How can I cancel an existing process from within another process?

I use it in one of my process that has a timer sub-process. If they cancel the trip.. I want to cancel the sub-process that has the timer. You'll get an alert from Appian when the process gets cancelled by the other process.

you can also accomplish this using message events. Have a message listener that would flow into a Terminate (via a DB Update probably, for logging) event. This message event can be triggered from within any process.

There are multiple approaches for cancelling a process from any other process:
1. Use the Process Management Services plugin, as suggested by @mjmallet (Not OOB)
2. Use the "Set External PV Smart Service" (forum.appian.com/.../. You can have a boolean flag in your process. Then you can set it from another process. You can have a trigger which will execute when that boolean flag becomes true. You can use this in case you desire synchronous behavior.(But this is not OOB)
3. Another way, as suggested by @senthilar is to use Send/Receive Message combination. It is OOB. But its behavior is asynchronous.

We have Process Management Services plugin for this.Have a look at it:forum.appian.com/.../summary

ok thanks very much.