The second day of the conference was even better than the first, in my opinion. There were several more talks which I was eager to hear. Here’s an overview of the second day’s presentations:
- Creating Rails Plugins by Chad Fowler and Bruce Williams
- The Presenter Pattern by Marcel Molina, Jr.
- The Deployment Golden Path by James Duncan Davidson
- Testing Rails Apps by Stu Halloway
- Red, Green, Refactor by Jim Weirich
- Building View Frameworks by Bruce Williams
- Lightning Talks
Read on for my notes. First up were Chad and Bruce who went through Creating Rails Plugins. Never having created a Rails plugin before, I was very interested in the process. They started by providing an overview of the plugin script and then the generate plugin script. Next they showed how you can provide your own controllers (in the lib subdir) and views (in the views/‘plugin name’ subdir), rake tasks (in the tasks subdir), models (right at the top-level of your plugin) and your own generators (in the generators/‘plugin name’ subdir). The remainder of the talk walked through the creation of their acts_as_ratable plugin. Marcel followed that with his talk on the Presenter Pattern. He was quick to point out that this is not a design pattern in the style of the Gang-of-Four book (especially since previous presenters had made derogatory comments about design patterns and their utility). The presenter pattern is basically a way to organize a chunk of view code. He started off with a discussion of the problems with helper modules, how they become a dumping ground for methods (one suggestion was to break-up your helpers into smaller modules organized around specific functionality and then include those in your helper). A comparison was made to the ‘method object’ in Kent Beck’s Smalltalk Best Practice Patterns (linked at bottom of this post). To finish, Marcel gave a brief demo of this but it’s basically vaporware at this point and didn’t have a date for when it would be released. JDD was up next with his talk on Deployment. He stressed that it was important to start deploying your app as soon as possible in the development cycle (he suggested that you do it at the same time you set up your Subversion repository). This is necessary to find all of the “interesting” deployment problems up front, so you can get into the deployment rhythm and so that you can show others what you’re working on for feedback. You just need a machine that works well enough, he suggested a Mac mini, but some folks in the audience suggested a virtual machine on the same box — Duncan said that while that might work he prefers having another machine to deploy to. The only deployment solution that he recommends right now is Mongrel fronted by Apache, Lighty, Pound, Pen or a hardware load balancer. Then he went on to describe what he calls ‘the golden path’ using Capistrano, Subversion and Unix machines. At the end he gave a live demo deploying his app to an Amazon EC2 machine. After lunch, Stu presented on Testing Rails Apps. Perhaps I’m insecure about my testing and test coverage (though Mike Clark’s rcov Rake task certainly provides peace-of-mind), but I always find myself very interested in the testing methodologies of others. Stu started off by discussion the reasons to write tests (tight feedback loop, easy refactoring, early warning, cheap measure of success and that it makes bad code painful). He went through testing models (ensure your tests are self-documenting, test everything in sight and then evolve your own style), fixtures (YAML, always use valid data, use ERB for dynamic data), controllers (check out the scaffold: it tests responses, redirects, model updates and uses restful verbs), managing your tests (group and run using rake, manage your fixtures with rake, put your common tasks in test_helper.rb). He then went through an example of testing a space station w/o having access to a rocket, so he used flexmock to mock one up, like this:
~~~~ {lang=“ruby”} def test_refuel_with_mock_recorder rocket = flexmock(“rocket”) rocket.should_expect do |rec|
rec.dock.ordered
rec.attach_fuel_hose.ordered
rec.add_fuel(Integer).returns(50).ordered
rec.detach_fuel_hose.ordered
rec.undock.ordered
end @station.refuel(rocket, 50) assert_equal 950, @station.fuel end ~~~~
He then went on to recommend rcov and said that you should have 100% of your code covered. He ran out of time before he could cover the Cerberus continuous integration tool. Jim Weirich sat down for a live coding presentation entitled, “Red, Green, Refactor” in which he demonstrated test/behavior driven development. The steps were:
- Write a new test and watch it fail
- Write just enough code for the test to pass
- remove duplication, clean up, etc. and repeat
He spoke in terms of dividing your perspective into two parts a Dr. Jekyll who writes a test that forces you to write the code you need and a Mr. Hyde who deliberately writes the minimal amount of code that passes the tests. His demo seemed pedantic at first, but because you have this extremely lazy Mr. Hyde you really have to think about your tests and write them such that you force the implementation to be correct. Bruce Williams spoke about Building View Frameworks and made the example code available at his site. I was really looking forward to this talk and Bruce didn’t disappoint. He started off discussion the traditional methods of DRYing up your views: Helpers, Block Helpers and Partials then he went into REST DRYing with the simply_helpful plugin. Next he went into some new territory for me, DRY interactions by creating a controller DSL, controller plugins and “big frameworks” as he called them. He gave examples of this from his work at Naviance: folder_for (which created a tabbed view for the different folders), paginated_index which was a controller DSL, roster_for (which was very similar to paginated_index) and a calendar which was a controller plugin. Bruce suggested using plugins and writing your own and contributing them back to the community as well as testing your views with Watir or Selenium. Following the presentations, were the lightning talks. I was unable to stay for all of them but some of the more notable ones were: Aaron from Revolution Health demo’ed their huge web app (or more accurately collection of integrated web apps) and spoke about their PluGems solution which has been document on their blog. It looks like they’re really doing some interesting work and having a lot of fun doing it (plus I’m jealous of their development environment — I wish my employer gave each of us MacBook Pros instead of Lenovo ThinkPads); Next Jared Richardon, author of Ship It, spoke about his consulting work on a new search engine site called ChaCha and how they scaled Rails by removing ActiveRecord in production. They use Rails as normal during development and then extract out all of the SQL queries and tune them for production; Mark Cornick gave a quick run-down on the service manager framework in Solaris and how he used it to launch his Rails app when the machine boots. Since we use a fair amount of Solaris at work and I’m not that familiar with this feature, I found his talk quite enlightening. The presenters have really been pimping Kent Beck’s book, Smalltalk Best Practice Patterns — so of course, I picked up a copy.