[0.14-0.16] Kessler: asynchronous, shared-world multiplayer (+ save editor)

[ToxicFrog]

After much testing on IRC and other forums, I am pleased to announce KESSLER, a client-server, shared-world system for Kerbal Space Program. Each server hosts a shared world; flights you launch will be uploaded to the server, and flights on the server will be downloaded by anyone who connects, populating your save file with orbits from other players around the world.

Here\'s what my save file looked like before:

[/ur]

And here\'s what it looked like after running a test server for a few days, with other people in the IRC connecting to it:

As a bonus, it also comes with a simple save file editor, which lets you edit object properties, rename objects, delete objects, teleport objects to or between orbits, make detached stages controllable again even if they don\'t have a MechJeb attached, or just arrange all your satellites into pleasing patterns like this:

Here\'s the FAQ, based on the questions people asked about it in IRC...

• Holy shit, multiplayer? So I can fly to the moon with my buddies?
  No. True multiplayer isn\'t possible yet. This is the next best thing: stuff you launch will show up in other players\' saves, and stuff they launch will show up in yours.
  
• Will this overwrite my save file?
  No. Kessler uses a non-destructive merge (the same as the save editor\'s [fixed]merge[/fixed] command, in fact) to insert new flights into your game without affecting what\'s already there.
  
• Will this corrupt my save file?
  It shouldn\'t! Just in case it does, though, the client makes a backup every time it syncs.
  
• Will it sync automatically while I play?
  Not yet - it can\'t do this safely while you\'re in flight or in the tracking centre, and there\'s no way for it to tell from outside when you\'re in flight and when you\'re safely at KSC or the VAB. There is a wrapper script provided that syncs, launches KSP, and then syncs again when it exits; if you want in-game syncing you\'ll have to alt-tab and tell it to sync when you\'re at KSC.
  
• Won\'t it fill the game with debris and bog down terribly?
  Well, it is named Kessler. :v: If that doesn\'t appeal to you, though, there\'s an option in the client config to only download pilotable ships, not debris.
  That said, large amounts of debris don\'t seem to affect actual flight at all. I\'m currently running with ~250 objects, and while the orbital map and the tracking centre are terribly slow, once it actually switches to a ship it runs just fine.
  
• What about all those ships using esoteric modded parts that I don\'t have?
  The client knows what parts you have installed and will skip any ship that requires parts you don\'t have. It also creates a log file listing exactly what you\'re missing for each ship, so when your friend\'s MIR replica doesn\'t show up you know why.
  
• Won\'t he be sad when I smash that MIR replica into the moon?
  Once you have a ship, changes made to it aren\'t copied back to the server - they stay local to your save file. So just because it\'s smashed into the moon on your save doesn\'t mean everyone else\'s copies of the same MIR will do the same.
  
• What other griefing protections are there?
  About all you can do to grief is flood space with asshole objects - physics-taxing ships, debris clouds orbiting right over KSP, etc. The server can be password-protected and there\'s no master server browser, so the best advice for avoiding this is 'don\'t play with assholes'. If it does happen, the server stores the shared world in the same format as KSP itself, so the server admin can always use the save editor to clean things up.
  The server and client both also have options to filter out certain classes of objects, such as debris or objects with the NaN bug.
  
• What about the save editor?
  The save editor was really just a side effect of the groundwork needed to develop Kessler. It\'s still included in the Kessler zip.
  
• What are the system requirements?
  A computer with Java 1.5 or later installed. You\'ll probably also want KSP installed to actually the play the game, though (unless you\'re just hosting the server, and playing KSP on another computer).
  
• Is it free? Open source? What\'s it written in?
  Yes, yes, and Scala. It is released under the MIT license; feel free to use Kessler, or parts of it, for any purpose you desire.
  
• Where can I get it?
  You can download the latest version here. The whole project is hosted on github and source code is available here. To install, just download the zip and unpack it to your KSP directory.
  If you already have Kessler installed and want to update to the latest version, you can download this instead, which is an update package that does not contain the supporting libraries and as a result is much smaller.
  
• What\'s planned for future versions?
  At the moment development is on hold while I wait to see what changes 14.2 makes to the save file format.
  Once Kessler is updated to support 14.2, I want to work on the ability to update ships that have already been copied to other people\'s saves - allowing for shared missions, not just shared worlds.
  I\'m also working on adding protocol compression to reduce the bandwidth costs of hosting a server; the save files get larger than originally anticipated.
  
• How can I get in contact with you?
  I\'m generally hanging out in the KSP official IRC channel on QuakeNet; just send me a PM. If you\'ve found a repeatable bug in Kessler or the editor, you can also use GitHub\'s Issues system to report it.
  

If you want to host a game, just install it, edit kessler/server_config.txt to choose a port and password, and then run [tt]kessler_server.bat[/tt]. Once started it shouldn\'t need any further care.

(Linux/OSX users: [tt]kessler_server.sh[/tt]. You can also specify the location of the config file on the command line, so you can have everything in one directory and just do: [tt]java -cp . -jar server.jar server_config.txt[/tt]. Make sure to edit the save path in server_config.txt appropriately if you do this!)

If you want to join a game, install it, edit kessler/client_config.txt for the host, port, and password (if any) of the server. Then just run [tt]kessler_client.bat[/tt] (while at the KSC screen or while KSP isn\'t running; do not run it while in flight or at the tracking centre) to sync with the server. (Linux/OSX: [tt]kessler_client.sh[/tt])

If you want to use the save editor, run [tt]kessler_editor.bat[/tt] (Linux/OSX: [tt]kessler_editor.sh[/tt]). Then type [tt]help[/tt] for a list of commands. Don\'t forget to [tt]save[/tt] when you\'re done making changes!

SynMonger is hosting a test server - host sashimi.synmonger.com, port 8988, no password.

dvc is also hosting a test server - host dvc.name, port 8988, no password.

I am also hosting a test server - host orias.homeip.net, port 8988, password kesslertest

[Gojira]

oh god

oh god

oh god

this is too awesome for words

[witeken]

Doesn\'t work

Do I need to install it somewhere? It\'s just randomly installed in a not KSP folder.

However, it looks very awesome .

[ToxicFrog]

Doesn\'t work

Do I need to install it somewhere? It\'s just randomly installed in a not KSP folder.

However, it looks very awesome .

From the FAQ: 'To install, just download the zip and unpack it to your KSP directory'. It assumes it\'s in the same dir as KSP (that is, [tt]kessler_client.bat[/tt] is in the same dir as [tt]KSP.exe[/tt]) so that it knows where to find your save file.

[witeken]

From the FAQ: 'To install, just download the zip and unpack it to your KSP directory'. It assumes it\'s in the same dir as KSP (that is, [tt]kessler_client.bat[/tt] is in the same dir as [tt]KSP.exe[/tt]) so that it knows where to find your save file.

Thanks, I think it works. I read over it. - Comfirmed: Yes it works.

But... If it\'s only one way traffic, I just get your save file? Or does it also send my new ships to the server?

edit: ohhh god, what a lagg .

[ToxicFrog]

Thanks, I think it works. I read over it. - Comfirmed: Yes it works.

But... If it\'s only one way traffic, I just get your save file? Or does it also send my new ships to the server?

It also sends your ships to the server. Most of the stuff you\'re getting from the server isn\'t mine; it\'s stuff other people uploaded to the test server. As best as it can it makes sure everyone has everyone else\'s stuff.

edit: ohhh god, what a lagg .

Kessler introduces a lot of objects on a crowded server and can result in severe lag in the tracking centre and orbital map. It\'s usually not an issue once you switch to actual control, but the actual process of switching can take a while.

You can drastically improve performance by telling Kessler to only accept controllable ships, not debris:

- open [tt]kessler/client_config.txt[/tt]

- find the line [tt]filter = nan,ghost,launchpad[/tt]

- change it to [tt]filter = nan,ghost,launchpad,debris[/tt]

- save

Note that this will only keep it from downloading new debris from the server, it won\'t delete debris already in your save file - so if you\'ve already run Kessler and had it download 200 pieces of debris, you might want to restore the backup of your save it made as well.

[trbinsc]

Tried to get this to run on my mac using terminal, but it won\'t work. Should I be launching client.jar or something else?

[ToxicFrog]

Tried to get this to run on my mac using terminal, but it won\'t work. Should I be launching client.jar or something else?

You\'re launching the right JAR, yes. You need some additional arguments, though - take a look at kessler_client.bat to see how it\'s invoked in windows.

I\'m not sure what a KSP install looks like on OSX - I only have linux and windows to test on - but if it has the same structure as a windows install, the following (in your KSP dir) should work, assuming you\'ve unpacked Kessler into your KSP directory:

java -cp kessler -jar kessler/client.jar put saves/default/persistent.sfs
java -cp kessler -jar kessler/client.jar get saves/default/persistent.sfs

If they\'re not equivalent I\'ll write up a shell script to do the heavy lifting and include that in the next release.

[trbinsc]

It doesn\'t work, it just throws up this.

bash-3.2$ java -cp kessler kessler/client.jar get saves/default/persistent.sfs
Exception in thread 'main' java.lang.NoClassDefFoundError: kessler/client/jar
Caused by: java.lang.ClassNotFoundException: kessler.client.jar
	at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

[ToxicFrog]

I had a thinko while writing the commands. I\'ve edited the post to include the correct commands instead; try those.

[Causeless]

How many ships and debris are on the test server? I\'m wondering what the game accepts as acceptable limits.

[NovaSilisko]

How many ships and debris are on the test server? I\'m wondering what the game accepts as acceptable limits.

There\'s an option for it. The maximum you can set it to is Unlimited, so...

[Tim_Barrett]

Holy.

[cteam]

You beat me to it i WAS working on something simler

[togfox]

Awesome work. This will be great for the roleplayers. The can set up their own server and see the works of other nations.

Question: KSP has a 'max objexts' that defaults to 250. Will that still work with this? Can i use this to scale down if the lag gets too much?

Love ya work. 8)

[Monkthespy]

I nerded all over the floor.

It was messy.

[Guest GroundHOG-2010]

Well done (I personally didn\'t think it could be done this quickly).

[ToxicFrog]

How many ships and debris are on the test server? I\'m wondering what the game accepts as acceptable limits.

As of this morning (ie, before releasing it here) it had 260-odd objects (debris and ships).

Right now it has 432 - 355 debris, 77 ships. The save file is 1.7MB.

I should probably make 'reject debris' the default in the next release; this is ruinous for tracking centre performance.

You beat me to it i WAS working on something simler

Sorry! While you\'re here, though, is there anything you think this should have that I\'ve forgotten to add?

Well done (I personally didn\'t think it could be done this quickly).

8) Actually, I started work on this as soon as 14x1 was released and had a working prototype by Feb 29th. The version I\'m releasing now has been finished for a week; I\'ve just had it running while the IRC users pound on it to make sure there were no lingering serious bugs.

[Seanoog]

Impressive work.

May I ask, what server is it?

Or how is the server managing this content?

An every indication has been suggested, that KSP 0.14.2 will break compatability with the present Persistance saves. Apparently adding more values.

So you may have to release a newer version soon.

[ToxicFrog]

Question: KSP has a 'max objexts' that defaults to 250. Will that still work with this? Can i use this to scale down if the lag gets too much?

It will work. However, the 'max persistent debris' setting is applied when the game is saved, not when it\'s loaded - so if you turn down the setting, you won\'t see debris disappear until you save and then reload the game. Fortunately, this is as easy as going to the tracking centre and then back to the main KSC screen.

In any case it won\'t affect controllable flights, though, only debris.

Impressive work.

May I ask, what server is it?

Or how is the server managing this content?

It\'s a custom server - the source code is with the rest (in the [tt]kesslerd[/tt] directory). The server content is saved as a KSP save file; there are better ways to do it, but I wanted to keep the ability to edit the server\'s world using the save editor (or a text editor) if necessary.

An every indication has been suggested, that KSP 0.14.2 will break compatability with the present Persistance saves. Apparently adding more values.

So you may have to release a newer version soon.

Yeah, I actually debated waiting until 14.2 hit and seeing what changes need to be made. I\'m hoping that it will just add new fields and possibly change the domain of existing ones, in which case the server should keep working with no need for updates - you\'ll just need to delete the old save and start over.

If it completely reworks the save format, or deletes/renames the fields the server uses for things like duplicate detection, then I\'ll need to update the SFS parser at least, and possibly other things like the merge logic.

[cteam]

nope this is exacly what i was working on so that rpers could play out wars better now to put it on a sever and have constent up dates

[jnrobinson]

Excellent work. Btw, you forgot to add '-jar' in your linux/osx command for the client.jar. I believe it should look something like: java -cp kessler -jar kessler/client.jar etc.

[jnrobinson]

Also, anyone have any luck running this with Hamachi? I have the jar running on a Linux server running hamachi but I\'m getting timeout errors although I\'ve set my ip address in the config file to the proper ip.

[trbinsc]

Still can\'t get it to work on my mac. To VMWare Fusion!

[ToxicFrog]

Excellent work. Btw, you forgot to add '-jar' in your linux/osx command for the client.jar. I believe it should look something like: java -cp kessler -jar kessler/client.jar etc.

Fixed, thanks.

Still can\'t get it to work on my mac. To VMWare Fusion!

Any chance you could pop onto IRC at some point? I\'d really like this to work out of the box on OSX, if possible, but it\'s hard when I don\'t have an OSX machine to test on.