Glossary of Terms for Device Independence (original) (raw)

Abstract

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.

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 indexat 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/ActivityThe 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.orgwith 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.

Table of Contents

Verbatim Definitions

Terms whose definitions are taken directly from other sources are marked as follows:

Term taken verbatim from another source

Definition taken from another source

Glossary

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 aharmonized 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 ofclient 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 ofgateway 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 ofentity 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 orHTTP 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 particularHTTP response status.

This term was developed from the definition forrepresentation 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 ofrequest 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 ofresponse in Hypertext Transfer Protocol -- HTTP/1.1.

HTTP Server

An application program that accepts connections in order to serviceHTTP 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 ofserver 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 anactive 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 anactive 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 orresource manifestations on behalf of otherclients. 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.

A Using and Maintaining the Glossary

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.

A.1 Using the Glossary

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/

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 bydef. For example, the fragment identifier for the definition of User Agent is def-user-agent, and forNavigation 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/

A.2 Maintaining the Glossary

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:

  1. The existing definition, complete with fragment identifier, must be copied to Appendix B.
  2. The definition must be updated within the main part of the glossary.
  3. 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.
  4. 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.
  5. 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.

B Previous Versions of Definitions

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.

B.1 Definitions that Have Been Updated

No definitions have yet been updated.

B.2 Definitions that Have Been Removed

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

B.3 Definitions that Have Been Deprecated

No definitions have yet been deprecated.

C References

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

D Acknowledgments

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)