In EPL applications, everything in a monitor instance is private. There is no direct way for a monitor instance to invoke an action or access the state of another monitor instance. Instead, messages, in the form of events, are the mechanism for communication among monitor instances. All events are visible to all interested monitor instances.

Consequently, how you divide your application operations into monitors and what events the monitor instances use to communicate are crucial design decisions. An understanding of the order in which the correlator processes events for monitors helps you determine where and when to allocate events.

The topics below provide information for making these decisions.

You can use the MemoryStore to share state between monitors, see Using the MemoryStore.