In A Synchronous whole page is refresh, client wait till the operation completes. there is no gap between data. data communicate server continuously
An Asynchronous part of the page is refresh, client browser not block, client can peform another operation. data will sent packetwise, we use Ajax engine to communicates with the server
3 - Disadvantage of Ajax.
Anyone can view source code that is written for Ajax.
Ajax integration with every browser is not good.
Ajax code is complex that is more difficult to web developers.
Ajax application does not index on search engines like google,yahoo etc.
Data is URL-encoded so that that increased request.
4 - Advantage of Ajax.
There is no need to buy extra software.
Whole page will not refresh only part of the page is refresh
We can access database from server without reloading page.
This is looking like desktop application.
Waiting time more reduced
5 - What are the different type of state in Ajax.
0 means request not initialized
1 means server connection established
2 means request received
3 means processing request
4 means request finished and response is ready