1、Introduction

The AECC Cloud Platform provides a cloud-side data forwarding channel so that third-party platforms can synchronize inverter device data. This document mainly introduces the data forwarding method and the data parsing format.

MQTT —— a lightweight message transport protocol based on a client/server publish/subscribe model.

JSON —— a lightweight data interchange format.

The content described in this document may differ slightly from actual usage due to version updates. We update this document periodically; if you encounter any problems during use, please contact us.

2、System Framework Diagram

3、Data Message Service Description

Data Message Service (DMS) is an MQTT server built by the AECC Cloud Platform; it is an efficient, reliable, secure and convenient messaging service. DMS helps application developers quickly integrate messaging capabilities into their applications and easily achieve reliable forwarding and synchronization of device data.

The third-party platform must establish a connection with the server via an MQTT client and subscribe to the corresponding topic. The required url, topic, client id, username and password are provided by the AECC Cloud Platform.

The platform assigns push topics based on the third-party account. After the third-party account and device are bound on the open platform, device data is pushed to the corresponding topic. The topic rules are as follows:

1. The topic is prefixed with SUB/, for example: SUB/{deviceType}/0;
2. A single account can be configured with multiple topics, separated by English commas; when pushing, the platform automatically matches the corresponding topic by device type (deviceType);
3. Topics are uniformly allocated by the AECC Cloud Platform and cannot be modified by third parties;
4. MQTT shared subscriptions are supported: when subscribing to $share/{consumerGroupName}/{topic}, clients within the same consumer group receive messages in a round-robin fashion (each message is delivered to only one client in the group), while different consumer groups each receive the full message stream.

The example connects to the server through the MQTTX client; the specific connection information needs to be obtained by contacting the AECC Cloud Platform.

1. Create a new connection, fill Host with the address and port provided by the platform, and fill Client ID with the mqttId assigned by the platform;
2. Check User Credentials, fill Username with keyId and Password with keySecret;
3. After connecting successfully via Connect, subscribe to the topic assigned by the platform (for multi-instance load balancing use $share/{consumerGroupName}/{topic});
4. After binding the device on the platform and waiting for the device to report, you can view the pushed JSON data in the subscription window.

String broker  = "tcp://<url>:8091";
String clientId = "<mqttId>";
MqttClient client = new MqttClient(broker, clientId, new MemoryPersistence());
MqttConnectOptions options = new MqttConnectOptions();
options.setUserName("<keyId>");
options.setPassword("<keySecret>".toCharArray());
options.setKeepAliveInterval(60);
options.setCleanSession(true);
client.setCallback(new MqttCallbackExtended() {
    @Override
    public void messageArrived(String topic, MqttMessage message) {
        String json = new String(message.getPayload(), StandardCharsets.UTF_8);
        // To process push data, it is recommended to use msgId for idempotent deduplication
    }
    // Implement other callbacks as needed: connectionLost / deliveryComplete / connectComplete
});
client.connect(options);
client.subscribe("<topic>", 1);

4、Data Forwarding Model

data is the data entity; different transmission types (type) correspond to different field structures. The fields below are based on the open-platform generic data model (inverter / energy-storage devices); fields may differ across device types — refer to the actual device report for the authoritative field set.

1. Push QoS is 1 (at least once); duplicate messages may be received on network jitter — idempotent dedup by msgId is recommended;
2. Push frequency is consistent with the device report period (commonly 1 to 15 minutes, depending on device model and configuration);
3. type=1 device rated data is transmitted once after the device powers on; type=2 device monitoring data is pushed continuously at the report interval;
4. data.faultCodeStr is the set of device fault codes (multiple fault codes separated by English commas); for the meaning of specific fault codes, please contact AECC Cloud for the mapping table;
5. After a third-party service reconnects (Clean Session=true), it must re-subscribe; exponential backoff reconnection is recommended to avoid frequent reconnections triggering server-side limits.