        </transition>
        
        <!--
           - Dialog is active 
         -->
        <transition state="connected" event="dialog.started" name="evt">
            <assign name="mystate" expr="'dialogActive'" />
        </transition>

        <!--
           - Dialog requests that we disconnect the call 
         -->
        <transition state="dialogActive" event="dialog.disconnect" name="evt">
            <disconnect connectionid="evt.connectionid" />
            <assign name="mystate" expr="'disconnecting'" />
        </transition>

        <!--
           - We have disconnected the call. We need to send an
           - event to the dialog saying we are done.
          -->
        <transition state="disconnecting" event="connection.disconnect" name="evt">
            <dialogterminate dialogid="dialogid"/>
        </transition>

        <!--
           - Dialog has exited after we disconnected the call. 
           - We just are going to exit from this CCXML session...
          -->
        <transition state="disconnecting" event="dialog.exit" name="evt">
            <exit/>
        </transition>

        <!--
           - The caller disconnected. We need to send the event up to
           - the Dialog and change our state.
          -->
        <transition state="dialogActive" 
                                event="connection.disconnect" 
                                name="evt">
            <dialogterminate dialogid="dialogid"/>
            <assign name="mystate" expr="'userDisconnect'" />
        </transition>

        <!--
           - Dialog has exited after the caller hungup. 
           - We just are going to exit from this CCXML session...
          -->
        <transition state="userDisconnect" event="dialog.exit" name="evt">
            <exit/>
        </transition>


        <!--
           -
           - Handle an transfer request from a VXML script.
           -
         -->
        <transition state="dialogActive" event="dialog.transfer" name="evt">
            <!-- Branch on transfer type -->
            <if cond="evt.type == 'blind'">
                <!-- Bridge == false. We are going to just redirect the call -->
                
                <!-- Update our state var -->
                <assign name="mystate" expr="'redirecting'" />
                
                <!-- And redirect to the uri specified in the event -->
                <redirect connectionid="in_connectionid" dest="evt.URI" />

                <!-- Just send the success event to the dialog -->
                <send data="connection.disconnect.transfer" 
                    target="dialogid" 
                    targettype="'dialog'"/>

            <else/>
                <!-- Bridge == true. In this case we need to 
                     place a call and bridge the calls -->

                <!-- save off maxtime -->
                <assign name="vxml_maxtime" expr="evt.maxtime" />

                <!-- Update our state var -->
                <assign name="mystate" expr="'calling'" />

                <!-- Place the call using the num from the transfer request -->
                <createcall dest="evt.URI" 
                    name="out_connectionid" 
                    aai="evt.aai" 
                    timeout="evt.connecttimeout"/>
            </if>
        </transition>

                <!--
                   - We will get the following events but we do not do anything 
                   - because in VoiceXML 2.0 you just ignore redirect errors.
                   - We do however process the dialog.exit and shutdown 
                   - the CCXML Session. 
                 -->
                <transition state="redirecting" 
                                        event="connection.redirected"
                                        name="evt">
                </transition>
                <transition state="redirecting" event="connection.failed" name="evt">
                </transition>
                <transition state="redirecting" event="dialog.exit" name="evt">
                        <exit/>
                </transition>
                

        <!-- 
           -
           - Handle bridge=true Events
           -
           - This first event is for if the outbound call failed.
           -
        -->
        <transition state="calling" event="connection.failed" name="evt">
            <!-- Just send the error event to the dialog -->
            <assign name="results" expr="evt.reason"/>
            <send data="dialog.vxml.transfer.complete" 
                target="dialogid" 
                targettype="'dialog'" 
                namelist="results" />

            <!-- Update our state var back to the original state -->
            <assign name="mystate" expr="'dialogActive'" />
        </transition>

        <!-- 
           - The outbound call has been answered. 
         -->
        <transition state="calling" event="connection.connected" name="evt">
            <!-- Update our state var back to show that we are connected -->
            <assign name="mystate" expr="'outgoing_call_active'" />
            
            <!-- Join the two calls together -->
            <join id1="in_connectionid" id2="in_connectionid" duplex="full" />
        </transition>

        <!-- 
           - We will get here once the join completes. 
         -->
        <transition state="outgoing_call_active" 
                                event="conference.joined" 
                                name="evt">
            <!-- If maxtime has been set then we setup a timer -->
            <if cond="vxml_maxtime != null">
                <send data="maxtime" 
                    target="session.id"
                    delay="vxml_maxtime" 
                    sendid="maxtime_sendid"/>
            </if>
        </transition>

        <!--  
           - Deal with someone disconnecting.
         -->    
        <transition state="outgoing_call_active" 
                                event="connection.disconnected" 
                                name="evt">

            <!-- Cancel any maxtime events that are waiting to be fired --> 
            <if cond="maxtime_sendid != null">
                <cancel sendid="maxtime_sendid"/>
                <assign name="maxtime_sendid" expr="null"/>
            </if>

            <!-- Branch off based on what call leg this is for and send 
                 the proper event to the dialog -->
            <if cond="evt.connectionid == out_connectionid">
                <assign name="results" expr="far_end_disconnect" />
                <send data="dialog.vxml.transfer.complete" 
                    target="dialogid" 
                    targettype="'dialog'" 
                    namelist="results" />

                <!-- Update our state var back to the original state -->
                <assign name="mystate" expr="'dialogActive'" />

            <else />
                <!-- Set our state to show that the 
                     original caller is disconnected. -->
                <assign name="mystate" expr="'userDisconnected'" />
                    <dialogterminate dialogid="dialogid"/>
            </if>

        </transition>

        <!--  
           - Deal with a "hotword" type event where the dialog
           - requests that we stop the transfer.
         -->
        <transition state="outgoing_call_active" 
                                event="dialog.terminatetransfer" 
                                name="evt">

            <!-- Change our state to show we are dealing with hotword stuff -->
            <assign name="mystate" expr="'hotword'" />

            <!-- Cancel any maxtime events that are waiting to be fired --> 
            <if cond="maxtime_sendid != null">
                <cancel sendid="maxtime_sendid"/>
                <assign name="maxtime_sendid" expr="null"/>
            </if>
            
            <!-- unjoin our connections -->
            <unjoin id1="in_connectionid" id2="out_connectionid"/>

        </transition>

        <!--  
           - Calls have been unjoined.
         -->
        <transition state="hotword" event="conference.unjoined" name="evt">
            <!-- Rejoin the first connection to the dialog --> 
            <join id1="in_connectionid" id2="dialogid"/>
            
            <!-- Disconnect the outbound call -->
            <disconnect connectionid="out_connectionid"/>
        </transition>
        
        <!--  
           - Send an event to the dialog once we are all back together again.
         -->
        <transition state="hotword" event="conference.joined" name="evt">

            <!-- Build up our event -->
            <assign name="results" expr="near_end_disconnect" />
            <send data="dialog.vxml.transfer.complete" 
                target="dialogid" 
                targettype="'dialog'" 
                namelist="results" />

            <!-- Update our state var back to the dialogActive state -->
            <assign name="mystate" expr="'dialogActive'" />
        </transition>
        

        <!--  
           - Deal with connection.disconnect events in the hotword state.
           - We are only going to deal with stuff if it the event is 
           - for the incoming call.
         -->
        <transition state="hotword" event="connection.disconnect" name="evt">
            <if cond="evt.connectionid == in_connectionid">
                    <dialogterminate dialogid="dialogid"/>
                <!-- Update our state var to the userDisconnect state -->
                <assign name="mystate" expr="'userDisconnect'" />
            </if>
        </transition>

        
        <!--  
           - Deal with the maxtime event during a call transfer.
           - Should this happen we just disconnect the outbound call let
           - and get back to the dialogActive state. 
           -
           - Step one is to disconnect the call...
         -->
        <transition state="outgoing_call_active" 
                                event="vxml_maxtime" 
                                name="evt">
            <assign name="maxtime_sendid" expr="null"/>

            <assign name="mystate" expr="'maxtime'" />
            <disconnect connectionid="out_connectionid"/>
        </transition>

        <!--  
           - Once we have the disconnect event we verify that we 
           - got it for the outbound call and rejoin the dialog to the 
           - inbound call. If the inbound call disconnected
           - we are going to go on and forward the event along 
           - and wait for the dialog to exit.
           -
         -->
        <transition state="maxtime" event="connection.disconnected" name="evt">
            <if cond="evt.connectionid == out_connectionid">
                <join id1="dialogid" id2="in_connectionid"/>
            <else />
                    <dialogterminate dialogid="dialogid"/>
            </if>
        </transition>

        <!--  
           -
           - We are rejoined. Update our state and send the transfer
           - event back to the dialog.
           -
         -->
        <transition state="maxtime" event="conference.joined" name="evt">
            <!-- Update our state var back to the dialogActive state -->
            <assign name="mystate" expr="'dialogActive'" />

            <assign name="results" expr="maxtime_disconnect" />
            <send data="dialog.vxml.transfer.complete" 
                target="dialogid" 
                targettype="'dialog'" 
                namelist="results" />
        </transition>

        <!--
           - Dialog has exited while we were in a hotword state. 
           - We just are going to exit from this CCXML session...
          -->
        <transition state="maxtime" event="dialog.exit" name="evt">
            <exit/>
        </transition>

        
        <!-- 
           -
           - Deal with any extra random events that may come in.
           -
         -->

        <!--  
           - Make sure that we deal with any extra dialog events
           - by ending the session. A real ccxml app would do something 
           - better here.
         -->
        <transition event="dialog.*" name="evt">
            <exit/>
        </transition>

        <!--  
           - And do the same for any exit events.
         -->
        <transition event="error.*" name="evt">
            <exit/>
        </transition>

        <!--  
           - And last but not least catch any connection.disconnect 
           - events that made it past us.
         -->
        <transition event="connection.disconnect" name="evt">
            <exit/>
        </transition>

    </eventprocessor>
</ccxml>

Appendix E - Telephony Protocol Names

Overview

This section defines a list of recommended telephony protocol names to be used in CCXML platforms within the connection event objects (See 10.2.3: Connection Events). Platforms MUST use the following list when available. If the protocol is not defined in this list the platform MUST prefix the name with an underscore, "_", to identify them as platform-dependent.

Protocol names

Appendix F - Changes

Changes in Working Draft 2

• Added the redirect element.
• Added the reason attribute to the disconnect and reject elements.
• Removed the submit element.
• Updated the fetch element.
• Updated the goto element.
• Updated the exit element.
• Updated the createccxml element.
• Added the move element.
• Updated the DTD.
• Added a Schema.
• Updated the examples to match the new spec changes.
• Major Editorial Work.
• Updated transition element with default cond of "true".
• Updated the join element.
• Updated the unjoin element.
• Updated the createconference element.
• Updated the destroyconference element.
• Added ECMAScript.
• Added the script element.
• Updated the dialog interaction.
• Updated the dialogstart element
• Updated the dialogterminate element
• Added VoiceXML interaction section
• Added new dialog events
• Added new ccxml core events
• Updated attribute names to be more consistent

Changes in Working Draft 3

• Major editorial changes to reflect current status of the document (Entire Document)
• Minor corrections to all examples to reflect changes to the spec (Entire Document)
• Rewrote introduction (Section 1)
• Rewrote background (Section 2)
• Updated overview of call management (Section 3.3)
• Added CSS 2 times reference to the definitions section (Section 3.4.2)
• Rewrote section 4 introduction to cover updated object models (Section 4)
• Updated description of <if>, <elseif> and <else> (Section 6.2.2-6.2.6)
• Updated namelist attribute of <fetch> (Section 6.2.7.2)
• Updated method attribute of <fetch> (Section 6.2.7.2)
• Added timeout attribute of <fetch> (Section 6.2.7.2)
• Updated namelist attribute of <exit> (Section 6.2.10.2)
• Added <log> tag (Section 6.2.11)
• Updated threading description of section 6.3.1 (Section 6.3.1)
• Added clarification to "ccxml.loaded" event (Section 6.3.5)
• Updated overview of <dialogstart> to reflect object model changes (Section 7.2.1.1)
• Updated overview of <dialogstart> having to do with passing of call data (Section 7.2.1.1)
• Renamed the callid attribute to conid on <dialogstart> (Section 7.2.1.2)
• Updated type attribute of <dialogstart> to make it a ECMAScript expression (Section 7.2.1.2)
• Updated namelist attribute of <dialogstart> (Section 7.2.1.2)
• Added duplex attribute of <dialogstart> (Section 7.2.1.2)
• Renamed callid attribute of the "dialog.started" event to conid (Section 7.3.2)
• Renamed callid attribute of the "dialog.exit" event to conid (Section 7.3.3)
• Renamed callid attribute of the "dialog.disconnect" event to conid (Section 7.3.4)
• Renamed callid attribute of the "dialog.transfer" event to conid (Section 7.3.5)
• Renamed callid attribute of the "error.dialog.notstarted" event to conid (Section 7.3.6)
• Renamed callid attribute of the "error.dialog.wrongstate" event to conid (Section 7.3.7)
• Renamed callid attribute of the "dialog.user.*" event to conid (Section 7.3.8)
• Added scope diagram to section 8.2.1.1 (Section 8.2.1.1)
• Updated event concepts in section 9.1 to reflect updated call control model (Section 9.1)
• Updated event delivery details in section 9.1 to deal with user specified event delay (Section 9.1)
• Added description to <eventhandler> details (Section 9.2.1)
• Removed id attribute from <eventhandler> (Section 9.2.1.1)
• Added description to <transition> details to explain event selection (Section 9.2.2)
• Updated state attribute of the <transition> element to allow for more then one state (Section 9.2.2.1)
• Updated event attribute of the <transition> element to add regex support (Section 9.2.2.1)
• Added event matching text to define regex behavior (Section 9.2.2.2)
• Added clarification to <send> element processing (Section 9.2.3.1)
• Updated namelist attribute of the <send> tag (Section 9.2.3.2)
• Added clarification to <move> element processing (Section 9.2.4.1)
• Renamed endpoint attribute of <move> element to source and minor updates (Section 9.2.4.2)
• Updated event attribute of <move> element (Section 9.2.4.2)
• Complete rewrite of most of section 9.4 to reflect new event model (Section 9.4)
• Added error events section (Section 9.5)
• Major rewrite of section 10 introduction to reflect new call control model (Section 10)
• Renamed callid attribute of <accept> element to conid (Section 10.1.2.2)
• Renamed callid attribute of <redirect> element to conid (Section 10.1.3.2)
• Updated dest attribute of <redirect> element (Section 10.1.3.2)
• Renamed callid attribute of <reject> element to conid (Section 10.1.4.2)
• Added <hold> tag (Section 10.1.5)
• Updated overview of <createcall> element (Section 10.2.1.1)
• Updated dest attribute of <createcall> (Section 10.2.1.2)
• Renamed name attribute of <createcall> to conid (Section 10.2.1.2)
• Added aai attribute to <createcall> (Section 10.2.1.2)
• Added callerid attribute to <createcall> (Section 10.2.1.2)
• Added hints attribute to <createcall> (Section 10.2.1.2)
• Added use attribute to <createcall> (Section 10.2.1.2)
• Added timeout attribute to <createcall> (Section 10.2.1.2)
• Added examples section to <createcall> (Section 10.2.1.3)
• Major rewrite of Section 10.3 and 10.4 to reflect new call control models (Section 10.3 and 10.4)
• Updated disconnect section to update call control model (Section 10.5)
• Renamed callid attribute of <disconnect> to conid (Section 10.5.1.2)
• Added dialog attribute to <disconnect> (Section 10.5.1.2)
• Updated reason attribute of <disconnect> (Section 10.5.1.2)
• Updated details of the <authenticate> tag having to do with the "ccxml.exit" event (Section 11.2.2)
• Updated all examples to work with changes (Section 12)
• Moved all issues to Appendix A (Appendix A)
• Added ECMA-CSTA to Appendix B (Appendix B)
• Updated DTD (Appendix C)
• Updated Schema (Appendix D)
• Updated VoiceXML Integration Details (Appendix E)
• Added Recommended Telephony Protocol names (Appendix F)
• Renamed Changes and Acknowledgments Appendixes (Appendixes G and H)

Changes in Last Call Working Draft

• Rewrite of dialog section to prepare for LCWD. This includes language cleanup and references to external specifications. (Section 7)
• Rewrite of variables and expressions section to prepare for LCWD. This includes language cleanup and references to external specifications. (Section 8)
• Better details on variable scope issues. (Section 8)
• charset Attribute added to script tag. (Section 8)
• New section listing session variables. (Section 8.3)
• Rewrite of Event Handling section to prepare for LCWD. This includes language cleanup and references to external specifications. Some content has been moved to section 10. (Section 9)
• Rewrite of Telephony Operations and Resources section to prepare for LCWD. This includes language cleanup and references to external specifications. (Section 10)
• Removed incomplete security section. (Section 11)
• Removed inline DTD. (Appendix C)
• Removed inline Schema. (Appendix D)
• Updated Schema text. (Appendix D)
• Updated telephony protocol names to change "SHOULD" to be "MUST". (Appendix F)
• Added CAS to list of telephony protocol names. (Appendix F)
• Added references section. (Appendix I)
• Update of if, elseif, else tags. (Section 6)
• New table formats
• New example formats
• Updated text for section 9. (Section 9)
• Updated text for section 10. (Section 10)
• Updated text for section 6. (Section 6)
• Cleanup of text in full spec. (All)
• New session text. (Sections 1, 2, 3 and 6)
• CR 122 Text for XMLNS and XML-BASE. (Section 6)
• CR 133 Text for meta and metadata. (Section 6)
• Cleanup of Schema text. (Appendix D)
• Removal of "Section" in section titles. (All)
• Update references of <eventhandler> to <eventprocessor>. (All)
• Update of Acknowledgments. (Appendix H)
• Change elements --> Elements in titles. (All)
• Correction of the use of the term "element". (All)
• Added ACRONYM tag for IVR. (All)
• Added telephony standard references in section 2. (Section 2)
• Added URI to defined terms. (Section 3.4.2)
• Cleanup of RFC2119 terms. (All)
• Added references to Appendix G. (Appendix G)
• Reworking of Appendix B (Appendix B)
• Update of Acknowledgments. (Appendix H)
• Split conid into conferenceid and connectionid for dialog stuff. (Section 7)
• CR-136, createccxml/fetch updates. (Section 6)
• CR-140, hints attributes on telephony elements. (Section 10.5)
• CR-141, move, send, and cancel have no positive confirmation event. (Section 9.3)
• Updated Schema (CR-130). (Appendix D)
• Updated DTD (CR-130). (Appendix C)
• Conference events. (Section 10)
• CR-131 src vs srcexpr on script. (Section 8)
• Added MIME Type registration info. (Appendix J)
• Some of the changes suggested by Paolo. (All)
• CR-139 text (Issues with send and cancel) (9.2.5)
• CR-52 (Conferencing) text. (10.5.5 and 10.5.7)
• CR-144 timeout attribute for createccxml. (6.2.9.2)
• Reworked Sections 1 and 2 from F2F meeting (Sections 1-2)
• CR-124 Session lifecycle (Section 3)
• CR-126 Simple Examples (Section 4)
• CR-128 Join Diagrams (Section 10)
• CR-138 Script src/expr changes (Section 8)
• CR-142 Dialog Dialogprepare (Section 7, Appendix E)
• Synced error attributes in all events to "reason" (All)
• changed session.mode to session.startupmode (Section 3 and 8)
• Added values for session.startupmode (Section 8)
• Reworked connection state text and changed from text list to HTML tables. (Section 10.2.1)
• Update of status (Status)
• Removed old issue text (Appendix A)
• Updated DTD. (Appendix C)
• Added missing conferenceid attribute to dialogprepare. (Section 7)
• Removed old cancel attribute.
• Changes as requested by Jeff Haynie. (All)
• Updated Examples 1, 2 and 4. (Section 12)
• New Event I/O text. (Section 9)
• New TOC. (TOC)
• Lowercase Event Names. (All)
• Lots of minor text cleanup/link updates. (All)
• Updates for W3C Publication Rules. (All)
• Added definition for "CCXML Application/Program". (Section 3.5)
• New VoiceXML Appendix. (Appendix D)
• Removed Issues Appendix. (Was Appendix A)
• Re-lettered Appendixes. (All)
• Lots of minor text cleanup/link updates. (All)
• Updates for W3C Publication Rules. (All)
• Removed change marks to prepare for publishing (All)
• Removed Complex Example 3 (Section 11)

Changes in Last Call Working Draft 2

• CR149: Lost changes from April 19th have been added back in (Several Sections)
• CR149: IBM Editorial Changes (Several Sections)
• CR159: HTTP Caching changes (Several Sections)
• CR160: disconnect clarification (Section 10.5.9)
• CR161: Extend dialog.prepared (and error.dialog.notprepared) (Section 7.3.10 and 7.3.11)
• CR162: Change disconnect examples to use dialog-terminate instead of send (Appendix D)
• CR163: VoxPilot Comments - Editorial (All)
• CR164: error.fetch vs. error.semantic - Emily Updates (Several Sections)
• CR165: DTD defines "eventprocesser" rather than "eventprocessor" (DTD)
• CR166: Error in error handling (Section 9.4.5.4)
• CR167: Remove FIA text from dialogprepare (Appendix D)
• CR169: Change dialogprepare connection rules (Section 7)
• CR170: merge tag (Section 10)
• CR172: dialogstart Attribute Detail (Section 7.2.2.2)
• CR173: error.dialog.notstarted attributes (Section 7.3.7)
• CR174: New connection state diagram (Section 10.2.1)
• CR176: HTTP Encoding changes (Several Sections)
• CR179: Clarification of createcall timeout (Section 10.5.4.2)
• CR182: Fetch Lifecycle (Several Sections)
• CR182: Removal of sync fetches (Several Sections)
• CR182: Change of script sync options (Several Sections)
• CR171: Master Session Lifecycle Diagram (Section 3.6.3.8)
• CR174: Added connection.signal to PROGRESSING state in connection state diagram (Section 10.2.1)
• CR184: ECMAScript Left Hand Side Expression (Section 3.5)
• CR184: Fetch/Goto example using and ECMAScript Left Hand Side Expression (Section 6.2.8.3)
• CR185: HP Comment - Typo (Section 6.1)
• CR187: HP Comment - Example Error (Section 11.2)
• CR190: HP Comment - Typo (Section 9.2.3.3)
• CR147: DTD Updates from Alex Davis (Appendix B)
• CR151: 3.x Section renumber from Greg Massard (Section 3.x)
• CR152: 6.x Section renumber from Greg Massard (Section 6.x)
• CR154: Missing elements in section 5 from Greg Massard (Section 5)
• CR155: DTD/Schema error for var from Greg Massard (Appendix B/C)
• CR156: DTD/Schema error for accept from Greg Massard (Appendix B/C)
• CR157: DTD/Schema error for else/elseif from Greg Massard (Appendix B/C)
• CR159: enctype attribute. First time some changes got lost (Several sections)
• CR178: Updated Scope Diagram (Section 8.1)
• CR183: Updates to ccxml.kill wording and event queue processing (Sections 3.6, 6 and 9.1)
• CR202: move effect on queued events from moved source (Section 9.2.4)
• CR203: Conferencing object mixer text changes (Section 10.3)
• CR210: Add DialogID to join/unjoin (Section 10)
• CR211: Remove start attribute from createccxml (Section 6)
• CR207: State Variable Updating (Section 9)
• CR212: DTD/Schema Updates (Appendix B/C)
• CR209: Move Updates (Section 9)
• CR181: Standard format for attribute tables (All)
• CR191: mediadirection attribute for dialogstart/dialogprepare(All)
• CR208: Scope of sendid, fetchid, dialogid and sessionid attribute values (All)
• CR177: Complex ECMA Objects and namelist (All)
• CR217: Early Media Support (All)
• CR213: Remove regex on transition (All)
• CR201: Intersession join and Connection/Confrencing ID's (All)
• CR214: send Delay Semantics on termination (All)
• CR216: Additional text for CCXML Join and disconnect (All)
• CR196: Application level variables (All)
• CR218: Send clarification (All)
• CR206: VoiceXML Session Vars (Appendix D)
• CR210: Dialogs as Connections (Section 10.5.7 and 10.5.8)
• CR219: Clean-up of dialog.vxml.transfer.complete (Section 7, Appendix D)
• CR180: Application Session/Cookies (Appendix D)
• Updated Acknowledgments Section (Appendix G)
• Clean up of images (All)
• CR193: Default attribute value text (All)
• CR175: Conformance Section (Appendix J)
• CR215: "endpoint" and "duplexmode" Connection/Dialog Object properties (Section 7/10)
• Minor example 1 fix (Added a tel: prefix)
• Fixed display issues for IE based browsers
• Renamed connection.error to error.connection
• Updated System Architecture Diagram
• Wording changes from Mark Scott (Reviewed on 11/11/2004
• 10.2.2 Protocol example change from Paolo Baggia
• Default dialog MIME type fixes
• Minor changes from VoiceGenie:
  • Updated <assign> to make expr required
  • On <dialogstart>, updated 'maxage', 'maxstale', 'enctype', and 'method' to be exclusive with 'prepareddialogid'
  • Updated <exit> expr default to be undefined
• Updated DTD/Schema
• Changed <dialogterminate> immediate to a ECMAScript Boolean Expression.

Changes in Last Call Working Draft 3

• Optimsys Comments 1-3, 5-9.
• Updated attribute tables for section 7 based on IR effort.
• Converted to external event tables.
• Editorial cleanup of inline code examples.
• Optimsys Comments 11-25.
• Misc editoral changes
• Added definitions for "CCXML Session", "CCXML Parent Session" and "Event" to section 3.4.
• Section 6.2.4.1: Changed SHOULD to MUST on else/if logic
• Section 6.2.7.1: Added texxt listing required URI schemes
• Section 7.1: Added text to address dialogs without connections
• Section 7.3.7: Added error.dialog event
• Section 8.2.1.1: Updated scope table
• Section 8.3: Added session.ioprocessors session var
• Section 9.2.3: Added basichttp to targettype list
• Section 9.2.3: Updated send text for inline content and xml:ns comments
• Section 9.5: Removed reference to error.ccxml event
• Section 10.2: Expanded Dialog description.
• Section 10.5.9.2: Removed requirement for connectionid attribute
• Section 10.6.20: Added error.connection.wrongstate event
• Appendix K/L: Added sections on basichttp I/O and session launch.
• Misc editoral changes
• Corrected CSTA XML namespace in examples
• Added text to address canceling an outbound call
• Moved Connection/Conference Object tables to XML includes
• Updated section 10.4
• Misc changes to section 10 from VoiceGenie
• Event/Element table cleanup for IR effort (Corrected MUST/MAY etc)

Appendix G - Acknowledgments

This version of CCXML was written with the participation of members of the W3C Voice Browser Working Group, and a special thanks is in order for the following contributors:

David Attwater, BTexact Technologies

RJ Auburn, Voxeo Corporation

Eric Burger, Snowshore

David Burke, VoxPilot

Emily Candell, Comverse

Ken Davies, Hey Anita

Rajiv Dharmadhikari, Genesys

Dave Donnelly, BTexact Technologies

Daniel Evans

Mike Galpin, Syntellect

Markus Hahn

Jeff Haynie, Vocalocity

David W Heileman, Unisys

Gadi Inon

Rob Marchand, VoiceGenie

Scott McGlashan, Hewlett-Packard

Rachel Muller, Aspect

Paolo Baggia, Loquendo

Brad Porter, TellMe Networks

Kenneth Rehor, Vocalocity

Dave Renshaw, IBM

Mark Scott, VoiceGenie

Saravanan Shanmugham, Cisco

Scott Slote, Nortel Networks

Govardhan Srikant, Nortel Networks

Jim Trethewey, Intel

Wai-Yip Tung, Cisco

This W3C specification is based upon a former CCXML specification, contributed to the Voice Browser Working Group in April 2001. The CCXML authors were:

RJ Auburn, Voxeo Corporation

Michael Cafarella, TellMe

Don Jackson, TellMe

Jeff Peck, Intel

Pramod Sharma, Telera

Saravanan Shanmughan, Cisco Systems

Corey Stohs, Cisco Systems

Yi Zhang, Telera

Appendix H - References

[CSTA]

" Services for Computer Supported Telecommunications Applications (CSTA) Phase III ", Standard Ecma-269, 2002.
See http://www.ecma-international.org/publications/standards/Ecma-269.htm

[IANA]

" IANA Character Sets ", IANA.
See http://www.iana.org/assignments/character-sets

[JSR021]

" JAIN Call Control ", JSR 000021, 2001.
See http://www.jcp.org/aboutJava/communityprocess/final/jsr021/

[MIME-TAG]

Client handling of MIME headers, Ian Jacobs (Editor) W3C TAG Finding 09 July 2003. Available at http://www.w3.org/2001/tag/doc/mime-respect.html

[RFC2119]

Key words for use in RFCs to Indicate Requirement Levels, S. Bradner Network Working Group RFC2119 March 1997. Available at http://www.rfc-editor.org/rfc/rfc2119.txt.

[RFC3261]

" SIP: Session Initiation Protocol ", IETF RFC 3261, 2002.
See http://www.ietf.org/rfc/rfc3261.txt

[RFC2806]

" URLs for Telephone Calls ", IETF RFC 2806, 2000.
See http://www.ietf.org/rfc/rfc2806.txt

[S.100]

" S.100 ", ECTF.
See http://www.comptia.org/sections/ectf/media_services.aspx

[SALT]

Speech Application Language Tags (SALT) 1.0 Specification, Cisco Systems Inc., Comverse Inc., Intel Corporation, Microsoft Corporation, et al. The SALT Forum, 15 July 2002. Available at http://www.saltforum.org/saltforum/downloads/SALT1.0.pdf.

[VOICEXML]

Voice Extensible Markup Language (VoiceXML) Version 2.0 , Scott McGlashan, Daniel C. Burnett, Jerry Carter, et al. W3C Candidate Recommendation 20 February 2003. Available at http://www.w3.org/TR/voicexml20/

[XML]

" Extensible Markup Language (XML) 1.0 ". Bray et al. W3C Recommendation.
See http://www.w3.org/TR/2000/REC-xml-20001006

[Q.931/DSS1]

" ITU-T Recommendation Q.931 ", ISDN user-network interface layer 3 specification (5/98).
See http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-Q.931

[SS7]

" ITU-T Recommendations Q.700-775 ", Signalling System No. 7 (3/93).
See http://www.itu.int/rec/recommendation.asp?type=items&lang=e&parent=T-REC-Q.700-199303-I

[ECMAScript]

" ECMAScript Language Specification ", Standard Ecma-262, 1999.
See http://www.ecma-international.org/publications/standards/Ecma-262.htm

[ECMA327]

"ECMAScript 3rd Edition Compact Profile", Standard Ecma-327, 2001.
See http://www.ecma-international.org/publications/standards/Ecma-327.htm

[XMLNS]

" Namespaces in XML ", World Wide Web Consortium, W3C Recommendation.
See href="http://www.w3.org/TR/REC-xml-names/ .

[XML-BASE]

" XML Base ", J. Marsh, editor, W3C Recommendation, June 2001.
See http://www.w3.org/TR/2001/REC-xmlbase-20010627/ .

[HTML]

" HTML 4.01 Specification ", Dave Raggett et al. W3C Recommendation, December 1999.
See http://www.w3.org/TR/1999/REC-html401-19991224/ .

[RDF-SYNTAX]

" Resource Description Framework (RDF) Model and Syntax Specification. ", Ora Lassila and Ralph R. Swick, W3C Recommendation, February 1999.
See http://www.w3.org/TR/1999/REC-rdf-syntax-19990222/ .

[RDF-SCHEMA]

" Resource Description Framework (RDF) Schema Specification 1.0. ", Dan Brickley and R.V. Guha, W3C Candidate Recommendation, March 2000.
See http://www.w3.org/TR/2000/CR-rdf-schema-20000327/ .

[DC]

" Dublin Core Metadata Element Set, Version 1.1: Reference Description ", See http://dublincore.org/documents/dces/ .

[SCHEMA2]

XML Schema Part 2: Datatypes, P.V. Biron and A. Malhotra, Editors. World Wide Web Consortium, 2 May 2001. This version of the XML Schema Part 2 Recommendation is http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/. The latest version of XML Schema 2 is available at http://www.w3.org/TR/xmlschema-2/.

[RFC2396]

Uniform Resource Identifiers (URI): Generic Syntax, T. Berners-Lee et al., Editors. IETF, August 1998. This RFC is available at http://www.ietf.org/rfc/rfc2396.txt.

[RFC2732]

Format for Literal IPv6 Addresses in URL's, R. Hinden, et al., Editors. IETF, December 1999. This RFC is available at http://www.ietf.org/rfc/rfc2732.txt.

[RFC3023]

XML Media Types, M. Murata, et al., Editors. IETF, January 2001 This RFC is available at http://www.ietf.org/rfc/rfc3023.txt

[CSS2]

Cascading Style Sheets, level 2: CSS2 Specification, B. Bos, et al., Editors. World Wide Web Consortium, 12 May 1998. This version of the CSS2 Recommendation is http://www.w3.org/TR/1998/REC-CSS2-19980512/. The latest version of CSS2 is available at http://www.w3.org/TR/REC-CSS2/.

[RFC2119]

" Key words for use in RFCs to Indicate Requirement Levels ", IETF RFC 2119, 1997.
See http://www.ietf.org/rfc/rfc2119.txt

[H.323]

" ITU-T Recommendation H.323 ", Packet-based multimedia communications systems (7/03).
See http://www.itu.int/rec/recommendation.asp?type=items&lang=e&parent=T-REC-H.323-200307-P

[CALLXML]

CallXML 1.0, Voxeo Corporation, October 1999.

[TXML]

Telera Extensible Markup Language, Telera.

[RFC2616]

" Hypertext Transfer Protocol -- HTTP/1.1 ", IETF RFC 2616, 1999.
See http://www.ietf.org/rfc/rfc2616.txt

[RFC2617]

HTTP Authentication: Basic and Digest Access Authentication , IETF RFC 2617, June 1999. See http://www.ietf.org/rfc/rfc2617.txt.

[RFC2109]

HTTP State Management Mechanism , IETF RFC 2109, February 1997. See http://www.ietf.org/rfc/rfc2109.txt.

[RFC2965]

HTTP State Management Mechanism , IETF RFC 2965, October 2000. See http://www.ietf.org/rfc/rfc2965.txt.

Appendix I - CCXML Media Type

This appendix registers a new MIME media type, "application/ccxml+xml".

I.1 Registration of MIME media type application/ccxml+xml

MIME media type name:

application

MIME subtype name:

ccxml+xml

Required parameters:

None.

Optional parameters:

charset

This parameter has identical semantics to the charset parameter of the application/xml media type as specified in [RFC3023].

Encoding considerations:

By virtue of CCXML content being XML, it has the same considerations when sent as "application/ccxml+xml" as does XML. See RFC 3023, section 3.2.

Security considerations:

Several CCXML instructions may cause arbitrary URIs to be referenced. In this case, the security issues of RFC1738, section 6, should be considered.

In addition, because of the extensibility features for CCXML, it is possible that "application/ccxml+xml" may describe content that has security implications beyond those described here. However, if the processor follows only the normative semantics of this specification, this content will be ignored. Only in the case where the processor recognizes and processes the additional content, or where further processing of that content is dispatched to other processors, would security issues potentially arise. And in that case, they would fall outside the domain of this registration document.

Interoperability considerations:

This specification describes processing semantics that dictate behavior that must be followed when dealing with, among other things, unrecognized elements.

Because CCXML is extensible, conferment "application/ccxml+xml" processors can expect that content received is well-formed XML, but it cannot be guaranteed that the content is valid CCXML or that the processor will recognize all of the elements and attributes in the document.

Published specification:

This media type registration is for CCXML documents as described by this specification.

Additional information:

Magic number(s):

There is no single initial octet sequence that is always present in CCXML documents.

File extension(s):

CCXML documents are most often identified with the extensions ".ccxml".

Macintosh File Type Code(s):

TEXT

Person & email address to contact for further information:

RJ Auburn, <rj@voxeo.com>.

Intended usage:

COMMON

Author/Change controller:

The CCXML specification is a work product of the World Wide Web Consortium's Voice Browser Working Group. The W3C has change control over these specifications.

I.2 Fragment Identifiers

For documents labeled as "application/ccxml+xml", the fragment identifier notation is exactly that for "application/xml", as specified in RFC 3023.

Appendix J - Conformance

This section is Normative.

J1. Conforming CCXML Document

A document is a Conforming CCXML Document if it meets all of the following conditions:

• it is a well-formed XML document [XML] conforming to namespaces in XML [XMLNS]
• it has a <ccxml> root element which includes a version attribute of "1.0"
• the <ccxml> element designates the CCXML namespace. This can be achieved by declaring an xmlns attribute or an attribute with an xmlns prefix [XMLNS]. The namespace for CCXML is defined to be "http://www.w3.org/2002/09/ccxml"
• it adheres to the specification described in this document (Voice Browser Call Control: CCXML Version 1.0) including the constraints expressed in the schema (see Appendix C)

It is recommended that the <ccxml> element indicate the location of the CCXML schema (see Appendix C) via the xsi:schemaLocation attribute from [SCHEMA2]:

xsi:schemaLocation="http://www.w3.org/2002/09/ccxml http://www.w3.org/TR/ccxml/ccxml.xsd"

There may be a DOCTYPE declaration in the document prior to the root element. If present, the public identifier included in the DOCTYPE declaration must reference the CCXML DTD (Appendix B) using its Formal Public Identifier:

<!DOCTYPE ccxml PUBLIC "-//W3C//DTD CCXML 1.0//EN" "http://www.w3.org/TR/ccxml/ccxml.dtd">

The system identifier may be modified appropriately. The DTD subset must not be used to override any parameter entities in the DTD.

Here is an example of a Conforming CCXML Document:

<?xml version="1.0" encoding="UTF-8"?>

<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.w3.org/2002/09/ccxml http://www.w3.org/TR/ccxml/ccxml.xsd">

  <eventprocessor>
    <transition event="connection.alerting" name="evt">
      <log expr="'Hello World'"/>
      <exit/>
    </transition>
  </eventprocessor>

</ccxml>

Note that in this example, the recommended xmlns:xsi and xsi:schemaLocation attributes are included. Note also, the inclusion of an XML declaration. An XML declaration like the one above is not required in all XML documents. CCXML document authors are strongly encouraged to use XML declarations in all their documents. Such a declaration is required when the character encoding of the document is other than the default UTF-8 or UTF-16 and no encoding was determined by a higher-level protocol.

The CCXML language or these conformance criteria provide no designated size limits on any aspect of CCXML documents. There are no maximum values on the number of elements, the amount of character data, or the number of characters in attribute values.

J2. Using CCXML with other namespaces

The CCXML namespace may be used with other XML namespaces as per [XMLNS], although such documents are not strictly conforming CCXML documents as defined above. Future work by W3C will address ways to specify conformance for documents involving multiple namespaces.

J3. Conforming CCXML Processors

A CCXML Processor is a program that can parse and process Conforming CCXML Documents. In a CCXML Processor, the XML parser must be able to parse and process all XML constructs defined by XML 1.0 [XML] and Namespaces in XML [XMLNS]. This XML parser is not required to perform validation of a CCXML document as per its schema or DTD; this implies that during processing of a CCXML document it is optional to apply or expand external entity references defined in an external DTD.

A Conforming CCXML Processor must correctly understand and apply the semantics of each markup element as described by this document.

When a Conforming CCXML Processor encounters elements or attributes, other than xml:lang and xml:base, in a non-CCXML namespace it may: