Remembering the Future

One of the problems that I had with the BPEL workflow specification standard that is being lead by Microsoft and IBM at Oasis is that it takes a structured view of workflow. If you look at what is being done in the Open Source community you see that many projects are taking a very different rule based approach based on pre and post conditions that provide for a much more loosely defined event based approach to workflow. Often things in the real world doesn't go as planned. This can make structured steps approaches very difficult to work with once things get off track. With a rule based system, activities are activated as their preconditions are met and released as their output is verified. The actual steps may be performed in a different sequence each time the work is performed. It was interesting for me to see that MS Biztalk 2004 has integrated support for both BPEL and rule based approaches. This is done by having a rule based block that can be embedded in a BPEL style workflow. Different parts of the workflow can be structured or rule based depending on the requirements.