Context and Problem
In a microservices architecture, services need to coordinate their actions:
- Direct service-to-service communication leads to tight coupling
- Managing dependencies across multiple services increases complexity
- Ensuring scalability while maintaining service independence
Solution
Choreography uses events to drive service interactions:
- Each service publishes events when an action occurs
- Other services subscribe and react to these events asynchronously
- No single service controls the workflow; actions occur independently
- Events propagate across the system without direct service dependencies
Benefits
- Loose Coupling
- Services communicate without direct dependencies
- Scalability
- Easily add new event subscribers without modifying existing services
- Flexibility
- Workflow can evolve dynamically without central control
Trade-offs
- Debugging Complexity
- Distributed event chains are harder to trace
- Event Ordering
- Ensuring events are processed in the correct sequence
- Monitoring Overhead
- Requires observability into event flows and failures
Issues and Considerations
- Event Duplication
- Handling duplicate or missed events correctly
- Service Coordination
- Defining clear event-based workflows
- Error Handling
- Managing failures when processing asynchronous events
When to Use This Pattern
- Your system requires loosely coupled, event-driven communication
- You need to scale services independently without tight dependencies
- New services may need to be integrated dynamically into workflows