Parallel Gateway (AND)

Fork: Activates all outgoing paths simultaneously. Join: Waits until tokens have arrived from all incoming paths before continuing.

<parallelGateway id="fork" />
<parallelGateway id="join" />

Fork behavior

When the engine reaches a parallel gateway with multiple outgoing flows it creates one token per outgoing flow and advances each immediately. All branches execute concurrently.

Join behavior

A parallel join tracks how many tokens have arrived. It advances only when arrivals >= number of incoming flows. The counter is then cleared.

If a parallel gateway has only one incoming flow, it acts as a pure fork. If it has only one outgoing flow, it acts as a pure join.