Why not rewrite the web from scratch?

This is a Challenge:

Design and implement a system that will accept a multipart form upload (say, containing an audio file) while displaying a percentage progress.

The basic HTML design should look like:

Display form with file input field
Display a title text field
Display a status text paragraph "select file"
Optionally display a submit button

Specification:

When the user picks a file from their computer and the form is submitted, the upload begins.
While uploading, the status text paragraph should be updating with the current percentage complete at least once every 2 seconds.
While uploading, the user should be able to enter text into the title text field.
When the upload completes, the status text should display the path on the server to the saved file, and the current value of the title text field should be posted to the server.
The response to the form post request should display both the title and the path to the file.

Requirements:

The upload should honor proxy settings on the browser
The system must function behind a firewall that blocks all but port 80
The server must support at least 2 concurrent uploads from different users
Any technology that can be web deployed to IE, Firefox, Safari, Chrome (iPad/iPhone is optional) on any platform is supported
Use any language you'd like but with fewest dependencies as possible

My Approach:

In order to show my skills and my understanding on protocol level up to the MVC pattern, I decided to take the requirement "fewest dependencies as possible" very serious. I did something I would never do in my daily work: I only depend on Ruby and its own libraries (socket and tempfile) in the Back-end and wrote everything from scratch.

Usually I would not reinvent things, but I want to prove that I am capable when it has to be done.

Decisions:

Ruby 1.9.2
MVC Application: A model layer, views and a set of actions. Completely separate from the web framework.
Sinatra-like DSL with named path params like "/uploads/:id/file/:title"
As RESTful as possible
A pseudo database which is just a nested Hash. But it is completely separate from the web framework and web application.
JQuery for Front-end code
High-level Front-end code with Ajax and JSON. No web server specific hacks.
No dynamic views, just JavaScript
Just two requires: socket and tempfile
A deadline of one week

Tested on:

Mac OS X
- Chrome 8
- Safari 5
- Firefox 3 (I had to completely disable Firebug in Add-ons menu)
- Firefox 4beta10
WinXP
- Firefox 2
- IE6
- IE8

Run it:

git clone git@github.com:arbovm/scratchweb.git
cd scratchweb/
rvm use 1.9.2
ruby app.rb