Notes from NH Ruby/Rails Group, 20-May-2008

Five members attended the May meeting of the New Hampshire Ruby / Rails group, held as usual at the offices of RMC Research in Portsmouth.

Nick Plante entertained and educated the group on Rack, a foundation layer that interfaces between the web application handler (like Mongrel or FastCGI) and the actual web application framework adaptor (like Merb or Camping or Halcyon or Sinatra) in a manner similar to the Python WSGI layer. It allows for the creation of custom web frameworks while removing a lot of the grunt work. Nick had a sample application whipped up where a few lines of code could define the routing of various requests and cleverly answered “Hello, World” to the correct RESTful query.

For those for whom Rails isn’t the complete answer or those who want to build their own web functions with components other than those used by the Rails framework, Rack is a foundation on which you should be plugging together your building blocks.

Brian Turnbull volunteered to fill in for Scott Garman, who had to cancel at the last minute. Brian had been using NetBeans only a brief while, but had a great story to tell on using the built-in debugger to trace out a problem with Rails-generated CSS meta tags always getting a cache-breaking URL. While a feature in development, when the CSS was being served from a caching store like Amazon’s S3, the ever-changing URL defeated the point of caching. Brian showed how breakpoints could be applied to the code and step-by-step tracing (why is it that all debuggers have Step-In, Step-Once, Step-Over, Step-Out icons that all look the same and can’t be told apart?) and walked from his code into the Rails framework down to the mis-behaving component.

Having identified the problem, our discussion took a tangent into a discussion about monkey-patching, and how this ‘feature’ was a bug deserving of an optional switch to disable, and ought to be submitted upstream to the Rails maintainers. To confirm, we went through the steps to grab the latest version of rails as a plug-in (gem? I’m not sure.) so that we were working with the latest ‘edge’ code to confirm the problem hadn’t already been fixed. By installing this way, we were overriding the Rails framework only for this application, and could easily revert to the stable version, without disturbing the main shared code on the machine. We talked about how this was a Best Practice when bringing an app under development up to production, so it was isolated from changes outside of the app’s control.

Plenty of time was available for discussion, and we talked with Tim a bit about configuring a new machine with all the tools he’d need to develop a Rails app with NetBeans: Ruby, Rails, a couple good gems, the Java runtime. Nick and Brian noted that the default Rails environment within NetBeans is JRuby not MRI (Matz’ Ruby Interpreter) and how you might want to reconfigure NetBeans to use MRI instead if you weren’t planning on deploying to a JRuby environment.

Thanks to Nick and Brian for their presentations, to Scott for arranging the meeting, to Tim and RMC for providing the great facilities and to all for attending the meetings! Discussion is ongoing now on the topics for the June meeting; join the mailing lists at http://mail.nhruby.org/mailman/listinfo/ and keep an eye on the new meeting plans at http://wiki.nhruby.org/index.php/Upcoming_meetings.

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