BIE (Business Integration Engine) is an open source integration system that makes it easy for organizations to exchange data with external trading partners regardless of their native applications. It competes in the same space as applications like Microsoft BizTalk except that it is truly cross-platform since it written in Java.
What's new in BIE
Version 5.4.2 adds new features in the Map Builder tool (including unit conversion macros), better recovery from internal exceptions in the Web interface, and fixes for a number of bugs in the 5.4 beta releases. This should be considered the most stable version of BIE currently available.