What it is
A process manager is a central component that maintains the state of a multi step business process and decides the next step based on results so far. Unlike a routing slip, it can branch dynamically.
How it works
- It receives a trigger message and creates a process instance with state.
- After each step replies, it inspects the result and decides the next step.
- It continues until the process reaches a terminal state.
Why it matters
- Handles workflows where the path depends on intermediate outcomes.
- Centralizes complex control flow in one testable place.
- Can manage timeouts, retries, and compensation for failed steps.
The tradeoff is centralization: the process manager knows about every participant, which couples it to the workflow and can become a hotspot. It must persist state so a crash does not lose in flight processes. It is the orchestration counterpart to choreography, where services react to events with no central brain. Choose it when control flow is complex enough that a slip or pure events become hard to follow.
Key idea
A process manager holds workflow state centrally and chooses each next step from results, enabling dynamic branching across a multi step process.