Chapter 16. Configuring a multi-site, fault-tolerant messaging system using broker connections

Procedure

1. Create a broker-connections element in the broker.xml file for the first broker, for example:

   <broker-connections>
     <amqp-connection uri="tcp://<hostname>:<port>" name="DC1">
       <mirror/>
     </amqp-connection>
   </broker-connections>

   <hostname>

   The hostname of the other broker instance.

   <port>

   The port used by the broker on the other host.

   All messages on the first broker are mirrored to the second broker, but messages that existed before the mirror was created are not mirrored.

2. If you want the first broker to mirror messages synchronously to ensure that the mirrored broker is up-to-date for disaster recovery, set the sync=true attribute in the amqp-connection element of the broker, as shown in the following example.

   Synchronous mirroring requires that messages sent by a broker to a mirrored broker are written to the volumes of both brokers at the same time. Once the write operation is complete on both brokers, the source broker acknowledges that the write request is complete and control is returned to clients.

   <broker-connections>
     <amqp-connection uri="tcp://<hostname>:<port>" name="DC2">
       <mirror sync="true"/>
     </amqp-connection>
   </broker-connections>

   Note

   If the write request cannot be completed on the mirrored broker, for example, if the broker is unavailable, client connections are blocked until a mirror is available to complete the most recent write request.

   You can also configure the following additional features:

   • queue-removal: Specifies whether a queue- or address-removal event is sent. The default value is true.
   • message-acknowledgments: Specifies whether message acknowledgments are sent. The default value is true.
   • queue-creation: Specifies whether a queue- or address-creation event is sent. The default value is true.
   Note

   The broker connections name in the example, DC1, is used to create a queue named $ACTIVEMQ_ARTEMIS_MIRROR_mirror. Make sure that the corresponding broker is configured to accept those messages, even though the queue is not visible on that broker.

3. Create a broker-connections element in the broker.xml file for the second broker, for example:

   <broker-connections>
     <amqp-connection uri="tcp://<hostname>:<port>" name="DC2">
       <mirror/>
     </amqp-connection>
   </broker-connections>

4. If you want the second broker to mirror messages synchronously, set the sync=true attribute in the amqp-connection element of the broker. For example:

   <broker-connections>
     <amqp-connection uri="tcp://<hostname>:<port>" name="DC2">
       <mirror sync="true"/>
     </amqp-connection>
   </broker-connections>

5. Configure clients using the instructions documented in Section 15.6, “Configuring clients in a multi-site, fault-tolerant messaging system”, noting that with broker connections, there is no shared storage.