This is a C based xPL framework that hides most of the details of dealing with xPL.  It will handle filtering messages, sending heartbeats, formatting and parsing messages, directing messages to handlers based on where they were bound from, etc.  You can use it as the simplest level to format/send/receive/parse xPL messages or add various layers of additional management to simplify more complex xPL idioms.  It's designed to be easy to design a new program around or to integrate into an existing program.  It includes some example applications showing how to use various features of the framework, including the source to the xPLHub.