Channels(Essential Windows Communication Foundation)

WCF supports three distinct message-exchange patterns: one-way, duplex, and request-reply. To facilitate each of these patterns, WCF provides ten different interfaces called channel shapes. The five shapes are IOutputChannel, IInputChannel, IDuplexChannel, IRequestChannel and IReplyChannel. Each of these shapes has an equivalent shape to support sessions. These include IOutputSessionChannel, IInputSessionChannel, IDuplexSessionChannel, IRequestSessionChannel and IReplySessionChannel.

The ICommunicationObject interface (see Listing 3.8) is the basis of all communication objects (channels, channel factories, channel listeners, and so on) within WCF. Developers who are planning to build custom channels or work with channels directly need to know this interface.