Web sites and applications can be divided into pools of sites that make the most sense to the administrator. These pools create complete sandbox isolation between the other application pools on the server, offering strong performance and security benefits.
This chapter covers the various aspects of application pools, from overlapping worker processes during a recycle to the new Integrated Pipeline mode. A background and comparison between IIS 5.0 and IIS 6.0 are covered to set the stage for understanding why application pools are necessary and the advantages that they bring.
Effective management of application pools requires an understanding of
Application pools, including what virtual directories and applications are in IIS.
w3wp.exe worker process.
The two pipeline modes.
Multiple methods of creating and managing application pools.
Back in the days of IIS 5.0, applications could be placed in one of three isolation modes: low, medium, or high. Low and medium isolation placed all web sites in a large shared pool that utilized a shared user identity. Failures that affected one site often would break other sites that were set in low or medium isolation, requiring a reset of IIS to fix the sites again. Sites in high isolation did better by partially protecting some sites from each other, but each high-isolation application had an extra memory footprint, and the user identities were not unique from each other. ...