AJAX is a technology that enables web applications to call the webserver without leaving the actual page. It's possible to do this in the background without notice of the user. This avoids loading the same form or page including the html markup multiple times, reduces the network traffic and increases the user acceptance.
The AJAX Engine that you can find here is built upon the webservice standard protocols SOAP and WSDL for transferring the data between the browser client and the web server instead of using a new or proprietary protocol.
The server side of this AJAX Engine uses the ASP.NET framework, Version 2.0 and the C# programming language to implement the WebServices and a server side control library. Because WebServices are part of other standard frameworks it is easy to port the engine to other platforms and so there is a port of the core parts to the java platform available too.
This implementation has its focus on building an AJAX Engine and Web Controls upon standard WebServices (SOAP, WSDL) on the web server instead of using a new or proprietary protocol. The benefit for that is that there is no special coding necessary for most parts of the networking infrastructure and that many aspects like caching and security of the WebService implementation can be reused.