pubasync - Man Page

Name

pubasync ā€” Asynchronous publication example

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

#if !defined(_WIN32)
#include <unistd.h>
#else
#include <windows.h>
#endif

#define ADDRESS     "tcp://mqtt.eclipse.org:1883"
#define CLIENTID    "ExampleClientPub"
#define TOPIC       "MQTT Examples"
#define PAYLOAD     "Hello World!"
#define QOS         1
#define TIMEOUT     10000L

MQTTClient_deliveryToken deliveredtoken;

void delivered(void *context, MQTTClient_deliveryToken dt)
{
    printf("Message with token value %d delivery confirmed0, dt);
    deliveredtoken = dt;
}

int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message)
{
    printf("Message arrived0);
    printf("     topic: %s0, topicName);
    printf("   message: %.*s0, message->payloadlen, (char*)message->payload);
    MQTTClient_freeMessage(&message);
    MQTTClient_free(topicName);
    return 1;
}

void connlost(void *context, char *cause)
{
    printf("0onnection lost0);
    printf("     cause: %s0, cause);
}

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

    if ((rc = MQTTClient_create(&client, ADDRESS, CLIENTID,
        MQTTCLIENT_PERSISTENCE_NONE, NULL)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to create client, return code %d0, rc);
        rc = EXIT_FAILURE;
        goto exit;
    }

    if ((rc = MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to set callbacks, return code %d0, rc);
        rc = EXIT_FAILURE;
        goto destroy_exit;
    }

    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;
    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to connect, return code %d0, rc);
        rc = EXIT_FAILURE;
        goto destroy_exit;
    }

    pubmsg.payload = PAYLOAD;
    pubmsg.payloadlen = (int)strlen(PAYLOAD);
    pubmsg.qos = QOS;
    pubmsg.retained = 0;
    deliveredtoken = 0;
    if ((rc = MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to publish message, return code %d0, rc);
        rc = EXIT_FAILURE;
    }
    else
    {
        printf("Waiting for publication of %s0
            "on topic %s for client with ClientID: %s0,
            PAYLOAD, TOPIC, CLIENTID);
        while (deliveredtoken != token)
        {
                        #if defined(_WIN32)
                                Sleep(100);
                        #else
                                usleep(10000L);
                        #endif
        }
    }

    if ((rc = MQTTClient_disconnect(client, 10000)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to disconnect, return code %d0, rc);
        rc = EXIT_FAILURE;
    }

destroy_exit:
    MQTTClient_destroy(&client);

exit:
    return rc;
}

Info

Tue Sep 14 2021 Paho MQTT C Client Library