BPMN and DMN are two of the most-cited OMG standards in business automation, and they're often confused. The short version: BPMN models processes over time. DMN models decisions at a point in time. They're complementary, not competitors. Most non-trivial systems end up using both.

This post walks through what each standard is, where each one fits, the boundary between them, and a worked example of the two working together.

When we started designing QuantumBPM's process engine, we ran into the same wall every workflow tool runs into: how do you make execution durable? Survive worker crashes, network partitions, weeks-long timers, replay after restart, exactly-once activity semantics? The honest answer turned out to be: don't build that yourself.

This post is about the bet we made - running BPMN on top of Temporal - what it cost us, what it bought us, and why we think Temporal developers are the audience that benefits the most from a BPMN layer sitting above their existing investment.