Understanding the Apache ActiveMQ Artemis Wildcard Syntax

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 delimited by the character '.' (full stop).

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

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

The character '*' means 'match a single word'.

So the wildcard 'news.europe.#' would match 'news.europe', 'news.europe.sport', 'news.europe.politics', and 'news.europe.politics.regional' but would not match 'news.usa', 'news.usa.sport' nor 'entertainment'.

The wildcard 'news.*' would match 'news.europe', but not 'news.europe.sport'.

The wildcard 'news.*.sport' would match 'news.europe.sport' and also 'news.usa.sport', but not 'news.europe.politics'.

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

The example above shows the default configuration.