Apache ActiveMQ (now referred to as "Classic") and ActiveMQ Artemis represent two generations of message brokers with fundamentally different architectures. While Artemis began as a subproject to eventually replace Classic, both now coexist with independent release cycles due to enterprise adoption patterns.

// Classic ActiveMQ (5.x)                      | // Artemis (2.x+)
Broker broker = new BrokerService();           | ServerLocator locator = ActiveMQClient
broker.addConnector("tcp://localhost:61616");  |    .createServerLocator("tcp://localhost:61616");
broker.start();                                | ClientSessionFactory factory = locator.createSessionFactory();
                                               | ClientSession session = factory.createSession();

Artemis demonstrates 10x higher throughput in persistent messaging scenarios due to:

• Journal-based storage (vs Classic's KahaDB)
• Lock-free threading model
• Zero-copy message buffering

// JMS 2.0 Delivery Delay (Artemis only)
MessageProducer producer = session.createProducer(destination);
producer.setDeliveryDelay(5000); // 5-second delay

// JMS 2.0 Async Send (Both support)
producer.sendAsync(message, new CompletionListener() {
    @Override
    public void onCompletion(Message message) {
        System.out.println("Message confirmed");
    }
});

Key factors when choosing:

# Artemis broker.xml snippet
<addresses>
    <address name="orders">
        <multicast>
            <queue name="fulfillment"/>
            <queue name="billing"/>
        </multicast>
    </address>
</addresses>

# vs Classic activemq.xml
<destinationInterceptors>
    <virtualDestinationInterceptor>
        <virtualDestinations>
            <compositeQueue name="orders">
                <forwardTo>
                    <queue physicalName="fulfillment"/>
                    <queue physicalName="billing"/>
                </forwardTo>
            </compositeQueue>
        </virtualDestinations>
    </virtualDestinationInterceptor>
</destinationInterceptors>

Artemis introduces:

// Artemis Metrics via Jolokia
curl http://localhost:8161/console/jolokia/read/org.apache.activemq.artemis:broker=\"0.0.0.0\"/MessageCount

// Classic JMX
ObjectName name = new ObjectName("org.apache.activemq:BrokerName=localhost,Type=Broker");
MBeanServerConnection conn = ManagementFactory.getPlatformMBeanServer();
conn.getAttribute(name, "TotalMessageCount");

Artemis simplifies scaling:

<cluster-connections>
    <cluster-connection name="my-cluster">
        <connector-ref>netty-connector</connector-ref>
        <retry-interval>500</retry-interval>
        <use-duplicate-detection>true</use-duplicate-detection>
        <static-connectors>
            <connector-ref>server1-connector</connector-ref>
        </static-connectors>
    </cluster-connection>
</cluster-connections>

The Apache ActiveMQ ecosystem currently exists in two parallel implementations:

• ActiveMQ "Classic" (v5.x): The original implementation with 15+ years of production history
• ActiveMQ Artemis (v2.x): A high-performance rewrite based on HornetQ codebase

// Classic ActiveMQ connection factory
ConnectionFactory factory = new ActiveMQConnectionFactory("tcp://localhost:61616");

// Artemis connection factory
ConnectionFactory factory = new ActiveMQConnectionFactory(
    "tcp://localhost:61616",
    "admin",
    "password");

Key technical distinctions:

Artemis demonstrates significant improvements in:

• Message throughput (2-5x higher in our tests)
• Lower latency (especially under heavy load)
• More efficient memory usage

// Artemis address configuration example
<address name="orders.queue">
    <anycast>
        <queue name="orders"/>
    </anycast>
</address>

When moving from Classic to Artemis:

1. Review protocol compatibility (OpenWire vs Core Protocol)
2. Adapt configuration files (artemis.xml vs activemq.xml)
3. Test client connection patterns
4. Verify persistence migration tools

For new deployments:

• Choose Artemis if you need JMS 2.0, higher performance, or plan for long-term support
• Consider Classic only for legacy system compatibility

The Apache Foundation has stated that Artemis will eventually replace Classic, though no official EOL date exists for Classic yet.