Hi Geek,

In our last post Channels , we see how messages are exchange in WCF using channels ,

In this post we will see the types of message exchange patterns in WCF .

WCF supports three distinct message-exchange patterns:

1) One Way

2) Duplex

3) Request Reply

1) One Way Communication Pattern

a) In the one-way communication pattern, messages are sent in only one direction, from the client to the server.

b) One-way communication is common when the sender does not need an informational response back right away;the sender just needs an acknowledgement that the message was sent.

c) After the message is sent, that is the end of the communication exchange

2) Duplex communication pattern

a) Duplex communication uses two one-way channel shapes combined into a third interface called IDuplexChannel.

b) The advantage of duplex communication over one-way or request-reply is that messages can be sent from either the client or the server.

c) Example

An example of duplex communication is an event notification system. A server will send events to a client that receives events. The client provides an endpoint on which the server can send messages to the client. The server will then use this endpoint to send messages to the client

3) Request Reply communication pattern

a) Request-reply communication is a special form of two-way communication where there is exactly one reply for each request, and it is always initiated by the client.

b) After the client sends a request, it must wait for a response before it can send another request.

c) Example  A common use of request-reply communication is an HTTP request from a browser

The browser makes an HTTP request to the server, such as GET or POST, the server processes that request, and then a reply is sent back.WCF handles request-reply communication using the IRequestChannel and IReplyChannel.

In coming posts we will go in depth with each message exchange pattern.

Thanks.