activemq-artemis/examples/features/standard/topic-hierarchies

Topic Hierarchy 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.

ActiveMQ Artemis supports topic hierarchies. With a topic hierarchy you can register a subscriber with a wild-card and that subscriber will receive any messages routed to an address that match the wildcard.

ActiveMQ Artemis wild-cards can use the character # which means "match any number of words", and the character * which means "match a single word". Words are delimited by the character ..

For example if I subscribe using the wild-card news.europe.#, then that would match messages sent to the addresses news.europe, news.europe.sport and news.europe.entertainment, but it does not match messages sent to the address news.usa.wrestling.

Note that wildcard subscribers need some explicit configuration with respect to paging. The entire hierarchy needs to page to a single address such that subscribers don't race to store and account for individual messages.

Notice the address setting in broker.xml that configures matching address (the root of the hierarchy) to use the shared "news-wildcard" page store.

         <address-setting match="news.#">
            <page-store-name>news-wildcard</page-store-name>
         </address-setting>

For more information on the wild-card syntax please consult the user manual.