From acea64790be45101ec8c70dbcc583721d914023b Mon Sep 17 00:00:00 2001
From: JianBo He <heeejianbo@gmail.com>
Date: Tue, 18 Apr 2023 17:00:37 +0800
Subject: [PATCH] chore: add README for emqx_modoules

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 apps/emqx_modules/README.md | 54 +++++++++++++++++++++++++++++++++++++
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 create mode 100644 apps/emqx_modules/README.md

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+# EMQX Modules
+
+The application provide some minor functional modules that are not included in the MQTT
+protocol standard, including "Delayed Publish", "Topic Rewrite", "Topic Metrics" and "Telemetry".
+
+
+## Delayed Publish
+
+After enabling this module, messages sent by the user with the prefix
+`$delayed/{Interval}/{Topic}` will be delayed by `{Interval}` seconds before
+being published to the `{Topic}`.
+
+More introduction about [Delayed Publish](https://www.emqx.io/docs/en/v5.0/mqtt/mqtt-delayed-publish.html).
+
+See [Enabling/Disabling Delayed Publish via HTTP API](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/MQTT/paths/~1mqtt~1delayed/put).
+
+
+## Topic Rewrite
+
+Topic Rewrite allows users to configure rules to change the topic strings that
+the client requests to subscribe or publish.
+
+This feature is very useful when designing topics that are compatible with different
+client versions. For example, an old device that has already been issued and cannot
+be upgraded may use old topic rules, but the production environment need to apply
+a new design rules for the topics.
+
+More introduction about [Topic Rewrite](https://www.emqx.io/docs/en/v5.0/mqtt/mqtt-topic-rewrite.html).
+
+See [List all rewrite rules](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/MQTT/paths/~1mqtt~1topic_rewrite/get)
+and [Create or Update rewrite rules](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/MQTT/paths/~1mqtt~1topic_rewrite/put).
+
+
+## Topic Metrics
+
+Topic Metrics is used for users to specify monitoring of certain topics and to
+count the number of messages, QoS distribution, and rate for all messages on that topic.
+
+More introduction about [Topic Metrics](https://www.emqx.io/docs/en/v5.0/dashboard/diagnose.html#topic-metrics).
+
+See HTTP API docs to [List all monitored topics](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/MQTT/paths/~1mqtt~1topic_metrics/get),
+[Create topic metrics](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/MQTT/paths/~1mqtt~1topic_metrics/post)
+and [Get the monitored result](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/MQTT/paths/~1mqtt~1topic_metrics~1%7Btopic%7D/get).
+
+
+## Telemetry
+
+Telemetry is used for collecting non-sensitive information about the EMQX cluster.
+
+More introduction about [Telemetry](https://www.emqx.io/docs/en/v5.0/telemetry/telemetry.html#telemetry).
+
+See HTTP API docs to [Enable/Disable telemetry](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/Telemetry/paths/~1telemetry~1status/put),
+[Get the enabled status](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/Telemetry/paths/~1telemetry~1status/get)
+and [Get the data of the module collected](https://www.emqx.io/docs/en/v5.0/admin/api-docs.html#tag/Telemetry/paths/~1telemetry~1data/get).