IIS and WAS dynamic activation

I am learin开发者_开发问答g the theory of WCF. In one of the book about WCF it reads that IIS and WAS supports dynamic activation, therefore it is possibile to create service host factory. What is dynamic activation?

It sounds like you are trying to understand what the Windows Process Activation Services (abbrreviated as 'WAS' in Microsoft's infinite wisdom) is and what it provides. WAS works with IIS to serve up an instance of a WCF service on demand. The demand is a request sent over some transport (HTTP, TCP, MSMQ) containing the soap or REST-based message for the WCF service to process. This is the dynamic activation of a service instance to process the message.

The alternative to "dynamic activation" is to write something like a Windows NT Service application to host the a WCF service. Dynamic activation is preferred because it provides the ability of the service to scale to handle a heavy load and later release those resources for other processes to use. With an NT service based host, the WCF service instance is always running and you need to decide how to handle scalability requirements. If you what to understand all the details, look at this article that explains how a WCF service can be hosted.