Introduction

This article is Zenn's online book

"Introduction to self-made Python web applications for third-year web engineers who are sluggish"

This is a partial excerpt from.

Here https://qiita.com/bigen1925/items/dde5575da6c45a91808d Please also read.

Try writing a web server in Python

Suddenly, let's create a server that receives a request from a browser in Python and returns a response to the browser. The following program starts as a server on port 8080 (localhost: 8080) of your PC, writes the contents to a file called server_recv.txt when receiving a request from the browser, and then server_send.txt Reads the contents of the file and returns it to the browser as a response.

TCPServer.py

import socket


class TCPServer:
    """
A class that represents a server that performs TCP communication
    """
    def serve(self):
        """
Start the server
        """

        print("===Start the server===")

        try:
            #Generate socket
            server_socket = socket.socket()
            server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

            #Assign socket to localhost port 8080
            server_socket.bind(("localhost", 8080))
            server_socket.listen(10)

            #Wait for a connection from the outside and establish a connection if there is a connection
            print("===Wait for a connection from the client===")
            (client_socket, address) = server_socket.accept()
            print(f"===The connection with the client is complete remote_address: {address} ===")

            #Get the data sent from the client
            request = client_socket.recv(4096)

            #Write the data sent from the client to a file
            with open("server_recv.txt", "wb") as f:
                f.write(request)

            #Get the response data to be sent to the client from the file
            with open("server_send.txt", "rb") as f:
                response = f.read()

            #Send a response to the client
            client_socket.send(response)

            #End communication
            client_socket.close()

        finally:
            print("===Stop the server.===")


if __name__ == '__main__':
    server = TCPServer()
    server.serve()

Let's also create a server_send.txt for return.

server_send.txt

HTTP/1.1 200 OK
Date: Wed, 28 Oct 2020 07:57:45 GMT
Server: Apache/2.4.41 (Unix)
Content-Location: index.html.en
Vary: negotiate
TCN: choice
Last-Modified: Thu, 29 Aug 2019 05:05:59 GMT
ETag: "2d-5913a76187bc0"
Accept-Ranges: bytes
Content-Length: 45
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html

<html><body><h1>It works!</h1></body></html>

Try running the program

Move to the directory where the source code is placed on the console, and execute the program with the following command.

$ python TCPServer.py
===Start the server===
===Wait for a connection from the client===

Keep the console tab open and try accessing http: // localhost: 8080 in your browser.

スクリーンショット 2020-10-26 18.49.04.png

It was displayed as a web page safely!

Understand how a web server works

Except for comments, I was able to run a fairly primitive web server in just over a dozen lines. (At the moment, it is more accurate to call it a TCP server, not a white server that can be called a Web server ...)

The best way to understand how everything works is to make it yourself.

If you want to understand how a web server or web framework works, please come to our online book. https://zenn.dev/bigen1925/books/e6c9492a82f5e2e10fca/viewer/504d96 Please read!

There is also a description of the source code for this article.

Getting Started with Python Web Applications

Introduction

Try writing a web server in Python

Try running the program

Understand how a web server works