Have XMLHttpRequest Your Way...Last Chance

If you like to review W3C standards before they become official, here's one you need to take a close look at. The W3C Web API Working Group has published the Last Call Working Draft of "The XMLHttpRequest Object" specification.

The XMLHttpRequest Object specification outlines a standard for sending data between a client and a server via a scripting engine. The data can be in XML or any text based format and can be transmitted over either HTTP or HTTPS.

The specification relies on the DOM, HTML 5 and HTTP specifications. All conforming user agents must support these specifications to some degree (or completely).

A quick overview of the XMLHttpRequest object tells us that there are:

Five States

• UNSENT: The state when first constructed.
• OPENED: Means the open() method has been successfully invoked. Request headers can be made and the request be sent.
• HEADERS_RECEIVED: The state when the response headers have been received.
• LOADING: The state when the response entity body is being received.
• DONE: This state means the data transfer is complete or something has gone wrong.

One Event

• readystatechange: This event must implement the Event interface and it's namespace URI attribute must be null. It also must not bubble or be cancel-able

Exceptions

The specification uses the DOMException object defined in DOM Level 3 Core. All exceptions are part of the group ExceptionCode. The specification extends this group with three new constants: SECURITY_ERR = 18, NETWORK_ERR = 101 and ABORT_ERR = 102

This specification is one of the missions of the W3C Rich Web Clients Activity who aim to improve the client-side experience of the web.

You have until June 2, 2008 to submit comments on the specification. Ensure your email has either [XHR] or [XMLHttpRequest] as the beginning of the Subject Line or it may get lost in the shuffle.

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