CONNECT Packet Structure CONNACK Packet Structure Conclusion In Introduction to MQTT 5.0 Packet, we introduced that MQTT packets are composed of three parts: Fixed Header, Variable Header, and Payload, as well as common concepts in MQTT packets such as Variable Byte Integer and Property. Now, we...
UNSUBSCRIBE Packet Structure Fixed Header Same as the SUBSCRIBE packet, the only difference is that the value of the Packet Type field changes from 8 (0b1000) to 10 (0b1010). Variable Header Same as the SUBSCRIBE packet. Payload The payload of the UNSUBSCRIBE packet contains one or more To...
MQTT Packet structure Fixed header As mentioned earlier, the MQTT packet always has a fixed header. The following image breaks it down further into the control field and remaining length.As shown, the fixed header in an MQTT packet has the following: ...
2.1 MQTT控制报文的结构 Structure of an MQTT Control PacketMQTT协议通过交换预定义的MQTT控制报文来通信。这一节描述这些报文的格式。MQTT控制报文由三部分组成,按照 图例2.1 –MQTT控制报文的结构 描述的顺序:图例2.1 –MQTT控制报文的结构Fixed header固定报头,所有控制报文都包含 Variable header 可变报头,部分控制...
MQTT_PACKET_STRUCTURE mqttPacket = {NULL, 0, 0, 0}; //协议包 char buf[128]; short body_len = 0, i = 0; UsartPrintf(USART_DEBUG, "Tips: OneNet_SendData-MQTT\r\n"); memset(buf, 0, sizeof(buf)); body_len = OneNet_FillBuf(buf); //获取当前需要发送的数据流的总长度 ...
MQTT_PACKET_STRUCTURE *mqttPacket) { //flags 用于接收 byte 8 ,判断用户名,密码,服务质量,遗嘱信息等 uint8 flags = 0; uint8 will_topic_len = 0; uint16 total_len = 15; int16 len = 0, devid_len = strlen(devid); //设备号
2.1 MQTT控制报文的结构 Structure of an MQTT Control Packet 2.2 固定报头 Fixed header 2.2.1 MQTT控制报文的类型 MQTT Control Packet type 2.2.2 标志 Flags 控制报文字类型是从值区分为0-15依次对应 Reserved Connect ConnAck Publish PubRec PubComp Subscribe SubAck Unsubscribe PingReq PingResp DisConnect ...
{ MQTT_PACKET_STRUCTURE mqttPacket = {NULL, 0, 0, 0}; unsigned char sCount = 3; //---步骤一:组包--- if(MQTT_PacketPing(&mqttPacket)) return; while(sCount--) { //---步骤二:发送数据---
一个MQTT控制包包含三部分,按照下图的顺序Figure 2.1 - Structure of an MQTT Control Packet. Figure 2.1 - Structure of an MQTT Control Packet |固定包头,存在于所有MQTT控制包 |可变包头,存在于某些MQTT控制包 |载荷,存在于某些MQTT控制包 2.2 固定包头 每一个MQTT控制包都包含一个固定包头。Figure 2.2 - ...
MQTT通过交换一些预定义的MQTT控制包来工作。这一节描述这些包的格式。 一个MQTT控制包包含三部分,按照下图的顺序Figure 2.1 - Structure of an MQTT Control Packet. Figure2.1-StructureofanMQTTControlPacket|固定包头,存在于所有MQTT控制包 |可变包头,存在于某些MQTT控制包 ...