Monday, June 29, 2009

Using Twitter OAuth with Rails + sample

I've been using rails with the Twitter REST API of late, using the oauth gem as the base. It works well, but keeping up with the API changes can be a challenge!

In the recent update to OAuth 1.0a, there were two critical changes required:

Web-apps should specify the oauth_callback


Through trial-and-error, I found that if you don't explicitly specify the oauth_callback when going through the authorization process, twitter will halt at the PIN page (behaving as if you are using a client application). That's easily fixed..
request_token = consumer.get_request_token( :oauth_callback => TWOAUTH_CALLBACK )
session[:request_token] = request_token.token
session[:request_token_secret] = request_token.secret
# Send to twitter.com to authorize
redirect_to request_token.authorize_url

NB: the root cause is that oauth 0.3.5 sets "oob" as the oauth_callback if you don't explicitly set it. This triggers the twitter desktop PIN flow.

Include the oauth_verifier when exchanging the request token for an access token


Next, the major change in 1.0a was to add an oauth_verifier parameter. Twitter sends this back to you after the user has authorized access, and you need to include this parameter when exchanging the request token for an access token.
request_token = OAuth::RequestToken.new(consumer, session[:request_token], session[:request_token_secret])
access_token = request_token.get_access_token( :oauth_verifier => params[:oauth_verifier] )


An example application


I've created a minimalist application that demonstrates the twitter API with OAuth 1.0a in rails. I've set this up to run at heroku.

The source is at github for all to share: http://github.com/tardate/rails-twitter-oauth-sample/tree/master

And there's a running demo site at http://rails-twitter-oauth-sample.heroku.com.

Tuesday, June 23, 2009

Running Heroku on Windows

What! Do rails development on Windows?

I've raved about heroku before, and it still roasts my bacon.

In recent months, there's been a bit of a switcheroo - first the migration to herokugarden, which retains all the original online editing and hosting. The perfect solution for hobby projects or prototypes. Now I'm migrating back to heroku itself, which has become their solid production hosting facility for rails applications.

As Sarah Mei reported, the heroku gem (used to create and manage your heroku application instances) had problems running under Windows, due to gem dependencies that do some decidely un-Windows things.

There is now an updated heroku gem (1.0) that I just tested out, and am happy to say it is now working fine under Windows. There are some dependent gems and it can be required to make sure you get the version that specifically supports windows. That used to include json, but at the moment the main version-pegged gem I'm using is sqlite3-ruby (at 1.2.3 instead of the head at 1.2.4)

$ gem install sqlite3-ruby -v 1.2.3
$ gem install heroku
Successfully installed heroku-1.0
1 gem installed
Installing ri documentation for heroku-1.0...
Installing RDoc documentation for heroku-1.0...

Perfect! Testing it out..

$ rails myapp
$ cd myapp
$ git init
$ git add .
$ git commit -m "init"
$ heroku create myapp
Created http://myapp.heroku.com/ | git@heroku.com:myapp.git
Git remote heroku added
$ git push heroku master
Enter passphrase for key '/d/MyDocs/My Dropbox/Config/Security/ssh/id_rsa':
Counting objects: 65, done.
Compressing objects: 100% (58/58), done.
Writing objects: 100% (65/65), 80.48 KiB, done.
Total 65 (delta 14), reused 0 (delta 0)

-----> Heroku receiving push
-----> Rails app detected
Compiled slug size is 80K

-----> Launching...... done
App deployed to Heroku

To git@heroku.com:myapp.git
* [new branch] master -> master

Sarah gave the hint as to how to fix the older heroku gem (0.9.1), and has a forked version on github. A few people collaborated to fix up the code there so no longer any script editing required (basically to remove any dependency on taps for the gem build). Installing Sarah's version involved cloning the repository, building the gem and performing the local gem installation:

$ git clone git://github.com/sarahmei/heroku.git
$ cd heroku
$ gem build Rakefile
$ gem install heroku

Tuesday, June 02, 2009

Java Puzzlers. Be Afraid of the Dark.


Apparently, Joshua Block and Neal Gafter started the "Java Puzzlers" idea at Oracle Open World 2001. I wish I was there.

Subsequently, they've turned it into a book
, and a website.

If you program in Java, you must read this book. It covers the kind of traps in your code you wouldn't even imagine could be there.

I can guarantee you have written at least one of these issues into your code. And QA never caught it. And it is out in the wild RIGHT NOW. Arrgh!!

These days, I think (and hope) that most professional developers are relatively atuned to coding security issues and the rise of opinionated testing methodologies (Unit testing, TDD, BDD etc).

But this book is a real eye-opener to the range of issues that you wouldn't even think worthy of a unit test case.
public static boolean isOdd(int i) {
return i % 2 == 1;
}
Seems like a reasonable test for odd numbers? Except it is wrong a quarter of the time.

And that is just puzzle #1.

The book takes you through issues with strings, loops, classes, libraries, all the way to puzzle #95, where you learn why you shouldn't program like your brother.

Get a flavour from this presentation on Scribd from JavaOne 2007... Java Puzzlers me java puzzlers from javaone 2007