Looking for solution to identify the application to be loaded based on the extensions. This should happen automatically picking the extension names. For instance if a file by name .pdf is provided it should open the file using "Arcobat reader", if a file by name .doc should open using "Word Document" .
Are you talking about the user downloading the file from an ASP.NET web application? In that case if just always make the content type application/octet-stream. Then when the user downloads the file, the user's OS will determine what to do with the file based on the extension, you don't have to sniff the extension and change the content-type for each file.
I am actually looking solution for windows based application. I just gave the above example, but really not looking solution for ASP.net/web based application. This is intended for Windows based application.
The equivalent for a Windows application is to use the Windows API ShellExecuteEx.
You can send the full path to a file in ShellExecuteEx and Windows will figure out what to do with it based on what the default application handler for that type of file is. You can even send URLs (http://someplace.com) to ShellExecuteEx and it will launch in the user's default web browser, and you don't have to figure out what that default web browser is or just hardcode something like "iexplore http://someplace.com" (which really irritates people that use a different browser.
For .NET (C#, VB.NET, etc) it looks like you can use System.Diagnostics.Process.Start(strParms) in order to perform the task (it probably launches ShellExecuteEx behind the scenes). Try that and see if it helps.
Infact looking for automatically opening the document in the application which it should actually open, instead of IE. For instance, .pdf should open using Acrobat Reader, .DOC should open using Word Application without using IE.
ShellExecuteEx and/or System.Diagnostics.Process.Start() should open the application that is associated with the file extension. It will bypass IE or any web browser if the file extension is registered with a different application. I ws just giving additional examples of what it can do (launching the default web browser for URLs).