Multiplayer

DoubleCube.gg provides real-time multiplayer backgammon via SignalR WebSocket connections.

Connection Flow

1. Authentication: Client receives JWT (anonymous or registered)
2. Connection: SignalR connects with token in query string
3. Join Game: Client invokes JoinGame(gameId)
4. Real-time Updates: Server pushes events to all connected clients

Multi-Tab Support

A unique feature is full multi-tab support:

• Open the same game in multiple browser tabs
• All tabs stay synchronized
• Any tab can make moves
• Reconnection is seamless

How It Works

Each player is tracked by a HashSet<string> of connection IDs:

public class GameSession
{
    public HashSet<string> WhiteConnections { get; } = new();
    public HashSet<string> RedConnections { get; } = new();

    public void AddPlayer(string playerId, string connectionId)
    {
        // Same player, new connection = just add to set
        if (WhitePlayerId == playerId)
            WhiteConnections.Add(connectionId);
    }
}

When broadcasting updates, all connections receive the event:

foreach (var connectionId in session.WhiteConnections)
{
    await Clients.Client(connectionId).SendAsync("GameUpdate", state);
}

Game Lifecycle

Creating a Game

// Create via SignalR
await connection.invoke('CreateMatch', {
  targetScore: 5,
  opponentType: 'human',
  lobbyType: 'open'
});

Joining a Game

await connection.invoke('JoinGame', gameId);

Making Moves

// Roll dice first
await connection.invoke('RollDice');

// Make moves
await connection.invoke('MakeMove', fromPoint, toPoint);

// End turn
await connection.invoke('EndTurn');

Reconnection Handling

SignalR automatically reconnects with exponential backoff:

.withAutomaticReconnect([0, 2000, 5000, 10000, 30000])

When reconnecting to a game:

1. Server detects reconnection (connection ID already in session)
2. Current game state sent to new connection
3. Game continues seamlessly

Spectating

Users can watch games without participating:

await connection.invoke('JoinGame', gameId); // As spectator

Spectators receive:

• GameUpdate events
• GameOver events
• No move capabilities

Connection Events

Client Events

Event	Description
GameStart	Both players joined, game begins
GameUpdate	Board state changed
GameOver	Game completed
OpponentJoined	Second player joined
OpponentLeft	Player disconnected

Handling Disconnection

connection.onreconnecting(() => {
  showToast('Reconnecting...');
});

connection.onreconnected(() => {
  // Re-join current game
  await connection.invoke('JoinGame', currentGameId);
});

connection.onclose(() => {
  showToast('Connection lost');
});