物联网协议 MQTT

1.keepalive=10设置对话断线后存活时间为10秒

mosquitto_connect(mosq_sub, mqtt_host, mqtt_port, keepalive)

2.客户端连接成功执行这个回调函数

void on_connect_wrapper(struct mosquitto *mosq, void *userdata, int rc)

4.客户端订阅成功

void on_subscribe_wrapper(struct mosquitto *mosq, void *userdata, int mid, int qos_count, const int *granted_qos)

5.断线10秒后，客户端离线超时执行这个回调函数

void disconnect_wrapper(struct mosquitto *mosq, void *userdata, int rc)