D.Ajax

http://msdn.microsoft.com/en-us/library/bb398874.aspx

http://www.asp.net/ajax

AJAX Control Tool Kit

JQuery

Juice UI

AJAX Downside

1. Multiple ASync calls may increase load on server.

2. More client side code makes debugging harder

3. Introduces Browser Incompatibility

4. It Creates programming challenges like dirty read , race conditions etc

Architecture

Conditional Updates : By Default all the panels updated once any one of them fire update request , usually we need to turn it on manually

Ajax enabled Web Services

1. http://forums.asp.net/t/1677212.aspx

2. http://www.asp.net/web-forms/tutorials/aspnet-ajax/understanding-asp-net-ajax-web-services

3. Cross Domain Calls

4. Use JSONP enabled web services If supported (Best Pick)

5. Make Web Service XDR Compatible if you own it

   1. Server Side Proxy

   2. User Server side Proxy Pages

   3. HttpHandlers as server-side proxies

http://msdn.microsoft.com/en-us/library/bb398874(v=vs.90).aspx