Added basic auto discovery functionality

- Servers can advertise themselves
- Clients can detect servers on their local network

Tags: #story[1247]

src/main/java/seng302/gameServer/ServerAdvertiser.java

@@ -0,0 +1,40 @@
+package seng302.gameServer;
+
+import javax.jmdns.JmDNS;
+import javax.jmdns.ServiceInfo;
+import java.io.IOException;
+import java.net.InetAddress;
+
+public class ServerAdvertiser {
+    private static String SERVICE = "_partyatsea_";
+    private static String PROTOCOL = "_tcp";
+    public static String SERVICE_TYPE = SERVICE + "." + PROTOCOL + ".local";
+    private static Integer PROTO_VERSION = 1;
+
+
+    private static ServerAdvertiser instance = null;
+    private static JmDNS jmdnsInstance = null;
+
+    private ServerAdvertiser() throws IOException{
+        jmdnsInstance = JmDNS.create(InetAddress.getLocalHost(), InetAddress.getByName(InetAddress.getLocalHost().getHostName()).toString());
+    }
+
+    public static ServerAdvertiser getInstance() throws IOException {
+        if (instance == null){
+            instance = new ServerAdvertiser();
+        }
+
+        return instance;
+    }
+
+    public void registerGame(Integer portNo, String serverName, Integer spacesLeft, String mapName) throws IOException {
+        String serviceData = packageServerData(spacesLeft, mapName, PROTO_VERSION);
+        ServiceInfo serviceInfo = ServiceInfo.create(SERVICE_TYPE, serverName, portNo, serviceData);
+
+        jmdnsInstance.registerService(serviceInfo);
+    }
+
+    private String packageServerData(Integer spacesLeft, String mapName, Integer version){
+        return spacesLeft.toString() + "|" + mapName + "|" + version.toString();
+    }
+}