I'd like to add multiplayer to one of my android strategy games.

Are there any free MP frameworks you can recommend? The server can be implemented in any language/environment. But the client needs to be Java, as I'm not using NDK. Since this is all hobby work, it needs to be free (or extremely cheap).

My main requirement is real-time messaging (~ 1-2 second delays). I haven't even decided if I want to support WAN. If you have something which is LAN only (one of the clients is the server), that might be enough.

Is there a staple opensource multi-player engine?

Also, while I was pondering the problem, google released this:

https://developers.google.com/games/services/android/multiplayer

Would you recommend using it?

Do you know what the pricing model is?

Have you used it before?

There are some recommended opensource network packages, including ENet and RakNet.

Unfortunately, Java is not the native language for those; they're C or C++ based.

Sun tried to make a Java system for multiplayer networked games called Project Darkstar, but they tried to solve too much at once and ended up not being able to deliver despite years of effort.

If all you need is local multiplayer, then you could build something super simple on top of the aio Java sockets support and UDP broadcasts!

I get the impression you are looking for something higher-level than the solutions being offered to you. Something like Smartfox Server or Photon would serve, but unfortunately they aren't free.

Yeah,

I could use any message queue for messaging, but I was hoping to get some added value besides packeting over TCP/IP. Message queus also tend to lack a security layer, which is a big deal over WAN.

Thanks for the links, I'm a complete newbee in multiplayer, so I was unaware of these.

Regarding Smartfox, 100 concurrent users should be enough at first. I see that smart-fox community edition supports it, but I can't find the license on their site. Do you know if I can use the community edition in a commercial game? Also Photon's 100 users for 10$ might also be fine, since if I use my own I'll probably pay ~10$ for hosting.

Also, what do you guys think of the Google offer I mentioned above? I cringe at the thought of forcing people to use Google+, but it looks very easy, and very robust. Also, I couldn't figure out the pricing.

I wouldn't go with a third-party hosting unless you actually know that you'll make money on the product.

Apache Thrift actually sounds like a reasonable solution for the level you're interested in.

Went with implementing my own server.

If it ever gets robust enough, I might make it open source.

Wograld, my multi-player online game uses a C server and a Java client. The sever is admittedly a difficult install with multiple steps, but Wograld (both client and server) is open source under gpl v2 or later.

www.wograld.org

I'm not sure how robust it is, I haven't gotten many people to test it partly due to the difficulty of install.

Cool,

I didn't find any files in the downloads section, though.