Added basic auto discovery functionality

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

Tags: #story[1247]

pom.xml

@@ -70,6 +70,13 @@
             <version>1.4</version>
         </dependency>
 
+        <!-- https://mvnrepository.com/artifact/javax.jmdns/jmdns -->
+        <dependency>
+            <groupId>javax.jmdns</groupId>
+            <artifactId>jmdns</artifactId>
+            <version>3.4.1</version>
+        </dependency>
+
     </dependencies>
 
     <build>

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();
+    }
+}

src/main/java/seng302/visualiser/ServerListener.java

@@ -0,0 +1,56 @@
+package seng302.visualiser;
+
+import seng302.gameServer.ServerAdvertiser;
+
+import javax.jmdns.JmDNS;
+import javax.jmdns.ServiceEvent;
+import javax.jmdns.ServiceListener;
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+public class ServerListener{
+    private static ServerListener instance;
+    private ServerListenerDelegate delegate;
+    private JmDNS jmdns = null;
+
+    private class GameServerListener implements ServiceListener {
+        GameServerListener(){
+            System.out.println("Created GSL instance");
+        }
+
+        @Override
+        public void serviceAdded(ServiceEvent event) {
+            delegate.serverDetected(event.getName(), "", 123, event.getInfo().getInet4Addresses().toString());
+        }
+
+        @Override
+        public void serviceRemoved(ServiceEvent event) {
+            delegate.serverRemoved(event.getName());
+        }
+
+        @Override
+        public void serviceResolved(ServiceEvent event) {
+            // Do nothing
+        }
+    }
+
+    private ServerListener() throws IOException {
+        jmdns = JmDNS.create(InetAddress.getLocalHost());
+        jmdns.addServiceListener(ServerAdvertiser.SERVICE_TYPE, new GameServerListener());
+    }
+
+    public static ServerListener getInstance() throws IOException {
+        if (instance == null){
+            instance = new ServerListener();
+        }
+
+        return instance;
+    }
+
+    public void setDelegate(ServerListenerDelegate delegate){
+        this.delegate = delegate;
+    }
+
+
+}

src/main/java/seng302/visualiser/ServerListenerDelegate.java

@@ -0,0 +1,6 @@
+package seng302.visualiser;
+
+public interface ServerListenerDelegate {
+    void serverDetected(String serverName, String mapName, Integer placesLeft, String serverAddress);
+    void serverRemoved(String serverName);
+}