concept EPA in category software development

This is an excerpt from Manning's book Event Processing in Action. Login to get full access to this book.

A Pattern detect EPA is an EPA that performs a pattern matching function on one or more input streams. It emits one or more derived events if it detects an occurrence of the specified pattern in the input events.

Figure 10.10. A dead end example. The EPA Handle Low Inventory with No PO does not have any outgoing events.

EPA is Not Reachable

This type of observation traces the fact that an EPA never executes because one or more of its input events never flows. This may be a design flaw or the result of a change that eliminates some event from being produced, derived, or routed to the EPA. This observation can be obtained by static analysis of the EPN, and the EPN designer can be alerted.