How to get client connection information in HiveMQ Client? (MQTT)

0
votes

I'm writing a main class that will create a few clients and test them subscribing and publishing. I'd like to display information of the clients connection, like the data & time connected, clientId, clientIP used to connect, whether they connected gracefully or not. I'm new to using tools like Logger so I'm not sure how I would do this. I left a link to the HiveMQ community edition (broker) and the client. I'd like to display this information in my main class in the HiveMQ client project but there a log file in the community edition called event.log which contains exactly the kind of information I want to display. I left an image below.

HiveMQ:

https://github.com/hivemq/hivemq-community-edition https://github.com/hivemq/hivemq-mqtt-client

There is an event.log file in hivemq-community-edition that has the kind of information I'd like to display. It was generated when I build the project as a Gradle project so it won't be found unless you imported into Eclipse and built in with Gradle so I left a screenshot of what it looks like.

event.log

Code in my Main class in HiveMQ Client:

package com.main;

import java.util.UUID;

import com.hivemq.client.mqtt.MqttGlobalPublishFilter;
import com.hivemq.client.mqtt.datatypes.MqttQos;
import com.hivemq.client.mqtt.mqtt5.Mqtt5BlockingClient;
import com.hivemq.client.mqtt.mqtt5.Mqtt5BlockingClient.Mqtt5Publishes;
import com.hivemq.client.mqtt.mqtt5.Mqtt5Client;
import com.hivemq.client.mqtt.mqtt5.message.publish.Mqtt5Publish;
import java.util.logging.Logger;
import java.util.NoSuchElementException;

import java.util.logging.Level;
import java.util.concurrent.TimeUnit;


public class Main {

    private static final Logger LOGGER = Logger.getLogger(Main.class.getName());  // Creates a logger instance 


    public static void main(String[] args) {

                Mqtt5BlockingClient client1 = Mqtt5Client.builder()
            .identifier(UUID.randomUUID().toString()) // the unique identifier of the MQTT client. The ID is randomly generated between 
            .serverHost("localhost")  // the host name or IP address of the MQTT server. Kept it 0.0.0.0 for testing. localhost is default if not specified.
            .serverPort(1883)  // specifies the port of the server
            .buildBlocking();  // creates the client builder

            client1.connect();  // connects the client
            System.out.println("Client1 Connected");
            System.out.println(client1.toString());


            String testmessage = "How is it going!";
            byte[] messagebytesend = testmessage.getBytes();   // stores a message as a byte array to be used in the payload 

    try {  

        Mqtt5Publishes publishes = client1.publishes(MqttGlobalPublishFilter.ALL);  // creates a "publishes" instance thats used to queue incoming messages

            client1.subscribeWith()  // creates a subscription 
            .topicFilter("test1/#")  // filters to receive messages only on this topic (# = Multilevel wild card, + = single level wild card)
            .qos(MqttQos.AT_LEAST_ONCE)  // Sets the QoS to 2 (At least once) 
            .send(); 
            System.out.println("The client1 has subscribed");


            client1.publishWith()  // publishes the message to the subscribed topic 
            .topic("test/pancakes/topic")   // publishes to the specified topic
            .qos(MqttQos.AT_LEAST_ONCE)  
            .payload(messagebytesend)  // the contents of the message 
            .send();
            System.out.println("The client1 has published");


            Mqtt5Publish receivedMessage = publishes.receive(5,TimeUnit.SECONDS).get(); // receives the message using the "publishes" instance waiting up to 5 seconds                                                                          // .get() returns the object if available or throws a NoSuchElementException 


         byte[] tempdata = receivedMessage.getPayloadAsBytes();    // converts the "Optional" type message to a byte array 
         System.out.println();
         String getdata = new String(tempdata); // converts the byte array to a String 
         System.out.println(getdata);


    }

    catch (InterruptedException e) {    // Catches interruptions in the thread 
        LOGGER.log(Level.SEVERE, "The thread was interrupted while waiting for a message to be received", e);
        }

    catch (NoSuchElementException e){
        System.out.println("There are no received messages");   // Handles when a publish instance has no messages 
    }

    client1.disconnect();  
    System.out.println("Client1 Disconnected");

    }

}
1
javaloggingmqtthivemq
An MQTT client cannot get information about other MQTT clients. If you want that information then you will need to parse it from the broker's logfile. – Roger
@Roger I'd like to parse the information from the broker's log file and output in this class. How would I do that? – Chigozie A.
Use Splunk or write your own. parser. – Roger
Do you want to parse the log file of the server in the client application? Keep in mind that MQTT server and clients (usually) do not run on the same machine. – SgtSilvio
Well since the broker side is also in your hand, you can also add an Extension to the broker which registers a ClientLifecycleEventListener to display the client information. – Lumpi47

1 Answers

5
votes

You can obtain information about the client with the method getConfig e.g.

Mqtt5ClientConfig config = client.getConfig();
config.getClientIdentifier();

To get the information of the current connection use getConnectionConfig e.g.

Optional<Mqtt5ClientConnectionConfig> connectionConfig = config.getConnectionConfig();
if (connectionConfig.isPresent()) {
    MqttClientTransportConfig transportConfig = connectionConfig.get().getTransportConfig();
}

You can also use listeners which are notified when the client is connected or disconnected e.g.

Mqtt5Client.builder()
        .addConnectedListener(context -> System.out.println("connected"))
        .addDisconnectedListener(context -> System.out.println("disconnected"))
        ...