Pro WCF: Practical Microsoft SOA Implementation

Looking at the WCF Layers "Inside"

WCF is a layered framework similar to the Open Systems Interactive (OSI) model. The service model layer is the layer you will use primarily to program against. The service model layer influences the layer underneath it, which is called the messaging layer. The messaging layer is the layer where all the actual transportation of messages across the channels on the network becomes reality. The reason for the separation is an architectural concept. It allows you to separate the actual messaging from the programming model, and this allows you to benefit just from the messaging layer (similar to what BizTalk Server does).

Figure 3-5 shows how the layering is organized. The messaging layer is the lower-level layer ...