subscribe - Subscription example

NAME 

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NAME

subscribe − Subscription example

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

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

#if defined(_WRS_KERNEL)
#include <OsWrapper.h>
#endif

#define ADDRESS "tcp://mqtt.eclipseprojects.io:1883"
#define CLIENTID "ExampleClientSub"
#define TOPIC "MQTT Examples"
#define PAYLOAD "Hello World!"
#define QOS 1
#define TIMEOUT 10000L

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("1onnection lost0);
if (cause)
printf(" cause: %s0, cause);

printf("Reconnecting0);
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;
if ((rc = MQTTAsync_connect(client, &conn_opts)) != MQTTASYNC_SUCCESS)
{
printf("Failed to start connect, return code %d0, rc);
finished = 1;
}
}

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

void onDisconnectFailure(void* context, MQTTAsync_failureData* response)
{
printf("Disconnect failed, rc %d0, response->code);
disc_finished = 1;
}

void onDisconnect(void* context, MQTTAsync_successData* response)
{
printf("Successful disconnection0);
disc_finished = 1;
}

void onSubscribe(void* context, MQTTAsync_successData* response)
{
printf("Subscribe succeeded0);
subscribed = 1;
}

void onSubscribeFailure(void* context, MQTTAsync_failureData* response)
{
printf("Subscribe failed, rc %d0, response->code);
finished = 1;
}

void onConnectFailure(void* context, MQTTAsync_failureData* response)
{
printf("Connect failed, rc %d0, response->code);
finished = 1;
}

void onConnect(void* context, MQTTAsync_successData* response)
{
MQTTAsync client = (MQTTAsync)context;
MQTTAsync_responseOptions opts = MQTTAsync_responseOptions_initializer;
int rc;

printf("Successful connection0);

printf("Subscribing to topic %s0or client %s using QoS%d0
"Press Q<Enter> to quit0, TOPIC, CLIENTID, QOS);
opts.onSuccess = onSubscribe;
opts.onFailure = onSubscribeFailure;
opts.context = client;
if ((rc = MQTTAsync_subscribe(client, TOPIC, QOS, &opts)) != MQTTASYNC_SUCCESS)
{
printf("Failed to start subscribe, return code %d0, rc);
finished = 1;
}
}

int main(int argc, char* argv[])
{
MQTTAsync client;
MQTTAsync_connectOptions conn_opts = MQTTAsync_connectOptions_initializer;
MQTTAsync_disconnectOptions disc_opts = MQTTAsync_disconnectOptions_initializer;
int rc;
int ch;

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

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

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 %d0, rc);
rc = EXIT_FAILURE;
goto destroy_exit;
}

while (!subscribed && !finished)
#if defined(_WIN32)
Sleep(100);
#else
usleep(10000L);
#endif

if (finished)
goto exit;

do
{
ch = getchar();
} while (ch!=’Q’ && ch != ’q’);

disc_opts.onSuccess = onDisconnect;
disc_opts.onFailure = onDisconnectFailure;
if ((rc = MQTTAsync_disconnect(client, &disc_opts)) != MQTTASYNC_SUCCESS)
{
printf("Failed to start disconnect, return code %d0, rc);
rc = EXIT_FAILURE;
goto destroy_exit;
}
while (!disc_finished)
{
#if defined(_WIN32)
Sleep(100);
#else
usleep(10000L);
#endif
}

destroy_exit:
MQTTAsync_destroy(&client);
exit:
return rc;
}

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