Android – Game server for an android/iOS turn-based board-game

androidiphonemultiplayer

i'm currently programming an iPhone game and I would like to create an online multiplayer mode. In the future, this app will be port to Android devices, so I was wondering how to create the game-server ?

First at all, which language should I choose ? How to make a server able to communicate both with programs written in objective-c and Java ?

Then, how to effectively do it ? Is it good if I open a socket by client (there'll be 2) ? What kind of information should I send to the server ? to the clients ?

Thanks for your time.

Best Answer

EDIT How massively multiplayer'ed will you game be?

Hi Cyril,

as you noticed, there are two main things two consider:

information sent to the server
information sent to the client

There's only one type of information to sent to the server: the user inputs. If you don't do that, you'll encounter headaches over headaches when rogue client will try to send fake data to your server (like saying "My tank now has 100 000 000 armor").

Then what you sent to the client is up to you but it's totally possible to only sent to the client the other player(s)'s input. This is the way to have the absolute minimum and tinies bandwith usage possible. That is how games like Blizzard's Warcraft 3 are doing it. As a bonus, this makes for tiny replay files (because all you need to do to be able to replay a game is the time (and the input) at which each player's input happened).

The one downsides with sending only the other player's input to the client is that it means all the game's logic is present on every client. For some games, this may be an issue because people may cheat by reverse engineering your game and finding flaws. This issue can be mitigated with careful, controlled, randomization (where in addition to the input+time you send input+time+randomness where randomness cannot be guessed by the client in advance.

Another way to do it is to do some logic computation on the server side. Then, obviously, you need to send the result of the server computation to the client. Done correctly, this has the benefit of both preventing cheats and maky piracy impossible (for example nobody managed to play World of Warcraft in the real economy --that is, on the real Blizzard servers-- using a fake licence key).

Regarding the phone-turn-based game server: just look at one top-selling turn-based game are doing it. Take Uniwar for example: works on iPhone and Android. Game server is written in Java "of course".

The one thing to realize is that a game like the one you plan to write is entirely deterministic: if you can't easily code a replayer or if you can't easily reproduce any kind of scenario leading to a logic bug, you're doing it wrong.

Note that being determistic doesn't mean you can't add what looks like randomness to your players: it's simply that the randomness shall also be deterministic (for example by simply using a different seed for each game + the time at which player inputs are made as a fake random source).

Related Solutions

Ios – Building the own game server for a turn-based multiplayer iPhone Game

You asked several separate questions, so I'll give brief answers.

How turn-based game servers are structured and implemented
Like any other server it listens for connections, processes requests and sends responses.
It's quite easy to write a web service which uses JSON / XML. I think this will be the best and quickest solution to your problem (subjective)!

Good libraries/APIs to use Though there're several good frameworks and libraries on the desktop side of game programming, I can't think of any "web based" library.

Security concerns and common solutions
Basic Authentifcation and OAuth are two of several possibilities to secure your web service.

Existing open source packages
You already mentioned Ruby on Rails but I recommend Django for it's great documentation to get you started. I built my iPhone webservice around Django Piston, which is a great mini framework.

I've been wanting to Learn Ruby on Rails for other upcoming projects and I'd like to kill two birds with one stone, could this framework work well for implementing a turn-based game server? Yes, see my answer above.

Java – Proper use cases for Android UserManager.isUserAGoat()

Android R Update:

From Android R, this method always returns false. Google says that this is done "to protect goat privacy":

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this method can
 * now automatically identify goats using advanced goat recognition technology.</p>
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#R}, this method always returns
 * {@code false} in order to protect goat privacy.</p>
 *
 * @return Returns whether the user making this call is a goat.
 */
public boolean isUserAGoat() {
    if (mContext.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.R) {
        return false;
    }
    return mContext.getPackageManager()
            .isPackageAvailable("com.coffeestainstudios.goatsimulator");
}

Previous answer:

From their source, the method used to return false until it was changed in API 21.

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 * @return whether the user making this call is a goat 
 */
public boolean isUserAGoat() {
    return false;
}

It looks like the method has no real use for us as developers. Someone has previously stated that it might be an Easter egg.

In API 21 the implementation was changed to check if there is an installed app with the package com.coffeestainstudios.goatsimulator

/**
 * Used to determine whether the user making this call is subject to
 * teleportations.
 *
 * <p>As of {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this method can
 * now automatically identify goats using advanced goat recognition technology.</p>
 *
 * @return Returns true if the user making this call is a goat.
 */
public boolean isUserAGoat() {
    return mContext.getPackageManager()
            .isPackageAvailable("com.coffeestainstudios.goatsimulator");
}

Here is the source and the change.