Used for creating interactive web applications or rich Internet applications and Update pages "on the fly". It is also used to retrieve data from the server asynchronously in the background. Ajax is a way of developing Web applications that combines:
> XHTML and CSS based presentation
> Interaction with the page through the DOM
> Data interchange with XML and XSLT
> Asynchronous data retrieval with XMLHttpRequest
> XML, XSLT object to manipulate data asynchronously with the Web server.
JRuby 1.3.1 is the latest release
Advantages> Speed and invisibility makes for a very slick user experience.
> The smaller server resources footprint helps server scalability.
> Reduce bandwidth.
> More interactivity.
> More complex applications (e.g. email clients)
> Fast and flexible to more robust and manageable
> Specialized skills vs existing skills
> Client based to more server centric
> Design of Server push capability
> Degree of built in Security
> Approach to scalability
> Library of rich components
> Interoperability with other solutions