What is IIS?
IIS (Internet Information Server) is one of the most powerful web servers from Microsoft Corporation that is used to host the Asp.Net web application. IIS has its own ASP.NET process engine to handle the ASP.NET request. So, when request comes from client to server, IIS takes the request and process it and send response back to the clients.
IIS means when request comes from client to the server a lot of operation is performed before sending response to the client. This is about how IIS process the request.What is Worker Process?
Worker process (w3wp.exe) runs the ASP.NET application in IIS. This process is responsible to manage all the request and response that are coming from the client system. All the ASP.NET functionality runs under the scope of worker process. When request comes to the server from a client worker process is responsible to generate the request and response.
In single word, we can say worker process is the heart of ASP.NET web application runs on IIS.
What is Application Pool?
Simply to say about what is application pool is: A group of one or more URLs are served by a particular worker process or set of worker processes.
Application pool is the container of worker process. Application pools are used toseparate sets of worker processes that share same configuration. Application pools enable a better security, reliability, and availability for any web application.
The worker process servers as the process boundary that separates each application pool so that when one worker process or application is having an issue or recycles, other applications or worker processes are not affected. This makes sure that a particular web application doesn’t impact other web application as they are configured into different application pool.
Application pool with multiple worker process is called “Web Garden”.http://msdn.microsoft.com/en-us/library/gg552610.aspx
Why are application pools important?
They provide a way for multiple sites to run on the same server but still have their own
worker processes and identity.
• Isolation of Different Web Application.
• Individual worker process for different web application.
• More reliably web application.
• Better Performance.
How to find the application pool account for a web application?
Go to IIS settings (type inetmgr in command mode) and select the web application on left pane and click on the “Basic Settings” on the right pane.