The W3C Compound Document Formats Working Group chartered in October 2004 has released an initial Working Draft specification for Compound Document by Reference Use Cases and Requirements Version 1.0.

The Compound Document Formats Working Group is part of W3C's Interaction Domain and is part of the CDF Activity. The Working Group is "producing recommendations on combining separate component technologies (e.g., XML-based languages, elements and attributes from separate namespaces), like XHTML, SVG, XForms, MathML, and SMIL, with a focus on user interface markups. This work is divided in phases and two technical solutions; compounding by reference, and by inclusion."

The CDF activity recognizes that W3C and other bodies have created "multiple XML syntaxes for various purposes, such as XHTML for on-line document viewing, SVG for 2D vector graphics, or SMIL for multi-media synchronization. There is a demand for letting content creators combine these markups so as to create richer documents, containing multi-media information: text, graphics, audio and video. The individual markups become even more compelling when combined: for example, being able to display scalable 2D images in XHTML pages provides the ability to define pages which can be printed with high quality. Similarly, using SVG images in an XHTML table provides an easy way to layout SVG images in a table."

The W3C Compound Document Formats Activity was started following a successful June 2004 'Workshop on Web Applications and Compound Documents' hosted by Adobe. About sixty people attended the workshop, where twenty of the forty-six position papers were presented. The Workshop attendees agreed that the W3C should develop a specification that combines profiles of W3C Technologies (choosing from XHTML, SVG, CSS, SMIL, and XForms), primarily focused on the mobile market space, with a conformance test suite.

The WG's first Working Draft addresses a technical solution for compounding document formats "by reference. This means that documents using different languages (namespaces) are linked by a reference such as XLink references, XHTML <img>, <object>, and <link> elements, and XForms model and instance src attributes. This allows separate languages to work together, but it allows implementations of the languages be separated. The standardization issues are for example, how events flow in multi-document environment, how different documents are accessed by the scripts, and how different languages should cooperate in drawing to the screen."

In a subsequent phase of design, the CDF Working Group "will address document combining by inclusion. The inclusion means that several languages (namespaces) are used within one document. There is no more need to put different languages (namespaces) in separate document but they can be used together. The standardization issues here are for example, how different language implementations share the document, how non-orthogonal language features interact, and how different language implementations cooperate in more general way."

The W3C CDF Working Group expects that compound documents "can be authored by a variety of means, and that there will be multiple categories of CDF authoring tools. For example, document-centric authoring tools will create content which mixes static text and graphics for the purpose of publishing on the Web; multimedia-centric authoring tools can create time-based, interactive content; application-centric authoring tools are used to create user interfaces. Forms-centric authoring tools may be used to create data templates, and device-independent authoring tools are available for creating content that can be adapted to different user requirements and across different media."

Use cases identified in the new Working Draft include web publishing and broadcasting, where services that mix text, audio, video and interactive elements are used to deliver information. "An interactive news service may provide the user with multimedia news content comprising traditional text and images, but also audio and video reports as well as diagrams which react to user behavior. A web portal application combines content and services from multiple back-end sources across multiple integration paths to create a cohesive user experience. An animated news or stock ticker that displays dynamic data, such as stock prices or current news headlines, can be displayed as part of a larger page of more static information, such as a news article. Infotainment services combine information and entertainment from different sources into a single interactive service with compelling presentation."

Web Applications are cited as another commmon application type, whether an order entry system, reservation system, on-line shopping, surveys, interactive maps, interactive games, etc. These Web applications "typically have some form of programmatic control, either on the client, on the server or a combination of both. This document addresses client-side Web applications only. They may run within the user agent, or within another host application. A Web application is typically downloaded on demand each time it is "executed", allowing a developer to update the application for all users when needed. Web applications are usually smaller than regular desktop applications, and can have rich graphical interactive interfaces."

Additional use cases are documented in the CDF Requirements document, including: Resident Applications; Content Authoring, Aggregation and Deployment; Navigation (SVG with links). To support these features in compound documents, the CDF specification also addresses UI languages in order to facilitate rich multimedia content handling. Rich multimedia may involve: graphically rich content, possibly including animated background image; layout adaptation, where layout can be based upon device characteristics; graphical menuing systems where items have an animated action when focused on; portable user interfaces; skinnable user interfaces with the ability to use animations and interactivity as a user interface template; content adaptation, such as when a portal delivers a mixed document with varying capabilities."

Bibliographic Information

Compound Document by Reference Use Cases and Requirements Version 1.0. Edited by Daniel Appelquist (Vodafone Group Services Limited), Timur Mehrvarz (Vodafone Group Services Limited), and Antoine Quint (Fuchsia Design, Invited Expert). W3C Working Draft. 15-March-2005. Version URL: http://www.w3.org/TR/2005/WD-CDRReqs-20050315/. Latest version URL: http://www.w3.org/TR/CDRReqs/.

About the W3C Compound Document Formats Working Group

"Extensibility is an important aspect of the Web, yet it isn't always practical to extend the specific formats beyond their requirements. An alternative extensibility path is to combine the formats within a single document, with each format containing the data it describes best. At W3C, a document such as this, composed from different formats, is called a Compound Document.

The mission of the W3C Compound Document Formats Working Group is to develop specifications which combine selected existing document formats from the W3C and elsewhere, and which specify the runtime behaviour of such combined documents.

The expected activities of the CDF Working Group include:

• Development of usage scenarios and requirements for Compound Document Formats.
• Creation of a specification or specifications that combine existing document formats, either by reference (linking from one base document to another) or by inclusion (embedding compound content within a host document), and to describe the runtime behavior of such formats. An example would be embedding SVG and SMIL within XHTML.
• Development of a comprehensive test suite to ensure conformance.
• Providing a forum for communities of practice, and a process through which adopters of Compound Documents can coordinate their interpretations of the technology.
• Liaison with other Working Groups within the W3C to ensure that the potential of Compound Documents are realized, for example, working with Web Accessibility Initiative (WAI) and Device Independence (DI) experts.
• Working with other organizations to strengthen the position of Compound Documents on the Web. [Charter and Activity Statement]

About the W3C Interaction Domain

"Work on Compound Documents is being managed as part of W3C's Interaction Domain. This activity is exploring new ways to access Web information: 'Mobile devices and audiovisual media are changing the way people are interacting with the Web. Web technology can accommodate these innovations, since the Web has been conceived as a universal system for distributing and accessing information'.

Led by Philipp Hoschka, the members of W3C's Interaction team have considerable knowledge in markup languages, graphics, multimedia, development of device-specific Web software, among other areas.

W3C's Interaction Domain is responsible for developing technologies that shape the Web's user interface. These technologies include (X)HTML, the markup language that started the Web. We also work on second-generation Web languages initiated at the W3C: CSS, MathML, SMIL and SVG all have become an integral part of the Web. Finally, we develop languages that will determine next generation Web user interfaces with cutting-edge technologies such as VoiceXML, Multimodal Interaction and XForms.

W3C Interaction Domain technologies enable millions of people every day to browse the Web and to author Web content. Industry uses these technologies for purposes such as distributing information within an organization and or creating new business opportunities.

Our major focus today is how to adapt current technologies to enable Web access for anyone, anywhere, anytime, using any device. This includes Web access from "smartphones", the new generation of mobile phones which integrate traditional phone functionality with new, powerful computing and Web browsing capabilities. But there is more: our work also targets other emerging environments for Web access such as interactive television, and even automobiles — W3C technologies can be integrated e.g., within car navigation systems..."

W3C Interaction Domain Activities:

• Compound Document Formats: combining multiple formats, such as XHTML, SVG, SMIL and XForms. The W3C Compound Document Formats (CDF) Activity will specify the behaviour of some format combinations, addressing the needs for an extensible and interoperable Web.

• Device Independence: working to ensure a seamless Web for all access devices. Web applications are becoming accessible from a wide range of devices from desktop PCs to in-car computers, TV, digital cameras, and cellular phones.

• Graphics: addressing most visible part of the modern Web and arguably one of the primary reasons for it popularity and explosive growth. Successful use of graphics on the Web depends on interoperability across platforms, output resolutions, color spaces, and software products.

• Hypertext Markup Language (HTML): the lingua franca for publishing on the Web. Following the success of W3C's HTML 3.2 and HTML 4.0, the HTML Activity is designing the next generation of the markup language; XHTML, is re-cast in XML and is being designed so that it can be used in combination with other XML applications.

• Math: communicating mathematical and other technical notation is a challenging and important task; W3C published a Recommendation entitled Mathematical Markup Language, or MathML, which provides a way of encoding both mathematical content and visual presentation for mathematics at all levels, from elementary school to scientific research, as well as forming the basis for machine to machine communication of mathematics on the Web.

• Multimodal Interaction: extending the Web user interface to allow multiple modes of interaction, offering users the choice of using their voice, or the use of a key pad, keyboard, mouse, stylus or other input device. For output, users will be able to listen to spoken prompts and audio, and to view information on graphical displays.

• Style Sheets: offering precise control over the presentation of Web pages. Not only can Web designers specify the visual effects they want, but also aural style sheets give control over voice, pitch and other aspects of how the text will sound when rendered into speech.

• Synchronized Multimedia: focusing on choreographing multimedia presentations where audio, video, text and graphics are combined in real-time.; the Activity has developed two versions of the Synchronized Multimedia Integration Language (SMIL)

• Voice Browser: working to expand access to the Web to allow people to interact with Web sites via spoken commands, and listening to prerecorded speech, music and synthetic speech. This will allow any telephone to be used to access Web-based applications, and will be a boon to people with visual impairments or needing Web access while keeping their hands anbd eyes free for other things.

• XForms: working to separate the user interface and presentation from the data model and logic, allowing the same form to be used on a wide variety of devices such as voice browsers, handhelds, desktops and even paper. XForms brings the benefits of XML to Web forms, transferring form data as XML... [from the Interaction Domain page]