Customization of message processing in Microsoft® BizTalk® Server 2006 R2 can be extended through the use of Windows Communication Foundation (WCF) custom behaviors. This article is the first of two parts discussing how the use of WCF custom behaviors within BizTalk Server gives increased control over the message transmission process.
From: http://msdn.microsoft.com/en-us/library/cc952299.aspx
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