Thursday, February 9, 2012
Today I got to pair with Doug Bradbury on some Rails work. Doug is currently working on a new project, so we got the chance to lay some of the foundation of the app. All of the stories for the iteration are currently blocked because they are dependent on work being done by other developers, so we got they rare opportunity to spend the day refactoring. For this Rails app we are trying to use the Boundary, Interactor (Control), Entity pattern inspired by Uncle Bob. The goal of this is to make our tests much faster. By decoupling our business logic from our delivery mechanism, we will produce a better design that is easier to test. So we started by refactoring a controller action to not depend on an Active Record model. The required us to isolate the calls and return values from active record in our interactor (business logic module). Once we finished this we decided that we wanted to remove the dependency on Active Record from our interactor. So we started to abstract the calls to Active Record into Database transaction objects. These objects represent one transaction with the database in the same way that application interactors represent one business rule. So, we created one Transaction class title FindAuthorizationByNameAndUid. The name of transaction itself clearly represents what this module is supposed to do. It can be implemented using Active Record or any other persistence mechanism. Most importantly, it can be easily mocked out in tests my an in-memory equivalent. By the end of the day we were able to remove Active Record models from the interactor and put them into transaction objects. The refactoring of the code was really easy. Since our interactor was already tested, we made all the refactors that we wanted and the tests still passed. However, we were unable to refactor our tests to not use active record objects. This is little bigger of a task because the in-memory test double must be built first. So, I'm going to pair with Doug again in the morning to see if we can find a good way to test the interactor without using the Database. All in all, it was a very enlightening day on how to decouple application logic away from Rails.
Wednesday, February 8, 2012
Today I got the opportunity to pair with Craig Demyanovich. The first part of the day we attended a project retrospective facilitated by Uncle Bob. The retro provided a lot of context as to the history of the project, the team members, feelings about progress and the goals of the project. Essentially, the project is a "great big redesign in the sky". They have decided that their current application is no longer meeting the needs of the business, especially in the area of extensibility. As their business has grown, there has been an obvious desire to extend their application to serve more markets are more consumers. However, the architecture of their current system isn't able to support the growth of their business. So they have decided to redesign a new one. In some ways the new system is rebuilding the old application, but in many other ways, the new system is a "platform" in which to build other applications on top of. I say platform in a very loose way, because it's not really a platform. However, they have utilized service oriented architecture with the mindset that many other applications will need to consume the business logic that they are building right now. This is intelligent way to approach the problem of future extensibility. The complexity of the SOA has caused a few pain points along the way, however, the team seems to be handle the application very well by practicing the disciplines of TDD, pair programming, and continuous integration, all of which are new to the company. The team has done a remarkable job of coming into a fresh project and practicing disciples that they did not use on previous projects. The second half of the day, Craig and I were able to work on a few stories for the application. Close to the end of the day, we ran into an issue with the Ruby Date class. Our problem was simple, we needed to check that a given date was less than or equal one year from the current date. Here was our first try.
Finally! Both sides of the expression produce a Rational object which can be compared to each other!
However, this didn't work at all. The expression on the left side takes the current date and subtracts the given date, with yields a Rational, representing the amount of days between them. The right hand side takes the current day and subtracts one year, which yields a Date one year ago. So in the end we were comparing a rational to a Date which blew up. Our next try was
(Date.current - given_date) < (Date.current - 1.year)
This time the right hand side takes the current day and subtracts it from 1 year ago. However, this doesn't work either because
(Date.current - given_date) < (Date.current - 1.year.ago)
1.year.agoyields a DateTime object as opposed to a Date object, so this blew up too. So we massaged this a little to get it to work.
(Date.current - given_date) < (Date.current - 1.year.ago.to_date)
Tuesday, February 7, 2012
Today I had the opportunity to spend the day with Dave Moore on some client work. We were able to work on a few interesting stories throughout the day. Dave is currently on a team that is working on internationalizing a Rails application. I was able to pair with Dave while we tried to internationalize the social media widgets on the site, specifically the Facebook login, button, like button, and login window. This can be accomplished through calls to the FB API. However, we were seeing a very specific bug with Facebook's Api. When we opened the application in a specific language, say German, the Facebook button would render in German, no problem. Also, we could click on the login button and the FB Connect window would show up in German, no problem. Also, once we changed languages on our application, say we switched to French, the buttons would render find in French, all through the FB API, no problem. However, after changing languages in our application, the FB API login window would not change languages with us, even though the FB button was changing languages with us. After some searching we deduced that FB renders it's buttons solely off of the API calls you make to it, which can change on every page refresh. However, it renders it's login window based on the language that was specified when we first logged in, so we would see the window in German even though we had switched to French. We were able to track that FB was storing the locale information that we first gave to it within a cookie on the browser. So, our first instinct was to attempt to mutate the FB cookie every time we changed languages in our application. However, after some searching we found that altering cross domain cookies is not allowed. So, at this point we were essentially stuck. Facebook is going to render the login window based on the first API made to it. I definitely learned a lesson today about 3rd party dependencies. Even though they are extremely convenient at times, they come at a price of freedom. When you use a 3rd party library, you lose the freedom to manipulate every detail, and as I learned today, that can be a high price to pay.
Saturday, February 4, 2012
Thursday, February 2, 2012
Wednesday, February 1, 2012
As part of my Apprenticeship, I get the pleasure of going on a pairing tour with four 8th Light Craftsmen. While pairing, the Craftsmen will be working on client projects, so I will gain some exposure to our current clients and an idea of what client work is like. This also gives me a great opportunity to learn from the Craftsmen I will be pairing with. The tour also gives a few Craftsmen some exposure to me, which will allow them to evaluate me fairly at the end of my apprenticeship. Today marked my first day pairing with a Craftsmen, Eric Meyer, whom I met with at a client office. We worked on two interesting stories that kept us busy all day. A few things a took away from the day. 1) Eric really takes ownership of his development environment. He was able to navigate around his system very quickly. He has lots of bash aliases set up. He has even set up a special windowing system. Recently, I made a conscious decision to avoid extravagant customization of my development machine because it makes context switching (changing machines, pairing on someone else's environment, etc...) a lot harder. I want to stay flexible with my set up. However, after watching Eric today, I'm starting to rethink that decision. 2) Continuous Integration servers (done right) can be pretty sweet. The CI server at the client had a lot of cool features, such as testing a branch based on the branch name, testing and then merging branches automatically. However, the downside to the really cool CI server is that it takes 45 minutes to run the test suite (Ouch!). This makes it hard to get instant feedback. Yet another example of why Rails needs to be contained. 3) The client we were at had a really cool talk over lunch today about reusing client and server code via node.js. It was extremely intriguing. It looks great in theory and I would love to build an application to see how well it works out in reality. Hopefully someday soon.