Event-Driven Architecture

Concepts: dmEventSourcing

State vs Events: Two Ways to Model Reality A state-based system stores the current truth: account_balance = $1,000. An event-based system stores what happened: deposit($500), withdrawal($200), deposit($700). The current balance is derived by replaying the events. Both representations contain the same information, but events are more powerful because you can reconstruct ANY past state, not just the current one. This is the fundamental insight of event-driven data modeling: events are the source of truth. State is a projection of events at a point in time. If you store the events, you can always recompute the state. If you store only the state, the events are lost. In data engineering, you work with both. Source systems are state-based (PostgreSQL, MySQL). Your pipeline captures the changes