Web Services Eventing (WS-Eventing)

2.1 Requirements

This specification intends to meet the following requirements:

• Define means to create and delete event subscriptions.

• Define expiration for subscriptions and allow them to be renewed.

• Define how one Web service can subscribe on behalf of another.

• Define how an event source delegates subscription management to another Web service.

• Allow subscribers to specify how notifications are to be delivered.

• Leverage other Web service specifications for secure, reliable, transacted message delivery.

• Support complex eventing topologies that allow the originating event source and the final event sink to be decoupled.

• Provide extensibility for more sophisticated and/or currently unanticipated subscription scenarios.

• Support a variety of encoding formats, including (but not limited to) both SOAP 1.1 [SOAP11] and SOAP 1.2 [SOAP12] Envelopes.

2.2 Delivery

This specification defines a method for transmitting notifications to the event sink through the use of the wse:NotifyTo element. Other methods or combination of methods MAY be defined through the use of delivery extensions.

When the wse:NotifyTo element is used within the Delivery element it specifies the endpoint to which notifications are sent. For delivery to addressable endpoints this is sufficient. However, for non-addressable endpoints some additional mechanisms are needed. A subscription manager MAY choose to support mechanisms, such as the [WS-MakeConnection] specification, to enable delivery of notifications to non-addressable endpoints. See the [WS-MakeConnection] specification for more information, and an example, of how this would work.

2.3 Notification Formats

This specification specifies two delivery formats: wrapped and unwrapped. Use of wrapped format indicates that notification messages MUST be contained in a wrapper element defined by this specification. Use of unwrapped format indicates that notification messages are not contained in a wrapper element.

Filtering occurs prior to any formatting of notification messages. This ensures that regardless of what type of formatting might occur, the same Filter dialect/expression can be used to subset the event stream.

2.4 Subscription Managers

In some scenarios the event source itself manages the subscriptions it has created. In other scenarios, for example a geographically distributed publish-and-subscribe system, it might be useful to delegate the management of a subscription to another Web service. To support this flexibility, the response to a subscription request to an event source will include the EPR of a service that the subscriber MAY interact with to manage this subscription. This EPR MUST be the target for future requests to renew or cancel the subscription. It can address the same Web service (Address and ReferenceParameters) as the event source itself, or it can address some other Web service to which the event source has delegated management of this subscription; however, the full subscription manager EPR (Address and Reference Parameters) MUST be unique for each subscription.

The term "subscription manager" is used in this specification to refer to the Web service that manages the subscription, whether it is the event source itself or some separate Web service.

2.5 Example

Example 2-1 lists a hypothetical request to create a subscription for storm warnings.

(01) <s12:Envelope
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ew="http://www.example.com/warnings" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/Subscribe
(09)     </wsa:Action>
(10)     <wsa:MessageID>
(11)       uuid:d7c5726b-de29-4313-b4d4-b3425b200839
(12)     </wsa:MessageID>
(13)     <wsa:ReplyTo>
(14)      <wsa:Address>http://www.example.com/MyEventSink</wsa:Address>
(15)     </wsa:ReplyTo>
(16)     <wsa:To>http://www.example.org/oceanwatch/EventSource</wsa:To>
(17)   </s12:Header>
(18)   <s12:Body>
(19)     <wse:Subscribe>
(20)       <wse:Delivery>
(21)         <wse:NotifyTo>
(22)           <wsa:Address>
(23)             http://www.example.com/MyEventSink/OnStormWarning
(24)           </wsa:Address>
(25)           <wsa:ReferenceParameters>
(26)             <ew:MySubscription>2597</ew:MySubscription>
(27)           </wsa:ReferenceParameters>
(28)         </wse:NotifyTo>
(29)       </wse:Delivery>
(30)     </wse:Subscribe>
(31)   </s12:Body>
(32) </s12:Envelope>

Lines (07-09) in Example 2-1 indicate the message is a request to create a subscription, and line (16) indicates that it is sent to a hypothetical event source of ocean events.

While lines (13-15) indicate where a reply is sent, lines (20-29) indicate where and how notifications are to be delivered; there is no requirement that these match. The absence of any extensions to the wse:Delivery or wse:NotifyTo elements indicates that notifications are sent as SOAP messages to the endpoint described in lines (21-28). Note that lines (25-27) illustrate a typical pattern where the event sink lists a reference parameter (line 26) that identifies the subscription and will be included in each notification.

Example 2-2 lists a hypothetical response to the request in Example 2-1.

(01) <s12:Envelope
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ow="http://www.example.org/oceanwatch" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/SubscribeResponse
(09)     </wsa:Action>
(10)     <wsa:RelatesTo>
(11)       uuid:d7c5726b-de29-4313-b4d4-b3425b200839
(12)     </wsa:RelatesTo>
(13)     <wsa:To>http://www.example.com/MyEventSink</wsa:To>
(14)   </s12:Header>
(15)   <s12:Body>
(16)     <wse:SubscribeResponse>
(17)       <wse:SubscriptionManager>
(18)         <wsa:Address>
(19)           http://www.example.org/oceanwatch/SubscriptionManager
(20)         </wsa:Address>
(21)         <wsa:ReferenceParameters>
(22)           <ow:MyId>
(23)             28
(24)           </ow:MyId>
(25)         </wsa:ReferenceParameters>
(26)       </wse:SubscriptionManager>
(27)       <wse:GrantedExpires>P0Y0M0DT30H0M0S</wse:GrantedExpires>
(28)     </wse:SubscribeResponse>
(29)   </s12:Body>
(30) </s12:Envelope>

Lines (07-09) in Example 2-2 indicate this message is a response to a request to create a subscription, and lines (10-12) indicate that it is a response to the request in Example 2-1. Lines (17-26) provide the subscription manager EPR for this subscription, and line (27) indicates the subscription will expire in 30 hours unless renewed.

3.1 Notational Conventions

The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC 2119].

This specification uses the following syntax to define normative outlines for messages:

• The syntax appears as an XML instance, but values in italics indicate data types instead of values.

• Characters are appended to elements and attributes to indicate cardinality:

  • "?" (0 or 1)

  • "*" (0 or more)

  • "+" (1 or more)

• The character "|" is used to indicate a choice between alternatives.

• The characters "(" and ")" are used to indicate that contained items are to be treated as a group with respect to cardinality or choice.

• The characters "[" and "]" are used to call out references and property names.

• Ellipsis (i.e. "...") indicate a point of extensibility.

• XML namespace prefixes (see Table 3-1) are used to indicate the namespace of the element being defined.

In addition to Message Information Header properties [WS-Addressing], this specification uses the following properties to define messages:

[Headers]

Unordered message headers.

[Action]

The value to be used for the wsa:Action IRI.

[Body]

A message body.

These properties bind to a SOAP Envelope as follows:

<s:Envelope>
  <s:Header>
    [Headers]
    <wsa:Action>[Action]</wsa:Action>
    ...
  </s:Header>
  <s:Body>[Body]</s:Body>
</s:Envelope>

This specification can be used in terms of XML Information Set (Infoset) [XML Infoset], even though the specification uses XML 1.0 terminology. Valid Infoset for this specification is the one serializable in XML 1.0, hence the use of XML 1.0.

3.2 Considerations on the Use of Extensibility Points

The elements defined in this specification MAY be extended at the points indicated by their outlines and schema. Implementations MAY add child elements and/or attributes at the indicated extension points but MUST NOT contradict the semantics of the parent and/or owner, respectively. If a receiver does not recognize an extension, the receiver SHOULD ignore that extension. Senders MAY indicate the presence of an extension that has to be understood through the use of a corresponding SOAP Header with a soap:mustUnderstand attribute with the value "1".

In cases where it is either desirable or necessary for the receiver of a request that has been extended to indicate that it has recognized and accepted the semantics associated with that extension, it is RECOMMENDED that the receiver add a corresponding extension to the response message. The definition of an extension SHOULD clearly specify how the extension that appears in the response correlates with that in the corresponding request.

Extension elements and attributes MUST NOT use the Web Services Eventing namespace URI.

3.3 XML Namespaces

The XML namespace URI that MUST be used by implementations of this specification is:

http://www.w3.org/2009/12/ws-evt

Table 3-1 lists XML namespaces that are used in this specification. The choice of any namespace prefix is arbitrary and not semantically significant.

The working group intends to update the value of the Web Services Eventing namespace URI each time a new version of this document is published until such time that the document reaches Candidate Recommendation status. Once it has reached Candidate Recommendation status, the working group intends to maintain the value of the Web Services Eventing namespace URI that was assigned in the Candidate Recommendation unless significant changes are made that impact the implementation or break post-CR implementations of the specification. Also see http://www.w3.org/2001/tag/doc/namespaceState.html and http://www.w3.org/2005/07/13-nsuri .

3.4 Terminology

Event Source

A Web service that accepts requests to create subscriptions. Notifications MAY be sent by any endpoint including the event source.

Event Sink

A Web service that receives notifications.

Notification

A message sent to indicate that an event, or events, have occurred.

Subscription

A registration of interest in receiving notification messages from an event source. Subscriptions MAY be created, renewed, expired or cancelled. A subscription is "active" when it has been created but has not been expired or cancelled.

Subscriber

A Web service that sends requests to create, renew, and/or delete subscriptions.

Subscription Manager

A Web service that accepts requests to manage, get the status of, renew, and/or delete subscriptions on behalf of an event source.

3.5 Compliance

An implementation is not compliant with this specification if it fails to satisfy one or more of the MUST or REQUIRED level requirements defined herein. A SOAP Node MUST NOT use the XML namespace identifier for this specification (listed in 3.3 XML Namespaces) within SOAP Envelopes unless it is compliant with this specification.

Normative text within this specification takes precedence over the XML Schema and WSDL descriptions, which in turn take precedence over outlines, which in turn take precedence over examples.

All messages defined by this specification MUST be sent to a Web service that is addressable by an EPR (see [WS-Addressing]).

Unless otherwise noted, all IRIs are absolute IRIs and IRI comparison MUST be performed according to [RFC 3987] section 5.3.1.

For any message defined by this specification, any OPTIONAL elements or attributes in the message MAY be used by senders of the message, however receivers of those messages MUST understand those OPTIONAL elements and attributes, unless other behavior is explicitly defined by this specification.

4.1 Subscribe

To create a subscription, a subscriber sends a request message of the following form to an event source:

[Action]
  http://www.w3.org/2009/12/ws-evt/Subscribe

[Body]
  <wse:Subscribe ...>
    <wse:EndTo> endpoint-reference </wse:EndTo> ?
    <wse:Delivery ...> xs:any* </wse:Delivery>
    <wse:Format Name="xs:anyURI"? > xs:any* </wse:Format> ?
    <wse:Expires min="(xs:dateTime | xs:duration)"?
                 max="(xs:dateTime | xs:duration)"?
                 exact="xs:boolean"? ...>
      (xs:dateTime | xs:duration)
    </wse:Expires> ?
    <wse:Filter Dialect="xs:anyURI"? ...> xs:any* </wse:Filter> ?
    xs:any*
  </wse:Subscribe>

The following describes additional, normative constraints on the outline listed above:

[Body]/wse:Subscribe/wse:EndTo

Where to send a SubscriptionEnd message if the subscription is terminated unexpectedly. (See 4.5 Subscription End.) If present, this element MUST be of type wsa:EndpointReferenceType. Default is not to send this message. The endpoint to which the EndTo EPR refers MUST support the SubcriptionEndPortType portType.

Note, subscribers wishing to correlate SubscriptionEnd messages with the subscription to which they apply MAY wish to add a distinguishing reference parameter to the EndTo EPR.

[Body]/wse:Subscribe/wse:Delivery

This element contains the information necessary to convey notification messages to the event sink in a manner required by the subscriber. This element MUST contain at least one child element.

[Body]/wse:Subscribe/wse:Delivery/wse:NotifyTo

This is an OPTIONAL element. When present, this element indicates that notifications MUST be sent to the EndpointReference identified by this element.

[Body]/wse:Subscribe/wse:Format

This OPTIONAL element contains the delivery format to be used for notification messages sent in relation to this subscription. Implied value is "http://www.w3.org/2009/12/ws-evt/DeliveryFormats/Unwrap", which indicates that unwrapped delivery MUST be used. See Section 2.3 Notification Formats for details.

If the event source does not support the requested delivery format, the request MUST generate a wse:DeliveryFormatRequestedUnavailable fault indicating that the requested delivery format is not supported.

[Body]/wse:Subscribe/wse:Format@Name="http://www.w3.org/2009/12/ws-evt/DeliveryFormats/Unwrap"

Indicate the unwrapped event delivery format.

[Body]/wse:Subscribe/wse:Format@Name="http://www.w3.org/2009/12/ws-evt/DeliveryFormats/Wrap"

Indicate the wrapped event delivery format.

[Body]/wse:Subscribe/wse:Expires

This OPTIONAL element can be used by the subscriber to indicate the expiration time of the requested subscription. The value of this element indicates the desired expiration time for the subscription. The implied default is indefinite (no expiry). The value of this element MUST be between the values of the @min and @max attributes inclusive. If the request is malformed, the event source MUST generate a wse:InvalidExpirationTime fault.

If the wse:Expires element is present and the event source is not able to grant an expiry time within range indicated by the @min and @max attribute values, it MUST generate a wse:ExpirationTimeExceeded fault.

The value of the wse:Expires element as well as those of its @min and @max attributes MAY be either a duration (xs:duration) or a specific time (xs:dateTime). Event sources and subscription managers MUST accept duration values and MAY accept specific time values. Upon receiving a request that contains specific time values, an event source or subscription manager that does not support such value types MUST fail the request and generate a wse:UnsupportedExpirationType fault.

The value types in a wse:Expires element MAY differ among the element and its attributes. For example, the element value can be a duration while the @max attribute can be a specific time. Regardless of the value types, it MUST be true that wse:Expires/@min <= wse:Expires <= wse:Expires/@max as interpreted by the event source or subscription manager at the time the wse:Subscribe request is processed. If this is not true, the request MUST fail and the receiver MUST generate a wse:InvalidExpirationTime fault.

If a subscriber chooses to use specific time values in a request, it is RECOMMENDED that these values include a time zone component. Specific time values that lack a time zone will be interpreted in the local time zone of the receiver.

[Body]/wse:Subscribe/wse:Expires@min

The implied default is PT0S. This specifies the minimum expiration time that the event subscriber is willing to accept.

[Body]/wse:Subscribe/wse:Expires@max

The implied default is indefinite (no expiry). This specifies the maximum expiration time that the event subscriber is willing to accept.

[Body]/wse:Subscribe/wse:Expires@exact

The default value is "false" in which case this attribute has no effect. If this attribute value is "true" both @min and @max attributes MUST be ignored and are treated as if they had the same value as the wse:Expires element.

[Body]/wse:Subscribe/wse:Filter

A Boolean expression in some dialect, either as a string or as an XML fragment (see [ [Body]/wse:Subscribe/wse:Filter/@Dialect ]). If the expression evaluates to false for a notification, the notification MUST NOT be sent to the event sink. Implied value is an expression that always returns true. If the event source does not support filtering, then a request that specifies a filter MUST fail, and the event source MUST generate a wse:FilteringNotSupported fault indicating that filtering is not supported.

If the event source supports filtering but cannot honor the requested filtering, the request MUST fail, and the event source MUST generate a wse:FilteringRequestedUnavailable fault indicating that the requested filter dialect is not supported.

It is possible for a Subscribe request to contain a filter that will never evaluate to true for the lifetime of the subscription. If an event source detects this condition it MUST generate a wse:EmptyFilter fault in response to the Subscribe request message.

[Body]/wse:Subscribe/wse:Filter/@Dialect

Implied value is "http://www.w3.org/2009/12/ws-evt/Dialects/XPath10".

While an XPath predicate expression provides great flexibility and power, alternate filter dialects MAY be defined. For instance, a simpler, less powerful dialect might be defined for resource-constrained implementations, or a new dialect might be defined to support filtering based on data not included in the notification message itself. If desired, a filter dialect could allow the definition of a composite filter that contained multiple filters from other dialects. New dialect definitions MUST include sufficient information for proper application. For example, it would need to include the context (which data) over which the filter operates.

[Body]/wse:Subscribe/wse:Filter/@Dialect=" http://www.w3.org/2009/12/ws-evt/Dialects/XPath10 "

Value of [Body]/wse:Subscribe/wse:Filter is an XPath [XPath1.0] predicate expression (PredicateExpr); the context of the expression is:

• Context Node: the root of the event XML.

• Context Position: 1.

• Context Size: 1.

• Variable Bindings: None.

• Function Libraries: Core Function Library [XPath1.0].

• Namespace Declarations: The [in-scope namespaces] property [XML Infoset] of /s:Envelope/s:Body/*/wse:Filter.

Other components of the outline above are not further constrained by this specification.

If included within the Subscribe request message, the wse:NotifyTo and wse:EndTo SHOULD have some cursory validity checking performed before the Subscribe response is returned. While not all errors can be detected prior to sending a message to those EPRs, some obvious ones can be detected. For example, an unsupported transport specified within the wsa:Address IRI. Detecting these errors during Subscribe processing will lessen the chances of the subscriber creating an unusable subscription. If this check is performed and a problem is detected then the event source MUST generate a wse:UnusableEPR fault rather than returning the SubscribeResponse message.

If the event source chooses not to accept a subscription due to the content of the Subscribe message, then the event source MUST generate a SOAP 1.1 Client fault or a SOAP 1.2 Sender fault. If the event source does not accept this subscription due to an internal processing reason and not due to the specific content of the Subscribe message, then the event source MUST generate a SOAP 1.1 Server fault or a SOAP 1.2 Receiver fault which MAY contain the RetryAfter fault detail element.

If the event source accepts a request to create a subscription, it MUST reply with a response of the following form:

[Action]
  http://www.w3.org/2009/12/ws-evt/SubscribeResponse

[Body]
  <wse:SubscribeResponse ...>
    <wse:SubscriptionManager>
      wsa:EndpointReferenceType
    </wse:SubscriptionManager>
    <wse:GrantedExpires ...>
      (xs:dateTime | xs:duration)
    </wse:GrantedExpires> ?
    xs:any*
  </wse:SubscribeResponse>

The following describes additional, normative constraints on the outline listed above:

[Body]/wse:SubscribeResponse/wse:SubscriptionManager

The EPR of the subscription manager for this subscription.

In some cases, it is convenient for all EPRs issued by a single event source to address a single Web service and use a reference parameter to distinguish among the active subscriptions.

[Body]/wse:SubscribeResponse/wse:GrantedExpires

The expiration time assigned by the event source. The expiration time MAY be either a specific time or a duration but MUST be of the same type as the wse:Expires element of the corresponding request. If the corresponding request did not contain a wse:Expires element, this element MUST be a duration (xs:duration).

When expressed as a duration, the wse:GrantedExpires element designates a time interval that began at the moment the subscription is created. Although this specification cannot dictate when, during the processing of a Subscribe request, a subscription is created, the event source MUST start the expiration interval at or before it transmits the wse:SubscribeResponse message.

If this element does not appear, then the subscription will not expire. That is, the subscription has an indefinite lifetime. It MAY be terminated by the subscriber using an Unsubscribe request, or it MAY be terminated by the event source at any time for reasons such as connection termination, resource constraints, or system shut-down.

Other components of the outline above are not further constrained by this specification.

Example 4-1 lists another hypothetical request to create a subscription.

(01) <s12:Envelope 
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ew="http://www.example.com/warnings" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/Subscribe
(09)     </wsa:Action>
(10)     <wsa:MessageID>
(11)       uuid:e1886c5c-5e86-48d1-8c77-fc1c28d47180
(12)     </wsa:MessageID>
(13)     <wsa:ReplyTo>
(14)      <wsa:Address>http://www.example.com/MyEvEntsink</wsa:Address>
(15)      <wsa:ReferenceParameters>
(16)        <ew:MySubscription>2597</ew:MySubscription>
(17)      </wsa:ReferenceParameters>
(18)     </wsa:ReplyTo>
(19)     <wsa:To>http://www.example.org/oceanwatch/EventSource</wsa:To>
(20)   </s12:Header>
(21)   <s12:Body>
(22)     <wse:Subscribe>
(23)       <wse:EndTo>
(24)         <wsa:Address>
(25)           http://www.example.com/MyEventSink
(26)         </wsa:Address>
(27)         <wsa:ReferenceParameters>
(28)           <ew:MySubscription>2597</ew:MySubscription>
(29)         </wsa:ReferenceParameters>
(30)       </wse:EndTo>
(31)       <wse:Delivery>
(32)         <wse:NotifyTo>
(33)           <wsa:Address>
(34)             http://www.other.example.com/OnStormWarning
(35)           </wsa:Address>
(36)           <wsa:ReferenceParameters>
(37)             <ew:MySubscription>2597</ew:MySubscription>
(38)           </wsa:ReferenceParameters>
(39)         </wse:NotifyTo>
(40)       </wse:Delivery>
(41)       <wse:Expires>2004-06-26T21:07:00.000-08:00</wse:Expires>
(42)       <wse:Filter xmlns:ow="http://www.example.org/oceanwatch" >
(43)         /*/ow:Speed/[node() &gt; 50]
(44)       </wse:Filter>
(45)     </wse:Subscribe>
(46)   </s12:Body>
(47) </s12:Envelope>

Like the request in Example 2-1, lines (07-09) of Example 4-1 indicate the message is a request to create a subscription. Line (19) indicates that it is sent to a hypothetical event source of ocean events.

Lines (13-18) indicate where to send the response to this request, lines (23-30) indicate where to send a SubscriptionEnd message if necessary, and lines (31-34) indicate how and where to send notifications.

Line (41) indicates the event sink would prefer to have the subscription expire on 26 June 2004 at 9:07 PM Pacific time.

Lines (42-44) indicate the event sink only wants weather reports where the speed of wind is greater than 50.

Example 4-2 lists a hypothetical response to the request in Example 4-1.

(01) <s12:Envelope 
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ew="http://www.example.com/warnings"
(06)     xmlns:ow="http://www.example.org/oceanwatch" >
(07)   <s12:Header>
(08)     <wsa:Action>
(09)       http://www.w3.org/2009/12/ws-evt/SubscribeResponse
(10)     </wsa:Action>
(11)     <wsa:RelatesTo>
(12)       uuid:e1886c5c-5e86-48d1-8c77-fc1c28d47180
(13)     </wsa:RelatesTo>
(14)     <wsa:To>http://www.example.com/MyEventSink</wsa:To>
(15)     <ew:MySubscription wsa:IsReferenceParameter="true">
(16)       2597
(17)     </ew:MySubscription>
(18)   </s12:Header>
(19)   <s12:Body>
(20)     <wse:SubscribeResponse>
(21)       <wse:SubscriptionManager>
(22)         <wsa:Address>
(23)           http://www.example.org/oceanwatch/SubscriptionManager
(24)         </wsa:Address>
(25)         <wsa:ReferenceParameters>
(26)           <x:SubID xmlns:x="http://example.com">
(27)             uuid:22e8a584-0d18-4228-b2a8-3716fa2097fa
(28)           </x:SubID>
(29)         </wsa:ReferenceParameters>
(30)       </wse:SubscriptionManager>
(31)       <wse:Expires>2004-07-01T00:00:00.000-00:00</wse:Expires>
(32)     </wse:SubscribeResponse>
(33)   </s12:Body>
(34) </s12:Envelope>

Like the response in Example 2-2, lines (08-10) of Example 4-2 indicate this message is a response to a request to create a subscription, and lines (11-13) indicate that it is a response to the request in Example 4-1 . Lines (14-17) indicate the response is sent to the event sink indicated in lines (13-18) of Example 4-1. Lines (21-30) provide the address of the subscription manager for this subscription; note that this particular response uses the x:SubID element as a reference parameter to distinguish this subscription EPR from other subscription EPRs. Finally, line (31) indicates the subscription will expire on 1 July 2004 unless renewed; there is no requirement that this time be necessarily longer or shorter than the requested expiration (line (41) of Example 4-1).

4.2 Renew

To update the expiration for a subscription, subscription managers MUST support requests to renew subscriptions.

To renew a subscription, the subscriber sends a request of the following form to the subscription manager:

[Action]
  http://www.w3.org/2009/12/ws-evt/Renew

[Body]
  <wse:Renew ...>
    <wse:Expires min="(xs:dateTime | xs:duration)"?
                 max="(xs:dateTime | xs:duration)"?
                 exact="xs:boolean"? ...>
      (xs:dateTime | xs:duration)
    </wse:Expires> ?
    xs:any*
  </wse:Renew>

Components of the outline listed above are additionally constrained as for a request to create a subscription (see 4.1 Subscribe). Other components of the outline above are not further constrained by this specification.

If the subscription is not active, the request MUST fail and the subscription manager MAY generate a wse:UnknownSubscription fault.

If the subscription manager chooses not to renew this subscription, the request MUST fail, and the subscription manager MUST generate a SOAP 1.1 Server fault or a SOAP 1.2 Receiver fault indicating that the renewal was not accepted. This fault MAY contain the RetryAfter fault detail element.

If the subscription manager accepts a request to renew a subscription, it MUST reply with a response of the following form:

[Action]
  http://www.w3.org/2009/12/ws-evt/RenewResponse

[Body]
  <wse:RenewResponse ...>
    <wse:GrantedExpires ...>
      (xs:dateTime | xs:duration)
    </wse:GrantedExpires> ?
    xs:any*
  </wse:RenewResponse>

Components of the outline listed above are constrained as for a response to a subscribe request (see 4.1 Subscribe). Other components of the outline above are not further constrained by this specification.

Example 4-3 lists a hypothetical request to renew the subscription created in Example 4-2.

(01) <s12:Envelope 
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ow="http://www.example.org/oceanwatch" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/Renew
(09)     </wsa:Action>
(10)     <wsa:MessageID>
(11)       uuid:bd88b3df-5db4-4392-9621-aee9160721f6
(12)     </wsa:MessageID>
(13)     <wsa:ReplyTo>
(14)      <wsa:Address>http://www.example.com/MyEventSink</wsa:Address>
(15)     </wsa:ReplyTo>
(16)     <wsa:To>
(17)       http://www.example.org/oceanwatch/SubscriptionManager
(18)     </wsa:To>
(19)     <x:SubID wsa:IsReferenceParameter="true" xmlns:x="http://example.com">
(20)       uuid:22e8a584-0d18-4228-b2a8-3716fa2097fa
(21)     </x:SubID>
(22)   </s12:Header>
(23)   <s12:Body>
(24)     <wse:Renew>
(25)       <wse:Expires>2004-06-26T21:07:00.000-08:00</wse:Expires>
(26)     </wse:Renew>
(27)   </s12:Body>
(28) </s12:Envelope>

Lines (07-09) indicate this is a request to renew a subscription. Lines (19-21) contain the reference parameter that indicates the subscription to be renewed is the one created in Example 4-2. Line (25) in Example 4-3 indicates the request is to extend the subscription until 26 June 2004 at 9:07 PM Pacific.

Example 4-4 lists a hypothetical response to the request in Example 4-3.

(01) <s12:Envelope
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ow="http://www.example.org/oceanwatch" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)      http://www.w3.org/2009/12/ws-evt/RenewResponse
(09)     </wsa:Action>
(10)     <wsa:RelatesTo>
(11)       uuid:bd88b3df-5db4-4392-9621-aee9160721f6
(12)     </wsa:RelatesTo>
(13)     <wsa:To>http://www.example.com/MyEventSink</wsa:To>
(14)   </s12:Header>
(15)   <s12:Body>
(16)     <wse:RenewResponse>
(17)       <wse:Expires>2004-06-26T12:00:00.000-00:00</wse:Expires>
(18)     </wse:RenewResponse>
(19)   </s12:Body>
(20) </s12:Envelope>

Line (17) in Example 4-4 indicates the subscription has been extended only until 26 June 2004 at noon.

4.3 GetStatus

To get the status of a subscription, the subscriber sends a request of the following form to the subscription manager:

[Action]
  http://www.w3.org/2009/12/ws-evt/GetStatus

[Body]
  <wse:GetStatus ...>
    xs:any*
  </wse:GetStatus>

Components of the outline listed above are additionally constrained as for a request to renew a subscription (see 4.2 Renew). Other components of the outline above are not further constrained by this specification.

If the subscription is active, the subscription manager MUST reply with a response of the following form:

[Action]
  http://www.w3.org/2009/12/ws-evt/GetStatusResponse

[Body]
  <wse:GetStatusResponse ...>
    <wse:GrantedExpires ...>
      (xs:dateTime | xs:duration)
    </wse:GrantedExpires> ?
    xs:any*
  </wse:GetStatusResponse>

If the subscription is not active, the request MUST fail and the subscription manager MAY generate a wse:UnknownSubscription fault.

Components of the outline listed above are constrained as for a response to a renew request (see 4.2 Renew). Other components of the outline above are not further constrained by this specification.

This operation is safe; it will not result in any side effect imputable to the requester. This means that in case of an underlying protocol error that might get unnoticed, resending the same request can be done automatically.

Example 4-5 lists a hypothetical request to get the status of the subscription created in Example 4-2.

(01) <s12:Envelope
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ow="http://www.example.org/oceanwatch" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/GetStatus
(09)     </wsa:Action>
(10)     <wsa:MessageID>
(11)       uuid:bd88b3df-5db4-4392-9621-aee9160721f6
(12)     </wsa:MessageID>
(13)     <wsa:ReplyTo>
(14)       <wsa:Address>http://www.example.com/MyEventSink</wsa:Address>
(15)     </wsa:ReplyTo>
(16)     <wsa:To>
(17)       http://www.example.org/oceanwatch/SubscriptionManager
(18)     </wsa:To>
(19)     <x:SubID wsa:IsReferenceParameter="true" xmlns:x="http://example.com">
(20)       uuid:22e8a584-0d18-4228-b2a8-3716fa2097fa
(21)     </x:SubID>
(22)   </s12:Header>
(23)   <s12:Body>
(24)     <wse:GetStatus />
(25)   </s12:Body>
(26) </s12:Envelope>

Lines (07-09) indicate this is a request to get the status of a subscription. Lines (16-21) indicate that the request is sent to the subscription manager for the subscription created in Example 4-2.

Example 4-6 lists a hypothetical response to the request in Example 4-5.

(01) <s12:Envelope 
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ow="http://www.example.org/oceanwatch" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/GetStatusResponse
(09)     </wsa:Action>
(10)     <wsa:RelatesTo>
(11)       uuid:bd88b3df-5db4-4392-9621-aee9160721f6
(12)     </wsa:RelatesTo>
(13)     <wsa:To>http://www.example.com/MyEventSink</wsa:To>
(14)   </s12:Header>
(15)   <s12:Body>
(16)     <wse:GetStatusResponse>
(17)       <wse:Expires>2004-06-26T12:00:00.000-00:00</wse:Expires>
(18)     </wse:GetStatusResponse>
(19)   </s12:Body>
(20) </s12:Envelope>

Line (17) in Example 4-6 indicates the subscription will expire on 26 June 2004 at noon.

4.4 Unsubscribe

Though subscriptions expire eventually, to minimize resources, the subscriber SHOULD explicitly delete a subscription when it no longer wants notifications associated with the subscription.

To explicitly delete a subscription, a subscriber sends a request of the following form to the subscription manager:

[Action]
  http://www.w3.org/2009/12/ws-evt/Unsubscribe

[Body]
  <wse:Unsubscribe ...>
    xs:any*
  </wse:Unsubscribe>

Components of the outline above are additionally constrained only as for a request to renew a subscription (see 4.2 Renew). For example, the faults listed there are also defined for a request to delete a subscription.

If the subscription manager accepts a request to delete a subscription, it MUST reply with a response of the following form:

[Action]
  http://www.w3.org/2009/12/ws-evt/UnsubscribeResponse

[Body]
  <wse:UnsubscribeResponse ...>
    xs:any*
  </wse:UnsubscribeResponse>

If the subscription is not active, the request MUST fail and the subscription manager MAY generate a wse:UnknownSubscription fault.

Components of the outline listed above are not further constrained by this specification.

Example 4-7 lists a hypothetical request to delete the subscription created in Example 4-2.

(01) <s12:Envelope 
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt"
(05)     xmlns:ow="http://www.example.org/oceanwatch" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/Unsubscribe
(09)     </wsa:Action>
(10)     <wsa:MessageID>
(11)       uuid:2653f89f-25bc-4c2a-a7c4-620504f6b216
(12)     </wsa:MessageID>
(13)     <wsa:ReplyTo>
(14)      <wsa:Address>http://www.example.com/MyEventSink</wsa:Address>
(15)     </wsa:ReplyTo>
(16)     <wsa:To>
(17)       http://www.example.org/oceanwatch/SubscriptionManager
(18)     </wsa:To>
(19)     <x:SubID wsa:IsReferenceParameter="true" xmlns:x="http://example.com">
(20)       uuid:22e8a584-0d18-4228-b2a8-3716fa2097fa
(21)     </x:SubID>
(22)   </s12:Header>
(23)   <s12:Body>
(24)     <wse:Unsubscribe />
(25)   </s12:Body>
(26) </s12:Envelope>

Lines (07-09) in Example 4-7 indicate the message is a request to delete a subscription. Lines (16-21) indicate that the request is addressed to the manager for the subscription created in Example 4-2.

Example 4-8 lists a hypothetical response to the request in Example 4-7.

(01) <s12:Envelope 
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing" >
(04)   <s12:Header>
(05)     <wsa:Action>
(06)       http://www.w3.org/2009/12/ws-evt/UnsubscribeResponse
(07)     </wsa:Action>
(08)     <wsa:RelatesTo>
(09)       uuid:2653f89f-25bc-4c2a-a7c4-620504f6b216
(10)     </wsa:RelatesTo>
(11)     <wsa:To>http://www.example.com/MyEventSink</wsa:To>
(12)   </s12:Header>
(13)   <s12:Body>
(14)     <wse:UnsubscribeResponse/>
(15)   </s12:Body>
(16) </s12:Envelope>

4.5 Subscription End

If the event source terminates a subscription unexpectedly, SubscriptionEnd SOAP message SHOULD be sent to the endpoint reference indicated when the subscription was created (see 4.1 Subscribe). This endpoint reference MUST refer to an endpoint that supports the SubscriptionEndPortType portType. The message MUST be of the following form:

[Action]
  http://www.w3.org/2009/12/ws-evt/SubscriptionEnd

[Body]
  <wse:SubscriptionEnd ...>
    <wse:Status>
      ( http://www.w3.org/2009/12/ws-evt/DeliveryFailure | 
        http://www.w3.org/2009/12/ws-evt/SourceShuttingDown |
        http://www.w3.org/2009/12/ws-evt/SourceCancelling |
        xs:anyURI )
    </wse:Status>
    <wse:Reason xml:lang="language identifier" >xs:string</wse:Reason> ?
    xs:any*
  </wse:SubscriptionEnd>

The following describes additional, normative constraints on the outline listed above:

[Body]/wse:SubscriptionEnd/wse:Status = "http://www.w3.org/2009/12/ws-evt/DeliveryFailure"

This value MUST be used if the event source terminated the subscription because of problems delivering notifications.

[Body]/wse:SubscriptionEnd/wse:Status = "http://www.w3.org/2009/12/ws-evt/SourceShuttingDown"

This value MUST be used if the event source terminated the subscription because the source is being shut down in a controlled manner; that is, if the event source is being shut down but has the opportunity to send a SubscriptionEnd message before it exits.

[Body]/wse:SubscriptionEnd/wse:Status = "http://www.w3.org/2009/12/ws-evt/SourceCancelling"

This value MUST be used if the event source terminated the subscription for some other reason before it expired.

[Body]/wse:SubscriptionEnd/wse:Reason

This OPTIONAL element contains text, in the language specified by the @xml:lang attribute, describing the reason for the unexpected subscription termination.

Other components of the outline above are not further constrained by this specification.

Example 4-9 lists a hypothetical SubscriptionEnd message corresponding to an early termination of the subscription created in Example 4-1.

(01) <s12:Envelope 
(02)     xmlns:s12="http://www.w3.org/2003/05/soap-envelope"
(03)     xmlns:wsa="http://www.w3.org/2005/08/addressing"
(04)     xmlns:wse="http://www.w3.org/2009/12/ws-evt" 
(05)     xmlns:ew="http://www.example.com/warnings" >
(06)   <s12:Header>
(07)     <wsa:Action>
(08)       http://www.w3.org/2009/12/ws-evt/SubscriptionEnd
(09)     </wsa:Action>
(10)     <wsa:To>http://www.example.com/MyEventSink</wsa:To>
(11)     <ew:MySubscription wsa:IsReferenceParameter="true">
(12)       2597
(13)     </ew:MySubscription>
(14)   </s12:Header>
(15)   <s12:Body>
(16)     <wse:SubscriptionEnd>
(17)       <wse:Status>wse:SourceShuttingDown</wse:Status>
(18)       <wse:Reason xml:lang="en-US" >
(19)         Event source going off line.
(20)       </wse:Reason>
(21)     </wse:SubscriptionEnd>
(22)   </s12:Body>
(23) </s12:Envelope>

Line (08) is the action IRI for SubscriptionEnd. Lines (10-13) indicate the message is sent to the EndTo of the subscribe request (lines (23-30) in Example 4-1). Line (17) indicates the event source is shutting down, and lines (18-20) indicate that the event source was going off line.

6.1 Fault Detail RetryAfter Element

The following element MAY be used to convey additional information in the detail element of a fault.

/wse:RetryAfter

This element (whose content is of type xs:unsignedLong) is a suggested minimum duration in milliseconds to wait before retransmitting the message. Omission of this element indicates that a retry is never likely to succeed.

/wse:RetryAfter/@any

OPTIONAL extensibility attributes that do not affect processing.

6.2 InvalidExpirationTime

This fault is generated when a request specifies an expiration that is malformed.

6.3 ExpirationTimeExceeded

This fault is generated when a request specifies an expiration that is not within the min/max range.

6.4 UnsupportedExpirationType

This fault is generated when a Subscribe request specifies an expiration time and the event source is only capable of accepting expiration durations; for instance, if the event source does not have access to absolute time.

6.5 FilteringNotSupported

This fault is generated when a Subscribe request contains a filter and the event source does not support filtering.

6.6 FilteringRequestedUnavailable

This fault is generated when a Subscribe request specifies a filter dialect that the event source does not support. OPTIONALLY, this fault MAY contain a list of supported filter dialect IRIs in the Detail property.

6.7 DeliveryFormatRequestUnavailable

This fault is generated when a Subscribe request specifies a delivery format that is not supported by the event source. OPTIONALLY, this fault MAY contain a list of supported delivery format IRIs in the Detail property.

6.8 EmptyFilter

This fault MAY be generated when an event source detects a wse:Subscribe request containing a filter that, for whatever reason, will never evaluate to true.

6.9 UnusableEPR

This fault MAY be generated when an event source detects that the wse:NotifyTo or wse:EndTo EPR is unusable.

6.10 UnknownSubscription

This fault is generated when a request specifies a subscription that is not active.

7.1 Message Security

It is strongly RECOMMENDED that the communication between services be secured using the mechanisms described in WS-Security [WS-Security]. In order to properly secure messages, the body and all relevant headers need to be included in the signature. Specifically, any headers identified in the <wse:NotifyTo> element and standard messaging headers, such as those from WS-Addressing [WS-Addressing], need to be signed with the body in order to "bind" the two together. For messages with empty bodies, the <s12:Body> element SHOULD be signed so content cannot be added in transit.

Different security mechanisms MAY be desired depending on the frequency of messages. For example, for infrequent messages, public key technologies MAY be adequate for integrity and confidentiality. However, for high-frequency events, it MAY be more performant to establish a security context for the events using the mechanisms described in WS-Trust [WS-Trust] and WS-SecureConversation [WS-SecureConversation].

Note that if a shared secret is used it is RECOMMENDED that derived keys be used to strengthen the secret as described in WS-SecureConversation.

The following list summarizes common classes of attacks that apply to this protocol and identifies the mechanism to prevent/mitigate the attacks:

• Message alteration - Alteration is prevented by including signatures of the message information using WS-Security.

• Message disclosure - Confidentiality is preserved by encrypting sensitive data using WS-Security.

• Key integrity - Key integrity is maintained by using the strongest algorithms possible (by comparing secured policies - see WS-Policy [WS-Policy] and WS-SecurityPolicy [WS-SecurityPolicy]).

• Authentication - Authentication is established using the mechanisms described in WS-Security and WS-Trust. Each message is authenticated using the mechanisms described in WS-Security.

• Accountability - Accountability is a function of the type of and string of the key and algorithms being used. In many cases, a strong symmetric key provides sufficient accountability. However, in some environments, strong PKI signatures are required.

• Availability - All reliable messaging services are subject to a variety of availability attacks. Replay detection is a common attack and it is RECOMMENDED that this be addressed by the mechanisms described in WS-Security. Other attacks, such as network-level denial of service attacks are harder to avoid and are outside the scope of this specification. That said, care SHOULD be taken to ensure that minimal state is saved prior to any authenticating sequences.

• Replay - Messages might be replayed for a variety of reasons. To detect and eliminate this attack, mechanisms SHOULD be used to identify replayed messages such as the timestamp/nonce outlined in WS-Security. Alternatively, and OPTIONALLY, other technologies, such as sequencing, can also be used to prevent replay of application messages.

7.2 Access Control

It is important for event sources and subscription managers to properly authorize requests. This is especially true for Subscribe requests, as otherwise the ability to subscribe on behalf of a third-party event sink could be used to create a distributed denial-of-service attack.

Some possible schemes for validating Subscribe requests include:

• Send a message to the event sink that describes the requested subscription, and then wait for a confirmation message to be returned by the event sink, before the event source accepts the subscription request. While this provides strong assurance that the event sink actually desires the requested subscription, it does not work for event sinks that are not capable of sending a confirmation, and requires additional logic on the event sink.

• Require user authentication on the Subscribe request, and allow only authorized users to Subscribe.

Other mechanisms are also possible. Note that event sources that are not reachable from the Internet have less need to control Subscribe requests.

9.1 EventSource Assertion

The mechanism for indicating that a binding or endpoint conforms to the WS-Eventing specification's definition of an event source is through the use of the Web Services Policy - Framework [WS-Policy] and Web Services Policy - Attachment [WS-Policy Attachment] specifications.

This specification defines a policy assertion (wse:EventSource). The wse:EventSource policy assertion applies to the endpoint policy subject.

For WSDL 1.1, these assertions MAY be attached to wsdl11:port or wsdl11:binding. For WSDL 2.0, they MAY be attached to wsdl20:endpoint or wsdl20:binding. A policy expression containing the wse:EventSource policy assertion MUST NOT be attached to a wsdl:portType or wsdl20:interface.

The wse:EventSource policy assertion is a nested policy container assertion. The meaning of this assertion, when present in a policy alternative, is that WS-Eventing is required to communicate with the subject and that the subject is a WS-Eventing event source.

In order to indicate that the subject supports WS-Eventing but does not require its use, an additional policy alternative SHOULD be provided which does not contain this assertion. The compact authoring style for an OPTIONAL policy assertion (the wsp:Optional attribute) provided by WS-Policy MAY be used to indicate two policy alternatives, one which contains the policy assertion, and another which does not.

The normative outline of this assertion is:

<wse:EventSource ...>
  <wse:DateTimeSupported .../> ?
  <wse:FilterDialect ...> xs:anyURI </wse:FilterDialect> * 
  <wse:MaxExpires ...> xs:duration </wse:MaxExpires> ? 
  <wse:FormatName ...> xs:anyURI </wse:FormatName> * 
  ...
</wse:EventSource>

The following describes additional, normative constraints on the outline listed above:

/wse:EventSource

A policy assertion that specifies that WS-Eventing protocol MUST be used when communicating with this endpoint and that the subject is an event source. This assertion has Endpoint Policy Subject.

/wse:EventSource/wse:DateTimeSupported

When present, this OPTIONAL parameter indicates support for expiration time expressed as specific time (rather than duration).

/wse:EventSource/wse:FilterDialect

When present, this OPTIONAL parameter indicates support for the specified filter dialect IRI.

/wse:EventSource/wse:MaxExpires

When present, this OPTIONAL parameter indicates the maximum subscription expiration time that this endpoint will support. The implied default is indefinite (no expiry). Note: a value of "PT0S" indicates that this endpoint supports subscriptions with an infinite lifetime.

/wse:EventSource/wse:FormatName

When present, this OPTIONAL parameter indicates support for the specified event delivery format name URI.

9.2 SubscriptionManager Assertion

The mechanism for indicating that a binding or endpoint conforms to the WS-Eventing specification's definition of a subscription manager is through the use of the Web Services Policy - Framework [WS-Policy] and Web Services Policy - Attachment [WS-Policy Attachment] specifications.

This specification defines a policy assertion (wse:SubscriptionManager). The wse:SubscriptionManager policy assertion applies to the endpoint policy subject.

For WSDL 1.1, these assertions MAY be attached to wsdl11:port or wsdl11:binding. For WSDL 2.0, they MAY be attached to wsdl20:endpoint or wsdl20:binding. A policy expression containing the wse:SubscriptionManager policy assertion MUST NOT be attached to a wsdl:portType or wsdl20:interface.

The wse:SubscriptionManager policy assertion is a nested policy container assertion. The meaning of this assertion, when present in a policy alternative, is that WS-Eventing is required to communicate with the subject and that the subject is a WS-Eventing subscription manager.

In order to indicate that the subject supports WS-Eventing but does not require its use, an additional policy alternative SHOULD be provided which does not contain this assertion. The compact authoring style for an OPTIONAL policy assertion (the wsp:Optional attribute) provided by WS-Policy MAY be used to indicate two policy alternatives, one which contains the policy assertion, and another which does not.

The normative outline of this assertion is:

<wse:SubscriptionManager ...>
  <wse:DateTimeSupported .../> ?
  <wse:GetStatusOperationSupported .../> ?
  <wse:UnsubscribeOperationSupported .../> ?
  <wse:MaxExpires ...> xs:duration </wse:MaxExpires> ? 
  ...
</wse:SubscriptionManager>

The following describes additional, normative constraints on the outline listed above:

/wse:SubscriptionManager

A policy assertion that specifies that WS-Eventing protocol MUST be used when communicating with this endpoint and that the subject is a subscription manager. This assertion has Endpoint Policy Subject.

/wse:SubscriptionManager/wse:DateTimeSupported

When present, this OPTIONAL parameter indicates support for expiration time expressed as specific time (rather than duration).

/wse:SubscriptionManager/wse:GetStatusOperationSupported

When present, this OPTIONAL parameter indicates that the GetStatus operation is supported by this endpoint.

/wse:SubscriptionManager/wse:UnsubscribeOperationSupported

When present, this OPTIONAL parameter indicates that the Unsubscribe operation is supported by this endpoint.

/wse:SubscriptionManager/wse:MaxExpires

When present, this OPTIONAL parameter indicates the maximum subscriptions expiration time that this endpoint will support. The implied default is indefinite (no expiry). Note: a value of "PT0S" indicates that this endpoint supports subscriptions with an infinite lifetime.

11.1 Normative References

RFC 2119

Key words for use in RFCs to Indicate Requirement Levels , S. Bradner, Author. Internet Engineering Task Force, March 1997. Available at http://www.ietf.org/rfc/rfc2119.txt.

RFC 3986

Uniform Resource Identifier (URI): Generic Syntax , T. Berners-Lee, R. Fields and L. Masinter, Authors. Network Working Group, January 2005. Available at http://www.ietf.org/rfc/rfc3986.txt.

RFC 3987

Internationalized Resource Identifiers (IRIs) , M. Duerst and M. Suignard, Authors. Internet Engineering Task Force, January 2005. Available at http://www.ietf.org/rfc/rfc3987.txt.

SOAP11

W3C Note, "Simple Object Access Protocol (SOAP) 1.1" , D. Box, et al, Editors. World Wide Web Consortium (W3C), 8 May 2000. Available at http://www.w3.org/TR/2000/NOTE-SOAP-20000508/.

SOAP12

W3C Recommendation, "SOAP Version 1.2 Part 1: Messaging Framework" , M. Gudgin, M. Hadley, N. Mendelsohn, J-J. Moreau, H. Frystyk Nielson, Editors. World Wide Web Consortium (W3C), 27 April 2007. Available at http://www.w3.org/TR/soap12-part1/.

WS-Addressing

W3C Recommendation, "Web Services Addressing 1.0 (WS-Addressing)" , M. Gudgin, M. Hadley, T. Rogers, Editors. World Wide Web Consortium (W3C), 9 May 2006. Available at http://www.w3.org/TR/ws-addr-core.

WS-Addressing 1.0 SOAP Binding

W3C Recommendation, "Web Services Addressing 1.0 - SOAP Binding" , M. Gudgin, M. Hadley, T. Rogers, Editors. World Wide Web Consortium (W3C), 9 May 2006. Available at http://www.w3.org/TR/ws-addr-soap.

WS-Policy

W3C Recommendation, "Web Services Policy (WS-Policy) 1.5 - Framework" , A. Vedamuthu, et al., Editors. World Wide Web Consortium (W3C), 4 September 2007. Available at http://www.w3.org/TR/ws-policy/.

WS-Policy Attachment

W3C Recommendation, "Web Services Policy (WS-Policy) 1.5 - Attachment" , A. Vedamuthu, et al., Editors. World Wide Web Consortium (W3C), 4 September 2007. Available at http://www.w3.org/TR/ws-policy-attach.

11.2 Informative References

WS-MakeConnection

OASIS Standard, "Web Services Make Connection (WS-MakeConnection) 1.1" Web Services Make Connection (WS-MakeConnection) , D. Davis, et al., Editors. Organization for the Advancement of Structured Information Standards (OASIS), 2 February 2009. Available at http://docs.oasis-open.org/ws-rx/wsmc/v1.1/wsmc.doc.

WS-MetadataExchange

W3C Working Group Draft, "Web Services Metadata Exchange (WS-MetadataExchange) 1.1" , D. Davis, et al., Editors. World Wide Web Consortium (W3C), 15 September 2009. Available at http://www.w3.org/TR/ws-metadata-exchange.

WS-ReliableMessaging

OASIS Standard, "Web Services Reliable Messaging Protocol (WS-ReliableMessaging) 1.2" , Davis, et al., Editors. Organization for the Advancement of Structured Information Standards (OASIS), 2 February 2009. Available at http://docs.oasis-open.org/ws-rx/wsrm/v1.2/wsrm.doc.

WS-SecureConversation

OASIS Standard, "Web Services Secure Conversation (WS-SecureConversation) 1.4" , A. Nadalin, et al., Editors. Organization for the Advancement of Structured Information Standards (OASIS), 2 February 2009. Available at http://docs.oasis-open.org/ws-sx/ws-secureconversation/v1.4/os/ws-secureconversation-1.4-spec-os.doc.

WS-Security

OASIS Standard, "Web Services Security: SOAP Message Security 1.1" , K. Lawrence, C. Kaler, Editors. Organization for the Advancement of Structured Information Standards (OASIS), 1 February 2006. Available at http://docs.oasis-open.org/wss/v1.1/wss-v1.1-spec-os-SOAPMessageSecurity.pdf.

WS-SecurityPolicy

OASIS Standard, "Web Services Security Policy (WS-SecurityPolicy) 1.3, Version 1.1" , K. Lawrence, C. Kaler, Editors. Organization for the Advancement of Structured Information Standards (OASIS), 2 February 2009. Available at http://docs.oasis-open.org/ws-sx/ws-securitypolicy/v1.3/os/ws-securitypolicy-1.3-spec-os.doc.

WS-Trust

OASIS Standard, "Web Services Trust (WS-Trust) 1.4" , K. Lawrence, C. Kaler, Editors. Organization for the Advancement of Structured Information Standards (OASIS), 2 February 2009. Available at http://docs.oasis-open.org/ws-sx/ws-trust/v1.4/os/ws-trust-1.4-spec-os.doc.

WSDL11

W3C Note, "Web Services Description Language (WSDL) 1.1" , E. Christensen, et al., Editors. World Wide Web Consortium (W3C), 15 March 2001 Available at http://www.w3.org/TR/2001/NOTE-wsdl-20010315.

XML Infoset

W3C Recommendation, "XML Information Set (Second Edition)" , J. Cowan, R. Tobin, Editors. World Wide Web Consortium (W3C), 4 February 2004. Available at http://www.w3.org/TR/xml-infoset.

XMLSchema - Part 1

W3C Recommendation, "XML Schema Part 1: Structures (Second Edition)" , H. Thompson, et al., Editors. World Wide Web Consortium (W3C), 28 October 2004. Available at http://www.w3.org/TR/xmlschema-1/.

XMLSchema - Part 2

W3C Recommendation, "XML Schema Part 2: Datatypes (Second Edition)" , P. Biron, A. Malhotra, Editors. World Wide Web Consortium (W3C), 28 October 2004. Available at http://www.w3.org/TR/xmlschema-2/.

XPath1.0

W3C Recommendation, "XML Path Language (XPath) Version 1.0" , J. Clark, S. DeRose, Editors. World Wide Web Consortium (W3C), 16 November 1999. Available at http://www.w3.org/TR/xpath.