關於TCP和MQTT之間的轉換（轉載）

如今物聯網流行的就是MQTT

其實MQTT就是在TCP的基礎上創建了一套協議

能夠看這個,原本我本身想用Wireshark監聽一下,不過百度一搜索一大把,我就不測試了

https://blog.csdn.net/libaineu2004/article/details/78773610

因此說只要能夠TCP鏈接了,而後只要知道了MQTT的協議,,,,直接就能夠用TCP來當作MQTT來使用了

不過要寫一些配合MQTT通訊的協議,而後發送和接收數據都經過協議處理以後,經過TCP發送和接收,

其實有現成的寫好的協議

能夠看這兩篇

http://sun2y.me/2017/05/12/MQTT協議在STM32上的移植/

https://blog.csdn.net/kh766200466/article/details/79694119

我也打算先移植(應用)到stm32上,不過我不打算用網絡模塊W5500,雖然用的挺熟,感受沒有新鮮感

我感受應該用ESP8266實現

其實思路很簡單,8266建TCP客戶端(用AT指令),由於如今沒有AT指令版的MQTT,因此用AT指令配置8266

而後鏈接的服務器的地址是個人云端的MQTT,固然TCP是透傳的,而後發數據的時候都經過MQTT協議封裝部分的程序,而後

發給WIFI模塊,而後WIFI模塊再發給MQTT服務器,,,接收也同樣......而後....就沒而後了,,能夠用了再說

 

不過剛恰好像看透了同樣.......

其實呢...只要用網絡監控的軟件看見了數據,而後再看下面的MQTT協議.....就能夠本身寫了

 

https://mcxiaoke.gitbooks.io/mqtt-cn/content/

咱試一試本身寫,我呢只是看着協議和傳回來的數據,,,而後咱本身試一試寫個在TCP鏈接以後,發個數據(就是MQTT規定的協議)鏈接MQTT

 

首先第一個字節是

0x10

算啦仍是直接一張圖搞定

用TCP鏈接上之後,而後用TCP發上面的指令,,,就鏈接上MQTT了 .....

 而後測試一下把........................................

而後就不說了,也不想說了,你們本身看協議把,,,,由於讓本身感受MQTT在我心中的地位大大的受到了..........唉,,,,感受本身講出來的東西確實感受居然的如此的簡單......

只要弄透了,本身寫協議就好啦,.....我本身去寫協議去,估計寫的變量少一點,51單片機就能夠....

最後說一下若是是4版本的MQTT

而後今天寫好了單片機程序,用本身寫的MQTT封裝的協議,在8266做爲TCP客戶端的基礎上,鏈接了個人雲端的MQTT服務器,而後用調試助手測試了遠程通訊,代碼不多,力求能夠直接移植到51單片機上

#define MQTTCONFIG_C_
#include "include.h"

unsigned char MqttSendData[70]={0};

/**
* @brief  鏈接服務器的打包函數
* @param  
* @retval 
* @example 
**/
int ConnectMqtt(char *ClientID,char *Username,char *Password)
{
    int ClientIDLen = strlen(ClientID);
    int UsernameLen    = strlen(Username);
    int PasswordLen = strlen(Password);
    int DataLen = 0;
    int Index = 2;
    int i = 0;
    DataLen = 12 + 2+2+ClientIDLen+UsernameLen+PasswordLen;
    MqttSendData[0] = 0x10;                //MQTT Message Type CONNECT
    MqttSendData[1] = DataLen;    //剩餘長度(不包括固定頭部)
    MqttSendData[Index++] = 0;        // Protocol Name Length MSB    
    MqttSendData[Index++] = 4;        // Protocol Name Length LSB    
    MqttSendData[Index++] = 'M';        // ASCII Code for M    
    MqttSendData[Index++] = 'Q';        // ASCII Code for Q    
    MqttSendData[Index++] = 'T';        // ASCII Code for T    
    MqttSendData[Index++] = 'T';        // ASCII Code for T    
    MqttSendData[Index++] = 4;        // MQTT Protocol version = 4    
    MqttSendData[Index++] = 0xc2;        // conn flags 
    MqttSendData[Index++] = 0;        // Keep-alive Time Length MSB    
    MqttSendData[Index++] = 60;        // Keep-alive Time Length LSB  60S心跳包  
    MqttSendData[Index++] = (0xff00&ClientIDLen)>>8;// Client ID length MSB    
    MqttSendData[Index++] = 0xff&ClientIDLen;    // Client ID length LSB  

    for(i = 0; i < ClientIDLen; i++)
    {
        MqttSendData[Index + i] = ClientID[i];          
    }
    Index = Index + ClientIDLen;
    
    if(UsernameLen > 0)
    {   
        MqttSendData[Index++] = (0xff00&UsernameLen)>>8;//username length MSB    
        MqttSendData[Index++] = 0xff&UsernameLen;    //username length LSB    
        for(i = 0; i < UsernameLen ; i++)
        {
            MqttSendData[Index + i] = Username[i];    
        }
        Index = Index + UsernameLen;
    }
    
    if(PasswordLen > 0)
    {    
        MqttSendData[Index++] = (0xff00&PasswordLen)>>8;//password length MSB    
        MqttSendData[Index++] = 0xff&PasswordLen;    //password length LSB    
        for(i = 0; i < PasswordLen ; i++)
        {
            MqttSendData[Index + i] = Password[i];    
        }
        Index = Index + PasswordLen; 
    }    
    return Index;
}


/**
* @brief  MQTT訂閱/取消訂閱數據打包函數
* @param  SendData 
* @param  topic                主題 
* @param  qos         消息等級 
* @param  whether     訂閱/取消訂閱請求包
* @retval 
* @example 
**/
int MqttSubscribeTopic(char *topic,u8 qos,u8 whether)
{    
    int topiclen = strlen(topic);
    int i=0,index = 0;
  
    if(whether)
        MqttSendData[index++] = 0x82;                        //0x82 //消息類型和標誌 SUBSCRIBE 訂閱
    else
        MqttSendData[index++] = 0xA2;                        //0xA2 取消訂閱
    MqttSendData[index++] = topiclen + 5;                //剩餘長度(不包括固定頭部)
    MqttSendData[index++] = 0;                          //消息標識符,高位
    MqttSendData[index++] = 0x01;                    //消息標識符,低位
    MqttSendData[index++] = (0xff00&topiclen)>>8;    //主題長度(高位在前,低位在後)
    MqttSendData[index++] = 0xff&topiclen;              //主題長度 
    
    for (i = 0;i < topiclen; i++)
    {
        MqttSendData[index + i] = topic[i];
    }
    index = index + topiclen;
    
    if(whether)
    {
        MqttSendData[index] = qos;//QoS級別
        index++;
    }
    return index;
}


/**
* @brief  MQTT發佈數據打包函數
* @param  mqtt_message 
* @param  topic                主題 
* @param  qos         消息等級 
* @retval 
* @example 
**/
int MqttPublishData(char * topic, char * message, u8 qos)
{  
    int topic_length = strlen(topic);    
    int message_length = strlen(message);  
    int i,index=0;    
    static u16 id=0;
    
    MqttSendData[index++] = 0x30;    // MQTT Message Type PUBLISH  

  
    if(qos)
        MqttSendData[index++] = 2 + topic_length + 2 + message_length;//數據長度
    else
        MqttSendData[index++] = 2 + topic_length + message_length;   // Remaining length  

  
    MqttSendData[index++] = (0xff00&topic_length)>>8;//主題長度
    MqttSendData[index++] = 0xff&topic_length;
         
    for(i = 0; i < topic_length; i++)
    {
        MqttSendData[index + i] = topic[i];//拷貝主題
    }
    index += topic_length;
        
    if(qos)
    {
        MqttSendData[index++] = (0xff00&id)>>8;
        MqttSendData[index++] = 0xff&id;
        id++;
    }
  
    for(i = 0; i < message_length; i++)
    {
        MqttSendData[index + i] = message[i];//拷貝數據
    }
    index += message_length;
        
    return index;
}

#ifndef MQTTCONFIG_H_
#define MQTTCONFIG_H_
#include <stm32f10x.h>
#ifndef MQTTCONFIG_C_//若是沒有定義  _TIME_C_
#define MQTTCONFIG_C_ extern
#else
#define MQTTCONFIG_C_
#endif

MQTTCONFIG_C_ unsigned char MqttSendData[200];

int ConnectMqtt(char *ClientID,char *Username,char *Password);
int MqttSubscribeTopic(char *topic,u8 qos,u8 whether);
int MqttPublishData(char * topic, char * message, u8 qos);

#endif

 

文章轉載自https://www.cnblogs.com/yangfengwu/p/9124299.html，若有侵權請聯繫我刪除