What is it?
Instead of reloading whole pages every time the user makes a change or request, the application exchanges the minimum possible data with the server, while the application remains available to the user. Ajax web applications can have the kind of rich user interfaces usually only available with desktop applications.
In February, Microsoft threw in its lot with the OpenAjax Alliance, having changed the name of its Atlas initiative to ASP.net Ajax. It is working with more than 70 organisations, including Google, Mozilla, Sun Microsystems and the Eclipse Foundation, to ensure that Ajax technologies remain open and interoperable.
Where did it originate?
The term Ajax was not coined until 2005, but the key technologies date back a decade or more.
What's it for?
As Jesse James Garrett, who coined the name Ajax, points out, HTML was developed to deliver hypertext, not interactive applications. Ajax acts as an intermediary between the user and the server, smoothing out the stops and starts that make using a web application so different to the desktop experience.
Ajax is being used to develop collaborative applications, and composite applications, or "mashups", which assemble content from multiple sources and applications.
What makes it special?
The OpenAjax Alliance, says, "Ajax enables rich user experiences while preserving existing back-end infrastructure. Users benefit from next-generation applications that have the feel of desktop applications and provide new capabilities, while IT preserves existing benefits from web-based application deployment and continuity with existing HTML-based back-end infrastructure."
However, there are drawbacks:
● The back button will not necessarily return the user to the unmodified page
● If an author copies a URL to include it as a hypertext anchor in one of their own pages, that anchor will not lead readers to the desired view but to the initial state of the page.
How difficult is it to master?
What systems does it run on?
Alongside Microsoft and Sun, other members of the OpenAjax Alliance include Adobe, BEA, IBM, Novell, Oracle, SAP and Zend.
What's coming up?
There are many free Ajax tutorials on the web. A good starting point is the Mozilla developer site.
Rates of pay
Salaries for Ajax web developers start at £25,000. Specialist graphical user interface developers can expect £35,000-plus.
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