Developer Challenge

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

Structure

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 optionally presses the submit button, 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.

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
• Any technology that can be web deployed to IE, Firefox, Safari, Chrome on any platform is supported

Solution

I came up with a small & simple rails app called The Traffic Machine - a demonstration of background File Upload with Progress Bar.

According to the specs, two major issues had to be solved:

1. upload the file in background, while user enters additional title/comment/text to the file
2. get the upload progress and show it to the user

Usually, Flash solutions address those problems, but bring other disadvantages as well (wrong version/not installed/disabled). So I was looking for a solution without Flash. The latest specs of HTML5 give some further possibilities as well, but are not supported by majority of current web browsers (greetings to IE - ahhrgg!!!). See sources at the bottom for further info

Luckily, I didn't had to reinvent the wheel, as there are already good solutions for both problems out there. For the background upload, Ajaxupload looked just fine for me. It's a jQuery implementation of uploading a file to a hidden iFrame which happens in background and doesn't block the user from adding additional infromation.

To track the upload progress, I used the Apache-upload-progress Module, which adds an access point to Apache, so you can easily retrieve the total and uploaded file size in JSON format.

Basic Infrastrukture

• Rails 2.3.5
• jQuery + jRails
• Paperclip Plugin
• DefaultValue Plugin
• Blueprint CSS
• github.com/rngtng
• sqlLite DB

The Magic

• Background File upload: Ajaxupload
• Upload Progress count: Apache-upload-progress-module

Deployment

• Apache 2 + Passenger Module
• capistrano

Passenger File

<VirtualHost *:80> ServerName nups.loc DocumentRoot "/Users/ted/Sites/rails/fup/public" RailsEnv development RailsAllowModRewrite off

#Porter On #PorterSharedSecret fup

<directory "/Users/ted/Sites/rails/fup/public"> Order allow,deny Allow from all

needed for tracking upload progess

# enable tracking uploads in / TrackUploads On

<Location /progress> # enable upload progress reports in /progress ReportUploads On

Future Improvements

• add HTML 5 features (Drag'n Drop, multiple??)
• Get rid of Apache module
• better error handling
• fix hover for file select button
• add awesome Buttons: http://github.com/gr2m/awesome-buttons

A quick step by step Howto:

• get apachemodule, compile with: sudo apxs -c -i -a -Wc,-arch -Wc,ppc7400 -Wl,-arch -Wl,ppc7400 -Wc,-arch -Wc,x86_64 -Wl,-arch -Wl,x86_64 -Wc,-arch -Wc,i386 -Wl,-arch -Wl,i386 mod_upload_progress.c

• update apache conf and create vhost

• create rails app

• add plugins

  • paperclip: config.gem 'paperclip', :source => 'http://gemcutter.org'
  • default value: script/plugin install git://github.com/FooBarWidget/default_value_for.git
  • jQuery + jRails: script/plugin install git://github.com/aaronchi/jrails.git

• add blueprint css files

• add basic html layout

• add asset controller

• add asset model, add uuid

• add tests

• add ajaxupload for background upload

• add jQuery Ajax call to check upload progress

• finish it up and make it nice

• deploy with capistrano and git+passenger

Further reading and other resources:

• http://railsillustrated.com/screencast-file-uploads-progress-in-rails-passenger.html
• http://drogomir.com/blog/2008/6/18/upload-progress-bar-with-mod_passenger-and-apache
• http://drogomir.com/blog/2008/6/30/upload-progress-script-with-safari-support
• http://www.therailsway.com/2009/4/23/uploading-files)
• http://github.com/drogus/jquery-upload-progress
• http://adamelliot.com/posts/using-paperclip-with-datamapper-sinatra--2
• http://casperfabricius.com/site/2009/03/26/uploading-multiple-files-with-progress-indicator-using-jquery-flash-and-rails
• http://sourceforge.net/projects/uber-uploader
• http://www.sibsoft.net/xupload.html
• http://encodable.com/filechucker
• http://talks.php.net/show/afup06/22 - PHP5
• http://github.com/digitarald/digitarald-fancyupload - with Flash
• http://code.google.com/p/noswfupload - without Flash
• http://webreflection.blogspot.com/2009/03/safari-4-multiple-upload-with-progress.html - Mutiple Files
• http://rakaz.nl/2009/08/uploading-multiple-files-using-html5.html - HTML5
• http://serverfault.com/questions/111721/how-can-i-do-a-large-file-upload-using-sinatra-haml-nginx-and-passenger - Sinatra
• http://www.quirksmode.org/dom/inputfile.html - nice Fileupload style