CQRS Aggregate Modeling

In CQRS, an aggregate is not a read model. It only needs the state required to decide whether a command is valid and which events to emit.

Workflow

1. Identify each command the aggregate handles.

2. List the state needed to validate and execute those commands.

3. Remove query-only projections, history lists, counters, denormalized display fields, and report data from the command aggregate.

4. Put read concerns into read models updated from events.

5. Redraw aggregate boundaries around true invariants and command contention.

Modeling Rules

• Keep state minimal, invariant-bearing, and command-oriented.