#include <stdio.h> #include <stdlib.h> #include <string.h> #include "MQTTClient.h" #define ADDRESS "tcp://localhost:1883" #define CLIENTID "ExampleClientSub" #define TOPIC "MQTT Examples" #define PAYLOAD "Hello World!" #define QOS 1 #define TIMEOUT 10000L volatile 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) { 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'); 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; int rc; int ch; MQTTClient_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL); conn_opts.keepAliveInterval = 20; conn_opts.cleansession = 1; MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered); if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) { printf("Failed to connect, return code %d\n", rc); exit(EXIT_FAILURE); } printf("Subscribing to topic %s\nfor client %s using QoS%d\n\n" "Press Q<Enter> to quit\n\n", TOPIC, CLIENTID, QOS); MQTTClient_subscribe(client, TOPIC, QOS); do { ch = getchar(); } while(ch!='Q' && ch != 'q'); MQTTClient_disconnect(client, 10000); MQTTClient_destroy(&client); return rc; }