Event sourcing works nicely with aggregates from Domain driven design.
An aggregate has the responsibility of creating immutable events, command handlers that emit these events and validate them too.
Besides creating these events, they can be instantiated and create a state from consuming this history of events, or in other words “applying these events” with event handlers.
Reference
Hoffman, Kevin. Real-World Event Sourcing: Distribute, Evolve, and Scale Your Elixir Applications. The Pragmatic Bookshelf, 2025. The Pragmatic Programmers.
Highlights or timestamps
- [?] An aggregate is a single, uniquely identifiable entity that has state, validates commands and emits events.
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An event sourcing aggregate has the following required characteristics:
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- Validates incoming commands and returns one or more events
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- Applies events to state to produce new state
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- Application of events and commands is pure and referentially transparent.
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