reconnection in mqtt receiver introduced

bin/log4j2.xml

@@ -4,10 +4,14 @@
     <Console name="ConsoleAppender" target="SYSTEM_OUT">
       <PatternLayout pattern="%d [%t, %F, %L] %-5level - %msg%n%throwable"/> 
     </Console>
+    <File name="FileAppender" fileName="/tmp/MeasurementCollector.log">
+      <PatternLayout pattern="%d [%t, %F, %L] %-5level - %msg%n%throwable"/> 
+    </File>
   </Appenders>
   <Loggers>
     <Root level="debug">
       <AppenderRef ref="ConsoleAppender"/>
+      <AppenderRef ref="FileAppender"/>
     </Root>
   </Loggers>
 </Configuration>

src/de/hottis/MeasurementCollector/MqttReceiver.java

@@ -4,9 +4,12 @@ import java.time.LocalDateTime;
 import java.util.HashMap;
 import java.util.Properties;
 
+import javax.management.RuntimeErrorException;
+
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.eclipse.paho.client.mqttv3.IMqttMessageListener;
+import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
+import org.eclipse.paho.client.mqttv3.MqttCallbackExtended;
 import org.eclipse.paho.client.mqttv3.MqttClient;
 import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
 import org.eclipse.paho.client.mqttv3.MqttException;
@@ -23,10 +26,23 @@ public class MqttReceiver {
 	static final String MQTT_PASSWORD_PROP = "mqtt.password";
 	
 	
-	class Listener implements IMqttMessageListener {
+	class Callback implements MqttCallbackExtended {
 		public void messageArrived(String topic, MqttMessage payload) {
 			parsers.get(topic).execute(LocalDateTime.now(), payload.toString());
 		}
+		
+		public void connectComplete(boolean reconnect, java.lang.String serverURI) {
+			logger.info("Connection established for " + serverURI);
+		}
+		
+		public void connectionLost(java.lang.Throwable cause) {
+			logger.error("Connection lost, cause: " + cause.toString());
+			reconnect();
+		}
+		
+		public void deliveryComplete(IMqttDeliveryToken token) {
+			
+		}
 	}
 	
 	private final String broker;
@@ -34,7 +50,7 @@ public class MqttReceiver {
 	private final MqttConnectOptions connOpts;
 	private MqttClient client;
 	private HashMap<String, AMessageParser> parsers;
-	private final Listener listener = new Listener();
+	private final Callback callback = new Callback();
 	
 	public MqttReceiver(Properties config) {
 		broker = config.getProperty(MQTT_BROKER_PROP, "localhost");
@@ -53,6 +69,7 @@ public class MqttReceiver {
 	public void connect() throws MeasurementCollectorException {
 		try {
 			client = new MqttClient(broker, clientId);
+			client.setCallback(callback);
 			client.connect(connOpts);
 			logger.info("Connected");
 		} catch (MqttException e) {
@@ -60,10 +77,35 @@ public class MqttReceiver {
 		}
 	}
 	
+	public void reconnect() {
+		logger.error("reconnect called");
+		if (! client.isConnected()) {
+			while (true) {
+				try {
+					client.connect(connOpts);
+					for (String topic : parsers.keySet()) {
+						client.subscribe(topic);
+						logger.info("Re-Subscribed: " + topic);
+					}
+					logger.error("reconnecting successfully completed");
+					break;
+				} catch (MqttException e) {
+					logger.error("Exception during reconnection: " + e.toString());
+					try {
+						Thread.sleep(10*1000);
+					} catch (InterruptedException e1) {
+					}
+				}
+			}
+		} else {
+			logger.error("client is still connected");
+		}
+	}
+	
 	public void registerParser(AMessageParser parser) throws MeasurementCollectorException {
 		try {
 			parsers.put(parser.getTopic(), parser);
-			client.subscribe(parser.getTopic(), listener);
+			client.subscribe(parser.getTopic());
 			logger.info("Subscribed: " + parser.getTopic());
 		} catch (MqttException e) {
 			throw new MeasurementCollectorException("MqttReceiver.registerParser", e);

src/log4j2.xml

@@ -4,10 +4,14 @@
     <Console name="ConsoleAppender" target="SYSTEM_OUT">
       <PatternLayout pattern="%d [%t, %F, %L] %-5level - %msg%n%throwable"/> 
     </Console>
+    <File name="FileAppender" fileName="/tmp/MeasurementCollector.log">
+      <PatternLayout pattern="%d [%t, %F, %L] %-5level - %msg%n%throwable"/> 
+    </File>
   </Appenders>
   <Loggers>
     <Root level="debug">
       <AppenderRef ref="ConsoleAppender"/>
+      <AppenderRef ref="FileAppender"/>
     </Root>
   </Loggers>
 </Configuration>