BPM Timers in embedded application

This is more of a “how does it work” question.

I have a small POC process that has a timer on one of the steps. This POC has the engine embed in the JAVA application. If this is part of a Web Application servicing periodic requests, which component is responsible for handling the timer and moving to the new step? How will this work when I have the application deployed to multiple servers for HA?