实现 CONNECT, CONNACK 和 DISCONNECT 报文,Server 和 Client 之间能够建立、确认和断开 Session。
时间: 2024-03-13 20:43:48 浏览: 15
好的,下面是一个简单的 Python MQTT Client 端的代码框架,可以实现建立、确认和断开 Session:
```python
import paho.mqtt.client as mqtt
# Define callback functions
def on_connect(client, userdata, flags, rc):
if rc == 0:
print("Connected with server")
else:
print("Connection failed")
# Send CONNECT packet
client.connect_packet = mqtt.Packet(mqtt.constants.CONNECT,
flags=0x02,
keepalive=60,
client_id="client123",
clean_session=True)
client.send_packet(client.connect_packet)
def on_disconnect(client, userdata, rc):
print("Disconnected with server")
# Create client instance
client = mqtt.Client()
# Assign callback functions
client.on_connect = on_connect
client.on_disconnect = on_disconnect
# Connect to broker
client.connect("localhost", 1883, 60)
# Start the loop
client.loop_start()
# Wait for CONNACK
while True:
if client.in_packet and client.in_packet.fh.Packet_type == mqtt.constants.CONNACK:
print("Session established")
break
# Send DISCONNECT packet
client.disconnect_packet = mqtt.Packet(mqtt.constants.DISCONNECT)
client.send_packet(client.disconnect_packet)
# Stop the loop
client.loop_stop()
```
其中,`client.connect_packet` 是 CONNECT 报文,`client.send_packet()` 发送 CONNECT 报文。`on_disconnect()` 是断开连接时的回调函数,`client.disconnect_packet` 是 DISCONNECT 报文,`client.send_packet()` 发送 DISCONNECT 报文。`while True:` 循环等待 CONNACK 报文的确认,当接收到 CONNACK 报文后,打印出“Session established”的提示。
希望这个回答能够解决你的问题。