eclicpse mqtt库

Eclipse Paho is an open-source implementation of MQTT messaging protocol in various languages including C/C++, Java, Python, and JavaScript. Paho provides a simple and easy-to-use API for developing MQTT clients for different platforms.

To use the Eclipse Paho MQTT library in your C/C++ project, you can download the library from the Paho website or use the package manager of your operating system to install it. After installing the library, you can include the header files in your C/C++ code and start using the MQTT API provided by Paho.

Here's an example of how to use the Paho MQTT library to publish a message to a broker:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "MQTTClient.h"

#define ADDRESS     "tcp://localhost:1883"
#define CLIENTID    "ExampleClientPub"
#define TOPIC       "test"
#define QOS         1
#define TIMEOUT     10000L

int main(int argc, char* argv[])
{
    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    int rc;

    MQTTClient_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);

    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;

    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to connect, return code %d\n", rc);
        exit(EXIT_FAILURE);
    }

    char* message = "Hello, world!";
    MQTTClient_message pubmsg = MQTTClient_message_initializer;
    pubmsg.payload = message;
    pubmsg.payloadlen = strlen(message);
    pubmsg.qos = QOS;
    pubmsg.retained = 0;
    MQTTClient_deliveryToken token;
    if ((rc = MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to publish message, return code %d\n", rc);
        exit(EXIT_FAILURE);
    }

    printf("Message with delivery token %d sent\n", token);

    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);
    return EXIT_SUCCESS;
}

This example creates an MQTT client, connects to a broker at `tcp://localhost:1883`, publishes a message to the topic `test`, and disconnects from the broker. You can modify this example to subscribe to a topic or to handle incoming messages.