Is there a W3C icon for DOM?

Document Object Model Activity

Activity statements provide a managerial overview of W3C's work in each area, covering: an introduction to the activity, the goals of W3C work, the accomplishments to date, and future plans. They are designed to be read from beginning to end, to be informative and interesting. The introductory section serves to set the scene and to explain any technical concepts used in subsequent sections. Where necessary the explanation is expanded into a short tutorial. The role of W3C is given, also the benefits to the Web community, accomplishments to date and a summary of what the future holds.

Work on the Document Object Model is being managed as part of W3C's Architecture domain.

Introduction

The Document Object Model (DOM) activity is concerned with giving browsers a clear internal model of a document, thereby enabling scripts to operate on that document in a consistent manner across all platforms.

The DOM represents a web document in terms of a tree with nodes conistsing of objects (headings, paragraphs, lists, hypertext links, etc.). Such a representation makes it easy for programers to access the various parts of a document and delete, add, or change them, edit their content or change thier attributes.

Scripts to manipulate the DOM

The DOM is designed with the operation of HTML scripts in mind. HTML 4.0 provides authors with a standard way to embed these small programs into Web pages. Scripts can be used to change the document "on the fly" by manipulating it at the level of its HTML elements. One of the most commonly used scripting languages used on the Web today is JavaScript. Dynamic HTML is one name often given for the ability to use DOM to change the document dynamically by scripting.

A simple example of a script would be a small program which changed the sequence of fields displayed by an on-screen form according to whether you said "yes" or "no" in answer to one of the questions.

Without a DOM, scripting reliably across platforms remains precarious. Because browsers do not "see" documents in a standard and consistent way, because they do not share a consistent internal model of a document, writing a script which works properly regardless of what browser is used to display the document, is currently rather precarious. The same scripting language might, for example, need two different programs to manipluate an HTML document in an identical fashion on two different browsers.

Worse still, two given scripting languages might use the same syntax to mean different things. This means that the same script running in the same HTML file might do different things, depending on the browser displaying the document.

Goals of W3C's work on DOM

The goal of the Document Object Model is to address the problems above by a providing a standard representation of a document to be used by all browsers. A critical part of the design of the Document Object Model its language-neutral interface. You can imagine this as a layer between the DOM itself and the programming languages used manipulate it.

Written in the Object Management Group Interface Definition Language (OMG IDL), the interface language gives programmers a library of functions for accessing and manipulating the document structure, using whatever language they want . By enabling programmers to do this in a language-neutral manner, the choice of scripting language is left open: programmers can use JavaScript, BBscript, C++, Tcl, etc. Scripts can access documents and modify them efficiently and consistently across all browsers in different langauges.

An applet, plugin or ActiveX control can also access the document structure via DOM.

DOM aims to work with XML and CSS style sheets

The Document Object Model aims also to work with the Extensible Markup Language (XML). The idea is to evolve a core functionality that works with XML and HTML, with an extra set of features for HTML only. In addition to supporting important emerging standards such as XML, XSL, and XLL,....Script authors will probably use more of the functions in the HTML and XML specifications,

In the case of the CSS style sheet language, DOM aims to give a way to manipulate and change these. There will be core functionality that may be applicable to other style sheet languages.

Looking for information on Dynamic HTML? Dynamic style sheets? W3C has received multiple proposals on web page scripting APIs from member organizations. None of these proposes new style sheets technology: they propose only to animate existing style sheets with scripting technology. The proposals fall under the Document Object Model activity.

The role of W3C in the area of DOM

W3C has a working group which was set in ????. Several organizations have sent representatives to the DOM WG. These include ArborText, Hewlett-Packard, IBM, Inso, JavaSoft, Microsoft, Netscape, Novell, the Object Management Group, SoftQuad, Sun. The expection is to establish:

The WG is currently defining level one. This is the foundation of the DOM, since it defines the structure of documents and the way a document is accessed and manipulated. Level one will concentrate on the actual core, HTML, and XML document models. It will contain functionality for document navigation and manipulation, and style manipulation.

Further levels will specify some interface to the possibly underlying window system, including some ways to prompt the user as well as some model for interaction events. They will also contain functions to manipulate the document's DTD, and make rich queries. They will include a style sheet object model. Finally, they will include some security model. It has not yet been decided precisely what will be in level two, and what will be in other levels.

Ready now.....

Links to drafts and other related information

• September 2, 1997. The DOM Requirements
• October 9, 1997. The DOM Level one core document as part of the Document Object Model Specification.

• September 2, 1997. The DOM Requirements
• October 9, 1997. The DOM Level one core document as part of the Document Object Model Specification.