A relatively simple sample of base system of networking using the Unity LLAPI.

I've been messing with the LLAPI because I feel like the HLAPI is somewhat lacking in documentation. Thus, has a lack in ease-of-use. So, instead using the HLAPI, I've been trying to understand the LLAPI so I could re-invent the wheel to suit my needs. I've viewed several articles and lessons on the LLAPI, and made a sample that may help some people getting started. I used this as a base: https://gist.github.com/LinaAdkins/a3bc0cee6f39bfd80110. If you wish to test the functionality of my script, add that script to a GameObject in the scene and build the game. Launch the build, and hit play in the editor. There are OnGUI buttons that allow you to make the running game a server or a client. Just make sure you change the IP and port it uses to suit your specific environment. You have to do it manually in the script.

I hope this helps someone out!

Here is the script:

Code (CSharp):

1.  
2. //NetworkingMain.cs
3. using UnityEngine;
4. using System.Collections;
5. using System.Collections.Generic;
6. using UnityEngine.Networking;
7. using System.Runtime.Serialization.Formatters.Binary;
8. using System.IO;
9.  
10. public class NetworkMain : MonoBehaviour {
11.  
12.    //Enum
13.    enum NetworkType {
14.      undefined,
15.      server,
16.      client
17.    }
18.  
19.  
20.  
21.    //Preference Variables
22.    public int maxConnections = 10;//Max connections allowed.
23.    public bool autoStartServer = false;//Will this automatically become a server when the game is started?
24.  
25.  
26.  
27.    //Script Variables
28.    int localSocket = -1;//The socket the server or client is connected to.
29.    int connectionId = -1;//The ID of connection. Used to distinguish different clients on the network.
30.    bool isInitialized = false;//Is the script currently networked, or offline?
31.    NetworkType networkType;//State of this game instance. Is it a server, client, or undefined (neither a client or server, yet).
32.    List<int> activeConnectionIds = new List<int>();//All active connections. Only manager on server.
33.  
34.  
35.  
36.    //Channels
37.    byte channelUnreliable;//Unreliable channel.
38.    byte channelReliable;//Reliable channel.
39.  
40.  
41.  
42.    //Configuration Variables
43.    GlobalConfig gc = new GlobalConfig();
44.    ConnectionConfig cc = new ConnectionConfig();
45.    HostTopology ht;
46.  
47.  
48.  
49.  
50.  
51.    //--MONOBEHAVIOR METHODS------------------------------------------------------------------------------------------------------------------------------\\
52.    void Start() {
53.  
54.      //Customize global config
55.      gc.ReactorModel = ReactorModel.FixRateReactor;
56.      gc.ThreadAwakeTimeout = 10;
57.  
58.      //Customize channel config
59.      channelReliable = cc.AddChannel(QosType.ReliableSequenced);
60.      channelUnreliable = cc.AddChannel(QosType.UnreliableSequenced);
61.  
62.      //Create host topology from config
63.      ht = new HostTopology(cc, maxConnections);
64.  
65.      //Initialize network transport. Allows for the creation/connection of servers.
66.      NetworkTransport.Init(gc);
67.  
68.      //If 'autoStartServer' is true, then start a server.
69.      if ( autoStartServer )
70.        StartServer();
71.  
72.      StartCoroutine( "TimedMessage" );
73.    }
74.  
75.  
76.  
77.  
78.  
79.    void Update() {
80.      //Recieve Network Messages
81.      ReceiveMessages();
82.    }
83.  
84.  
85.  
86.  
87.  
88.    void OnGUI() {
89.      if ( GUI.Button(new Rect(Screen.width * .5f - 50, Screen.height * .5f - 50, 100, 40), "Create a Server") ) {
90.        StartServer();
91.      }
92.      if ( GUI.Button(new Rect(Screen.width * .5f - 50, Screen.height * .5f + 50, 100, 40), "Join a Server") ) {
93.        JoinServer();
94.      }
95.      if ( GUI.Button(new Rect(Screen.width * .5f - 50, Screen.height * .5f + 150, 100, 40), "Disconnect") ) {
96.        Disconnect();
97.      }
98.    }
99.  
100.  
101.  
102.  
103.  
104.    //--START/CONNECT SERVER------------------------------------------------------------------------------------------------------------------------------\\
105.    public void StartServer(int port = 25565) {
106.      //Make sure this game is not already a server or client
107.      if ( networkType != NetworkType.undefined ) {
108.        Debug.LogError( "Error: This game is already a server or client. Cannot make it a server." );
109.        GameManager.gm.Log("Error: This game is already a server or client. Cannot make it a server.");
110.      }
111.  
112.      //Open socket for server
113.      localSocket = NetworkTransport.AddHost(ht, port);
114.  
115.      //Make sure the socket formations were successful
116.      if ( localSocket < 0 ) {
117.        GameManager.gm.Log("Server socket creation failed!");
118.      } else {
119.        GameManager.gm.Log("Server socket creation successful! Socket: " + localSocket);
120.        networkType = NetworkType.server;
121.      }
122.  
123.      isInitialized = true;
124.    }
125.  
126.  
127.  
128.  
129.  
130.    public void JoinServer(string ip = "127.0.0.1", int port = 25565) {
131.      //Make sure this game is not already a server or client
132.      if ( networkType != NetworkType.undefined ) {
133.        Debug.LogError("Error: This game is already a server or client. Cannot make it a client.");
134.        GameManager.gm.Log("Error: This game is already a server or client. Cannot make it a client.");
135.      }
136.  
137.      //Open socket for client
138.      localSocket = NetworkTransport.AddHost(ht);
139.  
140.      //Make sure the socket formations were successful
141.      if ( localSocket < 0 ) {
142.        GameManager.gm.Log("Client socket creation failed!");
143.      } else {
144.        GameManager.gm.Log("Client socket creation successful! Socket: " + localSocket);
145.        networkType = NetworkType.client;
146.      }
147.  
148.      isInitialized = true;
149.  
150.      //Connect to server
151.      byte error;
152.      connectionId = NetworkTransport.Connect(localSocket, ip, port, 0, out error);
153.      LogNetworkError(error);
154.    }
155.  
156.  
157.  
158.  
159.  
160.    //--SEND DATA------------------------------------------------------------------------------------------------------------------------------\\
161.    public void ServerSendDataToSingle(string message, int recipient) {//message, (send to single) int id
162.      List<int> recipients = new List<int>();
163.      recipients.Add(recipient);
164.      ServerSendDataInner(message, recipients);
165.    }
166.    public void ServerSendDataToMultiple(string message, List<int> recipients) {//message, (send to multiple) list<int> ids
167.      ServerSendDataInner(message, recipients);
168.    }
169.    public void ServerSendDataToAll(string message) {//message, (send to all)
170.      ServerSendDataInner(message, activeConnectionIds);
171.    }
172.    public void ServerSendDataInner(string message, List<int> recipients) {
173.      //If not server, return
174.      if ( networkType != NetworkType.server ) {
175.        if ( networkType == NetworkType.undefined ) {
176.          Debug.LogError("Error: Cannot sent message. No active connections");
177.        } else {
178.          Debug.LogError("Error: Client cannot send messages with this method. Use [ClientSendDataToHost] instead.");
179.        }
180.        return;
181.      }
182.  
183.      // Send the client(s) a message
184.      byte error;
185.      byte[] buffer = new byte[1024];
186.      Stream stream = new MemoryStream(buffer);
187.      BinaryFormatter f = new BinaryFormatter();
188.      f.Serialize(stream, message);
189.  
190.      foreach ( int id in recipients ) {
191.        NetworkTransport.Send(localSocket, id, channelReliable, buffer, ( int ) stream.Position, out error);
192.        LogNetworkError(error);
193.      }
194.    }
195.  
196.  
197.  
198.  
199.  
200.    public void ClientSendDataToHost(string message) {
201.      //If not client, return
202.      if ( networkType != NetworkType.client ) {
203.        if ( networkType == NetworkType.undefined ) {
204.          Debug.LogError("Error: Cannot sent message. No active connections");
205.        } else {
206.          Debug.LogError("Error: Server cannot send messages with this method. Use a variation of [ServerSendData___] instead.");
207.        }
208.        return;
209.      }
210.  
211.      // Send the server a message
212.      byte error;
213.      byte[] buffer = new byte[1024];
214.      Stream stream = new MemoryStream(buffer);
215.      BinaryFormatter f = new BinaryFormatter();
216.      f.Serialize(stream, message);
217.  
218.      NetworkTransport.Send(localSocket, connectionId, channelReliable, buffer, ( int ) stream.Position, out error);
219.      LogNetworkError(error);
220.    }
221.  
222.  
223.  
224.  
225.  
226.    //--RECEIVE DATA------------------------------------------------------------------------------------------------------------------------------\\
227.    void ReceiveMessages() {
228.      //Not a server or a connected client, return
229.      if ( !isInitialized ) {
230.        return;
231.      }
232.  
233.      int recHostId;
234.      int connId;
235.      int channelId;
236.      int dataSize;
237.      byte[] buffer = new byte[1024];
238.      byte error;
239.  
240.      NetworkEventType networkEvent = NetworkEventType.DataEvent;
241.  
242.      do {
243.        networkEvent = NetworkTransport.Receive(out recHostId, out connId, out channelId, buffer, 1024, out dataSize, out error);
244.  
245.        switch ( networkEvent ) {
246.          case NetworkEventType.Nothing:
247.            break;
248.  
249.  
250.  
251.          case NetworkEventType.ConnectEvent:
252.            if ( networkType == NetworkType.server ) {
253.              GameManager.gm.Log("Server: Player " + connId.ToString() + " connected!");
254.              activeConnectionIds.Add(connId);
255.              ServerSendDataToSingle("You connected to me!", connId);
256.              ServerSendDataToAll("A new player connected!");
257.            } else if ( networkType == NetworkType.client ) {
258.              GameManager.gm.Log("Client: Client connected to " + connId.ToString() + "!");
259.  
260.              ClientSendDataToHost("I connected to you!");
261.            }
262.            break;
263.  
264.  
265.  
266.          case NetworkEventType.DataEvent:
267.            //Decode data
268.            Stream stream = new MemoryStream(buffer);
269.            BinaryFormatter f = new BinaryFormatter();
270.            string msg = f.Deserialize(stream).ToString();
271.  
272.            //Received data
273.            if ( networkType == NetworkType.server ) {
274.  
275.              GameManager.gm.Log("Server: Received Data from " + connId.ToString() + "! Message: " + msg);
276.            } else if ( networkType == NetworkType.client ) {
277.              GameManager.gm.Log("Client: Received Data from " + connId.ToString() + "! Message: " + msg);
278.            }
279.            break;
280.  
281.  
282.  
283.          case NetworkEventType.DisconnectEvent:
284.            if ( networkType == NetworkType.server && connId != localSocket ) {
285.              GameManager.gm.Log("Server: Received disconnect from " + connId.ToString());
286.              int toRemove = -1;
287.              for ( int i = 0; i < activeConnectionIds.Count; i++ ) {
288.                if ( activeConnectionIds[i] == connId ) {
289.                  toRemove = i;
290.                  break;
291.                }
292.              }
293.              activeConnectionIds.RemoveAt(toRemove);
294.            } else if ( networkType == NetworkType.client ) {
295.              GameManager.gm.Log("Client: Disconnected from server!");
296.              Disconnect();
297.            }
298.            break;
299.        }
300.  
301.      } while ( networkEvent != NetworkEventType.Nothing );
302.    }
303.  
304.  
305.  
306.  
307.  
308.    //--DISCONNECT------------------------------------------------------------------------------------------------------------------------------\\
309.    public void Disconnect() {
310.      if ( networkType == NetworkType.client ) {
311.        byte error;
312.        NetworkTransport.Disconnect(localSocket, connectionId, out error);
313.        LogNetworkError(error);
314.      }
315.  
316.      //Close connection
317.      NetworkTransport.Shutdown();
318.  
319.      //Reset Variables
320.      localSocket = -1;
321.      connectionId = -1;
322.      isInitialized = false;
323.      networkType = NetworkType.undefined;
324.      List<int> activeConnectionIds = new List<int>();
325.      channelUnreliable = 0;
326.      channelReliable = 0;
327.      StopCoroutine( "TimedMessage" );
328.  
329.      //Re-Open connection
330.      NetworkTransport.Init(gc);
331.      StartCoroutine( "TimedMessage" );
332.    }
333.  
334.  
335.  
336.  
337.  
338.    //--OTHER------------------------------------------------------------------------------------------------------------------------------\\
339.    void LogNetworkError(byte error) {
340.      if ( error != ( byte ) NetworkError.Ok ) {
341.        NetworkError nerror = ( NetworkError ) error;
342.        Debug.LogError("Error: " + nerror.ToString());
343.        GameManager.gm.Log("Error: " + nerror.ToString());
344.      }
345.    }
346.  
347.    IEnumerator TimedMessage() {
348.      if ( networkType == NetworkType.server ) {
349.        ServerSendDataToAll( "Server to all: connected!" );
350.      } else if ( networkType == NetworkType.client ) {
351.        ClientSendDataToHost( "Client to host: connected!" );
352.      }
353.      yield return new WaitForSeconds(1);
354.      StartCoroutine( "TimedMessage" );
355.    }
356.  
357. }
358.  

That script also references GameManager.cs. I have that in everything I make, and it simply has a OnGUI console so it can be viewed in play mode. Here is that:

Code (CSharp):

1. //GameManager.cs
2. using UnityEngine;
3. using System.Collections;
4.  
5. public class GameManager : MonoBehaviour {
6.  
7.     public static GameManager gm;
8.  
9.     void Start() {
10.         gm = this;
11.  
12.         logs = new string[debugLength];
13.     }
14.  
15.     void OnGUI () {
16.         //In-Game Debug Console
17.         GUI.color = Color.black;
18.         if (debug && logs.Length > 0) {
19.             for (int i = 0; i <= debugLength - 1; i++) {
20.                 GUI.Label(new Rect(10, Screen.height - 165 - (i * 15), 1000, 20), logs[i]);
21.             }
22.             if (GUI.Button(new Rect(Screen.width * .5f - 50, Screen.height - 30, 100, 20), "CLEAR LOG")) {
23.                 for (int i = 0; i < debugLength; i++) {
24.                     logs[i] = "";
25.                 }
26.                 Log("");
27.             }
28.         }
29.     }
30.  
31.     //--[ Debug In-Game Console ]------------------------------------------------------------------------------------------------------------//
32.     public bool debug = true;
33.     public int debugLength = 20;
34.     private string[] logs;
35.     public void Log(string log) {
36.         for (int i = debugLength - 1; i > 0; i--) {
37.             logs[i] = logs[i - 1];
38.         }
39.         logs[0] = log;
40.     }
41. }
42.