Saturday, May 29, 2010

Software Engineering Craft (or Software Engineering as a performance art)

Experiment with full time students this summer to explore this topic.

In a language and framework of their choice, have students select a short project to build, ie a blog website, or twitter client mobile application. Include testing. In the first session, build the project. (Time it.) Repeat again. Repeat again. Repeat again. After each session reflect on what you learned. Was there insights about the IDE? Where there key command short cuts? Do your test cases get better from defects from previous sessions, or do they get worse because of short cuts? Is there an aspect of the technology that you are deficient in that requires additional practice? (Katana example) Look for trends across the student population.

Based upon trends across the student population, identify further areas of practice.

Try same experiment with paired programming.

http://github.com/edgecase/ruby_koans

Inspiration: improv - learning scene work or singing a song from scratch. Take an impossible task and break into small concrete steps. Slowly build upon the steps to reach the goal. Sometimes explore the concept of each step with positive and negative examples.

Inspiration: Katana for TDD

Inspiration: Learning to play the piano. Strength building exercises. The whole point of the exercise is to build up . Much like dance where there are patterns, technique and skill aspects to a class. The patterns make learning dancing fun and motivate the student to keep going. Playing a song is rewarding. Working on skill is tedious but makes the fun stuff more accessible and easier to accomplish.


http://rubyquiz.com/
Ruby Koans - http://github.com/edgecase/ruby_koans


Javascript learning - http://ejohn.org/apps/learn

Friday, May 28, 2010

Integrating openid, google apps, and ruby on rails

My university uses Google Apps for Universities. We wanted users to be able to authenticate to our rails application using their Google Apps account. Since Google Apps now supports openid, I thought that this would be really straightforward. A friend had just installed openid on his site and it was a breeze. I thought I would just install a few gems and get on with other rails development activities. I have no intention of becoming an openid expert. Here are the steps that I followed to get it to all work together.



Step 1) Enable Federated Login using OpenID on your Google Apps domain.

http://www.google.com/a/cpanel/{your-domain}/SetupIdp

Step 2) Download your needed gems

a) gem install ruby-openid
This is JanRan's ruby implementation of open id

b) gem install ruby-openid-apps-discovery
This is Google's extension of ruby-openid to work with Google Apps

c) gem install rack-openid
This is a rack wrapper around JanRan's open id

d) ./script/plugin install git://github.com/rails/open_id_authentication.git
This is Rails code to make integrating in with open id easier

e) Modify config/environment.erb and add this line
require 'gapps_openid'


Step 3) Add some code to your rails application.

 
class SessionsController < current_user =" @account.users.authenticate(params[:name]," required =""> ["http://axschema.org/contact/email", "http://axschema.org/namePerson/first", "http://axschema.org/namePerson/last"]) do |result, identity_url, registration|
ax_response = OpenID::AX::FetchResponse.from_success_response(request.env[Rack::OpenID::RESPONSE])
case result.status
when :missing
failed_login "Sorry, the OpenID server couldn't be found"
when :invalid
failed_login "Sorry, but this does not appear to be a valid OpenID"
when :canceled
failed_login "OpenID verification was canceled"
when :failed
failed_login "Sorry, the OpenID verification failed"
when :successful

email = ax_response['http://axschema.org/contact/email'].first()
first_name = ax_response['http://axschema.org/namePerson/first'].first()
last_name = ax_response['http://axschema.org/namePerson/last'].first()

if result.successful?
#Look up the user and if they don't exist then create the user
@current_user = ...
if @current_user
successful_login
else
failed_login "Sorry, no user by that identity URL exists (#{identity_url})"
end
else
failed_login result.message
end
end
end
end


private
def successful_login
session[:user_id] = @current_user.id
redirect_to(root_url)
end

def failed_login(message)
flash[:error] = message
redirect_to(new_session_url)
end
end





If you are still stuck, here are some other helpful links:

To understand open id: http://www.devx.com/opensource/Article/37692/1954?pf=true

To get google mail to work with rails plugin: http://stackoverflow.com/questions/2492043/ruby-open-id-authentication-with-google-openid

To understand all possible AX schema fields: http://www.axschema.org/types/#sreg

Discovering end points: http://groups.google.com/group/google-federated-login-api/web/openid-discovery-for-hosted-domains


Part 2


If you get a warning message like this
WARNING: making https request to https://www.google.com/accounts/o8/.well-known/host-meta?hd= without verifying server certificate; no CA path was specified.
WARNING: making https request to https://www.google.com/accounts/o8/site-xrds?ns=2&hd= without verifying server certificate; no CA path was specified.
WARNING: making https request to https://www.google.com/a//o8/ud?be=o8 without verifying server certificate; no CA path was specified.
Generated checkid_setup request to https://www.google.com/a//o8/ud?be=o8 with assocication AOQpcUfj9hGDs4DukDUrxhChnVBMbtoKAlXgvzQ1dp1L0yp6wCDxeFlx

The fix is pretty simple.
a) In your config/environment.rb file add the line
OpenID.fetcher.ca_file = "#{Rails.root}/config/ca-bundle.crt"
b) You'll need to get a ca-bundle.crt file. You should add in certificate authorities that you trust. If you are in a hurry, you can use the one in the ruby-openid-apps-discovery gem. Unpack it and find it in the lib directory. I copied mine to my application's config directory.