Handling “OR” Operators in the BizTalk Rules Engine

Once again, here we are talking about the BRE!

I have a set of rules that utilize the OR operator. I found a very, very interesting article describing in detail how the BRE handles the OR operator.


Cliff Notes:

  • OR is not handled like procedural languages, such as C# – there is no short-circuiting. All elements of the OR condition are evaluated, and therefore each submits a separate match to the Agenda to be followed by the BRE
  • In the BRE (or any Rete engine) OR is much more analogous to SQL. Since each member of an OR condition results in its own “record” per-se, it can be loosely understood as a SQL using the UNION ALL clause, having a separate SQL statement for each member of the OR condition
  • BizTalk BRE performs a de-duplication after processing rules that keeps the multiple Rete results from rules using OR from being added to the processing Agenda. This mitigates some of the, “What the…” you felt when reading bullet one above!
  • If you purposely want separate Agenda items to be processed, you can force the BRE to do this by creating a separate rule for each member of your OR condition (i.e. don’t use OR in your rules, create multiple rules instead).

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