I recently started implementing Workflow Foundation in our projects. I is really exciting to know how WCF and WF can be integrated together.
Any workflow created can be exposed at WCF endpoints. For us to implement this, .NET Framework 3.5 provides some objects.
Used send requests from workflow to WCF service
Used to receive and listen to requests at a WCF end point.
This is a bridge class between WCF ServiceHost class and WF WorkflowRuntime class. This class provides the WCF implementation and also the runtime necessary for workflow to function.