Message Group Example

If you have not already done so, prepare the broker distribution before running the example.

To run the example, simply type mvn verify from this directory, or mvn -PnoServer verify if you want to start and create the broker manually.

This example shows you how to configure and use message groups via a connection factory with ActiveMQ Artemis.

Message groups are sets of messages that has the following characteristics:

• Messages in a message group share the same group id, i.e. they have same JMSXGroupID string property values.
• Messages in a message group will be all delivered to no more than one of the queue's consumers. The consumer that receives the first message of a group will receive all the messages that belongs to the group.

You can make any message belong to a message group by setting a ‘group-id’ on the connection factory. All producers created via this connection factory will set that group id on its messages. In this example we set the group id ‘Group-0’on a connection factory and send messages via 2 different producers and check that only 1 consumer receives them.

Alternatively, ActiveMQ‘s connection factories can be configured to auto group messages. By setting autoGroup=true in the client’s URL a random unique id will be picked to create a message group. Every messages sent by a producer created from this connection factory will automatically be part of this message group.