Among the Microsoft servers today, BizTalk Server is one of the most complex products. In its 13-year history, it went from being a clumsy tool that was made to support XML messages to an enterprise-quality integration server with a variety of features and a large technical community around it.

In the year 2000, when the first version of BizTalk was launched, EDI was dominating the market. XML messaging was in its infancy, but seemed very promising. Many technology corporations were looking into it, and Microsoft was no exception.

The original version, and even the following version of BizTalk, was totally different from the BizTalk we know today. They were built using some code from other servers, had very poor orchestration abilities, and did not provide much functionality. They supported EDI, HTTP, MSMQ, SMTP—and that was pretty much it. The 2002 version was also influenced by the concept of web services.

BizTalk 2004 was a completely new product. The...