Simple HTTP Web Server and Client in Python

This time I’d like to show you how to make a simple HTTP server and client in python. It’s a bit different from other tutorials I’ve ever wrote and I’d like to say that I’m also a beginner in python. But, I’ll try to make sure you understand what I wrote because this tutorial is easy.

First, you need to know what HTTP is.

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web.

– HTTP definition based on Wikipedia

In simple words, HTTP is a protocol that used for world wide web communication. So, if you’re browsing the web, downloading data, and hosting a website, you’re using HTTP protocol.

There are many web server software that support HTTP protocol such as apache, nginx, and lighttpd. In this moment, I’d like to show you how to make something like that (a simple version obviously) in python language.

Step 1: Write HTTP server script using BaseHTTPServer module

Luckily, python provides us an HTTP server module, it’s called BaseHTTPServer. We use two classes from this module, namely BaseHTTPRequestHandler and HTTPServer. We also need to use os module to access file in your system.

First, we need to import those modules:

#!/usr/bin/env python  
  
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer  
import os

Next, write a custom class namely KodeFunHTTPRequestHandler that implement BaseHTTPRequestHandler.

#Create custom HTTPRequestHandler class  
class KodeFunHTTPRequestHandler(BaseHTTPRequestHandler):

In this tutorial, I just implement GET command from HTTP. To do that, we need to override do_GET() function. Our objective is to request an HTML file from server using our client (explained int the next step). Script inside do_GET() function is written to handle our objective.

  #handle GET command  
  def do_GET(self):  
    rootdir = 'c:/xampp/htdocs/' #file location  
    try:  
      if self.path.endswith('.html'):  
        f = open(rootdir + self.path) #open requested file  
  
        #send code 200 response  
        self.send_response(200)  
  
        #send header first  
        self.send_header('Content-type','text-html')  
        self.end_headers()  
  
        #send file content to client  
        self.wfile.write(f.read())  
        f.close()  
        return  

    except IOError:  
      self.send_error(404, 'file not found')

Next we need to add our __main__ function. We only need to create an HTTPServer object with defined IP address and port. We also need to pass HTTP request handler above as its parameter. Finally, to make the server always run, we only need to call server_forever() function.

def run():  
  print('http server is starting...')  
  
  #ip and port of server  
  #by default http server port is 80  
  server_address = ('127.0.0.1', 80)  
  httpd = HTTPServer(server_address, KodeFunHTTPRequestHandler)  
  print('http server is running...')  
  httpd.serve_forever()  

if __name__ == '__main__':  
  run()  

Save it and name it whatever you want (e.g, kodefun-httpserver.py). The following snipped is the complete script of http server.

#!/usr/bin/env python  
  
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer  
import os  
  
#Create custom HTTPRequestHandler class  
class KodeFunHTTPRequestHandler(BaseHTTPRequestHandler):  

  #handle GET command  
  def do_GET(self):  
    rootdir = 'c:/xampp/htdocs/' #file location  
    try:  
      if self.path.endswith('.html'):  
        f = open(rootdir + self.path) #open requested file  
  
        #send code 200 response  
        self.send_response(200)  
  
        #send header first  
        self.send_header('Content-type','text-html')  
        self.end_headers()  
  
        #send file content to client  
        self.wfile.write(f.read())  
        f.close()  
        return  

    except IOError:  
      self.send_error(404, 'file not found')  

def run():  
  print('http server is starting...')  
  
  #ip and port of servr  
  #by default http server port is 80  
  server_address = ('127.0.0.1', 80)  
  httpd = HTTPServer(server_address, KodeFunHTTPRequestHandler)  
  print('http server is running...')  
  httpd.serve_forever()  

if __name__ == '__main__':  
  run()  

Step 2: Write a simple HTTP client

To check if our server is working fine, we need an HTTP client. You can use your web browser to do this. But, It’ll be cool if you make your own client.

To accomplish this, let’s make another script, let’s name it kodefun-httpclient.py. This script only have two responsibilites based on user entry.

It’ll download an HTML file by typing command GET file.html. This will loop forever until user decide to type exit as a command.

The script is very simple to write. The following code snippet is the implementation of our simple HTTP client.

#!/usr/bin/env python  
  
import httplib  
import sys  
  
#get http server ip  
http_server = sys.argv[1]  
#create a connection  
conn = httplib.HTTPConnection(http_server)  
  
while 1:  
  cmd = raw_input('input command (ex. GET index.html): ')  
  cmd = cmd.split()  
  
  if cmd[0] == 'exit': #tipe exit to end it  
    break  

  #request command to server  
  conn.request(cmd[0], cmd[1])  
  
  #get response from server  
  rsp = conn.getresponse()  

  #print server response and data  
  print(rsp.status, rsp.reason)  
  data_received = rsp.read()  
  print(data_received)  

conn.close()  

Step 3: Test using GET command

The final step, we’ll test is our scripts above work just fine. To run the server, type the following command in your command prompt or terminal:

python kodefun-httpserver.py

If there is no problem, you’ll see "http server is running...". Next, we need to create a dummy HTML file, let’s call it dummy.html and copy the code below:

<head>  
 <title>Dummy HTML</title>  
</head>  
<body>  
 <h1>Kode Fun is Awesome</h1>  
 <h1>You're awesome</h1>  
</body>

Save it to your root folder defined in your script. In this example I use c:/xampp/htdocs/. Next, we need to run the client, type following command to run the client:

python kodefun-httpclient.py 127.0.0.1

When the client is running type following code to get dummy.html file:

GET dummy.html

If there is no problem, and it should be no problem, you’ll see the content of dummy.html file.

That’s all I can do this time. See you on my next tutorial.

Downloads

Fork or download the completed project on GitHub.

Further Reading

If you’re interested in learning more about network programming in python, I suggest to read Mastering Python Networking by Eric Chou.

Cover Photo by Sai Kiran Anagani on Unsplash.