IoT Platform:Example

Procedure

1. Initialize a client.

   For more information, see Step 1: Initialization.

2. Configure required features.

   For more information, see Step 2: Configure features.

3. Establish a connection.

   For more information, see Step 3: Request a connection.

4. Receive an RRPC message.

   1. After the device connects to IoT Platform, call the RRpc operation to send an RRPC command to the device. The following topics are available:

      • Use RRPC-specific topics

      • Call a custom topic (Recommended)

   2. The device calls the aiot_mqtt_recv function to receive the RRPC message. A callback function then processes the message.

      In this example, a callback function named demo_mqtt_default_recv_handler is used.

   3. Define a callback function to process the RRPC message.

      Important

      After the device receives the request, you must send a response within 8 seconds. Otherwise, IoT Platform determines that the call failed regardless of whether the device received the request.

      When you define the callback logic, note the following items:

      • Check whether the message is an RRPC message based on the topic format.

        • If you use an RRPC-specific topic, the device does not need to subscribe to the topic.

          Topic format: /sys/${YourProductKey}/${YourDeviceName}/rrpc/request/${messageId}. For more information, see Use RRPC-specific topics.

        • If you use a custom topic, the device must subscribe to it. For more information, see Step 6: Subscribe to a topic.

          When you use a custom topic to send a message, the message is delivered to the device through the corresponding RRPC request topic. RRPC request topic format: /ext/rrpc/${messageId}/${topic}. For more information, see Call a custom topic (Recommended).

      • Define the callback processing logic: after receiving the RRPC message, the device processes the command and sends a response to IoT Platform.

      • In this example, the RRPC message is printed and a response with the payload set to pong is returned to IoT Platform.

      void demo_mqtt_default_recv_handler(void *handle, const aiot_mqtt_recv_t *packet, void *userdata)
      {
          switch (packet->type) {
              ……
              ……
              case AIOT_MQTTRECV_PUB: {
                  printf("pub, qos: %d, topic: %.*s\n", packet->data.pub.qos, packet->data.pub.topic_len, packet->data.pub.topic);
                  printf("pub, payload: %.*s\n", packet->data.pub.payload_len, packet->data.pub.payload);
      
                  /* TODO: Define the logic for processing business messages that are sent by the server. */  */
                  /* The following sample code shows a sample RRPC response. */        
                  {
                      char *payload = "pong";
                      char resp_topic[256];
                      if(packet->data.pub.topic_len > 256) {
                          break;
                      }
      
                      memset(resp_topic, 0, sizeof(resp_topic));
                      memcpy(resp_topic, packet->data.pub.topic, packet->data.pub.topic_len);
      
                      aiot_mqtt_pub(handle, resp_topic, (uint8_t *)payload, (uint32_t)strlen(payload), 0);
                  } 
              }
              break;
      
              ……
              ……       
      
              default: {
      
              }
          }
      }

5. Close the connection.

   For more information, see Step 8: Disconnect.

6. Exit the program.

   For more information, see Step 9: Exit the program.