Eseménysourcing

Eseménysourcing, often referred to as event sourcing, is an architectural pattern used in software development. Instead of storing the current state of an application, event sourcing stores a sequence of immutable events that represent every change made to the application's data. The current state is then derived by replaying these events.

The core idea is that every action that modifies data is recorded as an event. These events are stored in an append-only log, meaning they are added to the end and cannot be altered or deleted. When a user or system needs to know the current state of an entity, the system processes the sequence of events associated with that entity from beginning to end.

This approach offers several advantages. It provides a complete audit trail of all changes, which is invaluable for debugging, auditing, and understanding the history of the application. It also facilitates temporal queries, allowing developers to reconstruct the state of the application at any point in time. Furthermore, event sourcing can simplify certain complex business logic and enable new features like materialized views, which are pre-computed representations of the current state for efficient querying.

However, event sourcing also introduces complexities. Replaying a large number of events to reconstruct state can be time-consuming, and strategies like snapshots are often employed to mitigate this. Managing the event store and ensuring its reliability and scalability are also critical considerations.