Fundamentals of Windows Communication Foundation
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by Keyvan Nayyeri
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Message

Message is the key in WCF.  Without messages we do not have anything!  As I stated in the first part, services, clients and intermediaries communicate with each other via messages.  They send and receive messages in order to do things.

Structure

First, it is better to give a background about message structure in WCF.  Each message in WCF is an XML document (especially SOAP Envelope) that consists of two main parts: headers and body.

Each message may contain one or more headers, but only has one body.  Headers are some means that infrastructures or developers consume and they are mainly used to represent some information about the message itself.  The body is what we (developers) should care about because most of our codes will be applied to the body.  The body is where our data is located.

Patterns

Based on our needs in WCF we deal with messages in one of following three patterns:

·         Simplex: This is a one way messaging pattern.

·         Request-Reply: This is a two way asynchronous messaging pattern.

·         Duplex: This is a two way synchronous pattern.

Let us take a look at these three patterns in more detail.

In simplex pattern, which is a one way asynchronous pattern, you send a message from client to service and nothing more (Figure 1).

Figure 1:

In the request-reply pattern the client sends a request to the service and waits until it returns a reply back.  Nothing can happen in this between service and client.  Request-reply is a common pattern for internet users and everyday you deal with this pattern on internet.

Figure 2:

In the duplex pattern the client and service can communicate with each other regardless of anything that is going on between them so a client can send a message to the service and the service can send a message to the client.  Here, neither the client nor service needs to wait.

Figure 3:


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Title: afdsfaff   
Name: fdsf
Date: 2012-11-21 6:37:14 AM
Comment:
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Title: gg   
Name: gg
Date: 2012-11-21 6:36:44 AM
Comment:
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Title: xzcnbzx   
Name: jxncvjkn
Date: 2012-05-16 7:01:49 AM
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Title: WCF   
Name: Gracy Pasca
Date: 2012-05-03 7:42:05 AM
Comment:
It is very understandable.....one
Title: WCF   
Name: Chandru
Date: 2011-03-10 12:06:38 AM
Comment:
simple and understandable for beginners and its hard to understand when new technology with prebuild modules so i recommends that you better given with an examples
Title: wcf   
Name: lakshmi
Date: 2010-12-22 7:29:10 AM
Comment:
This is a very good article for learners
Title: wcf   
Name: suvarna
Date: 2010-12-22 7:26:33 AM
Comment:
this is good article for beginners to understand
Title: Could you give an example for duplex pattern   
Name: Rosein
Date: 2010-08-25 7:38:24 AM
Comment:
Firstly, thanks for article but could you give some examples for duplex pattern?
Somewhere on net I read an example for duplex as "Fax machine"
But, I couldn't understand cause it also gets a request and with this request it recieves the message to the place and also send a response that tels the message send successfully or not.
Title: wcf   
Name: Indra
Date: 2009-07-27 8:23:11 AM
Comment:
pls be clear on sync and async
Title: can u clarify the where u have using content management in moss 2007   
Name: sreedhar verma
Date: 2009-02-21 7:30:53 AM
Comment:
NOw i want explanation of content management
Title: what are the precations of masterpages   
Name: sreedhar verma
Date: 2009-02-21 7:29:15 AM
Comment:
i observe the all concepts some what is more useful for all sharepoint developer.
Title: exllent   
Name: yangamuni prasad
Date: 2008-10-15 2:44:25 PM
Comment:
It's nice article, everybody can understand this
Title: Good article   
Name: Amit Ravi
Date: 2008-10-11 7:01:41 AM
Comment:
This is great article...especially for beginners.
But the asynchronous message exchange pattern is the Duplex pattern and not the Request/reply pattern which is synchronous.
Title: Asynchronous and asynchronous   
Name: Anubha
Date: 2008-09-28 5:44:34 PM
Comment:
You mentioned about request-reply is asynchronous but i believe the explanation for asynchronous is wrong..please correct it else it is definitely confusing and incorrect info.. Thanks.
Title: Request-Reply pattern is Synchronous   
Name: Shan
Date: 2008-01-28 2:56:58 AM
Comment:
You mentioned Request-Reply pattern is asnchronous but its waiting for response from service. So i believe this pattern is Synchronous one. Thanks for you Arthicle. Regards,Shan
Title: just some doubt   
Name: madhanMohan
Date: 2007-07-19 7:51:44 AM
Comment:
HI,
Just one small doubt, In above article "Request-Reply" pattern is defined as "two way asynchronous messaging pattern" but down when explaining the same it is specified that after sending a request client should wait for the reply from service(which is Synchronous i believe bcz as far i know in Asynchronous messaging client need not wait for server/service reply and meanwhile client can continue with its business).

It would be great if you clarify me.

Thanks,

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