Event Sourcing for PHP Applications

Event Sourcing is a state-management pattern where every change to application state is captured as an immutable sequence of events. The event log is the single source of truth; current state is derived by replaying events.

Event Sourcing is not: event-driven development, microservices, CQRS, or eventual consistency. Those are related but separate concerns that may coexist with Event Sourcing.

Event Sourcing naturally enables CQRS because the write model is the event stream and projections are the read models. But CQRS is optional.

When to Use Event Sourcing (and When NOT to)

Event Sourcing adds significant complexity. Use it only when you need its specific capabilities.