Apache ActiveMQ Artemis uses a specific syntax for representing wildcards in security settings, address settings and when creating consumers.

The syntax is similar to that used by AMQP.

An Apache ActiveMQ Artemis wildcard expression contains words separated by a delimiter. The default delimiter is . (full stop).

The special characters # and * also have special meaning and can take the place of a word.

To be clear, the wildcard characters cannot be used like wildcards in a regular expression. They operate exclusively on words separated by a delimiter.

1. Matching Any Word

The character # means “match any sequence of zero or more words”.

So the wildcard news.europe.# would match:

• news.europe

• news.europe.sport

• news.europe.politics

• news.europe.politics.regional

But news.europe.# would not match:

• news.usa

• news.usa.sport

• entertainment

2. Matching a Single Word

The character * means “match a single word”.

The wildcard news.* would match:

• news.europe

• news.usa

But news.* would not match:

• news.europe.sport

• news.usa.sport

• news.europe.politics.regional

The wildcard news.*.sport would match:

• news.europe.sport

• news.usa.sport

But news.*.sport would not match:

• news.europe.politics

3. Customizing the Syntax

It’s possible to further configure the syntax of the wildcard addresses using the broker configuration. For that, the <wildcard-addresses> configuration tag is used.

<wildcard-addresses>
   <routing-enabled>true</routing-enabled>
   <delimiter>.</delimiter>
   <any-words>#</any-words>
   <single-word>*</single-word>
</wildcard-addresses>

The example above shows the default configuration.