Although the correlator's native programming language, the Apama Event Processing Language (EPL), has most of the functionality of modern programming languages, its primary purpose is enabling the detection of, correlation across, and triggering on complex event patterns.

In most cases, existing code could be ported and rewritten in EPL, but in practice this might not be feasible. For example, an application might need to carry out advanced arithmetic operations and a significant programming library of such functions might already be available. Porting such complex code to EPL would be a lengthy, expensive and error prone task, and is unnecessary.

The following topics describe Apama's EPL plug-in APIs and illustrate how to use them.