Python server programming: implementing WebSocket server

In recent years, WebSocket technology has become increasingly popular and has become the standard choice for real-time communication between browsers and servers. In Python, we can implement WebSocket server development through some mature libraries. This article will explore how to use Python to develop a WebSocket server based on the introduction of WebSocket technology.

1. What is WebSocket

WebSocket is a protocol for full-duplex communication on a single TCP connection, that is, real-time communication can be achieved between the client and the server without A new HTTP connection needs to be opened for each communication. WebSocket is widely used in common real-time communication scenarios, such as chat rooms, web games, data visualization, etc.

In the WebSocket protocol, communication between the client and the server is completed through "Frame". Frame is the basic unit of data transmission in WebSocket, consisting of two types: "control frame" and "data frame". Control frames are used to control the process of information interaction, such as handshakes and other operations; data frames are used to transfer specific data content.

One advantage of WebSocket is that it only uses a single TCP socket to allow two-way communication between the client and the server, avoiding the problem of multiple HTTP connections and closures, and reducing communication delays.

2. Develop WebSocket server in Python

There are some excellent third-party open source libraries in the Python ecosystem that can be used to implement WebSocket server, such as: Tornado, Twisted, aiohttp, Sanic, etc., among which Both Tornado and Twisted are Python's traditional network programming tools, and they are the best choices when developing WebSocket servers in Python.

In the following, we will use Tornado as an example to introduce the specific implementation method of developing WebSocket server in Python.

First, you need to install the Tornado library, which can be installed through the pip install tornado command.

Next, we create the WebSocket server based on Tornado, the code is as follows:

import tornado.websocket
import tornado.httpserver
import tornado.ioloop
import tornado.web

class WebSocketHandler(tornado.websocket.WebSocketHandler):
    def open(self):
        print("WebSocket opened")

    def on_message(self, message):
        print("Message received: {}".format(message))
        self.write_message("You said: " + message)

    def on_close(self):
        print("WebSocket closed")

    def check_origin(self, origin):
        return True

app = tornado.web.Application([(r"/websocket", WebSocketHandler)])
server = tornado.httpserver.HTTPServer(app)
server.listen(8000)
tornado.ioloop.IOLoop.instance().start()

The above code defines a WebSocketHandler class, which implements the opening, message reception and closing of the WebSocket server. Among them, the open() method is called after the WebSocket connection is established, the on_message() method is called when a message is received during the WebSocket transmission process, and the on_close() method is called when the WebSocket connection is closed.

The check_origin() method is used to configure cross-origin requests. In this example, we allow all origins. In the WebSocketHandler class, we process HTTPRequest and WebSocketRequest requests at the same time, so we need to register the WebSocketHandler class through the app and specify the listening port as 8000.

Finally, monitor and process connection requests through IOLoop.

After running this code, you can start the WebSocket server and enter localhost:8000/websocket in the browser to test the connection.

3. Conclusion

This article introduces the principle of WebSocket technology and the implementation method in Python. In Python, we can use Tornado to implement the WebSocket server. Using WebSocket technology, we can easily communicate in real time. Functionality is added to various web applications. If you are currently using Python to develop web applications and want to use WebSocket to implement real-time communication functions, then Tornado is a good choice.

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