Spring MqttPahoMessageDrivenChannelAdapter丢失连接：连接丢失;重试 [英] Spring MqttPahoMessageDrivenChannelAdapter Lost connection:Connection lost; retrying

问题描述

我们正在使用 Spring message-driven-channel-adapter 来订阅 MQTT 主题。但是我们经常遇到错误。我已使用JavaScript客户端（ mqttws31.js ）测试了连接，该工作正常。意味着连接没有问题。

We are using Spring message-driven-channel-adapter to subscribe MQTT topic. But we are getting below error very frequently. I have tested connection using JavaScript client(mqttws31.js), which is working fine. Means there is no issue with connection.

错误： -

org.springframework.integration.mqtt.inbound.MqttPahoMessageDrivenChannelAdapter connectionLost
SEVERE: Lost connection:Connection lost; retrying...

MQTT消息： -

[payload=6483D03E4C75BA943148F18D73,1.00,1E, headers={mqtt_retained=false, mqtt_qos=0, 
id=5fa41168-34c6-1e3d-a775-e3146842990a, mqtt_topic=TEST/GATEWAY2, mqtt_duplicate=false, timestamp=1499067757559}]

配置： -

<bean id="clientFactory"
    class="org.springframework.integration.mqtt.core.DefaultMqttPahoClientFactory">
    <property name="userName" value="${mqtt.username}" />
    <property name="password" value="${mqtt.password}" />
</bean>

<int-mqtt:message-driven-channel-adapter
    id="mqttInbound" client-id="${mqtt.default.client.id}" url="${mqtt.url}"
    topics="${topics}" client-factory="clientFactory" auto-startup="true"
    channel="output" error-channel="errorChannel" />


<int:channel id="output" />
<int:channel id="errorChannel" />

<int:service-activator input-channel="errorChannel"
    ref="errorMessageLogger" method="logError" />
<bean id="errorMessageLogger" class="com.mqtt.ErrorMessageLogger" />

<int:service-activator input-channel="output"
    method="handleMessage" ref="mqttLogger" />
<bean id="mqttLogger" class="com.mqtt.MqttReciever" />

pom.xml：

<dependency>
    <groupId>org.eclipse.paho</groupId>
    <artifactId>org.eclipse.paho.client.mqttv3</artifactId>
    <version>1.1.1</version>
</dependency>
<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-mqtt</artifactId>
    <version>4.2.2.RELEASE</version>
</dependency>

调试 org.eclipse.paho.client.mqttv3-1.1.1 -sources.jar ： -

CommsReceiver.Java

public void run() {
        final String methodName = "run";
        MqttToken token = null;

        while (running && (in != null)) {
            try {
                //@TRACE 852=network read message
                log.fine(CLASS_NAME,methodName,"852");
                receiving = in.available() > 0;
                MqttWireMessage message = in.readMqttWireMessage();
                receiving = false;

                // instanceof checks if message is null
                if (message instanceof MqttAck) {
                    token = tokenStore.getToken(message);
                    if (token!=null) {
                        synchronized (token) {
                            // Ensure the notify processing is done under a lock on the token
                            // This ensures that the send processing can complete  before the
                            // receive processing starts! ( request and ack and ack processing
                            // can occur before request processing is complete if not!
                            clientState.notifyReceivedAck((MqttAck)message);
                        }
                    } else if(message instanceof MqttPubRec || message instanceof MqttPubComp || message instanceof MqttPubAck) {
                        //This is an ack for a message we no longer have a ticket for.
                        //This probably means we already received this message and it's being send again
                        //because of timeouts, crashes, disconnects, restarts etc.
                        //It should be safe to ignore these unexpected messages.
                        log.fine(CLASS_NAME, methodName, "857");
                    } else {
                        // It its an ack and there is no token then something is not right.
                        // An ack should always have a token assoicated with it.
                        throw new MqttException(MqttException.REASON_CODE_UNEXPECTED_ERROR);
                    }
                } else {
                    if (message != null) {
                        // A new message has arrived
                        clientState.notifyReceivedMsg(message);
                    }
                }
            }
            catch (MqttException ex) {
                //@TRACE 856=Stopping, MQttException
                log.fine(CLASS_NAME,methodName,"856",null,ex);
                running = false;
                // Token maybe null but that is handled in shutdown
                clientComms.shutdownConnection(token, ex);
            }
            catch (IOException ioe) {
                //@TRACE 853=Stopping due to IOException
                log.fine(CLASS_NAME,methodName,"853");

                running = false;
                // An EOFException could be raised if the broker processes the
                // DISCONNECT and ends the socket before we complete. As such,
                // only shutdown the connection if we're not already shutting down.
                if (!clientComms.isDisconnecting()) {
                    clientComms.shutdownConnection(token, new MqttException(MqttException.REASON_CODE_CONNECTION_LOST, ioe));
                }
            }
            finally {
                receiving = false;
            }
        }

        //@TRACE 854=<
        log.fine(CLASS_NAME,methodName,"854");
    }

在上述方法中，有时 in.readMqttWireMessage（） throw IOException 。因此，基于catch块，它使用 clientComms.shutdownConnection（令牌，...

In above method, sometime in.readMqttWireMessage() throw IOException. So based on catch block it reconnect using clientComms.shutdownConnection(token, ...

推荐答案

只是想分享以防万一...
我有同样的例外并通过确保生成一个唯一的客户端ID来修复它（使用 MqttAsyncClient.generateClientId（）），如下所述：
https://github.com/eclipse/paho.mqtt.java/issues/207#issuecomment-338246879

Just wanted to share in case it helps... I had the same exception and fixed it by ensuring a unique client ID was generated (with MqttAsyncClient.generateClientId()), as mentioned here: https://github.com/eclipse/paho.mqtt.java/issues/207#issuecomment-338246879

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