Overview
Both patterns coordinate a multi-step business process across independent services, but they differ in where the coordination logic lives. In choreography, each service reacts to events and decides its own next move with no central brain; in orchestration, a dedicated controller tells every service what to do and in what order.
Comparison Diagram
Comparison Table
| Aspect | Choreography | Orchestration |
|---|---|---|
| Trigger | Any service publishes an event when something happens | A client or event calls the orchestrator to start the process |
| Coordination logic | Distributed across each service’s event handlers | Centralized in one orchestrator component |
| Communication style | Asynchronous events broadcast to whoever is listening | Explicit commands and replies directed at specific services |
| Step sequencing | Emergent from chained event subscriptions | Explicitly defined as a workflow or state machine |
| Failure handling | Each service listens for failure events and compensates locally | Orchestrator detects failure and drives compensating transactions |
| Adding a new step | Add a listener; no existing service needs to change | Update the orchestrator’s workflow definition |
| Observability | Hard to see the full process; requires distributed tracing | Process state is visible in one place, easy to audit |
| Coupling | Low coupling between services, higher coupling to event schema | Services decoupled from each other, but coupled to the orchestrator |
Key Differences
- Choreography spreads decision-making across services via events; orchestration centralizes it in a single controller.
- Choreography scales extensibility easily but makes the overall process hard to trace.
- Orchestration makes the workflow explicit and easy to audit, at the cost of a single point of coordination.
- Compensation logic lives in each service under choreography, but is driven centrally under orchestration.
- Orchestration introduces a dependency on the orchestrator itself as new coupling, even as it decouples the services from each other.
When to Use Each
Choreography
- Simple event chains: When steps are few and loosely related, letting services react to events avoids building extra infrastructure.
- Independent team ownership: Teams can evolve their service’s event handling without coordinating changes to a shared workflow definition.
- High scalability needs: Removing a central coordinator avoids a bottleneck or single point of failure in high-throughput event pipelines.
Orchestration
- Complex multi-step transactions: A saga with many conditional branches and compensations is easier to reason about as an explicit workflow.
- Need for visibility and auditing: Regulated processes benefit from a single place showing the current state and history of each transaction.
- Coordinated rollback logic: When failures require carefully ordered compensating actions across services, a controller can sequence them reliably.