Websocket programming in Python

With the rapid development of the Internet, the Websocket protocol is also widely used as a new communication protocol. As a common programming language, Python has many excellent Websocket libraries, such as Tornado and WebSocket-Server, which provide developers with good support.

This article will introduce the Websocket protocol and its differences from the HTTP protocol, as well as the steps and implementation methods for developing Websocket applications using Python.

1. Introduction to Websocket protocol

The Websocket protocol is a full-duplex communication protocol that runs on top of the TCP protocol. This protocol provides a persistent connection, enabling real-time two-way data transmission between the client and the server, and can be used in real-time communication, online games and other scenarios.

The characteristics of Websocket protocol are as follows:

(1) All data transmission is based on frame (Frame).

(2) The Websocket protocol uses the HTTP protocol during the handshake phase.

(3) The Websocket protocol provides two types of frames: data frames and control frames. Data frames are used to transmit messages, and control frames are used to maintain connection status.

(4) The Websocket protocol provides a heartbeat mechanism to maintain the stability of the connection.

(5) The Websocket protocol can communicate through encrypted SSL/TLS and non-encrypted methods.

2. The difference between Websocket protocol and HTTP protocol

Websocket protocol and HTTP protocol are both application layer protocols, but there are the following main differences between them:

(1) Websocket is a persistent connection, while HTTP is a short connection.

(2) The Websocket protocol uses the HTTP protocol for communication during the handshake phase, but the Websocket handshake phase only needs to be performed once, and then real-time data communication can be carried out.

(3) The Websocket protocol uses binary frames and text frames for data transmission, while the HTTP protocol can only transmit text data.

(4) The Websocket protocol can perform two-way data transmission, while the HTTP protocol can only perform one-way data transmission.

3. Implementing Websocket applications in Python

There are many Websocket libraries in Python, among which Tornado and WebSocket-Server are the more commonly used ones. This article will take WebSocket-Server as an example to introduce how to use Python to implement Websocket applications.

1. Install the WebSocket-Server library

Enter the following command on the command line to install the WebSocket-Server library:

pip install websocket-server

2. Write the server Code

To implement the Websocket server in Python, you need to first create a WebsocketServer object, and then overload several of its event methods, such as on_open(), on_message(), on_close(), etc., to complete the data Operations such as connecting, data receiving and closing connections.

The specific code is as follows:

from websocket_server import WebsocketServer

# 客户端连接时触发
def new_client(client, server):
    print("New client connected and was given id %d" % client["id"])
    server.send_message_to_all("Hey all, a new client has joined us")

# 接收到客户端消息时触发
def message_received(client, server, message):
    print("Client(%d) said: %s" % (client["id"], message))
    server.send_message_to_all("Client(%d) said: %s" % (client["id"], message))

# 客户端关闭连接时触发
def client_left(client, server):
    print("Client(%d) disconnected" % client["id"])

# 建立 WebSocketServer 对象，监听 9001 端口
server = WebsocketServer(9001)
server.set_fn_new_client(new_client)
server.set_fn_message_received(message_received)
server.set_fn_client_left(client_left)

# 启动服务器
server.run_forever()

3. Run the Websocket server

Enter the following command on the command line to start the WebSocket server:

python server.py

4. Writing client code

To implement the Websocket client in Python, you need to create a WebSocketClient object and then call several of its methods, such as connect(), send(), close (), etc., to complete the connection, data sending and closing operations.

The specific code is as follows:

from websocket import create_connection

# 建立 WebSocket 连接
ws = create_connection("ws://localhost:9001/")

# 发送消息
ws.send("Hello, world!")

# 接收消息
result = ws.recv()
print("Received '%s'" % result)

# 关闭 WebSocket 连接
ws.close()

The above are the steps and implementation methods of Websocket programming in Python. In this way, applications such as real-time communication and online games can be realized. Of course, in addition to the WebSocket-Server library, there are other different Websocket libraries to choose from, and developers can choose and try them according to their own needs.

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