Hula hoop isn't a framework

I used around 2 hours to imagine and create my own web framework. The finish result has:

• Threaded server
• Session support
• Static handling support
• URL to object dispatcher (CherryPy style)
• AJAX based error handling
• HTTP error handling
• Fully WSGI compatible
• Endless WSGI extension possibilities
• Super performance - 800 requests per second

You want to know how I did it? Read on, because it's very easy.

If hula hoop isn't a framework, then what is WSGI?

WSGI stands for Web Server Gateway Interface. It's a "new" Python way of collaborating between web projects. This may come as a surprise for you, but Python has A LOT of web frameworks, and a lot of them can't work together. WSGI sets a convention that enables web frameworks to use each others components. This isn't an introduction for WSGI, but here are some links that can get you started on understanding WSGI:

• PEP-333 -- Python Web Server Gateway Interface v1.0
• A Do-It-Yourself Framework
• A perspective to WSGi and CherryPy

WSGI is really cool!

WSGI architecture

WSGI encapsulates the WSGI application:

Our architecture will be - notice that we reuse A LOT of code:

Now what it do? Creating the dispatcher

I like the URL to object approach that is used by CherryPy (and other frameworks). Too bad one can't directly reuse CherryPy's dispatcher. Here is a little visual explanation:

This is basically the only thing that you need to create! Everything else is served. One can also easily use other approaches for dispatching (or use existing solution - like routes). I had copied some code from CherryPy's dispatcher (which made it even easier :]).

Hello World on dope

A little example showing off:

• The object architecture
• The support for sessions
• The filter function
• How redirection is handled
• Static file and directory serving

import amiweb
import os
from paste.httpexceptions import HTTPFound

class Test:
  def filter(self, req):
    if req.session.has_key("logged_in"):
      raise HTTPFound("http://amix.dk/")

  def setLogin(self, req):
    req.session['logged_in'] = True
    req.session.save()
    return "Session saved"
  setLogin.exposed = True

  def index(self, req):
    return "Hello world"
  index.exposed = True

  def sessionTest(self, req):
    if req.session.has_key("counter"):
      req.session['counter'] += 1
    else:
      req.session['counter'] = 0
    req.session.save()
    return "%s" % req.session['counter']
  sessionTest.exposed = True

  def isNotExposed(self, req):
    return "Should not return anything"

    
rc = amiweb.RootController(Test())

#Serve some static directories
rc.dispatcher.setStaticPath("/images/",
    "%s/static/images" % os_path, True)
rc.dispatcher.setStaticPath("/uploads/",
    "%s" % os_path, False)
rc.dispatcher.setStaticPath("/ascii.h",
    "%s/static/ascii.h" % os_path, True)

amiweb.startServer(rc.wsgi_app, 8080)

Installing Python Paste and Beaker

I have included the CherryPy WSGI server. You will need to get Python Paste and Beaker. On their sites you can find guides how to install them. Their sites are:

• Python Paste
• Beaker

Get the code

You will find hula hoop amiweb (which isn't a framework) and a test.py (which basically is a hello world application showing different things).

Download the zip