Bob Hopgood, Head of Offices, World Wide Web Consortium, W3C UK Office, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX. firstname.lastname@example.org
This paper gives some background information concerning the World-Wide Web Consortium, its origins, objectives, structure and current situation. This is followed by an overview of what has been achieved to date and discusses the current and future activities particularly with regard to the family of XML standards, and XML applications such as XHTML, SMIL, SVG, and RDF.
The World Wide Web Consortium [HREF1] (W3C) was founded in 1994 to lead the web to its full potential by giving organisations a forum in which to develop technical specifications [HREF2] as the foundation for the Web. W3C's process allows everybody to contribute to and benefit from the W3C activities. Only by serving the entire Web community can W3C achieve its objective of leading the Web to its full potential.
W3C now has about 420 Members [HREF3] and 60 full-time staff [HREF4] (the W3C Team). It has developed 22 Recommendations [HREF5] that define the Web and future work aimed at extending this set is grouped into about 20 separate Activities [HREF6]).
The rapid changes taking place in terms of technology, user demands and societal needs requires W3C to work at a fast pace and it is only through the participation of its Members and others in terms of developing and reviewing specifications, trial implementations, translations and promotion that this pace is achieved.
The W3C Process [HREF7] aims to achieve consensus initially within a Working Group but later throughout the Membership and finally around the world. New activities arise from:
If a new area looks promising, an Activity Proposal is sent to the Membership for review and, if there is consensus to proceed, the Activity will start. Work may be divided among several Working Groups, Interest Groups, and Coordination Groups. For example, the XML Activity [HREF10] is carried out by four Working Groups (Core [HREF11], Schema [HREF12], Linking [HREF13], and Query [HREF14]), three Interest Groups (Plenary, Schema, Linking) and one Coordination Group. Unlike other standards bodies, the W3C Team works full-time to coordinate W3C Activities and develop Recommendations.
Within W3C, related Activities [HREF15] are grouped into Domains [HREF16]. Currently W3C has four Domains:
W3C specifications undergo a formal process of review, revision, and refinement to build consensus. Documents advance through four stages:
To participate in a Working Group requires a serious commitment with weekly teleconferences and several face-to-face meetings a year. Some Working Groups are restricted to employees of Members, the W3C Team, and invited experts while others adopt a more public forum.
W3C is primarily funded through the dues paid by its Members although some funding comes from public funds. In return, W3C Members can send staff to participate in Working Groups. Members have a seat on the Advisory Committee, access to Member-confidential information, the right to use the W3C Member logo, and access to W3C news services. The Advisory Committee meets twice a year face-to-face to review the W3C Activities and respond to proposals including a review of proposed Activities and proposed Recommendations. The May Advisory Committee Meetings for 1999 in Toronto and 2000 in Amsterdam have been co-located with the International World Wide Web Conference.
The W3C Team coordinates the work carried out by the Activities and handles the infrastructure required by the Consortium. The Team consists of the W3C Director (Tim Berners-Lee), the Chairman (Jean-Francois Abramatic) and the full-time staff. The Chairman manages the general operation of the Consortium while the Director is the lead architect for the technologies developed at the Consortium and ensures consensus is reached before a specification becomes a Recommendation.
W3C is hosted by the Massachusetts Institute of Technology [HREF17], Laboratory for Computer Science [HREF18] (MIT/LCS) in the United States; the Institut National de Recherche en Informatique et en Automatique [HREF19] (INRIA) in Europe; and the Keio University [HREF20] Shonan Fujisawa Campus in Japan. Most of the W3C Team works at one of these host locations. W3C is not a legal entity, so Members enter into a contractual relationship with the three hosts when they join W3C [HREF21].
The W3C Offices [HREF22] are local points of contact in specific countries that help ensure that W3C and its specifications are known in those countries. The Offices work with their regional Web community to promote participation in W3C. The current set are:
Offices are also planned for Australia and Tunisia. Some of the activities performed by the local Offices are:
Currently, the four Domains of W3C have the following activities:
It is impossible in a short paper to give full justice to all these activities. In consequence, what follows should be seen as a taster to encourage the reader to look more closely at the Recommendations being developed by the W3C Members.
The Extensible Markup Language (XML 1.0) became a W3C Recommendation in February 1998. Some of the main points [HREF23] about XML are:
name="value"and the quotes must be there.
In consequence, associated with XML 1.0, there is a set of related specifications under development:
While the family of XML specifications is large, it should be realised that only XML 1.0, XML Namespaces, DOM Level 1, XPath and XSLT have reached Recommendation so far. At the moment, the user can be confident of defining XML applications, using several together via the namespace mechanism, interacting with them via a standard API, and powerfully transforming XML documents using XSLT. For the remaining specifications, there is still time for them to change. However, the web community has accepted XML with enthusiasm. XML gives the user access to a large and growing community of tools independent of a single vendor.
Currently, the way to validate an XML document is via the Document Type Definition that is part of XML 1.0. Given a simple application, like marking up an exam paper:
<question>Who is the last King of England</question>
<question>How many queens were named Elizabeth</question>
This would have a DTD something like:
<!DOCTYPE exam [
<!ELEMENT exam (qapair)* >
<!ATTLIST exam paper CDATA #REQUIRED>
<!ELEMENT qapair (question,answer) >
<!ELEMENT question (#PCDATA) >
<!ELEMENT answer (#PCDATA) >
Note that the DTD has a different syntax from XML as it was based on the notation used by SGML. The DTD provides facilities for defining valid documents and also how to include text and other objects from other files in the XML document via the entity reference mechanism.
One of the major changes coming through will be the replacement of the validation part of the DTD by an XML Schema. An XML Schema has the advantage of using the XML syntax and will provide stronger datatyping than is currently available. The above DTD would be replaced by something like:
<attribute name="paper" type="course">
<element name="qapair" minOccurs="0" maxOccurs="*">
<element name="question" type="string"/>
<element name="answer" type="string"/>
The place where the stronger datatyping can be seen is in the definition of the
paper attribute whose value is of type
course and where it specifically states that this consists of two alphabetic characters followed by three digits. W3C will provide conversion facilities from DTDs to XML Schemas.
The aim of XLink, together with XPointer, is to provide advanced hyperlinking and addressing functionality for XML including:
For example, a link in an XML document is no longer limited in the type of element it can be associated with:
<ABC xlink:type="simple" xlink:href="http://www.w3.org/">The W3C</ABC>
This defines a simple link associated with the <XYZ> element that has similar functionality to the
<a href=" functionality of HTML. Extended links in XLink will allow links to connect a number of resources and the links can be defined away from the document they refer to.
The W3C User Interface Domain has a broad programme with a major activity aimed at moving the existing Web from HTML to XML via XHTML[HREF38].
HTML currently serves as the lingua franca for most people publishing on the Web. While that is the case today, the future of the Web is with XML. In designing XHTML 1.0, the challenge was to design the next generation language for Web documents without making obsolete what is already on the Web. The answer is to rewrite HTML 4.0 as an XML application. In simple terms that means making the HTML a well-formed XML document where start and end tags are always there and match precisely. Empty elements have to use the correct syntax. For example, the following valid HTML 4 fragment:
<P>This is a list:
<p>And so on</P>
would need to be changed to:
<p>This is a list:</p>
<p>And so on</p>
W3C's tidy[HREF39] tool will make the necessary changes for you. The benefits of changing to XHTML are:
By migrating to XHTML early, content developers can enter the XML world with all of its attendant benefits, while still remaining confident in their content's backward and future compatibility. XHTML also has an ambitious roadmap of future activities.
XHTML 1.1 will take the existing XHMTL 1.0 and reformulate it as a set of Modules. Once that has been achieved, the work will proceed in two directions. First will be a set of modules defined as XHTML Basic that will form the base set of modules that devices with limited functionality will be expected to handle. XHTML Basic will include the widely used HTML mark-up tags plus images, forms, and basic tables. It is designed for Web clients that do not support the full set of XHTML features such as mobile phones, PDAs, pagers, and settop boxes. Second will be some new improved modules with Form and Event Modules being the first two:
Nodelevel or centrally from a
Nodehigher in the document tree. The XHTML Event Module will contain
event-targetelement will be used to attach an event handler to an element. The
event-listenerelement represents the DOM event handler. The
eventelement is used to represent the DOM event.
This summer should see the completion of the following XML applications:
SVG will allow both simple vector graphics and high quality graphics arts rendering to be produced via an XML application. A simple SVG document is:
<svg viewBox="0 0 600 400">
<rect x="100" y="50" width="60" height="30" style="fill:red;stroke:yellow"/>
<rect x="200" y="50" width="60" height="30" style="fill:url(#radgrad);
<rect x="300" y="50" width="60" height="30" style="stroke:blue; fill:none;
stroke-width:6; stroke-dasharray:20 5; stroke-linejoin:miter"/>
<g transform="translate(10 10) scale(10)" style="stroke:none; fill:lime">
<path d="M 0.0 11.2 L 2.0 12.4 L 4.0 12.9 L 6.0 12.6 L 8.0 12.0 L 10.0 11.1
L 12.0 10.4 L 14.0 10.1 L 16.4 10.6 L 17.0 10.3 L 17.3 8.0 L 17.8 6.0
L 18.5 3.9 L 20.0 3.0 L 22.0 3.0 L 24.0 4.0 L 26.0 6.1 L 28.0 6.9
L 29.0 6.8 L 28.8 7.7 L 27.2 8.5 L 25.0 8.5 L 23.0 8.5 L 21.5 8.8
L 21.1 9.5 L 21.5 11.0 L 22.8 12.0 L 24.1 13.0 L 25.1 14.9 L 25.2 16.4
L 24.2 18.1 L 22.1 18.9 L 20.0 19.1 L 18.0 19.3 L 16.0 19.2 L 14.0 19.0
L 12.0 19.0 L 10.0 18.8 L 8.0 18.2 L 6.1 17.9 L 4.2 17.1 L 3.0 15.9
L 1.3 14.0 L 0.0 11.2 z"/>
<g style="fill:yellow; font-size:28pt">
<text x="150" y="150">My first text string</text>
<svg> element establishes the coordinate system for the drawing. Inside are three
<g> grouping elements. These can be nested to any depth and allow local CSS properties, SVG attributes and a local coordinate system to be established for the group. The first group uses the initial coordinate system established. The second group will scale all the coordinates by a factor of 10 and translate them in space.
The two main SVG drawing primitives are
text but common paths like lines, polylines, polygons, rectangles, circles and ellipses have shorthand descriptions that effectively get turned into paths. The
path element defines a path by a sequence of path data including:
A lowercase command letter implies that the coordinate following is relative rather than absolute. The whole aim is to transmit complex diagrams (maps, engineering data etc) across the internet efficiently. In consequence, path descriptions are not easy to read but are efficient to transmit.
CSS properties are used if appropriate and these have been extended to allow areas to be filled with radial and linear changes of colour as can be seen in the second rectangle.
Several implementations of SVG are available both as stand-alone viewers and as plug-ins. Adobe, IBM, JacKaroo and CSIRO are examples. The SVG Working Group has developed a test suite to check implementations against. Below is an example of one of the basic tests of functionality. Each test has a PNG image to check the SVG against:
The Resource Description Framework, RDF Model and Syntax[HREF41], for specifying metadata associated with a resource has been a W3C Recommendation since February 1999. A simple example is:
<DC:title>The W3C Folio 1999</DC:title>
<DC:creator>W3C Communications Team</DC:creator>
<DC:subject>Web development, World Wide Web Consortium, Interoperability of the Web</DC:subject>
The metadata consists of a collection of properties called an RDF Description, in this case about the W3C Folio. The
<RDF> element declares that this is an RDF expression using the format defined by the RDF Model and Syntax specification. The next line indicates that the Dublin Core RDF vocabulary is to be used and the prefix "DC" will be used for elements and attributes in that namespace. The Description element indicates that the metadata concerns the W3C Folio. The subsequent RDF statements define the metadata (title, creator, date, and subject) and they are part of the Dublin Core RDF vocabulary.
RDF provides a framework in which industry sectors can develop vocabularies that suit their needs and share these vocabularies with others. To do this, the meaning of the terms must be defined precisely and this is done using an RDF Schema[HREF42]. It defines the meaning, characteristics, and relationships of a set of properties, including constraints on potential values and the inheritance of properties from other schemas. One schema is the Dublin Core used by the library community. The Dublin Core is a set of 15 properties associated with bibliographic information. The RDF Schema specification will become a Recommendation in the near future.
A goal of RDF was to allow the mechanical translation of PICS metadata into RDF form. A recent W3C Note defines one possible mapping of PICS into XML/RDF. This Note was orginally going to appear as part of the RDF Schema document but it has been published separately so that it can evolve independently of the RDF Schema specification.
Many Web sites collect information about users particularly when conducting e-commerce but also as a prerequisite to providing information. Users need to know whether the Web site is trustworthy and what the site plans to do with the information collected. A particular concern is to whom the information will be given. The Platform for Privacy Preferences Project (P3P[HREF43]) defines how a user can be informed of a site's practices. The user, or an agent working for the user, can then decide whether to proceed with a transaction.
A web site might have as its policy that: "it collects clickstream data in HTTP logs and collects first name, age and gender to personalise the responses. The information is not given to any other organisation and it has a third-party that audits its Web site to ensure that it keeps to this policy."
The P3P specifications is currently at the Working Draft stage and consists of:
A P3P Preference Exchange Language (APPEL[HREF44]) is also being defined to encode user preferences about privacy. However, P3P can be used without using APPEL.
W3C is hosting an interoperability session in New York on June 21, 2000 to "test drive" P3P and to demonstrate its potential uses and capabilities to a broad audience of software and hardware developers, and Web site operators.
The Accessibility Domain will soon complete its first round of Guidelines aimed at:
The Web Content Guidelines have been in wide use for some time. The Authoring Tools Guidelines appeared this Spring and at least one existing tool satisfies each checkpoint of these guidelines (even though no tool yet satisfies all of them).
The User Agent Guidelines explain to developers how to design user agents that are accessible to people with disabilities. User agents include graphical desktop browsers, multimedia players, text browsers, voice browsers, plug-ins, and other assistive technologies that give full access to Web content. While these guidelines primarily address the accessibility of general-purpose graphical user agents (including communication with assistive technologies), the principles presented apply to other types of user agents as well. Following these principles will make the Web accessible to users with disabilities and will benefit all users.
Here is a flavour of what is in the user agent guidelines:
In all there are seven main guidelines with a great deal of background information plus a priority check list for the tool designer.
IBM, RealNetworks, Sausage, SoftQuad, Amaya and others have all agreed to implement the relevant guidelines in their products. Also large companies like Boeing, Bell Atlantic and Electricty de France have welcomed the guidelines as valuable in allowing them to use tools that produce accessible output.
Hopefully, this introduction to the W3C and its activities gives a flavour of what W3C does and how it accomplishes it. The web continues to develop at a great pace and W3C and its Members are the major driving force to lead the web to its full potential.
Below is a complete list of the current W3C Recommendations.
|PNG||Portable Network Graphics||October 1996|
Rating Services and Systems
Label Format and Distribution
|Platform for Internet Content Selection
Language for describing rating services
Formats for labels and their distribution
|PICS Rules 1.1||PICS Rules||December 1997|
|XML 1.0||Extensible Markup Language||February 1998|
|CSS2||Cascading Style Sheets||May 1998|
|DSig 1.0||PICS Signed Labels 1.0||May 1998|
|SMIL 1.0||Synchronised Multimedia Integration Language||June 1998|
|HTTP 1.1||HyperText Transfer Protocol||September 1998|
|DOM Level 1||Document Object Model||October 1998|
|Namespaces in XML||Defines how XML namespaces can coexist||January 1999|
|Web CGM Profile||Computer Graphics Metafile Profile for use on the Web||January 1999|
|RDF Model and Syntax||Resource Description Framework Model and syntax||February 1999|
|Guidelines for making Web content
accessible to people with disabilities
with XML documents
|Using Processing Instructions
to link a style sheet to an XML document
|MathML 1.01||Mathematical Markup Language||July 1999|
|XPath 1.0||XML Path Language||November 1999|
|XSLT 1.0||XSL Transformations||November 1999|
|HTML 4.01||HyperText Markup Language||December 1999|
|XHTML 1.0||Reformulation of HTML 4.0 in XML||January 2000|
|Guidelines for editors and systems
that create documents for the web
|DOM Level 2.0||Document Object Model level 2|
|RDF Schemas||Resource Description Framework Schemas|
|User Agent Accessibility Guidelines 1.0||What browsers, screen readers etc need to support accessibility|
|MathML 2.0||A new version of the Mathematical Markup language|
Bob Hopgood, (c) 2000. The author assigns to Southern Cross University and other educational and non-profit institutions a non-exclusive licence to use this document for personal use and in courses of instruction provided that the article is used in full and this copyright statement is reproduced. The author also grants a non-exclusive licence to Southern Cross University to publish this document in full on the World Wide Web and on CD-ROM and in printed form with the conference papers and for the document to be published on mirrors on the World Wide Web.
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