Chapter 7. Network Connections: Protocols

Unlike JMS, the AMQP protocol does not include topics. However, it is still possible to treat AMQP consumers or receivers as subscriptions rather than just consumers on a queue. By default, any receiving link that attaches to an address with the prefix jms.topic. is treated as a subscription, and a subscription queue is created. The subscription queue is made durable or volatile, depending on how the Terminus Durability is configured, as captured in the following table:

AMQ Broker also supports the qpid-jms client and will respect its use of topics regardless of the prefix used for the address.

The broker supports AMQP SASL Authentication. See Security for more information about how to configure SASL-based authentication on the broker.

When using STOMP, the following limitations apply:

When receiving STOMP messages through a JMS consumer or a QueueBrowser, the messages do not contain any JMS properties, for example JMSMessageID, by default. However, you can set a message ID on each incoming STOMP message by using a broker paramater.

<acceptors>
  <acceptor name="stomp-acceptor">tcp://localhost:61613?protocols=STOMP;stompEnableMessageId=true</acceptor>
  ...
</acceptors>

By using the stompEnableMessageId parameter, each stomp message sent using this acceptor has an extra property added. The property key is amq-message-id and the value is a String representation of an internal message id prefixed with “STOMP”, as shown in the following example:

amq-message-id : STOMP12345

If stompEnableMessageId is not specified in the configuration, the default value is false.

STOMP clients must send a DISCONNECT frame before closing their connections. This allows the broker to close any server-side resources, such as sessions and consumers. However, if STOMP clients exit without sending a DISCONNECT frame, or if they fail, the broker will have no way of knowing immediately whether the client is still alive. STOMP connections therefore are configured to have a "Time to Live" (TTL) of 1 minute. The means that the broker stops the connection to the STOMP client if it has been idle for more than one minute.

<acceptors>
  <acceptor name="stomp-acceptor">tcp://localhost:61613?protocols=STOMP;connectionTtl=20000</acceptor>
  ...
</acceptors>

In the preceding example, any stomp connection that using the stomp-acceptor will have its TTL set to 20 seconds.

Overriding the Broker’s Default Time to Live (TTL)

As noted, the default TTL for a STOMP connection is one minute. You can override this value by adding the connection-ttl-override attribute to the broker configuration.

<configuration ...>
  ...
  <core ...>
    ...
    <connection-ttl-override>30000</connection-ttl-override>
    ...
  </core>
<configuration>

In the preceding example, the default Time to Live (TTL) for a STOMP connection is set to 30 seconds, 30000 milliseconds.

STOMP is mainly a text-orientated protocol. To make it simpler to interoperate with JMS, the STOMP implementation checks for presence of the content-length header to decide how to map a STOMP message to JMS.

The same logic applies when mapping a JMS message to STOMP. A STOMP client can confirm the presence of the content-length header to determine the type of the message body (string or bytes).

See the STOMP specification for more information about message headers.

When sending messages and subscribing, STOMP clients typically include a destination header. Destination names are string values, which are mapped to a destination on the broker. In AMQ Broker, these destinations are mapped to addresses and queues. See the STOMP specification for more information about the destination frame.

Take for example a STOMP client that sends the following message (headers and body included):

SEND
destination:/my/stomp/queue

hello queue a
^@

In this case, the broker will forward the message to any queues associated with the address /my/stomp/queue.

For example, when a STOMP client sends a message (by using a SEND frame), the specified destination is mapped to an address.

It works the same way when the client sends a SUBSCRIBE or UNSUBSCRIBE frame, but in this case AMQ Broker maps the destination to a queue.

SUBSCRIBE
destination: /other/stomp/queue
ack: client

^@

In the preceding example, the broker will map the destination to the queue /other/stomp/queue.

Mapping STOMP Destinations to JMS Destinations

JMS destinations are also mapped to broker addresses and queues. If you want to use STOMP to send messages to JMS destinations, the STOMP destinations must follow the same convention: