Integrating a game client for Realtime Servers

This topic describes how to prepare your game client to be able to join and participate in Amazon GameLift-hosted game sessions.

There are two sets of tasks needed to prepare your game client:

Find or create game sessions and player sessions

Set up your game client to find or start game sessions, request FlexMatch matchmaking, and reserve space for players in a game by creating player sessions. As a best practice, create a backend service and use it to make the direct requests to the Amazon GameLift service when triggered by a game client action. The backend service then relays relevant responses back to the game client.

Connect to games on Realtime Servers

Enable your game client to connect directly with a hosted game session on a Realtime server and exchange messages with the server and with other players.

When working with Realtime fleets that have TLS certificate generation enabled, the server is automatically authenticated using the TLS certificate. TCP and UDP traffic is encrypted in flight to provide transport layer security. TCP traffic is encrypted using TLS 1.2, and UDP traffic is encrypted using DTLS 1.2.

Game client examples

Basic realtime client (C#)

This example illustrates a basic game client integration with the Realtime Client SDK (C#). As shown, the example initializes a Realtime client object, sets up event handlers and implements the client-side callbacks, connects to a Realtime server, sends a message, and disconnects.

using System;
using System.Text;
using Aws.GameLift.Realtime;
using Aws.GameLift.Realtime.Event;
using Aws.GameLift.Realtime.Types;

namespace Example
{
    /**
     * An example client that wraps the GameLift Realtime client SDK
     * 
     * You can redirect logging from the SDK by setting up the LogHandler as such:
     * ClientLogger.LogHandler = (x) => Console.WriteLine(x);
     *
     */
    class RealTimeClient
    {
        public Aws.GameLift.Realtime.Client Client { get; private set; }
        
        // An opcode defined by client and your server script that represents a custom message type
        private const int MY_TEST_OP_CODE = 10;

        /// Initialize a client for GameLift Realtime and connect to a player session.
        /// <param name="endpoint">The DNS name that is assigned to Realtime server</param>
        /// <param name="remoteTcpPort">A TCP port for the Realtime server</param>
        /// <param name="listeningUdpPort">A local port for listening to UDP traffic</param>
        /// <param name="connectionType">Type of connection to establish between client and the Realtime server</param>
        /// <param name="playerSessionId">The player session ID that is assigned to the game client for a game session </param>
        /// <param name="connectionPayload">Developer-defined data to be used during client connection, such as for player authentication</param>
       public RealTimeClient(string endpoint, int remoteTcpPort, int listeningUdpPort, ConnectionType connectionType,
                    string playerSessionId, byte[] connectionPayload)
        {
            // Create a client configuration to specify a secure or unsecure connection type
            // Best practice is to set up a secure connection using the connection type RT_OVER_WSS_DTLS_TLS12.
            ClientConfiguration clientConfiguration = new ClientConfiguration()
	     {
                // C# notation to set the field ConnectionType in the new instance of ClientConfiguration
	         ConnectionType = connectionType
	     };

            // Create a Realtime client with the client configuration            
            Client = new Client(clientConfiguration);

            // Initialize event handlers for the Realtime client
            Client.ConnectionOpen += OnOpenEvent;
            Client.ConnectionClose += OnCloseEvent;
            Client.GroupMembershipUpdated += OnGroupMembershipUpdate;
            Client.DataReceived += OnDataReceived;

            // Create a connection token to authenticate the client with the Realtime server
            // Player session IDs can be retrieved using AWS SDK for GameLift
            ConnectionToken connectionToken = new ConnectionToken(playerSessionId, connectionPayload);

            // Initiate a connection with the Realtime server with the given connection information
            Client.Connect(endpoint, remoteTcpPort, listeningUdpPort, connectionToken);
        }

        public void Disconnect()
        {
            if (Client.Connected)
            {
                Client.Disconnect();
            }
        }

        public bool IsConnected()
        {
            return Client.Connected;
        }

        /// <summary>
        /// Example of sending to a custom message to the server.
        /// 
        /// Server could be replaced by known peer Id etc.
        /// </summary>
        /// <param name="intent">Choice of delivery intent i.e. Reliable, Fast etc. </param>
        /// <param name="payload">Custom payload to send with message</param>
        public void SendMessage(DeliveryIntent intent, string payload)
        {
            Client.SendMessage(Client.NewMessage(MY_TEST_OP_CODE)
                .WithDeliveryIntent(intent)
                .WithTargetPlayer(Constants.PLAYER_ID_SERVER)
                .WithPayload(StringToBytes(payload)));
        }

        /**
         * Handle connection open events
         */
        public void OnOpenEvent(object sender, EventArgs e)
        {
        }

        /**
         * Handle connection close events
         */
        public void OnCloseEvent(object sender, EventArgs e)
        {
        }

        /**
         * Handle Group membership update events 
         */
        public void OnGroupMembershipUpdate(object sender, GroupMembershipEventArgs e)
        {
        }

        /**
         *  Handle data received from the Realtime server 
         */
        public virtual void OnDataReceived(object sender, DataReceivedEventArgs e)
        {
            switch (e.OpCode)
            {
                // handle message based on OpCode
                default:
                    break;
            }
        }

        /**
         * Helper method to simplify task of sending/receiving payloads.
         */
        public static byte[] StringToBytes(string str)
        {
            return Encoding.UTF8.GetBytes(str);
        }

        /**
         * Helper method to simplify task of sending/receiving payloads.
         */
        public static string BytesToString(byte[] bytes)
        {
            return Encoding.UTF8.GetString(bytes);
        }
    }
}