Nice work and some thoughs

Nice work!

Not using JavaScript sorting made it easier to link sorted tables from other pages. Also, with a melee database reset, getting rid of battles with retired bots may change the rankings. And you put %wins scoring. =D

But I miss some kind of Condorcet ranking. PL was the only one we had, and the one Combat was doing best.

Also miss some kind of statistical ranking. Elo was what we had and allowed fun statistics like problem bot index, specialization index and that non-working JavaScript diagram. Mirror bots and ram bots will lose some of their appeal without those statistics.

I tried to raise a RoboRumble server in App Engine a long time ago, but they didn´t allow me into the free tier. :(

My %Wins is a bit of a cheat. It is just 1 point per PL win, divided by bots in rumble. I prefer it to PL because it is not dependant on the number of bots in the rumble. So if Combat was doing well in PL, it should do well in %Win.

I'm still not using my Backend for anything, so I was thinking that once a day I could use it to generate some sort of pseudo-problembot stats stuff. ELO/Glicko is nice, but it is really designed for being good approximations when pairings are missing. In our case, the pairings are fairly easy to fill, so that isn't a problem; APS tends to converge to the same ranking order, and it isn't full of voodoo that makes it difficult to comprehend. It is also possible to correct APS easily if results get lost due to being in memcache =)

One ranking idea I had an idea for was doing a The Best Bot calculation (get a point for being the best against any competitor). It would increase my number of database writes in the only reasonably robust/non-batch way I can think of, which is what is holding me back at the moment. I could use a Backend for calculating it once or twice a day, I guess, or make it expire once every 6 hours and be triggered by a page load. It needs n*n runtime. Maybe I can fit it into the regular rankings calculations.

The hardest part is getting the rumble to stay in the free tier. I think it will be limited to about 6 melee clients in total, or maybe 12 1v1 clients instead (less pairings per battle in 1v1).

The last time I checked, App Engine offered about 1GB database in the free tier. Which is enough to store all pairings and all uploaded battles, as long as you delete data from retired bots once in a while.

As for the amount of clients the server can handle, it should not really be an issue, since there are usually 3 to 4 simultaneous clients at most.

If you want to use some batch processing, adding a Ranked Pairs ranking would make my day. I has O(n^4) complexity, but I think it can still fit inside the 10 minutes window from cron, so no need for a backend.

The problem isn't so much total storage space, but that I'm limited at 50k writes per day. Each bot counts as 2 writes, so effectively I have 25k updates I can do. I've figured out a caching scheme so that each melee battle comes out to 10 updates (1 per bot) instead of 45 updates (1 per pairing). I also need to update the total rumble battles count and the user upload count, so that leaves a bit of overhead, meaning I can have ~2000 melee battles per day uploaded.

I'l see what ratings systems are feasible..

Batch updates are more useful in a limited environment like that. Maybe it´s time for a refactoring in the upload protocol (1 update per batch upload), even if it breaks backward compatibility.

I've actually figured out a sort of temporary caching between requests where I wait for bots to accumulate a certain number of pairings before pushing them to disk. I don't think it's necessary to re-work the rumble upload protocol yet. One thing I would like the rumble to tell me is how many bots are in a melee battle though. Right now I just have it hardcoded at 10. It would help with my caching if I knew how many they were uploading per battle.

Hey that's neat! A quick and lightweight rumble setup could be really useful for tournaments and experiments. You just need a participants list URL, you make up a rumble name, and everything just works? Makes me want to try some new divisions. :-) Though that never seems to gain momentum...

What is App Engine pricing like? I'll take a look. I'd certainly be willing to pitch in some for Robocode related stuff if we needed more horsepower.

There is one division I would like to see. A twin melee rumble (like 5 teams of 2 bots each). Joining concepts of both melee and team/twin.

I like the idea, but I think it would be so crowded that it would pretty much reduce to melee strategy. (Having to fight off 8 other bots with 1 ally out there somewhere is not much different than fighting off 9 other bots.) Maybe 3 teams of 3? I've thought about MegaBot TwinDuel for a while...

I think megabot TwinDuel would be awesome! Although it might reduce to wavesurfing quite quickly. I'd also be interested in a TriDuel - a 3 vs 3. I think having that extra bot will completely change the dynamics compared to twinduel, and make surfing much harder.

Imagine 2 melee bots using minimum risk movement (dominant in melee), and 2 bots using provocative movement (dominant in twin duel). The 2 melee bots will be each on a different corner, but the 2 with provocative movement will be on the same corner ganking on the lonely melee bot. But at the same time, 3 bots close together become tasty targets for swarm targeting from other 3 teams.

There must be a balance between minimum risk and provocative movement, or a third undiscovered strategy. Maybe there is still room for inovation.

Yeah, my thoughts are that something like this would be perfect for school/lab/office tournaments. Just give it a new name in the client, set up a participants list somewhere and away you go.

In the free tier I'm not really going to run out of disk space any time soon, a rumble of 300 bots comes out at around 2MB, it's the database writes which are the killer. From what I can tell, App Engine pricing starts at $2.10 a week for the minimum paying tier. That gets you quite a bit more quota than the free tier, which probably should be enough for everything, pretty much forever, without crossing that $2.10 limit. For now I'm going to see how much I can push the free tier, though.

I still have a bunch of optimisations I need to make - like not pulling all of the rumble data into memory just to serve the rankings page (it's all cached, doesn't affect my quota, just speed) - which should make it more snappy both on the main rankings pages and on the RatingDetails page the RR client queries occasionally.

A hidden feature: if you add timing=1 as an argument into your GET for any of the pages it summarises the timing breakdown for CPU usage at the bottom of the page and lets you know how many bots were pulled from cache vs. from the datastore.