The HTTP request-response model

The HTTP protocol is nearly stateless: a user agent (or browser) makes a request and the server provides a response. For services that don't involve cookies, a client application can take a functional view of the protocol. We can build a client using the http.client or urllib library. An HTTP user agent essentially executes something similar to the following:

import urllib.request
def urllib_demo(url):
    with urllib.request.urlopen(url) as response:
        print(response.read())

urllib_demo("http://slott-softwarearchitect.blogspot.com")

A program like wget or curl does this kind of processing using a URL supplied as a command-line argument. A browser does this in response to the user pointing and clicking; the URL is taken from the user's actions, often the action of clicking on linked text or images.

The practical considerations...