Event Sourcing: Building Event-Driven Systems
In modern distributed systems, maintaining data consistency, tracking changes, and scaling effectively can be challenging. Event Sourcing offers a powerful architectural pattern that addresses these challenges by storing all changes to an application’s state as a sequence of events. Let’s explore how to implement this pattern in a production environment. Why Event Sourcing? Before diving into implementation details, let’s understand why you might want to use Event Sourcing: Complete Audit Trail: Every state change is captured as an immutable event, providing a perfect audit history. Temporal Queries: You can determine the system’s state at any point in time by replaying events. Debug Friendly: When issues occur, you have a complete history of what led to the current state. Event Replay: You can fix bugs by correcting the event handling logic and replaying events. Scale Write/Read Separately: Event storage and read models can be scaled independently. Core Components The Event Store The Event Store is the heart of any event-sourced system. It’s responsible for storing and retrieving events while ensuring consistency. Here’s a TypeScript implementation that handles the core functionality: ...