Subscription example

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "MQTTAsync.h"
 
#define ADDRESS     "tcp://localhost:1883"
#define CLIENTID    "ExampleClientSub"
#define TOPIC       "MQTT Examples"
#define PAYLOAD     "Hello World!"
#define QOS         1
#define TIMEOUT     10000L
 
volatile MQTTAsync_token deliveredtoken;
 
int disc_finished = 0;
int subscribed = 0;
int finished = 0;
 
void connlost(void *context, char *cause)
{
        MQTTAsync client = (MQTTAsync)context;
        MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
        int rc;
 
        printf("\nConnection lost\n");
        printf("     cause: %s\n", cause);
 
        printf("Reconnecting\n");
        conn_opts.keepAliveInterval = 20;
        conn_opts.cleansession = 1;
        if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
        {
                printf("Failed to start connect, return code %d\n", rc);
            finished = 1;
        }
}
 
 
int msgarrvd(void *context, char *topicName, int topicLen, MQTTAsync_message *message)
{
    int i;
    char* payloadptr;
 
    printf("Message arrived\n");
    printf("     topic: %s\n", topicName);
    printf("   message: ");
 
    payloadptr = message->payload;
    for(i=0; i<message->payloadlen; i++)
    {
        putchar(*payloadptr++);
    }
    putchar('\n');
    MQTTAsync_freeMessage(&message);
    MQTTAsync_free(topicName);
    return 1;
}
 
 
void onDisconnect(void* context, MQTTAsync_successData* response)
{
        printf("Successful disconnection\n");
        disc_finished = 1;
}
 
 
void onSubscribe(void* context, MQTTAsync_successData* response)
{
        printf("Subscribe succeeded\n");
        subscribed = 1;
}
 
void onSubscribeFailure(void* context, MQTTAsync_failureData* response)
{
        printf("Subscribe failed, rc %d\n", response ? response->code : 0);
        finished = 1;
}
 
 
void onConnectFailure(void* context, MQTTAsync_failureData* response)
{
        printf("Connect failed, rc %d\n", response ? response->code : 0);
        finished = 1;
}
 
 
void onConnect(void* context, MQTTAsync_successData* response)
{
        MQTTAsync client = (MQTTAsync)context;
        MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
        MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
        int rc;
 
        printf("Successful connection\n");
 
        printf("Subscribing to topic %s\nfor client %s using QoS%d\n\n"
           "Press Q<Enter> to quit\n\n", TOPIC, CLIENTID, QOS);
        opts.onSuccess = onSubscribe;
        opts.onFailure = onSubscribeFailure;
        opts.context = client;
 
        deliveredtoken = 0;
 
        if ((rc = MQTTAsync_subscribe(client, TOPIC, QOS, &opts)) != MQTTASYNC_SUCCESS)
        {
                printf("Failed to start subscribe, return code %d\n", rc);
                exit(EXIT_FAILURE);
        }
}
 
 
int main(int argc, char* argv[])
{
        MQTTAsync client;
        MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
        MQTTAsync_disconnectOptions disc_opts = MQTTAsync_disconnectOptions_initializer;
        MQTTAsync_message pubmsg = MQTTAsync_message_initializer;
        MQTTAsync_token token;
        int rc;
        int ch;
 
        MQTTAsync_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);
 
        MQTTAsync_setCallbacks(client, NULL, connlost, msgarrvd, NULL);
 
        conn_opts.keepAliveInterval = 20;
        conn_opts.cleansession = 1;
        conn_opts.onSuccess = onConnect;
        conn_opts.onFailure = onConnectFailure;
        conn_opts.context = client;
        if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
        {
                printf("Failed to start connect, return code %d\n", rc);
                exit(EXIT_FAILURE);
        }
 
        while   (!subscribed)
                #if defined(WIN32) || defined(WIN64)
                        Sleep(100);
                #else
                        usleep(10000L);
                #endif
 
        if (finished)
                goto exit;
 
        do
        {
                ch = getchar();
        } while (ch!='Q' && ch != 'q');
 
        disc_opts.onSuccess = onDisconnect;
        if ((rc = MQTTAsync_disconnect(client, &disc_opts)) != MQTTASYNC_SUCCESS)
        {
                printf("Failed to start disconnect, return code %d\n", rc);
                exit(EXIT_FAILURE);
        }
        while   (!disc_finished)
                #if defined(WIN32) || defined(WIN64)
                        Sleep(100);
                #else
                        usleep(10000L);
                #endif
 
exit:
        MQTTAsync_destroy(&client);
        return rc;
}