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September 30, 2009

New HTML5 introduced

Filed under: General — Newbiesite Admin @ 7:11 am

Author: Ethan

HTML5

HTML4 was introduced roughly ten years before and there was no major update apart from XHTML, HTML5 is the major revision of HTML (Hypertext Markup Language), the core markup language of the World Wide Web.

HTML5 is the proposed next standard for HTML 4.01, XHTML 1.0 and DOM Level 2 HTML.

HTML5 is expected to be a game-changer in Web application development, making obsolete such plug-in-based rich Internet application (RIA) technologies as Adobe Flash, Microsoft Silverlight, and Sun JavaFX.[2]

Impact on Web Architecture

These are some of the areas / features defined in HTML 5:

The use of the DOM as a basis for defining the language.

The concept of browsing contexts.

The distinction between user agent requirements and authoring requirements.

The use of imperative definitions rather than abstract definitions with the requirement of black-box equivalence in implementations.

The new content model concepts (replacing HTML 4’s block and inline concepts).

The focus on accessibility as a built-in concept for new features (such as the hidden attribute, the progress element, etcetera) instead of an add-on (like the alt attribute).

The focus on defining the semantics in detail (e.g. the outline algorithm, replacing the vague semantics in HTML 4).

The new sandboxing features for iframe.

The definition of URL.

Syntax

HTML 5 defines an HTML syntax that is compatible with HTML 4 and XHTML 1 documents published on the Web. SGML features of HTML 4, such as processing instructions and shorthand markup. Documents using the HTML syntax must be served with the text/html media type. HTML 5 also defines detailed parsing rules (including “error handling”) for this syntax which are largely compatible with popular implementations. User agents must use these rules for resources that have the text/html media type.

The DOCTYPE

The HTML syntax of HTML 5 requires a DOCTYPE to be specified to ensure that the browser renders the page in standards mode.

MathML and SVG

The HTML syntax of HTML 5 allows for MathML and SVG elements to be used inside a document.

Miscellaneous

There are a few other syntax changes worthy of mentioning:

HTML now has native support for IRIs, though they can only be fully used if the document encoding is UTF-8 or UTF-16.

The lang attribute takes the empty string in addition to a valid language identifier, just like xml:lang does in XML.

APIs

HTML 5 introduces a number of APIs that help in creating Web applications. These can be used together with the new elements introduced for applications:

  1. 2D drawing API which can be used with the new canvas element.

The < canvas > tag is a 2D (at the moment – other dimensions may be forthcoming) drawing area controlled by Javascript. You can use it for a wide variety of things – graphs, games, presentations etc. Because it’s controlled by Javascript you can interact with it very easily.

  1. API for playing of video and audio which can be used with the new video and audio elements.

The < video > tag makes it easier to embed video clips into your web pages. It has attributes like src (naturally), autoplay and loop. The tag has implications on usability (eg blind access), and so can contain additional markup describing the video. Ideally, the full transcript of the video.

  1. An API that enables offline Web applications.

  2. An API that allows a Web application to register itself for certain protocols or media types.

  3. Editing API in combination with a new global contenteditable attribute.

  4. Drag & drop API in combination with a draggable attribute.

  5. API that exposes the history and allows pages to add to it to prevent breaking the back button.

  6. Cross-document messaging.

  7. Extensions to HTMLDocument

HTML 5 has extended the HTMLDocument interface from DOM Level 2 HTML in a number of ways. The interface is now implemented on all objects implementing the Document interface so it stays meaningful in a compound document context.

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