Chapter 2. Windows Communication Foundation and Windows Workflow 4.0 Primer

Windows Communication Foundation (WCF) and Windows Workflow Foundation (WF) were first introduced with the release of the .NET Framework 3.0 in November 2006. The goal of WCF was to introduce a framework that aids in building distributed applications that leverages web services, MSMQ interfaces, and remoting with a consistent, service-oriented, communication platform. This platform abstracts the communication details (including transport, encoding, encryption, and authentication) from implementation logic. Because of this abstraction, we can often modify service behavior through configuration changes without impacting existing logic or compiled code. WCF controls WS-* implementation, distributed transactions, security, and serialization in a manageable fashion, and in a way that is relatively consistent across service platforms. With Windows Workflow, the concept of designer-based workflow was brought to the mass developer audience. This allowed for a drag-and-drop based coding experience within the confines of the well known Visual Studio designer.

The developer adoption of WCF as a replacement for traditional web services was widespread while, in contrast, WF lacked a robust hosting environment and failed to impress in terms of out-of-the-box features. With the release 3.5 and 3.5 SP1 of the .NET framework, new features like workflow services (exposing Workflows as WCF services), basic correlation, and persistence were added and brought more attention specifically to workflow. This also increased the number of possible use cases, but still lacked a real attention-grabbing feature or a scalable hosting environment.