thingsboard使用MQTT遥测数据理解

跳过建立连接阶段：

1、加载MqttTransportService服务类

2、MqttTransportServerInitializer对MqttTransportService初始化

3、MqttTransportHandler描述怎么处理

4、传入消息类型是遥测数据，执行processPublish(ctx, (MqttPublishMessage) msg);

5、根据设备上报的数据类型，执行对应的方法。这里传入的是遥测数据，执行第一个process方法。

 private void processDevicePublish(ChannelHandlerContext ctx, MqttPublishMessage mqttMsg, String topicName, int msgId) {
        try {
            if (topicName.equals(MqttTopics.DEVICE_TELEMETRY_TOPIC)) {
                TransportProtos.PostTelemetryMsg postTelemetryMsg = adaptor.convertToPostTelemetry(deviceSessionCtx, mqttMsg);
                transportService.process(sessionInfo, postTelemetryMsg, getPubAckCallback(ctx, msgId, postTelemetryMsg));
            } else if (topicName.equals(MqttTopics.DEVICE_ATTRIBUTES_TOPIC)) {
                TransportProtos.PostAttributeMsg postAttributeMsg = adaptor.convertToPostAttributes(deviceSessionCtx, mqttMsg);
                transportService.process(sessionInfo, postAttributeMsg, getPubAckCallback(ctx, msgId, postAttributeMsg));
            } else if (topicName.startsWith(MqttTopics.DEVICE_ATTRIBUTES_REQUEST_TOPIC_PREFIX)) {
                TransportProtos.GetAttributeRequestMsg getAttributeMsg = adaptor.convertToGetAttributes(deviceSessionCtx, mqttMsg);
                transportService.process(sessionInfo, getAttributeMsg, getPubAckCallback(ctx, msgId, getAttributeMsg));
            } else if (topicName.startsWith(MqttTopics.DEVICE_RPC_RESPONSE_TOPIC)) {
                TransportProtos.ToDeviceRpcResponseMsg rpcResponseMsg = adaptor.convertToDeviceRpcResponse(deviceSessionCtx, mqttMsg);
                transportService.process(sessionInfo, rpcResponseMsg, getPubAckCallback(ctx, msgId, rpcResponseMsg));
            } else if (topicName.startsWith(MqttTopics.DEVICE_RPC_REQUESTS_TOPIC)) {
                TransportProtos.ToServerRpcRequestMsg rpcRequestMsg = adaptor.convertToServerRpcRequest(deviceSessionCtx, mqttMsg);
                transportService.process(sessionInfo, rpcRequestMsg, getPubAckCallback(ctx, msgId, rpcRequestMsg));
            } else if (topicName.equals(MqttTopics.DEVICE_CLAIM_TOPIC)) {
                TransportProtos.ClaimDeviceMsg claimDeviceMsg = adaptor.convertToClaimDevice(deviceSessionCtx, mqttMsg);
                transportService.process(sessionInfo, claimDeviceMsg, getPubAckCallback(ctx, msgId, claimDeviceMsg));
            } else {
                transportService.reportActivity(sessionInfo);
            }
        } catch (AdaptorException e) {
            log.warn("[{}] Failed to process publish msg [{}][{}]", sessionId, topicName, msgId, e);
            log.info("[{}] Closing current session due to invalid publish msg [{}][{}]", sessionId, topicName, msgId);
            ctx.close();
        }
    }

5、process是TransportService中的方法，这里我们使用断点调试可以看到这里使用TransportService接口的实现类时DefaultTransportService

6、查看DefaultTransportService的process方法

 @Override
    public void process(TransportProtos.SessionInfoProto sessionInfo, TransportProtos.PostTelemetryMsg msg, TransportServiceCallback<Void> callback) {
        if (checkLimits(sessionInfo, msg, callback)) {
            reportActivityInternal(sessionInfo);
            TenantId tenantId = new TenantId(new UUID(sessionInfo.getTenantIdMSB(), sessionInfo.getTenantIdLSB()));
            DeviceId deviceId = new DeviceId(new UUID(sessionInfo.getDeviceIdMSB(), sessionInfo.getDeviceIdLSB()));
            MsgPackCallback packCallback = new MsgPackCallback(msg.getTsKvListCount(), callback);
            for (TransportProtos.TsKvListProto tsKv : msg.getTsKvListList()) {
                TbMsgMetaData metaData = new TbMsgMetaData();
                metaData.putValue("deviceName", sessionInfo.getDeviceName());
                metaData.putValue("deviceType", sessionInfo.getDeviceType());
                metaData.putValue("ts", tsKv.getTs() + "");
                JsonObject json = JsonUtils.getJsonObject(tsKv.getKvList());
                TbMsg tbMsg = TbMsg.newMsg(SessionMsgType.POST_TELEMETRY_REQUEST.name(), deviceId, metaData, gson.toJson(json));
                sendToRuleEngine(tenantId, tbMsg, packCallback);
            }
        }
    }

7、执行完process方法，调用sendToRuleEngine方法将消息传入规则引擎。

 protected void sendToRuleEngine(TenantId tenantId, TbMsg tbMsg, TbQueueCallback callback) {
        TopicPartitionInfo tpi = partitionService.resolve(ServiceType.TB_RULE_ENGINE, tenantId, tbMsg.getOriginator());
        if (log.isTraceEnabled()) {
            log.trace("[{}][{}] Pushing to topic {} message {}", tenantId, tbMsg.getOriginator(), tpi.getFullTopicName(), tbMsg);
        }
        ToRuleEngineMsg msg = ToRuleEngineMsg.newBuilder().setTbMsg(TbMsg.toByteString(tbMsg))
                .setTenantIdMSB(tenantId.getId().getMostSignificantBits())
                .setTenantIdLSB(tenantId.getId().getLeastSignificantBits()).build();
        ruleEngineMsgProducer.send(tpi, new TbProtoQueueMsg<>(tbMsg.getId(), msg), callback);
    }

这个send方法是TbQueueProducer> 接口中的，这里使用断点调试可以看到实现类为InMemoryTbQueueProducer。send方法详情如下：

public void send(TopicPartitionInfo tpi, T msg, TbQueueCallback callback) {
        boolean result = storage.put(tpi.getFullTopicName(), msg);
        if (result) {
            if (callback != null) {
                callback.onSuccess(null);
            }
        } else {
            if (callback != null) {
                callback.onFailure(new RuntimeException("Failure add msg to InMemoryQueue"));
            }
        }
    }

这里的storage来自于private final InMemoryStorage storage = InMemoryStorage.getInstance();进一步分析可以看到：
未完待续……