1pubasync(3)                Library Functions Manual                pubasync(3)
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NAME

6       pubasync - Asynchronous publication example
7
8       #include <stdio.h>
9       #include <stdlib.h>
10       #include <string.h>
11       #include "MQTTClient.h"
12
13       #if !defined(_WIN32)
14       #include <unistd.h>
15       #else
16       #include <windows.h>
17       #endif
18
19       #define ADDRESS     "tcp://mqtt.eclipse.org:1883"
20       #define CLIENTID    "ExampleClientPub"
21       #define TOPIC       "MQTT Examples"
22       #define PAYLOAD     "Hello World!"
23       #define QOS         1
24       #define TIMEOUT     10000L
25
26       MQTTClient_deliveryToken deliveredtoken;
27
28       void delivered(void *context, MQTTClient_deliveryToken dt)
29       {
30           printf("Message with token value %d delivery confirmed\n", dt);
31           deliveredtoken = dt;
32       }
33
34       int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message)
35       {
36           printf("Message arrived\n");
37           printf("     topic: %s\n", topicName);
38           printf("   message: %.*s\n", message->payloadlen, (char*)message->payload);
39           MQTTClient_freeMessage(&message);
40           MQTTClient_free(topicName);
41           return 1;
42       }
43
44       void connlost(void *context, char *cause)
45       {
46           printf("\nConnection lost\n");
47           printf("     cause: %s\n", cause);
48       }
49
50       int main(int argc, char* argv[])
51       {
52           MQTTClient client;
53           MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
54           MQTTClient_message pubmsg = MQTTClient_message_initializer;
55           MQTTClient_deliveryToken token;
56           int rc;
57
58           if ((rc = MQTTClient_create(&client, ADDRESS, CLIENTID,
59               MQTTCLIENT_PERSISTENCE_NONE, NULL)) != MQTTCLIENT_SUCCESS)
60           {
61               printf("Failed to create client, return code %d\n", rc);
62               rc = EXIT_FAILURE;
63               goto exit;
64           }
65
66           if ((rc = MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered)) != MQTTCLIENT_SUCCESS)
67           {
68               printf("Failed to set callbacks, return code %d\n", rc);
69               rc = EXIT_FAILURE;
70               goto destroy_exit;
71           }
72
73           conn_opts.keepAliveInterval = 20;
74           conn_opts.cleansession = 1;
75           if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
76           {
77               printf("Failed to connect, return code %d\n", rc);
78               rc = EXIT_FAILURE;
79               goto destroy_exit;
80           }
81
82           pubmsg.payload = PAYLOAD;
83           pubmsg.payloadlen = (int)strlen(PAYLOAD);
84           pubmsg.qos = QOS;
85           pubmsg.retained = 0;
86           deliveredtoken = 0;
87           if ((rc = MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token)) != MQTTCLIENT_SUCCESS)
88           {
89               printf("Failed to publish message, return code %d\n", rc);
90               rc = EXIT_FAILURE;
91           }
92           else
93           {
94               printf("Waiting for publication of %s\n"
95                   "on topic %s for client with ClientID: %s\n",
96                   PAYLOAD, TOPIC, CLIENTID);
97               while (deliveredtoken != token)
98               {
99                               #if defined(_WIN32)
100                                       Sleep(100);
101                               #else
102                                       usleep(10000L);
103                               #endif
104               }
105           }
106
107           if ((rc = MQTTClient_disconnect(client, 10000)) != MQTTCLIENT_SUCCESS)
108           {
109               printf("Failed to disconnect, return code %d\n", rc);
110               rc = EXIT_FAILURE;
111           }
112
113       destroy_exit:
114           MQTTClient_destroy(&client);
115
116       exit:
117           return rc;
118       }
119
120
121Paho MQTT C Client Library      Thu Jan 19 2023                    pubasync(3)
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