priorities

If you're using some sort of IPC, why not TCP? Then it opens the option of running remote battle runners.

Well :), of course TCP would be the obvious choice for IPC, but i think you bring a whole new bunch of complexity into the program and i'm not sure if it is worth the struggle.

Beside copying the bot JARs, copying the user score classes, configuring the robocode path on every extra machine there are some other more technically issues to consider. Of course if done right it would be a very nice and strong feature, beyond question.

Using the scenario you described, with JSON, sound quite interesting, maybe i should reconsider my concerns about having the user classes running on two different places. I'm sure i'm nitpicking to much on that point.

Sidenode: It is possible with reflection to check if a method is overloaded just by doing

myBattleAdaptor.getClass().getMethod("onBattleCompleted",BattleCompletedEvent.class).getDeclaringClass()

if it gives back the name of myBattleAdaptor it is overloaded.

Right now i have discarded the tmp file approach, simple because i don't liked it and switched to named pipes. The BattleRunner got some watcher threads where he is communicating with the BattleProcesses, using ObjectStreams and watch out for errors and feed the score class. Don't worry i'm doing all this just for curiosity and will be fine with whatever you come up.

Take Care