Fixed issues.

src/main/java/org/apache/jmeter/protocol/mqtt/client/MqttPublisher.java

@@ -67,16 +67,18 @@ public void setupTest(JavaSamplerContext context) {
         String brokerURL = context.getParameter("BROKER_URL");
         String clientId = context.getParameter("CLIENT_ID");
         topicName = context.getParameter("TOPIC_NAME");
-        retained = Boolean.parseBoolean(context.getParameter("CLEAN_SESSION"));
+        retained = Boolean.parseBoolean(context.getParameter("MESSAGE_RETAINED"));
         String username = context.getParameter("USERNAME");
         String password = context.getParameter("PASSWORD");
         String client_type = context.getParameter("CLIENT_TYPE");
         String messageInputType = context.getParameter("MESSAGE_INPUT_TYPE");
 
         // Generating client ID if empty
         if (StringUtils.isEmpty(clientId)){
-            clientId  = System.currentTimeMillis() + "." + System.getProperty("user.name");
-            clientId = clientId.substring(0, 23);
+            clientId  = System.nanoTime() + "." + System.getProperty("user.name");
+            if (clientId.length() > 23) {
+                clientId = clientId.substring(0, 23);
+            }
         }
 
         // Quality

src/main/java/org/apache/jmeter/protocol/mqtt/client/MqttSubscriber.java

@@ -96,8 +96,10 @@ private void setupTest(String brokerURL, String clientId, String topic,
 
             // Generating client ID if empty
             if (StringUtils.isEmpty(clientId)){
-                clientId  = System.currentTimeMillis() + "." + System.getProperty("user.name");
-                clientId = clientId.substring(0, 23);
+                clientId  = System.nanoTime() + "." + System.getProperty("user.name");
+                if (clientId.length() > 23) {
+                    clientId = clientId.substring(0, 23);
+                }
             }
 
             // Quality

src/main/java/org/apache/jmeter/protocol/mqtt/paho/clients/AsyncClient.java

@@ -67,9 +67,14 @@ public AsyncClient(String brokerUrl, String clientId, boolean cleanSession,
         // stored until the message has been delivered to the server.
         //..a real application ought to store them somewhere
         // where they are not likely to get deleted or tampered with
-        String testPlanFile = GuiPackage.getInstance().getTestPlanFile();
-        String testPlanFileDir = FilenameUtils.getFullPathNoEndSeparator(testPlanFile);
-        testPlanFileDir = testPlanFileDir + File.separator + "tmp" + File.separator + clientId + File.separator + Thread.currentThread().getId();
+        String testPlanFileDir = System.getProperty("java.io.tmpdir");
+
+        if (null != GuiPackage.getInstance()) {
+            String testPlanFile = GuiPackage.getInstance().getTestPlanFile();
+            testPlanFileDir = FilenameUtils.getFullPathNoEndSeparator(testPlanFile);
+            testPlanFileDir = testPlanFileDir + File.separator + "tmp" + File.separator + clientId + File.separator + Thread.currentThread().getId();
+        }
+
         MqttDefaultFilePersistence dataStore = new MqttDefaultFilePersistence(testPlanFileDir);
 
         try {

src/main/java/org/apache°jmeter/protocol/mqtt/paho/clients/BlockingClient.java

@@ -0,0 +1,174 @@
+/**
+ * Author : Hemika Yasinda Kodikara
+ *
+ * Copyright (c) 2015.
+ */
+
+package org.apache.jmeter.protocol.mqtt.paho.clients;
+
+import org.apache.commons.io.FilenameUtils;
+import org.apache.jmeter.gui.GuiPackage;
+import org.apache.jmeter.protocol.mqtt.data.objects.Message;
+import org.apache.jorphan.logging.LoggingManager;
+import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
+import org.eclipse.paho.client.mqttv3.MqttClient;
+import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
+import org.eclipse.paho.client.mqttv3.MqttException;
+import org.eclipse.paho.client.mqttv3.MqttMessage;
+import org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence;
+
+import java.io.File;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * A sample application that demonstrates how to use the Paho MQTT v3.1 Client blocking API.
+ * <p/>
+ * It can be run from the command line in one of two modes:
+ * - as a publisher, sending a single message to a topic on the server
+ * - as a subscriber, listening for messages from the server
+ * <p/>
+ * There are three versions of the sample that implement the same features
+ * but do so using using different programming styles:
+ * <ol>
+ * <li>Sample (this one) which uses the API which blocks until the operation completes</li>
+ * <li>SampleAsyncWait shows how to use the asynchronous API with waiters that block until
+ * an action completes</li>
+ * <li>SampleAsyncCallBack shows how to use the asynchronous API where events are
+ * used to notify the application when an action completes<li>
+ * </ol>
+ * <p/>
+ * If the application is run with the -h parameter then info is displayed that
+ * describes all of the options / parameters.
+ */
+public class BlockingClient extends BaseClient {
+
+    private static final org.apache.log.Logger log = LoggingManager.getLoggerForClass();
+    private MqttClient client;
+    private String brokerUrl;
+
+    /**
+     * Constructs an instance of the sample client wrapper
+     *
+     * @param brokerUrl    the url of the server to connect to
+     * @param clientId     the client id to connect with
+     * @param cleanSession clear state at end of connection or not (durable or non-durable subscriptions)
+     * @param userName     the username to connect with
+     * @param password     the password for the user
+     * @throws MqttException
+     */
+    public BlockingClient(String brokerUrl, String clientId, boolean cleanSession, String userName,
+                          String password) throws MqttException {
+        this.brokerUrl = brokerUrl;
+        //This sample stores in a temporary directory... where messages temporarily
+        // stored until the message has been delivered to the server.
+        //..a real application ought to store them somewhere
+        // where they are not likely to get deleted or tampered with
+        String testPlanFileDir = System.getProperty("java.io.tmpdir");
+
+        if (null != GuiPackage.getInstance()) {
+            String testPlanFile = GuiPackage.getInstance().getTestPlanFile();
+            testPlanFileDir = FilenameUtils.getFullPathNoEndSeparator(testPlanFile);
+            testPlanFileDir = testPlanFileDir + File.separator + "tmp" + File.separator + clientId + File.separator + Thread.currentThread().getId();
+        }
+
+        MqttDefaultFilePersistence dataStore = new MqttDefaultFilePersistence(testPlanFileDir);
+
+        // Construct the connection options object that contains connection parameters
+        // such as cleanSession and LWT
+        MqttConnectOptions conOpt = new MqttConnectOptions();
+        conOpt.setCleanSession(cleanSession);
+        if (password != null) {
+            conOpt.setPassword(password.toCharArray());
+        }
+        if (userName != null) {
+            conOpt.setUserName(userName);
+        }
+
+        // Construct an MQTT blocking mode client
+        client = new MqttClient(this.brokerUrl, clientId, dataStore);
+
+        // Set this wrapper as the callback handler
+        client.setCallback(this);
+
+        // Connect to the MQTT server
+        log.info("Connecting to " + brokerUrl + " with client ID '" + client.getClientId() + "' as a blocking client");
+        client.connect(conOpt);
+        log.info("Connected");
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void disconnect() throws MqttException {
+        // Disconnect the client
+        client.disconnect();
+        log.info("Disconnected");
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public boolean isConnected() {
+        return client.isConnected();
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void publish(String topicName, int qos, byte[] payload, boolean isRetained) throws MqttException {
+        // Create and configure a message
+        MqttMessage message = new MqttMessage(payload);
+        message.setRetained(isRetained);
+        message.setQos(qos);
+
+        // Send the message to the server, control is not returned until
+        // it has been delivered to the server meeting the specified
+        // quality of service.
+        client.publish(topicName, message);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void subscribe(String topicName, int qos) throws MqttException {
+        mqttMessageStorage = new ConcurrentLinkedQueue<Message>();
+        receivedMessageCounter = new AtomicLong(0);
+
+        // Subscribe to the requested topic
+        // The QoS specified is the maximum level that messages will be sent to the client at.
+        // For instance if QoS 1 is specified, any messages originally published at QoS 2 will
+        // be downgraded to 1 when delivering to the client but messages published at 1 and 0
+        // will be received at the same level they were published at.
+        log.info("Subscribing to topic \"" + topicName + "\" qos " + qos);
+        client.subscribe(topicName, qos);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void connectionLost(Throwable cause) {
+        log.info("Connection to " + brokerUrl + " lost!" + cause);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void deliveryComplete(IMqttDeliveryToken token) {
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void messageArrived(String topic, MqttMessage message) throws MqttException {
+        Message newMessage = new Message(message);
+        mqttMessageStorage.add(newMessage);
+    }
+}

src/main/java/org/apache°jmeter/protocol/mqtt/utilities/Utils.java

@@ -0,0 +1,44 @@
+/**
+ * Author : Hemika Yasinda Kodikara
+ *
+ * Copyright (c) 2015.
+ */
+
+package org.apache.jmeter.protocol.mqtt.utilities;
+
+import org.apache.jorphan.io.TextFile;
+
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+
+/**
+ * Utility class for plugin
+ */
+public class Utils {
+
+    /**
+     * Creates a UUID. The UUID is modified to avoid "ClientId longer than 23 characters" for MQTT.
+     *
+     * @return A UUID as a string.
+     * @throws NoSuchAlgorithmException
+     */
+    public static String UUIDGenerator() throws NoSuchAlgorithmException {
+        String clientId = System.currentTimeMillis() + "." + System.getProperty("user.name");
+        if (clientId.length() > 23) {
+            clientId = clientId.substring(0, 23);
+        }
+        return clientId;
+    }
+
+    /**
+     * The implementation uses TextFile to load the contents of the file and
+     * returns a string.
+     *
+     * @param path path to the file to read in
+     * @return the contents of the file
+     */
+    public static String getFileContent(String path) {
+        TextFile tf = new TextFile(path);
+        return tf.getText();
+    }
+}