Category Archives: ActiveMQ

Simple JMS Producer

Here is a JMS Producer template to use when I forget how to write them. It uses ActiveMQ as JMS provider and JNDI for connection propereties:

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.Message;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.naming.InitialContext;

public class Producer {

    public static void main(String[] args) throws Exception {

        InitialContext context = new InitialContext();
        ConnectionFactory factory = 
                 (ConnectionFactory) context.lookup("ConnectionFactory");

        Connection connection = factory.createConnection();
        connection.start();

        // Start a non-transacted session for sending messages
        Session session = 
               connection.createSession(false, Session.AUTO_ACKNOWLEDGE);

        Destination destination = (Destination) context.lookup("test");
        MessageProducer consumer = session.createProducer(destination);

        // Create text message
        Message message = session.createTextMessage("Hello World");

        // Send 10 "Hello World" messages to queue
        for (int i = 0; i < 10; i++) {
            consumer.send(message);
        }

        // Clean up
        session.close();
        connection.close();
        context.close();

    }
}

jndi.properties:

java.naming.factory.initial = org.apache.activemq.jndi.ActiveMQInitialContextFactory

# Use the following property to configure the default connector
java.naming.provider.url = tcp://localhost:61616

# Register some queues in JNDI using the form
# queue.[jndiName] = [physicalName]
queue.test = NIKLAS.TEST

ActiveMQ Client lib dependency pom:

<dependency>
     <groupid>org.apache.activemq</groupid>
     <artifactid>activemq-client</artifactid>
     <version>5.7.0</version>
</dependency>

Tested on Windows 10, Maven 3.8.4, Java 11.0.18 and ActiveMQ Client 5.7.0

Simple transacted JMS consumer

Ever looked for a simple JMS Consumer template – here is one and it is transacted too 🙂

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.Session;
import javax.naming.InitialContext;


public class Consumer {

    public static void main(String[] args) throws Exception {

        InitialContext context = new InitialContext();
        ConnectionFactory factory = 
                       (ConnectionFactory) context.lookup("ConnectionFactory");

        Connection connection = factory.createConnection();
        connection.start();

        // Start the transaction
        Session session = 
                    connection.createSession(true, Session.SESSION_TRANSACTED);

        Destination destination = (Destination) context.lookup("test");
        MessageConsumer consumer = session.createConsumer(destination);

        Message message;

        try {
            // Get all messages of the queue
            while ((message = consumer.receive(3000)) != null) {
                System.out.println("Message: " + message);
            }
            // All is well - commit transaction
            session.commit();

        } catch (Exception e) {
            e.printStackTrace();
            // Something is wrong - rollback transaction
            session.rollback();
        }

        // Cleanup
        session.close();
        connection.close();
        context.close();

    }
}

This solution depends on JNDI so here is the jndi.properties also:

java.naming.factory.initial = org.apache.activemq.jndi.ActiveMQInitialContextFactory

# Use the following property to configure the default connector
java.naming.provider.url = tcp://localhost:61616

# Register some queues in JNDI using the form
# queue.[jndiName] = [physicalName]
queue.test = NIKLAS.TEST

I’m using an ActiveMQ server as JMS provider which works good with the ActiveMQ client:
pom.xml

 
       
            org.apache.activemq
            activemq-client
            5.7.0
        

Tested on Windows 10, Maven 3.8.4, Java 11.0.18 and ActiveMQ Client 5.7.0

A simple chat application with javascript and ActiveMQ using STOMP messaging

Here is a small chat program that can be used for building a rich chat application, or if you just want a very simple chat program for your friends. It contains sending and receiving STOMP messages from an Apache ActiveMQ topic.

Prerequisites:
* Apace ActiveMQ server which can be found here: https://activemq.apache.org/components/classic/download/ Usually no configuration needed. Just start the server (./activemq start) and everything should work ok
* Stomp.js. A helper script for handling the WebSocket communication between ActiveMQ and your javascript application. This script can be found here, courtesy of Jeff Mesnil and Mark Broadbent: https://github.com/jmesnil/stomp-websocket/tree/master/lib

HTML:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>A simple ActiveMQ chat application</title>
    
    <script src="stomp.js"></script>
    <script src="index.js"></script>
</head>
<body>
    <textarea id="chat" rows="10" cols="35"></textarea>
    <br />
    <input id="message" size="40" type="text">
    <br />
    <button id="send" type="button" onclick="send()">Send</button>
</body>
</html>

Javascript:

// Setup websocket connection
const client = Stomp.client("ws://localhost:61614/stomp", "v11.stomp");
// Setup header options
const headers = {id: 'JUST.FCX', ack: 'client'};

// Connect to ActiveMQ (via websocket)
client.connect("admin", "admin", function () {
    // Setup subscription of topic (/topic/chat)
    client.subscribe("/topic/chat",
        function (message) {
            const msg = message.body;
            // Add message to textarea
            document.getElementById("chat").value += msg + "\n";
            // Acknowledge the message
            message.ack();
        }, headers);
});

function send() {
    const message = document.getElementById("message");
    // Send message to topic (/topic/chat)
    client.send("/topic/chat", {}, message.value);
    // Reset input field
    message.value = "";
}

Tested on OSX 10.15.7 and Apache ActiveMQ v5.16.3