Asynchronous Programming With WCF

I’m currently spending a lot of time exposing intrinsically asynchronous server operations to a client application, and I’ve been really impressed with the way WCF caters for this. Asynchronicity is very important for performance and scalability of high-volume systems, but it’s a confusing area, and often something that’s poorly understood.

So I thought I’d write a series of posts to try and shed some light into these areas, as well as share some of the more interesting things I’ve learnt along the way.

Before we start you’ll have to have at least passing familiarity with the Asynchronous Programming Model (APM), which describes the general rules surrounding the expression of an operation as a pair of Begin/End methods. At very least, you need to get your head around the fact that these signatures:

	// sync version
	int DoWork();

	// async version as Begin/End pair
	IAsyncResult BeginDoWork(AsyncCallback callback, object state);
	int EndDoWork(IAsyncResult result);

…are equivalent.