Mongoose 开源库--mqtt client使用笔记
一、Mongoose 简介
文章
官网：
https://mongoose.ws/documentation/#user-guide二、mqtt client 使用 Mongoose 开源库
开发环境：Ubuntu18.04 。
官方mqtt client文档：
https://mongoose.ws/documentation/tutorials/mqtt-client/直接使用官方测试代码,代码功能介绍如下：
This tutorial demonstrates how Mongoose Library can be used to implement an MQTT client. We'll create an MQTT client that:
1.Connects to the public HiveMQ MQTT server mqtt://broker.hivemq.com:1883
2.When connected, subscribes to the topic mg/+/test
3.Publishes a hello message to the mg/clnt/test topic
4.Receives that message back from the subscribed topic and closes the connection
5.Creates a timer that checks if a connection is closed, and reconnects to repeat the whole process代码如下：
// Copyright (c) 2023 Cesanta Software Limited
// All rights reserved
//
// Example MQTT client. It performs the following steps:
// 1. Connects to the MQTT server specified by `s_url` variable
// 2. When connected, subscribes to the topic `s_sub_topic`
// 3. Publishes message `hello` to the `s_pub_topic`
// 4. Receives that message back from the subscribed topic and closes
// 5. Timer-based reconnection logic revives the connection when it is down
//
// To enable SSL/TLS, see https://mongoose.ws/tutorials/tls/#how-to-build
#include "mongoose.h"
static const char *s_url = "mqtt://broker.hivemq.com:1883";
static const char *s_sub_topic = "mg/+/test"; // Publish topic
static const char *s_pub_topic = "mg/clnt/test"; // Subscribe topic
static int s_qos = 1; // MQTT QoS
static struct mg_connection *s_conn; // Client connection
// Handle interrupts, like Ctrl-C
static int s_signo;
static void signal_handler(int signo) {
s_signo = signo;
}
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
if (ev == MG_EV_OPEN) {
MG_INFO(("%lu CREATED", c->id));
// c->is_hexdumping = 1;
} else if (ev == MG_EV_CONNECT) {
if (mg_url_is_ssl(s_url)) {
struct mg_tls_opts opts = {.ca = mg_unpacked("/certs/ca.pem"),
.name = mg_url_host(s_url)};
mg_tls_init(c, &opts);
}
} else if (ev == MG_EV_ERROR) {
// On error, log error message
MG_ERROR(("%lu ERROR %s", c->id, (char *) ev_data));
} else if (ev == MG_EV_MQTT_OPEN) {
// MQTT connect is successful
struct mg_str subt = mg_str(s_sub_topic);
struct mg_str pubt = mg_str(s_pub_topic), data = mg_str("hello");
MG_INFO(("%lu CONNECTED to %s", c->id, s_url));
struct mg_mqtt_opts sub_opts;
memset(&sub_opts, 0, sizeof(sub_opts));
sub_opts.topic = subt;
sub_opts.qos = s_qos;
mg_mqtt_sub(c, &sub_opts);
MG_INFO(("%lu SUBSCRIBED to %.*s", c->id, (int) subt.len, subt.ptr));
struct mg_mqtt_opts pub_opts;
memset(&pub_opts, 0, sizeof(pub_opts));
pub_opts.topic = pubt;
pub_opts.message = data;
pub_opts.qos = s_qos, pub_opts.retain = false;
mg_mqtt_pub(c, &pub_opts);
MG_INFO(("%lu PUBLISHED %.*s -> %.*s", c->id, (int) data.len, data.ptr,
(int) pubt.len, pubt.ptr));
} else if (ev == MG_EV_MQTT_MSG) {
// When we get echo response, print it
struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
MG_INFO(("%lu RECEIVED %.*s <- %.*s", c->id, (int) mm->data.len,
mm->data.ptr, (int) mm->topic.len, mm->topic.ptr));
} else if (ev == MG_EV_CLOSE) {
MG_INFO(("%lu CLOSED", c->id));
s_conn = NULL; // Mark that we're closed
}
(void) fn_data;
}
// Timer function - recreate client connection if it is closed
static void timer_fn(void *arg) {
struct mg_mgr *mgr = (struct mg_mgr *) arg;
struct mg_mqtt_opts opts = {.clean = true,
.qos = s_qos,
.topic = mg_str(s_pub_topic),
.version = 4,
.message = mg_str("bye")};
if (s_conn == NULL) s_conn = mg_mqtt_connect(mgr, s_url, &opts, fn, NULL);
}
int main(int argc, char *argv[]) {
struct mg_mgr mgr;
int i;
// Parse command-line flags
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-u") == 0 && argv[i + 1] != NULL) {
s_url = argv[++i];
} else if (strcmp(argv[i], "-p") == 0 && argv[i + 1] != NULL) {
s_pub_topic = argv[++i];
} else if (strcmp(argv[i], "-s") == 0 && argv[i + 1] != NULL) {
s_sub_topic = argv[++i];
} else if (strcmp(argv[i], "-v") == 0 && argv[i + 1] != NULL) {
mg_log_set(atoi(argv[++i]));
} else {
MG_ERROR(("Unknown option: %s. Usage:", argv[i]));
MG_ERROR(
("%s [-u mqtts://SERVER:PORT] [-p PUB_TOPIC] [-s SUB_TOPIC] "
"[-v DEBUG_LEVEL]",
argv[0], argv[i]));
return 1;
}
}
signal(SIGINT, signal_handler); // Setup signal handlers - exist event
signal(SIGTERM, signal_handler); // manager loop on SIGINT and SIGTERM
mg_mgr_init(&mgr);
mg_timer_add(&mgr, 3000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, timer_fn, &mgr);
while (s_signo == 0) mg_mgr_poll(&mgr, 1000); // Event loop, 1s timeout
mg_mgr_free(&mgr); // Finished, cleanup
return 0;
}程序执行，测试结果，如下图。
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