Can we run both 1.1 and 2.0 web projects on the same Windows 2003 server? Many times I have answered this question on the forums, so thought of writing a post on the same.
IIS 6.0 can run both ASP.NET 1.1 and 2.0 web applications simultaneously on the same server, if each version specific application is assigned a different application pool. Now what is an application pool?
We know that each ASP.NET application is assigned a separate Application domain in the same worker process (w3wp.exe in Windows 2003). If a request comes for a different application on the same server, then another application domain is created within the same worker process. This avoids the overhead associated with creating a new worker process each time a new application is requested.
IIS also provides the facility of creating new new worker processes for each web application. This means that instead of running in the same worker process, IIS will create a new worker process and run the application within it. This information is maintained through application pools.
You can create a new application pool in IIS 6.0. Open IIS->Select your machine->Go to Application Pools folder->Right click->New Application Pool.
For assocating an application with a particular application pool:
1. Open IIS
2. Go to Websites
3. Select your website
4. Right click and Select properties
5. Go to Home Directory tab
6. Change the application pool by select the Application Pool drop down at the bottom.
So if we want to run both 1.1 and 2.0 web applications on the same server, we can create two application pools and assign one to 1.1 and the other one to 2.0 applications.
We can have an application pool which has multiple worker processes (a Web Garden) and is used for reliability so that if one worker process fails, the other one can continue handling the same request (requests are shared among the worker processes in a Web Garden).
See this link for more details and tips on application pools:
http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/2a231dcb-d786-4b6d-b3ba-bda04061a5e7.mspx?mfr=true