A constraint is a restriction in the problem space that limits what a command can do. It turns an abstract business need into a condition the team must respect. section 2.3.2 section 2.1
Surface constraints while exploring business problems instead of jumping directly to feature solutions. Teams can represent them in EventStorming, then investigate their concrete cases with Example Mapping. section 2.1 section 2.3.3
Use a constraint to ask practical questions about a decision:
- What must be true before the command succeeds? section 2.3.2
- Which outcomes are possible, and which condition prevents each alternative? section 2.3.3
- Can the condition be expressed as a concrete example or acceptance criterion? section 2.3.3
- Would stakeholders understand another label, such as business rule? section 2.3.2
Reserving cinema seats
A Reserve Seats command can produce Seats Reserved or No available seats found. Example Mapping explores why: one ticket cannot occupy more than one seat, and a single reservation may require adjacent seats. Discussing concrete cases exposes further rules and acceptance criteria. section 2.3.3
