Use case :
Workflow running for a long period of time with several approbations.
Event : Someone cancel the request
You have a process that trigger when someone cancel a request.
In it you can use : Send Event :
Event name : "Request Cancelled"
Event Type : "Request Cancelled"
source : Process.requestID
In the process with the approbation. you create another "corridor" (not sure if it's called like this in english version).
In it you add a "Monitor Event" operator, you link it at the beginning of your process, and link it to the Stop operator (Green sign). (Stop operator must be configured to "ignore running task : immediate stop")
You configure the "Monitor Event" operator to look at "Request Cancelled" event, with the source being the request related to the current process.
The Monitor Event operator will monitor as long as your process is running, when it finds an event with the parameters you entered, it will end the process going to the Stop operator.
After re-reading myself i found my explanations not crystal clear so here's a simple solution to test it :
Event monitoring process :
Process that sends an event