Is Biztalk an ESB?

BizTalk can certainly be used as an Enterprise Service Bus, the Microsoft Patterns and Practices ESB Guidance is based on BizTalk Server and .NET components (see http://www.codeplex.com/esb and http://msdn.microsoft.com/en-us/library/cc487894.aspx)

There are somegood discussions on BizTalk as an ESB over on the InfoSys blog (http://infosysblogs.com/microsoft/2006/09/biztalk_as_an_esb_2.html) and the Developer Network Journal (http://www.dnjonline.com/article.aspx?ID=dec05_biztalk).

You might also want to read the Microsoft ESB Guidance over on the Microsoft BizTalk pages (http://www.microsoft.com/biztalk/solutions/soa/esb.mspx).

Rgds, Nick.

No, BizTalk is not an ESB.  It is a great platform for building an ESB though.  BizTalk does most of the core ESB functions such as transformation, routing, and messagin patterns, but you need hardcore developers to make these things happen.  I feel like an ESB should be more configuration based so that it is accessible to less technical people.  Microsoft did provide a guidance package that shows how you can build an ESB with BizTalk.  It demonstrates some really nice ESB patterns, but it still takes a lot of developer effort to get it running.  You can download it here:  http://www.codeplex.com/esb. 

Regards,