A Dive into Network Programming in Python 101

A Dive into Network Programming in Python 101

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HTTP (Hypertext Transfer Protocol):

HTTP is a protocol used for sending and receiving data over the internet. In Python, you can use the requests module to send HTTP requests and receive HTTP responses. Here's an example of sending an HTTP GET request using the requests module:

import requests

response = requests.get('https://www.example.com')
print(response.status_code) 
print(response.content)

In this example, requests.get sends an HTTP GET request to the specified URL and returns an HTTP response object. The content attribute of the response object contains the response body as bytes.

HTTP Application Protocol:

HTTP is an application protocol used for transmitting data between applications. In Python, you can use the http.server module to create a simple HTTP server. Here's an example of creating an HTTP server that serves a single file:

from http.server import HTTPServer, SimpleHTTPRequestHandler

class MyHandler(SimpleHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.end_headers()
        with open('index.html', 'rb') as f:
            self.wfile.write(f.read())

httpd = HTTPServer(('localhost', 8000), MyHandler)
httpd.serve_forever()

In this example, MyHandler is a subclass of SimpleHTTPRequestHandler that overrides the do_GET method to serve a single file (index.html). The HTTPServer class is used to create an HTTP server that listens on port 8000.

HTTP Request:

An HTTP request is a message sent by a client to a server. In Python, you can use the requests module to send HTTP requests. Here's an example of sending an HTTP POST request with data using the requests module:

import requests

data = {'name': 'John', 'age': 30}
response = requests.post('https://www.example.com', data=data)
print(response.content)

In this example, requests.post sends an HTTP POST request to the specified URL with the data in the data dictionary. The content attribute of the response object contains the response body as bytes.

Unicode and UTF-8:

Unicode is a character encoding standard that represents each character in a unique code point. UTF-8 is a variable-width encoding that can represent all Unicode characters using one to four bytes. In Python, you can use the encode and decode methods to convert between Unicode strings and bytes using the UTF-8 encoding. Here's an example of encoding a Unicode string as bytes using the UTF-8 encoding:

text = 'Hello, world!'
bytes = text.encode('utf-8')
print(bytes)

In this example, text.encode('utf-8') encodes the Unicode string text as bytes using the UTF-8 encoding.

HTTP URL Library:

Python's built-in urllib module provides a convenient way to access web pages and other resources over the internet. Here's an example of using the urllib.request module to retrieve the contents of a web page:

import urllib.request

url = 'https://www.example.com'
response = urllib.request.urlopen(url)
data = response.read()
text = data.decode('utf-8')
print(text)

In this example, urllib.request.urlopen sends an HTTP GET request to the specified URL and returns an HTTP response object. The read method of the response object reads the contents of the response into a bytes object, which is then decoded using the UTF-8 encoding to convert it to a string.

URL Parsing:

You can use the urllib.parse module to parse URLs into their component parts. Here's an example of parsing a URL into its component parts:

from urllib.parse import urlparse

url = 'https://www.example.com/path/to/resource?param=value'
parsed = urlparse(url)
print(parsed.scheme)   # 'https'
print(parsed.netloc)   # 'www.example.com'
print(parsed.path)     # '/path/to/resource'
print(parsed.query)    # 'param=value'

In this example, urlparse parses the URL url into its component parts (scheme, netloc, path, and query), which are then printed.

URL Encoding:

You can use the urllib.parse module to encode special characters in URLs. Here's an example of encoding a URL with special characters:

from urllib.parse import quote

url = 'https://www.example.com/search?q=Python tutorial'
encoded = quote(url)
print(encoded)   # 'https%3A//www.example.com/search%3Fq%3DPython%20tutorial'

In this example, quote encodes the special characters in the URL url (colon, slash, and space) using percent-encoding.

URL Decoding:

You can use the urllib.parse module to decode percent-encoded characters in URLs. Here's an example of decoding a URL with percent-encoded characters:

from urllib.parse import unquote

url = 'https%3A//www.example.com/search%3Fq%3DPython%20tutorial'
decoded = unquote(url)
print(decoded)   # 'https://www.example.com/search?q=Python tutorial'

In this example, unquote decodes the percent-encoded characters in the URL url using UTF-8 decoding.

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