Professional ASP.NET 3.5 Security, Membership, and Role Management with C# and VB

1.2. Application Pools

IIS 6.0 introduced the concept of application pools when operating in the worker process isolation-mode compared to working in the IIS 5 mode. An application pool by definition is a unit of separation, at the web server level, that is used to logically group applications into different boundaries, hence providing an isolation of execution from one application to another. If an application in one of the application pools on the web server crashes, not all the applications on the web server will be crashed too. This is because if each application is assigned to a separate application pool, then only this specific application pool will recycle and all applications assigned to the same application pool will also crash. Other applications assigned to other application pools continue to function properly as if nothing happened on the web server. Therefore, application pools provide isolation of execution under the boundaries of the server resources allocated to every application pool, which are allocated differently from one application pool to another.

In the previous release of IIS, the web server was configured to either run in the worker process isolation mode or in the IIS 5.0 mode. However, in IIS 7.0, an application pool is created and its managed pipeline mode property is either set to Integrated mode or Classic mode. This means that the managed pipeline mode is not configured on the web server as a whole. On the contrary, several application pools can ...