Hackatron

The Italian Ruby community organizes an annual meeting: the italian RubyDay. This year it was the third edition of the event, held in Milan on June 14th, 2013. Two Hackatron’s members had been able to attend it and here you find a brief review of the talks and the event in general.

Talks

The schedule was pretty dense, with two parallel tracks. A lot of attention has been put on software patterns and code design. Overall, the talks were interesting and the speakers did a good job in entertaining the audience.

A Rails Criticism

The day started with a critic to Rails by Luca Guidi.

Luca first highlighted some problems in the choices Rails does for you. For example, talking about ActiveRecord, the fact that Model != Record (a.k.a. fat models), the common use of implicit API instead of implementing a method with an explicit meaning and callbacks abuse (raise your hand if you have never sent an email in an after_save callback).

Moving to the ActionController world, the main issues are Frankenstein Controllers that commonly violates the simple responsibility principle (indeed a controller does routing, via redirect, and are also in charge of rendering pages), controllers are odd classes (e.g., you never ever instantiate a controller), use of class variables passed to the views’ templates which is a clear example of encapsulation violation.

Luca then presented some solutions: decouple logic from AR as much as possible, let public API to declare intent, keep AR methods (and accessors) private as much as possible, extract ad-hoc classes with the aim of having skinny controllers and skinny models, use presenters and refactor a lot. It’s been a really nice talk and Luca is a good presenter.

Redis and Ruby like a pro

After that it has been the time for Stefano Fontanelli to talk about Redis and Ruby.

The talk focused on the design of a reliable queue system to manage the process of mining big data. Stefano, which work for Gild, showed how to use Redis’s queues to distribute jobs among a set of workers in a reliable fashion: his solution involves a processing queue keeping track of jobs being, you guess it, processed so that if a worker die you have a way to get back staled processes.

The backend-toolkit github project implements such a system in Ruby. You can find useful concept within that code, for example the implementation of a locking strategy.

In the afternoon Francesco Laurita, another guy from Gild, had a talk on rolling your own web crawler which also involved Redis. In this case Redis has been used a way to share memory over TCP/IP. The project presented is on github under the name of polipous together with other cool projects by Francesco which are really worth a mention: redis-bloomfilter and redis-queue.

All in all it seems that Gild is a really active company in the open source scene: as we get it, a lot of the project which they work on and are not specific to their business are released to the community. Well done guys!

Fat models must die

The morning session has been closed by Fat models must die. Ju Liu and Stefano Verna took the stage for what has been (in our humble opinion) the best talk for this year RubyDay.

They first noted that following the “Fat models, skinny controllers” philosophy often leads to put all the application logic inside models, which thus become God objects: these are omnipresent and basically own too much responsibilities.

Applying the Single Responsiblity Principle to ActiveRecord and ActionController one can state that the first are in charge of persisting data to a DB while the latter manage HTTP requests and responses. The latest version of Rails introduced ActiveSupport::Concern which is the solution proposed by the core team to have a separation for the application business logic. However, Concerns does not avoid run-time God objects (see Ju and Stefano’s slides with note for all info) and also do not favourite composition over inheritance.

The right path is then to apply well-known software design patterns. The speakers show-cased some examples of applying Value Object, Command Object, Query Object, Decorator, Presenter and DCI patterns. I really recommend you to review the slides.

Ju and Stefano really did a great presentation, they have been able to keep attention high and not fall us asleep while talking of topics which can sometime seems boring (they are not!).

These have been the three talks we enjoyed the most. A particular mention goes also to Claudio Ortolina and his Cooking lessons with Vim and Tmux which has been really interesting and full of useful advice on Vim (the only real editor out there :P).

The Event

It is always fun to meet with the other guys of ruby-it and this is also really important to make the community grow.

The organizers did a very good job: all attendances had a morning coffee break and lunch included in the ticket (which had the really affordable price of 30 euros). The location was also nice, the event had been hosted by University of Milan-Bicocca, and quite easy to reach by public transport. If there is one thing missing, it was wifi connection, even if this could have helped us keep attention to the talks.

If you love Ruby and you are Italian (or have the chance to pass by Italy in the right period), be sure to add the Italian RubyDay to your list of “don’t miss” event: let’s make the Italian Ruby community grow!