Demystifying the HTML 5 Working Draft

The World Wide Web Consortium (W3C) has released a draft of the HTML 5 specification, the first major revision since HTML 4 was released more than a decade ago. During this time, as developers have gradually ported their applications to the Web, it has evolved from a primarily static medium to interactive applications with rich media content. HTML 5 aims to reflect this change.
The new features are fully considered by application developers, therefore, HTML 5 introduces a large number of new Javascript APIs. These can be used to associate content with corresponding HTML elements, including:
1/2D drawing API that can be used on a new Canvas element to render images, game graphics, or other visual graphics on the fly.
2/An API that allows web applications to register themselves as a certain protocol or MIME type.
3/An API that introduces a new caching mechanism to support offline web applications.
4/An API that can play video and audio, using the new video and audio elements.
5/A history API that exposes the browsing history, allowing pages to better support the back button in AJAX applications after adding it.
6/Cross-document messaging, which provides a way for documents to communicate with each other regardless of their source domains. 7/To some extent, this design is intended to prevent cross-site scripting attacks.
8/An API that supports drag and drop operations, which can be used to associate with the draggable feature.
9/An API to support editing operations, which can be associated with a new global contenteditable feature.
10/A new network API that enables web applications to communicate with each other on the local network and maintain two-way communication with their origin servers.
Use JavaScript API key/value pairs to implement client-side persistent storage, and support embedded SQL database.
Server-sent events can be associated with the new event-source element, which facilitates persistent connections to remote data sources and largely eliminates the need for polling in Web applications.
HTML 5 also introduces many new presentation elements to support common page components, such as headers, footers, figures, dialogs, and navigation. In addition, there is a new datagrid element to support interactive tables and trees, a datalist element for combo boxes, and a progress feature that can show the completion of a long-running task. Also, page tags have been added to support RSS feeds.
For forms, the input element type includes new support for dates, times, emails, and URLs, allowing browsers to provide user interface elements such as a calendar date picker or integration with the user's address book while submitting the data to the server in a defined format.
HTML 5 also drops support for some well-known features. The most notable of these is the drop in support for frames, which have long been considered to undermine the accessibility and usability of web pages. It is worth noting that even if a browser fully supports the HTML 5 standard, it will continue to support these abandoned features, because support for older versions of HTML will continue for many years.
HTML 5 is being developed under the guidance of the W3C's HTML Working Group, which was established in March 2007. The working group operates in full transparency and counts nearly 500 participants, including members from Apple, Google, IBM, Microsoft, the Mozilla Foundation, Nokia, and Opera.
"HTML is undoubtedly a very important standard," said Tim Berners-Lee, W3C Director and author of the first version of HTML. "I am pleased to see the developer community, including browser vendors, working together to create the best possible trajectory for the Web. It is a difficult task to integrate the ideas of so many people, and the challenge we face is to find a balance between innovation and preservation, idealism and pragmatism."
HTML 5 will gradually replace HTML 4, but the finalization of the HTML 5 specification is still a long way to go. The current plan is to initially adopt it as a candidate for recommendation during 2009, and then promote it as a final official version in September 2010.
ByCharles Humble
Translated by Zhang Yi

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