multiplayer_server_script.js

// Example Realtime Server Script
'use strict';

// Example override configuration
const configuration = {
    pingIntervalTime: 30000
};

// Timing mechanism used to trigger end of game session. Defines how long, in milliseconds, between each tick in the example tick loop
const tickTime = 1000;

// Defines how to long to wait in Seconds before beginning early termination check in the example tick loop
const minimumElapsedTime = 120;

var session;                        // The Realtime server session object
var logger;                         // Log at appropriate level via .info(), .warn(), .error(), .debug()
var startTime;                      // Records the time the process started
var activePlayers = 0;              // Records the number of connected players
var onProcessStartedCalled = false; // Record if onProcessStarted has been called

var players = {};

// Example custom op codes for user-defined messages
// Any positive op code number can be defined here. These should match your client code.
const CURRENT_PLAYER_ACCEPTED = 100;
const PLAYER_ACCEPTED = 101;
const PLAYER_DISCONNECTED = 102;
const CURRENT_PLAYER_UPDATE = 200;
const PLAYER_UPDATE = 201;


// Called when game server is initialized, passed server's object of current session
function init(rtSession) {
    session = rtSession;
    logger = session.getLogger();
}

// On Process Started is called when the process has begun and we need to perform any
// bootstrapping.  This is where the developer should insert any code to prepare
// the process to be able to host a game session, for example load some settings or set state
//
// Return true if the process has been appropriately prepared and it is okay to invoke the
// GameLift ProcessReady() call.
function onProcessStarted(args) {
    onProcessStartedCalled = true;
    logger.info("Starting process with args: " + args);
    logger.info("Ready to host games...");

    return true;
}

// Called when a new game session is started on the process
function onStartGameSession(gameSession) {
    // Complete any game session set-up

    // Set up an example tick loop to perform server initiated actions
    startTime = getTimeInS();
    tickLoop();
}

// Handle process termination if the process is being terminated by GameLift
// You do not need to call ProcessEnding here
function onProcessTerminate() {
    // Perform any clean up
}

// Return true if the process is healthy
function onHealthCheck() {
    return true;
}

// On Player Connect is called when a player has passed initial validation
// Return true if player should connect, false to reject
function onPlayerConnect(connectMsg) {
    // Perform any validation needed for connectMsg.payload, connectMsg.peerId
    return true;
}

// Called when a Player is accepted into the game
function onPlayerAccepted(currentPlayer) {
    const playersValues = Object.values(players);
    const playersStr = (playersValues.length == 0) ? ('{"players":[]}') : ('{"players":[' + playersValues.join(',') + ']}');

    const outPlayerAcceptedMessage = session.newTextGameMessage(PLAYER_ACCEPTED, currentPlayer.peerId, "");
    const outCurrentPlayerAcceptedMessage = session.newTextGameMessage(CURRENT_PLAYER_ACCEPTED, currentPlayer.peerId, playersStr);

    for (var playerId in players) {
        if (players.hasOwnProperty(playerId)) {
            session.sendReliableMessage(outPlayerAcceptedMessage, parseInt(playerId));
        }
    }

    session.sendReliableMessage(outCurrentPlayerAcceptedMessage, currentPlayer.peerId);
    players[currentPlayer.peerId] = "";
    activePlayers++;
}

// On Player Disconnect is called when a player has left or been forcibly terminated
// Is only called for players that actually connected to the server and not those rejected by validation
// This is called before the player is removed from the player list
function onPlayerDisconnect(peerId) {

    const outMessage = session.newTextGameMessage(PLAYER_DISCONNECTED, peerId, "");
    delete players[peerId];

    for (var playerId in players) {
        if (players.hasOwnProperty(playerId)) {
            session.sendReliableMessage(outMessage, parseInt(playerId));
        }
    }

    activePlayers--;
}

// Handle a message to the server
function onMessage(gameMessage) {
    switch (gameMessage.opCode) {
        case PLAYER_UPDATE:
            players[gameMessage.sender] = String.fromCharCode(...Object.values(gameMessage.payload));

            const outPlayerChangedMessage = session.newTextGameMessage(PLAYER_UPDATE, gameMessage.sender, gameMessage.payload);
            const outPlayerChangedCurrentMessage = session.newTextGameMessage(CURRENT_PLAYER_UPDATE, gameMessage.sender, gameMessage.payload);

            for (var playerId in players) {
                if (players.hasOwnProperty(playerId)) {
                    playerId = parseInt(playerId);

                    if (playerId != gameMessage.sender) {
                        session.sendReliableMessage(outPlayerChangedMessage, playerId);
                    }
                }
            }

            session.sendReliableMessage(outPlayerChangedCurrentMessage, gameMessage.sender);

            break;
    }
}

// Return true if the send should be allowed
function onSendToPlayer(gameMessage) {
    // This example rejects any payloads containing "Reject"
    return (!gameMessage.getPayloadAsText().includes("Reject"));
}

// Return true if the send to group should be allowed
// Use gameMessage.getPayloadAsText() to get the message contents
function onSendToGroup(gameMessage) {
    return true;
}

// Return true if the player is allowed to join the group
function onPlayerJoinGroup(groupId, peerId) {
    return true;
}

// Return true if the player is allowed to leave the group
function onPlayerLeaveGroup(groupId, peerId) {
    return true;
}

// A simple tick loop example
// Checks to see if a minimum amount of time has passed before seeing if the game has ended
async function tickLoop() {
    const elapsedTime = getTimeInS() - startTime;
    logger.info("Tick... " + elapsedTime + " activePlayers: " + activePlayers);

    // In Tick loop - see if all players have left early after a minimum period of time has passed
    // Call processEnding() to terminate the process and quit
    if ((activePlayers == 0) && (elapsedTime > minimumElapsedTime)) {
        logger.info("All players disconnected. Ending game");
        const outcome = await session.processEnding();
        logger.info("Completed process ending with: " + outcome);
        process.exit(0);
    }
    else {
        setTimeout(tickLoop, tickTime);
    }
}

// Calculates the current time in seconds
function getTimeInS() {
    return Math.round(new Date().getTime() / 1000);
}

exports.ssExports = {
    configuration: configuration,
    init: init,
    onProcessStarted: onProcessStarted,
    onMessage: onMessage,
    onPlayerConnect: onPlayerConnect,
    onPlayerAccepted: onPlayerAccepted,
    onPlayerDisconnect: onPlayerDisconnect,
    onSendToPlayer: onSendToPlayer,
    onSendToGroup: onSendToGroup,
    onPlayerJoinGroup: onPlayerJoinGroup,
    onPlayerLeaveGroup: onPlayerLeaveGroup,
    onStartGameSession: onStartGameSession,
    onProcessTerminate: onProcessTerminate,
    onHealthCheck: onHealthCheck
};