Event Sourcing

Event Sourcing is a software architectural pattern where state changes in an application are captured as a sequence of events. Instead of storing the current state of an entity, the system stores a log of all changes to that state.

• Event: A record of a state change that has occurred.
• Aggregate: A cluster of related objects that are treated as a single unit for data changes.
• Event Store: A database specifically designed for storing events.
• Snapshot: A point-in-time representation of an aggregate's state, which can be used to optimize performance.

The following sequence illustrates the event sourcing workflow:

graph TD;
                A[User Action] --> B[Generate Event];
                B --> C[Store Event in Event Store];
                C --> D[Update Read Model];
                D --> E[Notify Users];

• Use a dedicated event store for better performance and scalability.
• Implement snapshotting to reduce the number of events that need to be replayed.
• Design events to be immutable and descriptive.
• Ensure event versioning to handle changes in the event schema.