For some time had an experimental external interface to POPFile through XML-RPC. Beginning in PF v0.22 the XML-RPC component is no longer experimental. If XML-RPC is enabled, an external program written in many different programming languages can communicate with POPFile to use its services.

Full details of the API and methods can be found here: POPFile's XML-RPC

General information about XML-RPC can be found here: XMLRPC.com