Setting up service discovery

AndroidManifest.xml

@@ -6,7 +6,7 @@
 
     <uses-sdk
         android:minSdkVersion="10"
-        android:targetSdkVersion="18" />
+        android:targetSdkVersion="19" />
 
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
@@ -21,6 +21,7 @@
     <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
     <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
+    <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
 
     <application
         android:allowBackup="true"

project.properties

@@ -11,4 +11,4 @@
 #proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
 
 # Project target.
-target=android-18
+target=android-19

res/layout/activity_main.xml

@@ -17,7 +17,7 @@
         android:layout_centerHorizontal="true"
         android:text="@string/start_button" />
 
-    <EditText
+    <!--  <EditText
         android:id="@+id/ipAddressField"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
@@ -34,5 +34,6 @@
         android:layout_alignBottom="@+id/ipAddressField"
         android:layout_toLeftOf="@+id/ipAddressField"
         android:text="@string/ipAddressLabel" />
+    -->
     
 </RelativeLayout>

res/values-es/strings.xml

@@ -7,7 +7,7 @@
     <string name="camera_success">Cámara abierta exitosamente</string>
     <string name="camera_failure">La cámara no pudo abrirse</string>
     <string name="get_server_button">Conectar con NxtAR</string>
-    <string name="start_button">Encender cámara</string>
+    <string name="start_button">Conectar con dispositivo controlador</string>
     <string name="title_activity_cam">CamActivity</string>
     <string name="ipAddressLabel">Dirección IP de NxtAR</string>
     <string name="badIpToast">La dirección IP no es válida</string>

res/values/strings.xml

@@ -8,7 +8,7 @@
     <string name="camera_failure">Camera could not be opened</string>
     <string name="title_activity_cam">CamActivity</string>
     <string name="get_server_button">Connect with NxtAR</string>
-    <string name="start_button">Start camera</string>
+    <string name="start_button">Connect with controller device</string>
     <string name="ipAddressLabel">NxtAR IP Address</string>
     <string name="badIpToast">Invalid IP address</string>
     <string name="emptyIpToast">Fill out the IP address field</string>

src/ve/ucv/ciens/ccg/nxtcam/CamActivity.java

@@ -5,6 +5,7 @@ import ve.ucv.ciens.ccg.nxtcam.network.ImageTransferThread;
 import ve.ucv.ciens.ccg.nxtcam.utils.Logger;
 import ve.ucv.ciens.ccg.nxtcam.utils.ProjectConstants;
 import android.app.Activity;
+import android.content.Intent;
 import android.hardware.Camera;
 import android.os.AsyncTask;
 import android.os.Bundle;
@@ -23,6 +24,7 @@ public class CamActivity extends Activity{
 	private CameraPreview cPreview;
 	private CameraSetupTask camSetupTask;
 	private ImageTransferThread imThread;
+	private String serverIp;
 
 	/*******************
 	 * Android methods *
@@ -35,6 +37,9 @@ public class CamActivity extends Activity{
 		cPreview = new CameraPreview(this, hwCamera);
 		setContentView(cPreview);
 		
+		Intent intent = getIntent();
+		serverIp = intent.getStringExtra("address");
+		
 		imThread = new ImageTransferThread();
 	}
 

src/ve/ucv/ciens/ccg/nxtcam/MainActivity.java

@@ -1,13 +1,18 @@
 package ve.ucv.ciens.ccg.nxtcam;
 
+import java.io.IOException;
+import java.net.DatagramPacket;
 import java.net.InetAddress;
+import java.net.MulticastSocket;
 import java.net.UnknownHostException;
 
 import ve.ucv.ciens.ccg.nxtcam.utils.Logger;
+import ve.ucv.ciens.ccg.nxtcam.utils.ProjectConstants;
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.net.wifi.WifiManager;
+import android.net.wifi.WifiManager.MulticastLock;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.view.Menu;
@@ -16,14 +21,32 @@ import android.widget.Button;
 import android.widget.TextView;
 import android.widget.Toast;
 
+/**
+ * Entry point por the NxtCAM application.
+ * 
+ * This activity shows a splashscreen and handles the search for the controller device
+ * via a simle ad hoc UDP based service discovery method. Basically, it just listens for
+ * multicast packets sent by the controller device on the multicast address defined in
+ * ProjectConstants.java. When the packet is received the next activity of the application
+ * is launched with the ip address found. The service discovery process continues until a
+ * datagram carrying the string "NxtAR server here!" is received.
+ * 
+ * @author miky
+ *
+ */
 public class MainActivity extends Activity {
+	// Cosntant fields.
 	private final String TAG = "NXTCAM_MAIN";
 	private final String CLASS_NAME = MainActivity.class.getSimpleName();
 
+	// Gui components.
 	private Button startButton;
-	private TextView ipField;
+	//private TextView ipField;
 
+	// Resources.
 	private WifiManager wifiManager;
+
+	// Variables.
 	private boolean wifiOnByMe;
 
 	@Override
@@ -31,35 +54,34 @@ public class MainActivity extends Activity {
 		super.onCreate(savedInstanceState);
 		setContentView(R.layout.activity_main);
 
+		// Set up fields.
+		wifiOnByMe = false;
+
+		// Set up gui components.
 		startButton = (Button)findViewById(R.id.startButton);
 		startButton.setOnClickListener(startClickListener);
+		// ipField = (TextView)findViewById(R.id.ipAddressField);
 
-		ipField = (TextView)findViewById(R.id.ipAddressField);
+		// Set up services.
-
 		wifiManager = (WifiManager)getSystemService(Context.WIFI_SERVICE);
-
+		if(!wifiManager.isWifiEnabled())
-		if(!wifiManager.isWifiEnabled()) setWifi(true);
+			setWifi(true);
 	}
 
 	@Override
 	public void onResume(){
 		super.onResume();
 
-		if(!wifiManager.isWifiEnabled()) setWifi(true);
+		if(!wifiManager.isWifiEnabled())
+			setWifi(true);
 	}
 
 	@Override
 	public void onPause(){
 		super.onPause();
 
-		if(wifiManager.isWifiEnabled() && wifiOnByMe) setWifi(false);
+		if(wifiManager.isWifiEnabled() && wifiOnByMe)
-	}
+			setWifi(false);
-
-	@Override
-	public void onDestroy(){
-		super.onDestroy();
-
-		if(wifiManager.isWifiEnabled() && wifiOnByMe) wifiManager.setWifiEnabled(false);
 	}
 
 	@Override
@@ -69,10 +91,17 @@ public class MainActivity extends Activity {
 		return true;
 	}
 
-	private void startCamActivity(boolean canStart){
+	/**
-		if(canStart){
+	 * Start the camera capture activity if a server was found through service discovery.
+	 * 
+	 * @param serverFound Indicates if a server was found, doh!
+	 * @param ipAddress The ip address of the server.
+	 */
+	private void startCamActivity(boolean serverFound, String ipAddress){
+		if(serverFound){
 			Logger.log(Logger.LOG_TYPES.DEBUG, TAG, CLASS_NAME + ".startCamActivity() :: Launching camera activity.");
 			Intent intent = new Intent(this, CamActivity.class);
+			intent.putExtra("address", ipAddress);
 			startActivity(intent);
 		}else{
 			Logger.log(Logger.LOG_TYPES.DEBUG, TAG, CLASS_NAME + ".startCamActivity() :: Cannot launch camera activity.");
@@ -80,16 +109,21 @@ public class MainActivity extends Activity {
 		}
 	}
 
-	private void setWifi(boolean on){
+	/**
-		wifiManager.setWifiEnabled(on);
+	 * Sets the state of the device's WiFi radio.
-		Logger.log(Logger.LOG_TYPES.DEBUG, TAG, CLASS_NAME + ".ImageTransferThread() :: setting wifi to " + (on ? "on" : "off"));
+	 * 
-		if(on)
+	 * @param radioState The state to set the radio to; true for on, false for off.
+	 */
+	private void setWifi(boolean radioState){
+		wifiManager.setWifiEnabled(radioState);
+		Logger.log(Logger.LOG_TYPES.DEBUG, TAG, CLASS_NAME + ".setWifi() :: setting wifi to " + (radioState ? "on" : "off"));
+		if(radioState)
 			wifiOnByMe = true;
 		else
 			wifiOnByMe = false;
 	}
 
-	private void validateIpAddress(){
+	/*private void validateIpAddress(){
 		if(ipField.getText().toString().compareTo("") != 0){
 			Logger.log(Logger.LOG_TYPES.DEBUG, TAG, CLASS_NAME + "validateIpAddress() :: Launching verification task.");
 			VerifyIpAddressTask verifyIp = new VerifyIpAddressTask();
@@ -98,16 +132,93 @@ public class MainActivity extends Activity {
 			Logger.log(Logger.LOG_TYPES.DEBUG, TAG, CLASS_NAME + "validateIpAddress() :: Ip address field is empty.");
 			Toast.makeText(this, R.string.emptyIpToast, Toast.LENGTH_SHORT).show();
 		}
-	}
+	}*/
 
+	/**
+	 * Event listener for the connection button.
+	 */
 	private final View.OnClickListener startClickListener = new View.OnClickListener() {
 		@Override
 		public void onClick(View v) {
-			validateIpAddress();
+			//validateIpAddress();
+			ServiceDiscoveryTask serviceDiscovery = new ServiceDiscoveryTask();
+			serviceDiscovery.execute();
 		}
 	};
 
-	private class VerifyIpAddressTask extends AsyncTask<String, Void, Boolean>{
+	/**
+	 * Asynchronous task for ad hoc UDP service discovery.
+	 * 
+	 * @author Miguel Angel Astor Romero
+	 */
+	private class ServiceDiscoveryTask extends AsyncTask<Void, Void, Boolean>{
+
+		private final String CLASS_NAME = ServiceDiscoveryTask.class.getSimpleName();
+
+		private MulticastSocket udpSocket;
+		private DatagramPacket packet;
+		private MulticastLock multicastLock;
+
+		public ServiceDiscoveryTask(){
+			// Open a multicast socket and join the project's multicast group.
+			try{
+				udpSocket = new MulticastSocket(ProjectConstants.SERVER_UDP_PORT);
+				InetAddress group = InetAddress.getByName(ProjectConstants.MULTICAST_ADDRESS);
+				udpSocket.joinGroup(group);
+			}catch(IOException io){
+				Logger.log(Logger.LOG_TYPES.ERROR, TAG ,CLASS_NAME + ".ServiceDiscoveryTask() :: " + io.getMessage());
+			}
+		}
+
+		@Override
+		protected Boolean doInBackground(Void... params){
+			boolean result, done = false;
+			byte[] buffer = (new String("Server is here")).getBytes();
+
+			// Create a buffer and tell Android we want to receive multicast datagrams.
+			packet = new DatagramPacket(buffer, buffer.length);
+			multicastLock = wifiManager.createMulticastLock(TAG);
+			multicastLock.setReferenceCounted(true);
+			multicastLock.acquire();
+
+			// Listen for a UDP datagram on the multicast group.
+			// If the datagram received contains a string with it's content equal to "NxtAR server here!"
+			// then assume the server found is a valid controller device.
+			try{
+				while(!done){
+					udpSocket.receive(packet);
+					Logger.log(Logger.LOG_TYPES.DEBUG, TAG, CLASS_NAME + ".run() :: Found a server at " + packet.getAddress().getHostAddress());
+					String received = new String(packet.getData());
+					if(received.compareTo("NxtAR server here!") == 0)
+						done = true;
+				}
+				result = true;
+			}catch(IOException io){
+				Logger.log(Logger.LOG_TYPES.ERROR, TAG, CLASS_NAME + ".doInBackground() :: " + io.getMessage());
+				result = false;
+			}
+
+			// Tell Android we do not want to receive more UDP datagrams to save battery life.
+			if(multicastLock != null){
+				multicastLock.release();
+				multicastLock = null;
+			}
+
+			return result;
+		}
+
+		@Override
+		protected void onPostExecute(Boolean result){
+			super.onPostExecute(result);
+			// If a server was found then start the next activity.
+			if(packet != null)
+				startCamActivity(result, packet.getAddress().getHostAddress());
+			else
+				startCamActivity(false, null);
+		}
+	};
+
+	/*	private class VerifyIpAddressTask extends AsyncTask<String, Void, Boolean>{
 		private final String CLASS_NAME = VerifyIpAddressTask.class.getSimpleName();
 
 		@Override
@@ -127,5 +238,5 @@ public class MainActivity extends Activity {
 			super.onPostExecute(result);
 			startCamActivity(result);
 		}
-	};
+	};*/
 }

src/ve/ucv/ciens/ccg/nxtcam/network/ServiceDiscoveryThread.java

@@ -1,13 +0,0 @@
-package ve.ucv.ciens.ccg.nxtcam.network;
-
-public class ServiceDiscoveryThread extends Thread {
-
-	public ServiceDiscoveryThread(){
-
-	}
-
-	@Override
-	public void run(){
-
-	}
-}

src/ve/ucv/ciens/ccg/nxtcam/utils/ProjectConstants.java

@@ -5,5 +5,7 @@ public abstract class ProjectConstants {
 	public static final int SERVER_TCP_PORT_1 = 9989;
 	public static final int SERVER_TCP_PORT_2 = 9990;
 	
+	public static final String MULTICAST_ADDRESS = "230.0.0.1";
+	
 	public static final boolean DEBUG = true;
 }