API Orchestration Patterns: Fan-out, Fan-in, and Pipelines in Agentic AI
API Orchestration Patterns: Fan-out, Fan-in, and Pipelines
The reality: agents rarely call one tool
Real workflows require multiple systems: CRM + DB + email + analytics. Orchestration is how you manage these calls without turning your agent into spaghetti.
Fan-out / Fan-in
Fan-out: call multiple services in parallel. Fan-in: aggregate results into a single decision context.
Use this when latency matters and calls are independent.
Pipelines (sequential steps)
Use pipelines when steps depend on earlier outputs (e.g., fetch user → fetch orders → compute refunds → draft response).
Error handling strategy
- Retry transient errors
- Fail fast on auth/permission errors
- Return partial results with explicit warnings
