| Paho MQTT C Client Library

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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://test.mosquitto.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 confirmed\n", dt);
deliveredtoken = dt;
}
int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message)
{
printf("Message arrived\n");
printf(" topic: %s\n", topicName);
printf(" message: %.*s\n", message->payloadlen, (char*)message->payload);
MQTTClient_freeMessage(&message);
MQTTClient_free(topicName);
return 1;
}
void connlost(void *context, char *cause)
{
printf("\nConnection lost\n");
printf(" cause: %s\n", 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 %d\n", rc);
rc = EXIT_FAILURE;
goto exit;
}
if ((rc = MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to set callbacks, return code %d\n", 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 %d\n", 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 %d\n", rc);
rc = EXIT_FAILURE;
}
else
{
printf("Waiting for publication of %s\n"
"on topic %s for client with ClientID: %s\n",
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 %d\n", rc);
rc = EXIT_FAILURE;
}
destroy_exit:
MQTTClient_destroy(&client);
exit:
return rc;
}
MQTTClient.h
MQTTClient_disconnect
int MQTTClient_disconnect(MQTTClient handle, int timeout)
MQTTClient_free
void MQTTClient_free(void *ptr)
MQTTClient_deliveryToken
int MQTTClient_deliveryToken
Definition MQTTClient.h:267
MQTTClient
void * MQTTClient
Definition MQTTClient.h:256
MQTTClient_create
int MQTTClient_create(MQTTClient *handle, const char *serverURI, const char *clientId, int persistence_type, void *persistence_context)
MQTTClient_message_initializer
#define MQTTClient_message_initializer
Definition MQTTClient.h:337
MQTTClient_connect
int MQTTClient_connect(MQTTClient handle, MQTTClient_connectOptions *options)
MQTTClient_setCallbacks
int MQTTClient_setCallbacks(MQTTClient handle, void *context, MQTTClient_connectionLost *cl, MQTTClient_messageArrived *ma, MQTTClient_deliveryComplete *dc)
MQTTClient_freeMessage
void MQTTClient_freeMessage(MQTTClient_message **msg)
MQTTCLIENT_SUCCESS
#define MQTTCLIENT_SUCCESS
Definition MQTTClient.h:137
MQTTClient_publishMessage
int MQTTClient_publishMessage(MQTTClient handle, const char *topicName, MQTTClient_message *msg, MQTTClient_deliveryToken *dt)
MQTTClient_destroy
void MQTTClient_destroy(MQTTClient *handle)
MQTTClient_connectOptions_initializer
#define MQTTClient_connectOptions_initializer
Definition MQTTClient.h:990
MQTTCLIENT_PERSISTENCE_NONE
#define MQTTCLIENT_PERSISTENCE_NONE
Definition MQTTClientPersistence.h:74
MQTTClient_connectOptions
Definition MQTTClient.h:831
MQTTClient_connectOptions::cleansession
int cleansession
Definition MQTTClient.h:876
MQTTClient_connectOptions::keepAliveInterval
int keepAliveInterval
Definition MQTTClient.h:854
MQTTClient_message
Definition MQTTClient.h:277
MQTTClient_message::qos
int qos
Definition MQTTClient.h:300
MQTTClient_message::retained
int retained
Definition MQTTClient.h:319
MQTTClient_message::payload
void * payload
Definition MQTTClient.h:286
MQTTClient_message::payloadlen
int payloadlen
Definition MQTTClient.h:284