Sending and listening to custom events between applications

[JoonKim]

Hello all,

I have question about sending and listening events between applications.

An VAN interal SDN application can register a listener to specific, built-in events which HP VAN provides. For example, an application can register a MessageListener or Sequenced Packet Listerner and get notified when OpenFlow messages or Packet-ins arrive at the controller. The application can implement a callback function to decide how to handle such events. I also see there is a built-in service called TopologyManager, which allows other applications to register a listener and get notified when the topology is recomputed.

Now my question is:

Is it possible to create a custom listener for my own application so that other arbitrary applications can register for that listener and get notified when my application raises a certain event? If it is possible, is there any example source code that I can check out so that I can implement my own?

I want this essentially because I want to make my own service application which other applications can consume by getting notifications from it.

I am currently using HP VAN 2.0.0, and cannot find a useful document that explains or guides me to do this. I skimmed through the 2.3.5's programming guide, but I cannot find something useful either.  Please let me know if you have any pointers or guidance.

Thank you in advance!

Thanks,

Joon Kim