Topic Wildcard Subscription
When the * and > characters are used in topic subscriptions, they function as wildcards, which affect the topic matches that may occur.
About *:
- A * by itself at a level within a subscription topic (as in, animals/*/cats, or animals/domestic/*) indicates a wildcard match at that level
- When * is preceded by a topic prefix at a level within a subscription topic (as in, animals/red*/wild) indicates a 'prefix and 0 or more” match at that level
- The * may be used at multiple levels within a subscription topic, with or without topic prefixes (as in, animals/*/cats/*)
- Use of * in an arbitrary location within a level, and not covered by the previous rules, supports general sub-string matching.
About >:
- When > appears by itself at the last level of a subscription topic (as in, animals/domestic/>) provides a “one or more” wildcard match for any topics with an identical prefix to the subscription
- A > that appears anywhere else other than by itself at the last level of a subscription topic (as in animals> and animals/domestic>) in the string is treated as the > character rather than a wildcard
- The > and * characters may be used together within a subscription topic (example animals/*/cats/> )
About *:
- A * by itself at a level within a subscription topic (as in, animals/*/cats, or animals/domestic/*) indicates a wildcard match at that level
- When * is preceded by a topic prefix at a level within a subscription topic (as in, animals/red*/wild) indicates a 'prefix and 0 or more” match at that level
- The * may be used at multiple levels within a subscription topic, with or without topic prefixes (as in, animals/*/cats/*)
- Use of * in an arbitrary location within a level, and not covered by the previous rules, supports general sub-string matching.
About >:
- When > appears by itself at the last level of a subscription topic (as in, animals/domestic/>) provides a “one or more” wildcard match for any topics with an identical prefix to the subscription
- A > that appears anywhere else other than by itself at the last level of a subscription topic (as in animals> and animals/domestic>) in the string is treated as the > character rather than a wildcard
- The > and * characters may be used together within a subscription topic (example animals/*/cats/> )