Professional Microsoft IIS 8

Windows Process Activation Service

Windows Server 2008 adds a new tool called the Windows Process Activation Service (WAS). This service replaces the WWW service in managing application pool configuration and worker processes. The functionality that existed with the WWW service that ran only HTTP sites now allows WAS to run non-HTTP sites in addition to the HTTP sites. WAS is not part of IIS 8.0, but rather an external service that works in conjunction with IIS to manage the application pools and processes.

WAS can be run either with the WWW service or without it if HTTP functionality is not needed. The Windows Communication Foundation (WCF) is an example of a situation in which the HTTP protocol may not be needed. WCF uses a listener adapter to take the requests from WAS and route them to the WCF application, rather than using the HTTP protocol.

WAS is a prerequisite for IIS 8.0 and is automatically installed when you install IIS 8.0 on Windows Server 2012. WAS uses the same applicationHost.config file for its configuration that IIS uses. When the server is started, WAS reads the configuration and then shares that information with the listener adapters. The listener adapter then takes the configuration information and creates a communication link between WAS and a protocol listener. At this point, the protocol listeners just sit and listen. When they receive a request, WAS is used to determine if there is a worker process. If there is one, the request is passed to the worker process; ...