XML Vs JSON

All these days we were learing about XML as only the data transfer technology and the whole world were crazy for learning XML and institutes were earning bucks in the name of XML as it was highly demanded in the era of web technology.But after the incubation of Java Script object notation(JSON) XML has lost its glossiness to some extent in the field of web application.Because the truth behind this is JSON is much more faster than XML as it occupies less memory than its counterpart XML.So imagine if u have to transfer data and with XML it comes 1 MB .By using JSON you can transfer the same data with just 1/2 MB of size.So start using JSON for any server and client data transfer.Also we have java based JSON library a good news for java developer

Ext JS

Ext JS is a javascript api for desktop looks and feels for a web application.It follows the concept of oops as wells as lots of good design pattern is integrated with it.It heavily depends on JSON for data to and forth between the server and the client.
The beautiful advantage of Ext Js is it faster than other javascript libraries as it caches the data and also it uses JSON String for Ajax type data transfer.As JSON takes less memory from its counterpart XML data transfer.I have spoken the good part of Ext JS,but let me tell about its sad part its a licenced based api.But can be used free if you are not making any profit from your apps where you are using Ext Js.Also Ext JS can be integrated with JSF for developing ajax based custom components.