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At this point, this tool does everything I need and I'm really happy with it, so if anyone wants to offer feedback as far as features or prioritizing the to-do's, let me know. =) I'll probably bang out some of the more important stuff in the next week or so (like letting you configure JVM arguments), and the option for dynamically loading battle listeners for custom scoring sounds really cool, so I might tinker with that soon too.

Hi mate. I got a little intimate with your code and finally figured out how it works :). I wrote a dynamic class loader that can load classes from a specific directory/jar. The classes will only be loaded if they provide a certain interface. So far so good. After this i was digging through the code and was looking for a good point to use these classes. Unfortunately it looks like, there is no good way to pass classes between the 'BattleProcess' and the 'BattleRunner'. I tried to redirect the 'System.out/in' of the BattleProcess to Serialization streams but this is not working as i now know. I guess object serialization over temp files is nothing that you are fond of, neither to speak of RMI. The other idea that came to me, would it be possible to map the events of the BattleProcess BattleListener (on...()) to strings, then pass it over the in/out stream to the BattleRunner and rebuild the events there. In my opinion this would have the advantage that you can pass the events to the user made score class and would have no need to do all the score parsing within your code. If the user class decide it has no need for the event it will simply be ignored.

Hmm i have right now a hard time to explain this :). Lets give you a scenario.

I write a score class for the PatternChallenge. The score class interface has a getName() method and this name has to be in the 'pattern.rrc' to. The class will be loaded RoboRunner reads the "rrc" file looks for the available score classes and find my PatternChallenge class. Now you can register this class on the BattleRunner (similar to the BattleResultHandler you have). The score interface has, lets say onBattleCompleted(..) implemented and you pass all the events (in this case just one) to my score class. There i can read the damage fields and calculate my score and if i want to print the results to the console i can do this as well (no work for you so far :)). If the score interface provides a toString() method i could use this to provide a output string for the data file. The only thing you had to do, would be to get this string and write it to the data file at the end of everything. I'm sure i missed something but so far as i see it, could you get rid of all the hard coded score you have right now.

Well, i hope it makes at least a little bit of sense what i have said. If you think i'm wrong on one/all points let me know, i'm not offended at all by it.

Anyway enough mumbling for today :)

Take Care

Cool! Well, I have a few thoughts on how all this could tie together:

• Instead of (or in addition to) RoboRunner/BattleRunner dynamically loading the listener/scoring class, I think we should pass a flag to BattleProcess that tells it the name of the listeners to load and attach to Robocode engine.
• I think it would be good if the listener interface extends IBattleListener, or includes one, so you can just attach it to the RobocodeEngine (addBattleListener) and have it listen to the events it wants.
• Then I guess it would need some setup to pass its output back to BattleRunner so we can store it and print it. I'm fine with printing to stdout or writing to temp files or whatever. I guess if we load the interface on the RoboRunner side, too, it could also have a method that runs after each battle to print whatever it wants from the data file.
• I don't think it's reasonable for BattleProcess to always listen to all events and pass all that data back for every battle. If you look at IBattleListener, it's possible to listen to every detail about every single turn in the battle. That's a lot of extra processing if you're not using it. =)

Does most of that make sense? Thanks for getting the ball rolling on this! I think it'd be a really exciting feature. Even if nobody but us uses it. =)

Hmm ...

• Is there another way then dynamic loading a class, if the program does not know about it? Maybe including the score class directory in the class path and making the challenge name the fully package name but this would still need the class loader part.
• I was starting with the interface to be IBattleListener but i could not get the event classes within BattleRunner and therefore i mapped it to the same methods but with different parameter objects.
• This sounds interesting. I was playing with this but had to face some issues that i could not solve. Loading the same class in different environments but not using all methods equally would be very inconsistent (not to say bad style :)) i guess. The user is probably not aware that the class has no idea where the events are processed and would put his output stuff just within the on..() methods - but never got a result, because it works in a different environment. And making two different classes (one for BattleRunner one for BattleProcess) would be not very user friendly and increases the probability to doing something wrong.

If you have no problem with temp files i guess this would be a good way to solve the issues. This way you can load the score class (should be extend BattleAdaptor) and RoboRunner can check if a certain method is overloaded (translates to - is he interested in this information). This information could be flagged to the BattleProcess and he can use it to process the needed events. If you use temp files you have the possibility to serialize almost every event to the file - pass the temp file name to BattleRunner, restore the Events and pass them to the score class. I cannot point my finger on it, but something tells me that there is something wrong with this approach :)

• yep you are right :) - i was not fully aware of the cascading level of the onTurn..() events and this could lead to some issues with the temp files to i guess. If you, lets say, just interested in the energy level of all bots, it would certainly not make sense to save the whole turn event cascade. Maybe you have a idea to overcome this.

Hehe, thats quite a point you got there :). But i hope it will pay off somehow, especially if i look at the time i have spend to write output classes to get some data visualized through GnuPlot. I easily can see some nice GUI statistic diagrams or movement plots for later runs and that really excites me :).

Take Care

Edit: Another incredible easy to use IPC would be to use named pipes. But this would put the Windows user out of business until someone is willing to write a JNI adaptor, or find another way to establish a named pipe there.

So I guess there's two major things being weighed here:

• User code running in 1 vs 2 places - Having the user code running on just the RoboRunner side of things may avoid some programming pitfalls if someone tries to store state between the battle listener and the score output.
• Having to flatten the battle events for post-processing - If the user code is not in the BattleProcess, we need to figure out what events to listen to, log them, and pass them back to the other side for post-processing after the battle.

I guess I have a pretty strong preference for having user code in the battle listener itself instead of processing and transferring all the desired events. Figuring out which methods to listen to, serializing all the events, then processing them on the other side just seems like a lot of unnecessary work, and possibly error prone. A big note in the Javadoc that the listener methods should be idempotent, or using separate interfaces both seem like OK options to me.

I get the impression you'd rather make the other trade-off. =) The main thing I'm not sure of is whether reflection can figure out which methods you actually override. All of them would be overridden by BattleAdaptor, so I'm just not sure we can tell the difference. You could end up with some big temp files if you listen to onTurnEnded, but I don't think processing time would be much compared to running the battle itself.

So I guess what I'm imagining is something like:

• RoboRunner finds the custom listeners (command line argument and/or in challenge file). It loads an instance to process scoring output and passes the listener names to BattleProcess, which also loads them.
• BattleProcess sets some object on the listening class, which the listener can use to store custom values. (Eg, "skipped_turns" = 50, or "score_snapshots = {100, 150, 250, 575}".) Maybe an XML or JSON object.
• BattleProcess loads the battle listener and attaches it to the Robocode Engine, and runs the battle. The listener processes things on the fly and stores data in the data object.
• The values stored by the listener would be output by BattleProcess, read by BattleRunner, and stored in the bot's data file. (With XML or JSON, converting to/from ASCII like this would be pretty easy.)
• The scoring method would take the score data for that bot set and/or battle and display whatever it wants.

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

This could actually work really smoothly. By default, it spins up the processes as now, but passing a port number to each process and communicating over TCP/IP. The data sent / received could remain the same. Then we could add command line arguments for:

1. Launching Robocode processes and doing nothing, just listening for commands.
2. Accepting a list of host:port of additional processes. In addition to the normal processes, launch a thread for each remote process.

So on your extra machine, you do #1, and on your primary machine you do #2, and voila!

Edit: Except for copying the necessary bot JARs. That would be a little more complicated.

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