generated from guanyuankai/bonus-edge-proxy
112 lines
2.9 KiB
Groff
112 lines
2.9 KiB
Groff
.TH "subasync" 3 "Sat Aug 16 2025 14:15:23" "Paho MQTT C Client Library" \" -*- nroff -*-
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.ad l
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.nh
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.SH NAME
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subasync \- Asynchronous subscription example
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.PP
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.PP
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.nf
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#include <stdio\&.h>
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#include <stdlib\&.h>
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#include <string\&.h>
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#include "MQTTClient\&.h"
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#define ADDRESS "tcp://test\&.mosquitto\&.org:1883"
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#define CLIENTID "ExampleClientSub"
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#define TOPIC "MQTT Examples"
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#define PAYLOAD "Hello World!"
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#define QOS 1
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#define TIMEOUT 10000L
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volatile MQTTClient_deliveryToken deliveredtoken;
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void delivered(void *context, MQTTClient_deliveryToken dt)
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{
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printf("Message with token value %d delivery confirmed\\n", dt);
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deliveredtoken = dt;
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}
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int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message)
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{
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printf("Message arrived\\n");
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printf(" topic: %s\\n", topicName);
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printf(" message: %\&.*s\\n", message\->payloadlen, (char*)message\->payload);
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MQTTClient_freeMessage(&message);
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MQTTClient_free(topicName);
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return 1;
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}
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void connlost(void *context, char *cause)
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{
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printf("\\nConnection lost\\n");
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printf(" cause: %s\\n", cause);
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}
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int main(int argc, char* argv[])
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{
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MQTTClient client;
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MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
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int rc;
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if ((rc = MQTTClient_create(&client, ADDRESS, CLIENTID,
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MQTTCLIENT_PERSISTENCE_NONE, NULL)) != MQTTCLIENT_SUCCESS)
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{
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printf("Failed to create client, return code %d\\n", rc);
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rc = EXIT_FAILURE;
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goto exit;
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}
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if ((rc = MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered)) != MQTTCLIENT_SUCCESS)
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{
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printf("Failed to set callbacks, return code %d\\n", rc);
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rc = EXIT_FAILURE;
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goto destroy_exit;
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}
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conn_opts\&.keepAliveInterval = 20;
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conn_opts\&.cleansession = 1;
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if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
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{
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printf("Failed to connect, return code %d\\n", rc);
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rc = EXIT_FAILURE;
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goto destroy_exit;
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}
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printf("Subscribing to topic %s\\nfor client %s using QoS%d\\n\\n"
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"Press Q<Enter> to quit\\n\\n", TOPIC, CLIENTID, QOS);
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if ((rc = MQTTClient_subscribe(client, TOPIC, QOS)) != MQTTCLIENT_SUCCESS)
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{
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printf("Failed to subscribe, return code %d\\n", rc);
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rc = EXIT_FAILURE;
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}
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else
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{
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int ch;
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do
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{
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ch = getchar();
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} while (ch!='Q' && ch != 'q');
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if ((rc = MQTTClient_unsubscribe(client, TOPIC)) != MQTTCLIENT_SUCCESS)
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{
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printf("Failed to unsubscribe, return code %d\\n", rc);
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rc = EXIT_FAILURE;
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}
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}
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if ((rc = MQTTClient_disconnect(client, 10000)) != MQTTCLIENT_SUCCESS)
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{
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printf("Failed to disconnect, return code %d\\n", rc);
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rc = EXIT_FAILURE;
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}
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destroy_exit:
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MQTTClient_destroy(&client);
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exit:
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return rc;
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}
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.fi
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.PP
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