I've been trying to do this kind of thing, too. I haven't been able to make it work via JLink. I'm no expert with Java, though. I would've thought that this would be a common application of Mathematica. It would be nice if there were some built in commands for communicating with devices over HTTP over TCP/IP (even better would be using Websocket protocol on top of TCP). As far as I've been able to determine, some of the pieces of HTTP needed are not in Mathematica (or maybe not documented). I'm hoping someone else with more knowledge and experience will comment here.

See my original post. I got no interest/response at that time. It's surprising that no one seems interested because WRI does seem to be aware of the proliferation of internet connected devices.