Add StoreMulticastRunnable.java, Multicast receiver

.idea/inspectionProfiles/Project_Default.xml

@@ -0,0 +1,6 @@
+<component name="InspectionProjectProfileManager">
+  <profile version="1.0">
+    <option name="myName" value="Project Default" />
+    <inspection_tool class="InfiniteLoopStatement" enabled="false" level="WARNING" enabled_by_default="false" />
+  </profile>
+</component>

app/src/main/java/lightcontainer/App.java

@@ -3,12 +3,26 @@
  */
 package lightcontainer;
 
+import lightcontainer.domains.StoreMulticastRunnable;
+
 public class App {
-    public String getGreeting() {
-        return "Hello World!";
+    public static void main(String[] args) {
+        System.out.println("Hello World !");
+
+        int port = 42500;
+        String ip = "226.0.0.1";
+
+        StoreMulticastRunnable multicast = new StoreMulticastRunnable(ip, port);
+        (new Thread(multicast)).start();
+
+        // Sleep
+        try {
+            Thread.sleep(5000);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
         }
 
-    public static void main(String[] args) {
-        System.out.println(new App().getGreeting());
+        // Close
+        multicast.stop();
     }
 }

app/src/main/java/lightcontainer/domains/StoreMulticastRunnable.java

@@ -0,0 +1,69 @@
+package lightcontainer.domains;
+
+import java.net.DatagramPacket;
+import java.net.InetAddress;
+import java.net.MulticastSocket;
+
+/**
+ * StoreMulticastRunnable
+ *
+ * Class listening to the announcement of new StoreBackEnd.
+ * Allowing it to be used as a storage unit.
+ *
+ * @version     1.0
+ *
+ * @see         Runnable
+ * @author      Jérémi NIHART <j.nihart@student.helmo.be>
+ */
+public class StoreMulticastRunnable implements Runnable {
+    // Variable
+    private final String multicast_address;
+    private final int multicast_port;
+
+    private final byte[] buffer = new byte[256];
+    private MulticastSocket listener;
+
+    // Constructor
+    public StoreMulticastRunnable(String multicast_address, int multicast_port) {
+        this.multicast_address = multicast_address;
+        this.multicast_port = multicast_port;
+    }
+
+    /**
+     * Start Multicast listening on indicated port and IP group.
+     *
+     * @since       1.0
+     *
+     * @see         MulticastSocket#receive(DatagramPacket) 
+     * @see         DatagramPacket
+     */
+    @Override
+    public void run() {
+        try {
+            // Create a new listening socket
+            this.listener = new MulticastSocket(this.multicast_port);
+            // Create an identifier for the multicast group on the specified ip
+            InetAddress listener_group = InetAddress.getByName(this.multicast_address);
+            // Creation of a packet for the information received
+            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
+            // Add the listener to the multicast group
+            listener.joinGroup(listener_group);
+            while(true) {
+                listener.receive(packet);
+                String data = new String(packet.getData(), 0, packet.getLength());
+                System.out.println(data); // TODO ajouter un controller et lui signaler qu'il y a un nouveau StoreBackEnd
+            }
+        } catch (Exception ignore) { }
+    }
+
+    /**
+     * Closes the MulticastSocket connection and aborts the listening and infinite listening loop.
+     *
+     * @since       1.0
+     *
+     * @see         StoreMulticastRunnable#run()
+     */
+    public void stop() {
+        this.listener.close();
+    }
+}

app/src/test/java/lightcontainer/AppTest.java

@@ -7,8 +7,8 @@ import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.*;
 
 class AppTest {
-    @Test void appHasAGreeting() {
-        App classUnderTest = new App();
-        assertNotNull(classUnderTest.getGreeting(), "app should have a greeting");
-    }
+//    @Test void appHasAGreeting() {
+//        App classUnderTest = new App();
+//        assertNotNull(classUnderTest.getGreeting(), "app should have a greeting");
+//    }
 }