AJAX: you agree or not it is back with new name. It’s nothing new, it’s the same JavaScript DOM model, and asynchronous request & responses traveling forth and back to update part of the tree. Even JSF is a component model, i.e. each component has a set of stages, in which they will update their part/some other part of components, i.e. a piece in overall is the DOM tree presented to the browser.
AJAX/JavaScript is very much needed to provide rich user interfaces, without having to load activex/applet plug-ins. JavaScript supported by most browsers, would be the light weight way of doing things than running any plug-in with browser.
It’s easy to use ajax in a wrong way causing, complexity in code [not able to trace what is happening where, for a maintenance developer], and un-expected user behavior.
Ajax’s Mistakes...
http://alexbosworth.backpackit.com/pub/67688
To reduce the complexity involved in coding an ajax applications, tools has to be introduced, which makes common utilities available. With JSF, you can create Faces Components which behind-the-scenes uses AJAX to make the components interactive. The ordinary UI developer/programmer can merely use those components, than coding directly with ajax. The hardness of dealing the XMLHttpRequest can be kept alone to components developer.
Dojo, gives you set of JavaScript utilities, which we may need to develop interactive applications, also has templating with support for widgets.
DWR - Direct Web Remoting, allows server side functions/objects to be exposed over for interaction from client-side JavaScript. This engine, acts transparently between the client and the server. It takes the burden of creating asynchronous requests, and getting responses. This seems to be simple, see the overview here. Also refer the java.net article. DWR is certainly worth to give a try.
