# BPMN gateways

Gateways control flow. The marker inside the diamond decides whether one path is taken, all of them are, or the process waits.

A gateway does no work. If your diamond has a verb in it, it is probably a task.

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## When it matters

* Any process with a branch, which is most of them.
* Parallel work that must all complete before continuing.

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## The symbols

| **Symbol**    | **Means**                                             |
| ------------- | ----------------------------------------------------- |
| Exclusive (X) | Exactly one outgoing path is taken.                   |
| Parallel (+)  | All paths are taken, and all must arrive to continue. |
| Inclusive (O) | One or more paths, based on conditions.               |
| Event-based   | Waits, and the first event to occur decides the path. |
| Complex       | Rare, and usually a sign the model needs simplifying. |

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## A few things that catch people out

* Every exclusive gateway needs a default path, or the process can get stuck with no valid route.
* A parallel split must be joined by a parallel gateway. Mixing split and join types deadlocks.
* Event-based gateways are how you model "whichever happens first", including timeouts.

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## Related

[BPMN sub processesCollapsing detail without losing it.](https://help.gocapable.com/diagrams/bpmn-sub-processes.html)

[BPMN sequence and message flowsSolid lines stay inside; dashed lines cross.](https://help.gocapable.com/diagrams/bpmn-sequence-and-message-flows.html)

[BPMN notation referenceBack to the full symbol reference.](https://help.gocapable.com/diagrams/bpmn-notation-reference.html)

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_Sequence flow stays inside the pool._