Decouple mqtt from iotdb-server using ExternalService framework #17042

Wei-hao-Li · 2026-01-19T11:22:44Z

No description provided.

Signed-off-by: Weihao Li <18110526956@163.com>

JackieTien97 · 2026-01-19T11:27:50Z

...anode/src/main/java/org/apache/iotdb/db/service/externalservice/BuiltinExternalServices.java

-      "org.apache.iotdb.externalservice.Mqtt",
-      // IoTDBDescriptor.getInstance().getConfig()::isEnableMQTTService
-      () -> false),
+  MQTT("MQTT", "org.apache.iotdb.mqtt.MQTTService", () -> true),


Suggested change

MQTT("MQTT", "org.apache.iotdb.mqtt.MQTTService", () -> true),

MQTT("MQTT", "org.apache.iotdb.mqtt.MQTTService", IoTDBDescriptor.getInstance().getConfig()::isEnableMQTTService),

Copilot

Pull request overview

This pull request refactors the MQTT service from a built-in component of iotdb-server to an external service using the ExternalService framework. This change improves modularity by separating MQTT functionality into its own deployable module.

Changes:

Created new external-service-impl/mqtt module with MQTT service implementation
Removed MQTT dependencies from iotdb-core/datanode module
Updated package structure from org.apache.iotdb.db.protocol.mqtt to org.apache.iotdb.mqtt
Added lifecycle management for external services in DataNode
Updated build and distribution configurations to package MQTT as a separate jar

Reviewed changes

Copilot reviewed 30 out of 31 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
pom.xml	Added external-service-impl module to the reactor build
ServiceType.java	Removed MQTT_SERVICE enum value as MQTT is now external
ExternalServiceManagementService.java	Enhanced service lifecycle management with directory creation, service restoration, and stop functionality
BuiltinExternalServices.java	Updated MQTT and REST service class names for external service framework
DataNode.java	Modified initialization to use external service framework and added service cleanup on shutdown
iotdb-core/datanode/pom.xml	Removed MQTT-related dependencies (netty-codec-mqtt, moquette-broker)
external-service-impl/pom.xml	New parent POM for external service implementations
external-service-impl/mqtt/pom.xml	New MQTT module with dependencies and jar-with-dependencies packaging
external-service-impl/mqtt/src/main/java/*/.java	Moved and refactored MQTT implementation classes to new package structure
external-service-impl/mqtt/src/test/java/*/.java	Migrated and cleaned up MQTT test classes
distribution/*.xml	Updated assembly descriptors to include MQTT jar in distributions
example/mqtt-customize/**	Updated example to reference new MQTT package structure

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Copilot · 2026-01-19T11:36:02Z

.../main/java/org/apache/iotdb/db/service/externalservice/ExternalServiceManagementService.java

+    try {
+      ExternalServiceClassLoader classLoader = new ExternalServiceClassLoader(libRoot);


The ClassLoader is no longer being closed, which could lead to a resource leak. The original code used try-with-resources to automatically close the ExternalServiceClassLoader. Removing this will prevent the file handles from being released properly. Consider either reverting to try-with-resources or explicitly closing the classLoader in a finally block.

Suggested change

try {

ExternalServiceClassLoader classLoader = new ExternalServiceClassLoader(libRoot);

try (ExternalServiceClassLoader classLoader = new ExternalServiceClassLoader(libRoot)) {

Copilot · 2026-01-19T11:36:03Z

.../main/java/org/apache/iotdb/db/service/externalservice/ExternalServiceManagementService.java

+    makDir(libRoot);
+  }
+
+  private static void makDir(String dir) {


The method name 'makDir' is misspelled. It should be 'makeDir' or 'mkDir' to follow standard naming conventions.

Suggested change

makDir(libRoot);

}

private static void makDir(String dir) {

makeDir(libRoot);

}

private static void makeDir(String dir) {

Copilot · 2026-01-19T11:36:03Z

.../main/java/org/apache/iotdb/db/service/externalservice/ExternalServiceManagementService.java

+                } finally {
+                  // set STOPPED to avoid the case: service is RUNNING, but its instance is null
+                  if (serviceInfo.getServiceInstance() == null) {
+                    serviceInfo.setState(STOPPED);
+                  }
+                }
+
+                serviceInfo.getServiceInstance().start();


There's a logic issue where serviceInstance.start() is called outside the try-finally block. If serviceInfo.getServiceInstance() is null (which is explicitly handled in the finally block by setting state to STOPPED), this will throw a NullPointerException when trying to call start() on line 344. The start() call should be inside the try block or checked for null before calling.

Suggested change

} finally {

// set STOPPED to avoid the case: service is RUNNING, but its instance is null

if (serviceInfo.getServiceInstance() == null) {

serviceInfo.setState(STOPPED);

}

}

serviceInfo.getServiceInstance().start();

if (serviceInstance != null) {

serviceInstance.start();

}

} finally {

// set STOPPED to avoid the case: service is RUNNING, but its instance is null

if (serviceInfo.getServiceInstance() == null) {

serviceInfo.setState(STOPPED);

}

}

Copilot · 2026-01-19T11:36:03Z

.../main/java/org/apache/iotdb/db/service/externalservice/ExternalServiceManagementService.java

+        .values()
+        .forEach(
+            serviceInfo -> {
+              // start services with RUNNING state


The comment says 'start services with RUNNING state' but the method actually stops services. This should be 'stop services with RUNNING state' to accurately describe what the code does.

Suggested change

// start services with RUNNING state

// stop services with RUNNING state

Copilot · 2026-01-19T11:36:04Z

...anode/src/main/java/org/apache/iotdb/db/service/externalservice/BuiltinExternalServices.java

-      "org.apache.iotdb.externalservice.Mqtt",
-      // IoTDBDescriptor.getInstance().getConfig()::isEnableMQTTService
-      () -> false),
+  MQTT("MQTT", "org.apache.iotdb.mqtt.MQTTService", () -> true),


The MQTT service is now hardcoded to always be enabled (supplier returns true), ignoring the previous configuration check for isEnableMQTTService. This changes the behavior from the commented-out line and may cause the MQTT service to start even when users have it disabled in their configuration. The configuration check should be restored or this change should be documented as an intentional behavior change.

Copilot · 2026-01-19T11:36:04Z

external-service-impl/mqtt/pom.xml

+            <groupId>com.github.moquette-io.moquette</groupId>
+            <artifactId>moquette-broker</artifactId>
+            <exclusions>
+                <!-- exclude dependencies has included by iotdb-server -->


Grammar issue in the comment: 'dependencies has included' should be 'dependencies already included' or 'dependencies that have been included'.

Suggested change

Copilot · 2026-01-19T11:36:04Z

.../main/java/org/apache/iotdb/db/service/externalservice/ExternalServiceManagementService.java

+    makDir(libRoot);
+  }
+
+  private static void makDir(String dir) {


The method name 'makDir' is misspelled. It should be 'makeDir' or 'mkDir' to follow standard naming conventions.

Suggested change

makDir(libRoot);

}

private static void makDir(String dir) {

makeDir(libRoot);

}

private static void makeDir(String dir) {

Copilot · 2026-01-19T11:36:04Z

...anode/src/main/java/org/apache/iotdb/db/service/externalservice/BuiltinExternalServices.java

  REST(
      "REST",
-      "org.apache.iotdb.externalservice.Rest",
+      "org.apache.iotdb.mqtt.RestService",


The REST service class name 'org.apache.iotdb.mqtt.RestService' appears to be incorrectly placed in the mqtt package. REST service should have its own package structure, not be part of the MQTT package. This is misleading and violates package organization principles.

Suggested change

"org.apache.iotdb.mqtt.RestService",

"org.apache.iotdb.rest.RestService",

Signed-off-by: Weihao Li <18110526956@163.com>

external-service-impl/pom.xml

Signed-off-by: Weihao Li <18110526956@163.com>

Wei-hao-Li added 6 commits January 16, 2026 11:17

draft

d2f1c12

Signed-off-by: Weihao Li <18110526956@163.com>

draft

5a88310

Signed-off-by: Weihao Li <18110526956@163.com>

add file put

9175879

Signed-off-by: Weihao Li <18110526956@163.com>

fix some

a52aa84

Signed-off-by: Weihao Li <18110526956@163.com>

fix some

6f82027

Signed-off-by: Weihao Li <18110526956@163.com>

Merge branch 'master' of github.com:apache/iotdb into splitMqtt

2c44fc2

JackieTien97 requested a review from Copilot January 19, 2026 11:26

Copilot started reviewing on behalf of JackieTien97 January 19, 2026 11:27 View session

JackieTien97 requested changes Jan 19, 2026

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Copilot AI reviewed Jan 19, 2026

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Wei-hao-Li added 7 commits January 19, 2026 20:21

fix some

d9bd1ea

Signed-off-by: Weihao Li <18110526956@163.com>

modify CI profile to location error

c3216dc

Signed-off-by: Weihao Li <18110526956@163.com>

fix some

e1b2a51

Signed-off-by: Weihao Li <18110526956@163.com>

fix some

2c6a207

Signed-off-by: Weihao Li <18110526956@163.com>

fix some

98ce9a6

Signed-off-by: Weihao Li <18110526956@163.com>

change path

db24596

Signed-off-by: Weihao Li <18110526956@163.com>

change path

162b47e

Signed-off-by: Weihao Li <18110526956@163.com>

HTHou reviewed Jan 20, 2026

View reviewed changes

external-service-impl/pom.xml Outdated Show resolved Hide resolved

fix

ab25b3e

Signed-off-by: Weihao Li <18110526956@163.com>

Wei-hao-Li changed the title ~~Split mqtt from iotdb-server by using ExternalService framework~~ Decouple mqtt from iotdb-server using ExternalService framework Jan 20, 2026

add transmitted dependencies declaration

cefeba4

Signed-off-by: Weihao Li <18110526956@163.com>

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Decouple mqtt from iotdb-server using ExternalService framework #17042

Decouple mqtt from iotdb-server using ExternalService framework #17042

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	MQTT("MQTT", "org.apache.iotdb.mqtt.MQTTService", () -> true),
	MQTT("MQTT", "org.apache.iotdb.mqtt.MQTTService", IoTDBDescriptor.getInstance().getConfig()::isEnableMQTTService),

		try {
		ExternalServiceClassLoader classLoader = new ExternalServiceClassLoader(libRoot);

	try {
	ExternalServiceClassLoader classLoader = new ExternalServiceClassLoader(libRoot);
	try (ExternalServiceClassLoader classLoader = new ExternalServiceClassLoader(libRoot)) {

	// start services with RUNNING state
	// stop services with RUNNING state

	<!-- exclude dependencies has included by iotdb-server -->
	<!-- exclude dependencies already included by iotdb-server -->

	"org.apache.iotdb.mqtt.RestService",
	"org.apache.iotdb.rest.RestService",

Decouple mqtt from iotdb-server using ExternalService framework #17042

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Decouple mqtt from iotdb-server using ExternalService framework #17042

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