An exclusive event-based gateway is used to branch a process when alternative paths are determined by events (various messages or signals) rather than by conditional flows.
This can happen when the decision about one of the alternative paths is taken by someone out of the process. For example, a signing contract process expects the signal about a client's decision from the negotiation process. The further development of the process depends on this decision (Fig. 136).
Fig. 136 Exclusive event-based gateway
Depending on which event occurs first, the process will take the corresponding path. In the mentioned example, if the customer agreed to the conditions, the process will proceed the “Sign contract” user task, and if the customer refused – the process will end. In any case, only the expected event that occurs first will be processed, and all other events will be considered as no longer valid.
Outgoing flows for the exclusive event-based gateway are sequence flows. The gateway logic is defined by the [Message] and [Signal] intermediate catching events.
When the first catching event is triggered, the gateway ignores any other expected events.
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