A message called an event may actually instruct another system to act. Mixing the two makes responsibility for success and failure hard to see. Create purchase order asks a system to do something; purchase order approved reports a fact that has already happened. Mixing the two can make consumers believe an unapproved action is final. The distinction affects ownership, validation and what a receiver may legitimately reject.
What good engineering looks like
Is the sender asking one owner to perform an action, or reporting that a business fact already occurred? Answer this for a named workflow and an accountable team. Identify the information needed at the moment of decision, the system that can settle a dispute, and the route for correcting dependent copies. The technical design should make those business rules visible to the people who operate and support the handoff.
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Name commands as requested actions and events as completed facts.
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Assign the owner that may accept or reject a command.
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Define acknowledgements, follow-up events and error handling for both paths.
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A named owner for a rejected, delayed or repeated item.
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Evidence that the receiving system applied the intended business state.
A practical starting point
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Choose one real case and write down its trigger, expected outcome and responsible team.
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Take three messages from the proposed flow and ask whether each expects a decision or announces one.
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Name the accountable system for that decision, then test a refusal, a duplicate and an out-of-order delivery. The wording should still make sense to an operations owner outside the implementation team.
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Record what the test exposed, who will resolve each open question and how the fix will be checked.
Keep the first design small enough to review with the people who run the process. Test an exception alongside the normal case. A successful transport test shows that data moved; it does not by itself prove that the receiving team can make the right decision or recover from a partial failure.
The decision to make
Naming alone does not fix coupling. Review whether consumers can act independently and whether the sender needs a definite answer. Decide what level of timing, traceability and recovery this workflow actually needs. Document assumptions that remain untested and revisit the choice when a partner, process or business rule changes. The point is a dependable operating decision, not simply a working interface.
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