This document is a glossary of terms used in other documents produced by
the Device Independence Working Group (DIWG). Details of the entire series of
documents can be found on the W3C Device
Independence Activity home page.
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 glossary is published and maintained by DIWG, part of the W3C Device Independence Activity. The
DIWG activity statement can be seen at http://www.w3.org/2001/di/Activity
The glossary is maintained as a Working Draft of a future W3C Note. This
allows it to be revised at appropriate intervals. Updates take place in
support of new work being carried out by the DIWG. In general, it is
inappropriate to use W3C Working Drafts as formal reference material or to
cite them as other than "work in progress". Because this document is subject
to change, other authors wishing to cite definitions in this glossary should
exercise caution. Updates to the glossary are made in such a way as to avoid
invalidating references, as long as those references conform to the
mechanisms described in the section Using and Maintaining the Glossary.
However, in support of its work, DIWG may need to modify definitions in newer
versions of this document.
A list of current public W3C Working Drafts can be found at http://www.w3.org/TR.
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.
Comments on this document can be sent to www-di@w3.org, the public forum for
discussion of the W3C's work on Device Independence. To subscribe, send an
email to www-di-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 online.
Information on how to use this document and how it is maintained can be
found in Using and Maintaining the
Glossary.
Patent disclosures relevant to this document may be found on the WG patent disclosure page.
Terms whose definitions are taken directly from other sources are marked
as follows:
- Term taken verbatim from another source
- Definition taken from another source
- Access Mechanism
- A combination of hardware (including one or more devices and network connections) and software
(including one or more user agents) that
allows a user to perceive and interact with the Web using one or more modalities. (sight, sound, keyboard, voice
etc.)
- Active Perceivable Unit
- A perceivable unit that is
currently being rendered by the user
agent and with which interaction may
be possible.
- Adaptation
- a process of selection, generation or modification that produces one
or more perceivable units in
response to a requested uniform resource identifier
in a given delivery context.
- Adaptation Preferences
- A set of preferences, specified by a user,
that may affect the adaptation for a
given delivery context, and so change the resultant user experience.
- Application
Personalization
- A set of factors, specified by a user or
other aspects of the delivery
context, that may affect the functionality of an application,
independently of its adaptation and
delivery, and so change the resultant user experience."
- Authored Unit
- Some set of material created as a single entity by an author.
Examples include a collection of markup, a style sheet, and a media resource, such as an image or audio clip.
- Browser
- A user agent that allows a user to perceive and interact with information on the Web.
- This definition was developed from that in Weaving the Web: Glossary.
- Client
- The role adopted by an application when it is
retrieving and/or rendering resources or resource manifestations.
- This term was taken verbatim from Web
Characterization Terminology & Definitions Sheet.
- Content Negotiation
- The mechanism for selecting the appropriate HTTP representation when servicing
a request. The HTTP representation of entities in
any response can be negotiated (including error responses).
- This term was developed from that in Hypertext
Transfer Protocol -- HTTP/1.1.
- Decomposition
- The act of dividing up one or more authored units during creation of a set
of perceivable units appropriate
for a particular delivery context.
- Delivery Context
- A set of attributes that characterizes the capabilities of the access mechanism and the preferences
of the user
- Delivery Unit
- A set of material transfered between two cooperating web programs as
the response to a single HTTP request.
The transfer might, for example, be between an origin server and a user agent.
- Users are not normally aware of individual delivery units.
- Device
- An apparatus through which a user can
perceive and interact with the Web
- Focus of Attention
- The point in an active
perceivable unit on which the user's attention is currently
focused.
- For example, this might be a paragraph of text or an image on which
the user is concentrating.
- Functional Adaptation
- An adaptation that generates a functional user experience
from a particular resource.
- Functional User
Experience
- A set of one or more perceivable
units that enables a user to complete the
function intended by the author for a given resource via a given access mechanism.
- Gateway
- A gateway is an intermediary which acts as a server on behalf of some other server with the purpose of supplying resources or resource manifestations from
that other server. Clients using a gateway know the gateway is
present but do not know that it is an intermediary.
- This term was taken verbatim from Web
Characterization Terminology & Definitions Sheet.
- Harmonized Adaptation
- A functional adaptation
sufficiently harmonized with the delivery context that it generates a
harmonized user
experience.
- Harmonized User
Experience
- A functional user
experience that is sufficiently harmonized with the delivery context to meet the quality
criteria of the author.
- HTTP Client
- A program that establishes connections for the purpose of sending HTTP requests.
- This term was developed from the definition of
client in Hypertext Transfer
Protocol -- HTTP/1.1.
- HTTP Gateway
- An HTTP server which acts as an
intermediary for some other HTTP server.
Unlike an HTTP proxy, an HTTP gateway
receives requests as if it were the origin
server for the requested resource; the
requesting HTTP client may not be aware
that it is communicating with an HTTP gateway.
- This term was developed from the definition of
gateway in Hypertext Transfer
Protocol -- HTTP/1.1.
- HTTP Payload Entity
- The information transferred as the payload of an HTTP request or HTTP response.
- An HTTP payload entity consists of meta-information in the form of
entity-header fields and content in the form of an entity-body.
- This term was developed from the definition of
entity in Hypertext Transfer
Protocol -- HTTP/1.1.
- HTTP Proxy
- An intermediary program which acts as both an HTTP server and as an HTTP client for the purpose of making
requests on behalf of other HTTP
clients.
- HTTP requests are serviced internally
or by passing them on, with possible translation, to other HTTP servers. An HTTP proxy must implement
both the client and server requirements of this specification. A
"transparent proxy" is a proxy that does not modify the HTTP request or the HTTP response beyond what is required for
proxy authentication and identification. A "non-transparent proxy" is a
proxy that modifies the HTTP request or
HTTP response in order to provide some
added service to the user agent, such as
group annotation services, media type transformation, protocol
reduction, or anonymity filtering. Except where either transparent or
non-transparent behavior is explicitly stated, the HTTP proxy
requirements apply to both types of proxies.
- This term was developed from the definition of proxy
in Hypertext Transfer Protocol -- HTTP/1.1.
- HTTP Representation
- An HTTP payload entity,
included in an HTTP response, that is
subject to content negotiation.
There may exist multiple representations associated with a particular
HTTP response status.
- This term was developed from the definition for
representation in Hypertext
Transfer Protocol -- HTTP/1.1.
- HTTP Request
- An HTTP message sent by an HTTP client
requesting that some operation be performed on some resource. Also, the act of sending such a
message is termed making a request.
- This term was developed from the definition of
request in Hypertext Transfer
Protocol -- HTTP/1.1.
- HTTP Response
- An HTTP message sent back to an HTTP
client in response to a previous HTTP
request.
- This term was developed from the definition of
response in Hypertext Transfer
Protocol -- HTTP/1.1.
- HTTP Server
- An application program that accepts connections in order to service
HTTP requests by sending back HTTP responses.
- Any given program may be capable of being both an HTTP client and an HTTP server; our use of
these terms refers only to the role being performed by the program for
a particular connection, rather than to the program's capabilities in
general. Likewise, any HTTP server may
act as an origin server, HTTP proxy, HTTP
gateway, or tunnel, switching behavior based on the nature of each
request.
- This term was developed from the definition of
server in Hypertext Transfer
Protocol -- HTTP/1.1.
- Interaction
- An activity by which a user can influence the data and processing of
an application by modifying the information associated with an active perceivable unit.
- A common form of this kind of activity is the entry of data into an
active perceivable unit that
contains a form.
- Modality
- The type of communication channel used for interaction . This might be, for example,
visual, gestural or based on speech. It also covers the way an idea is
expressed or perceived, or the manner in which an action is performed.
This definition is based on unpublished work of the Multimodal
Interaction group.
- Navigation
- An activity, based on a mechanism provided by an active perceivable unit, by
which a user can alter their focus of
attention. If the new focus of
attention is in a different perceivable unit, that unit becomes an
active perceivable unit.
- One common form of this kind of mechanism is the link, a region
within an active perceivable
unit which can be activated by a suitable user action.
- Origin Server
- The server on which a
given resource resides or is to be created.
- This term was taken verbatim from Hypertext
Transfer Protocol -- HTTP/1.1.
- Perceivable Unit
- A set of material which, when rendered
by a user agent, may be perceived by a user and with which interaction may be possible.
- User agents may choose to render some
or all of the material they receive in a delivery unit unit as a single
perceivable unit or as multiple perceivable units.
- Most perceivable units provide both presentation and the means for interaction. However, on some types of
device, such as printers, perceivable units might contain only
presentation.
- Proxy
- A proxy is an intermediary which acts as both a server and a client
for the purpose of retrieving resources or
resource manifestations on behalf of other
clients. Clients
using a proxy know the proxy is present and that it is an
intermediary.
- This term was taken verbatim from Web
Characterization Terminology & Definitions Sheet.
- Rendering
- The act of converting perceivable
units into physical effects that can be perceivable by a user and with which a user
may be able to interact.
- Rendering Preferences
- A set of preferences, specified by a user,
that may affect the way the user agent renders a perceivable unit, and
so change the resultant user experience.
- Request
- A message describing an atomic operation to be
carried out in the context of a specified resource.
- This term was taken verbatim from Web
Characterization Terminology & Definitions Sheet.
- Resource
- A network data object or service that can be
identified by a URI.
Resources may be available in multiple representations (e.g. multiple
languages, data formats, size, resolutions) or vary in other ways.
- This term was taken verbatim from Hypertext
Transfer Protocol -- HTTP/1.1
- Resource Manifestation
- One specific rendition of a resource at a specific point in time and
space.
- A conceptual mapping exists between a resource and a resource manifestation (or set
of manifestations), in the sense that the resource has certain
properties - e.g., its URI, its intended purpose,
etc. - which are inherited by each manifestation, although the specific
structure, form, and content of the manifestation may vary according to
factors such as the environment in which it is displayed, the time it
is accessed, etc. Regardless of the form the manifestation's rendering
ultimately takes, the conceptual mapping to the resource is preserved.
- This term was taken verbatim from Web
Characterization Terminology & Definitions Sheet
- Response
- A message containing the result of an executed request.
- This term was taken verbatim from Web
Characterization Terminology & Definitions Sheet.
- Server
- The role adopted by an application when it is
supplying resources or resource manifestations.
- This term was taken verbatim from Web
Characterization Terminology & Definitions Sheet.
- Uniform Resource
Identifier
- A short string that uniquely identifies a resource such as an HTML document, an image, a
down-loadable file, a service, or an electronic mailbox.
- User
- A human who perceives and interacts
with the web
- User Agent
- A client within a device that performs rendering.
- Browsers are examples of user agents,
as are web robots that automatically traverse the web collecting
information.
- User Experience
- A set of material rendered by a user agent which may be perceived by a user and with which interaction may be possible.
- Variant
- A resource may have one, or more than
one, representation(s) associated with it at any given instant. Each of
these representations is termed a `variant.' Use of the term `variant'
does not necessarily imply that the resource is subject to content negotiation.
- This term is taken verbatim from Hypertext
Transfer Protocol -- HTTP/1.1.
- Web Page
- A collection of information, consisting of one or more resources, intended to be rendered
simultaneously, and identified by a single Uniform Resource
Identifier.
- More specifically, a web page consists of a resource with zero, one, or more embedded resources intended to be rendered as a single
unit, and referred to by the URI of the one resource which is not embedded.
- This term was developed from the definition of web
page in Web Characterization
Terminology & Definitions Sheet.
- Web Page Identifier
- A Uniform Resource
Identifier intended to be recognized by a user as representing the
identity of a specific Web Page (resource).
- It may need to be entered explicitly by a user.
This section documents the way in which the glossary should be used from
other DIWG documents. It also documents how changes are to be made to the
glossary itself in a way that will not invalidate links to the
definitions.
Every definition in the glossary has an associated anchor. As a
consequence every definition can be directly referenced externally from other
documents. Such references should use the public URL associated with the DIWG
glossary. For the latest version of the glossary, this has been established
as
http://www.w3.org/TR/di-gloss/
Dated versions of the glossary will appear at URLs in the form of the
following
http://www.w3.org/TR/2003/WD-di-gloss-20030825/
To refer to a particular definition, a document should create a URL based
on the appropriately dated, public URL and the fragment identifier for the
definition. Fragment identifiers consist of the definition name, in
lowercase, with words separated by dashes and prefixed by
def. For example, the fragment identifier for the definition
of User Agent is def-user-agent, and for
Navigation is def-navigation. The URL to
use for the definition of Navigation for the dated version mentioned above
would be:
http://www.w3.org/TR/2003/WD-di-gloss-20030825/#def-navigation
One important guarantee for documents that reference the glossary is that
the fragment identifier for a given definition never changes. If, for
example, a new version of a particular definition is needed, the older
version will be retained within the glossary with its fragment identifier.
The new version will be given a new identifier. The process used to maintain
the glossary and to retain this uniqueness of definition identifiers is
described in the following section.
In addition to referring directly to individual definitions in the
glossary, documents that use it should include a reference to the dated
version in use in their References section. The following is an example of
such a reference:
- Glossary of Terms for Device
Independence (version used for definitions)
- Glossary
of Terms for Device Independence, Rhys Lewis, 2003. W3C
Working Draft available at:
http://www.w3.org/TR/2003/WD-di-gloss-20030825/
The DIWG glossary will remain a public working draft. This reflects the
need to update it as new work is carried out in DIWG. The need to revise the
glossary, and in particular the potential requirement to revise definitions,
leads to a need for a mechanism that can allow older documents to refer
unambiguously to older revisions of particular definitions.
Once a version of the glossary has been published, the definitions it
contains have fragment identifiers that must not be changed. As new
definitions are added they are given new identifiers. This poses no issues
for documents authored before the new definitions were published. However,
when a definition is revised, it is vital that older documents that used the
old version are still valid. They are protected by versionning the fragment
identifiers and by keeping the old versions of definitions in Appendix B of the glossary.
To revise a glossary definition, the following steps must be carried
out:
- The existing definition, complete with fragment identifier, must be
copied to Appendix B.
- The definition must be updated within the main part of the
glossary.
- The revised definition must be given an updated fragment identifier
constructed by adding a version number where none exists, or incrementing
it if one already exists. For example, if the fragment identifier before
revision were #def-navigation it would become
#def-navigation-v2. Alternatively, if the fragment
identifier before revision were #def-navigation-v7 it
would become #def-navigation-v8.
- All references to the definition within the glossary
itself must be updated to refer to this new fragment identifier. In
addition, all definitions that refer to the revised definition must be
reviewed to see whether they need modification because of the change. If
so, this same procedure must be applied those definitions and new
versions must be created.
- The old definition that has been moved to Appendix B must have a reference added
that refers to the newer definition in the body of the glossary. As an
example, the reference for an old version of the definition of Navigation
might include the reference:
"This definition has been superseded. There is a newer definition of Navigation".
Notice that these links should not be updated
when a new version of a definition is added. By not changing them, they
form a chain through the versions of the definition from the one
referenced by the external document up to the latest version.
This section contains definitions that have been superseded within the
existing glossary. The first section holds definitions that have been
updated. The second section holds definitions that have been removed.
No definitions have yet been updated.
- User Experience
Preferences
- A set of preferences, specified by a user,
that affect the user experience that
results from adaptation for a given delivery context
- Fragmentation
- The act of dividing up one or more authored units to create a set of perceivable units appropriate for a
particular delivery context.
- This term has been replaced by the new term decomposition
No definitions have yet been deprecated.
- Hypertext Transfer Protocol --
HTTP/1.1.1
- Hypertext
Transfer Protocol -- HTTP/1.1, June 1999. IETF RFC-2616
available at http://www.w3.org/Protocols/rfc2616/rfc2616.html
- Uniform Resource Identifiers (URI):
Generic Syntax
- Uniform Resource
Identifiers (URI): Generic Syntax, June 1998. IETF RFC-2396
available at http://www.ietf.org/rfc/rfc2396.txt
- Naming and Addressing: URIs, URLs,
...
- Naming and Addressing:
URIs, URLs, ... available at
http://www.w3.org/Addressing/
- Web Characterization Terminology
& Definitions Sheet
- Web
Characterization Terminology & Definitions Sheet, May
1999. W3C Working Draft available at
http://www.w3.org/1999/05/WCA-terms/
- Weaving the Web: Glossary
- Weaving
the Web: Glossary, 1999, Tim Berners-Lee. Available at
http://www.w3.org/People/Berners-Lee/Weaving/glossary.html
Members of the W3C Device Independence Working Group have helped develop
this Working Group Note through their comments, proposals and discussions at
teleconferences, face-to-face meetings and via the group discussion list.
At the time of publication, the principal and active members of the group
were as follows:
- Stephane Boyera (W3C)
- Steve Farowich (Boeing)
- Roger Gimson (HP)
- Yoshihisa Gonno (Sony Corp)
- Guido Grassel (Nokia)
- Rotan Hanrahan (MobileAware Ltd)
- Kazuhiro Kitagawa (W3C)
- Markus Lauff (SAP AG)
- Tayeb Lemlouma (INRIA)
- Rhys Lewis (Volantis Systems Ltd)
- Roland Merrick (IBM)
- Franklin Reynolds (Nokia)
- Andreas Schade (IBM)
- Ryuji Tamagawa (Sky Think System)
- Luu Tran (Sun Microsystems)
- Michael Wasmund (IBM)
- Stan Wiechers (Merkwelt)
- Jason White (University of Melbourne)
- Candy Wong (NTT DoCoMo)
- Amy Yu (SAP AG)
The following were members of the group at earlier stages of its
drafting:
- Yasser AlSafadi (Philips Research)
- Abbie Barbir (Nortel Networks)
- Einar Breen (Adaptive Media)
- Shlomit Ritz Finkelstein (invited expert)
- Vidhya Golkar (Argogroup)
- Luo Haiping (Comverse)
- Eric Hsi (Philips Research)
- Lynda Jones (SHARE)
- William Loughborough (Smith-Kettlewell Institute)
- Stephane Maes (IBM)
- Kaori Nakai (NTT DoCoMo)
- Hidetaka Ohto (W3C/Panasonic)
- Garland Phillips (Motorola)
- Lalitha Suryanarayana (SBC Technology Resources)
- Yoshifumi Yonemoto (NTT DoCoMo)