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More complete MQTT example

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Sergey Lyubka 2024-05-18 12:09:51 +01:00
parent c26bd2ffe8
commit a473cf99b5
1 changed files with 41 additions and 6 deletions
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@ -79,20 +79,55 @@ static void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
}
```
MQTT client that subscribes to a topic `aa/bb` and prints all incoming messages:
MQTT client that subscribes to a topic `device1/rx` and
echoes incoming messages to `device1/tx`:
```c
#include "mongoose.h"
static const char *s_mqtt_url = "mqtt://broker.hivemq.com:1883";
static struct mg_connection *s_mqtt_conn = NULL;
// MQTT connection event handler function
static void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
if (ev == MG_EV_MQTT_OPEN) {
struct mg_mqtt_opts opts = {.qos = 1, .topic = mg_str("aa/bb")};
if (ev == MG_EV_OPEN) {
MG_INFO(("%lu created, connecting to %s ...", c->id, s_mqtt_url));
} else if (ev == MG_EV_MQTT_OPEN) {
struct mg_mqtt_opts opts = {.qos = 1, .topic = mg_str("device1/rx")};
mg_mqtt_sub(c, &opts);
MG_INFO(("%lu connected, subscribing to %s", c->id, opts.topic.buf));
} else if (ev == MG_EV_MQTT_MSG) {
char response[100];
struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
printf("Topic: %.*s, Message: %.*s",
mm->topic.len, mm->topic.ptr,
mm->data.len, mm->data.ptr);
struct mg_mqtt_opts opts = {.qos = 1, .topic = mg_str("device1/tx")};
mg_snprintf(response, sizeof(response), "Received [%.*s] / [%.*s]",
mm->topic.len, mm->topic.buf, mm->data.len, mm->data.buf);
opts.message = mg_str(response);
mg_mqtt_pub(c, &opts);
} else if (ev == MG_EV_CLOSE) {
MG_INFO(("%u closing", c->id));
s_mqtt_conn = NULL;
}
}
// Reconnection timer function. If we get disconnected, reconnect again
static void timer_fn(void *arg) {
struct mg_mgr *mgr = (struct mg_mgr *) arg;
if (s_mqtt_conn == NULL) {
struct mg_mqtt_opts opts = {.clean = true};
s_mqtt_conn = mg_mqtt_connect(mgr, s_mqtt_url, &opts, ev_handler, NULL);
}
}
int main() {
struct mg_mgr mgr; // Mongoose event manager. Holds all connections
mg_mgr_init(&mgr); // Initialise event manager
mg_timer_add(&mgr, 3000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, timer_fn, &mgr);
for (;;) {
mg_mgr_poll(&mgr, 1000); // Infinite event loop
}
return 0;
}
```
## Commercial use