What I have :
A C++ application server running, Ready to send data to client which is supposed to a HTML5 page or app.
What I want : Is there any way to communicate using udp port with HTML5 given both c++ server and HTML5 app are local to system ?
What I know :
WebRTC is based on UDP, it may cover your use cases: http://www.html5rocks.com/en/tutorials/webrtc/datachannels/