MQTT Topic Filter Support #2690
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added 2 commits
July 1, 2025 10:05
Adds support (parsing, validation, conflict-checking) for traits to reference MQTT topic filters, which allow single-level and multi-level wildcard expressions. Further information about topics and topic filters can be found in MQTT specification docs: https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901241 Fixes a bug where the topic parser incorrectly skip a trailing or preceding empty topic level.
sugmanue
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Jul 8, 2025
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| // Note: I disagree with the above assertion and what it implies for the definition (which is not | ||
| // given anywhere) of "topic conflict." My definition of "topic conflict" is "could potentially have | ||
| // a non-empty routing intersection." | ||
| // | ||
| // In particular, the above check can lead to a non-empty intersection if the label substitution | ||
| // yields a value that matches the non-label level's value. | ||
| // | ||
| // Despite this, I don't want to change the behavior of what currently exists. |
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Can you please move this note to an issue instead? Having it here is confusing and difficult to find to improve whatever the current situation is.
| @@ -21,32 +21,73 @@ | |||
| public final class Topic { | |||
| private static final Pattern LABEL_PATTERN = Pattern.compile("^[a-zA-Z0-9_]+$"); | |||
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| private final TopicRule rule; | |||
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The rule is only used for parsing. This field is never used, let's remove it.
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Background
Adds support (parsing, validation, conflict-checking) for traits to reference MQTT topic filters. Topic filter support is required for the new request-response MQTT service clients being released by the IoT SDKs.
Fixes a bug where the topic parser incorrectly skips a trailing or preceding empty topic level.
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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.