Monday, 1 July 2013

"Easy Credit" IS "Easy Debt". It sucks for finance. It sucks just as much for your code.

One of the great things about the Rails ecosystem is that there are lots of different tools that can save you time and pain during development. Some of them work by embracing and extending the Rails standard bits, like replacing (nearly) bog-standard ApplicationController subclasses with subclasses of InheritedResources::Base. Some of them instead swap out pieces of the original Rails stack, like replacing ActionView with Erector or something similar. I wouldn't be at all surprised if my current app that mixes the two practices (in different areas) isn't at all unusual.

But whichever route or routes you choose, you need to constantly remain aware of that choice, especially when considering new tools you'd like to incorporate into your app. And you may also find that the tools you're using, while superb for their intended purpose, complicate other choices you make in the course of developing your project. A tool which was the greatest painkiller since morphine when you first picked it up, now seems to be "getting in the way" as you get farther along in development.

As practitioners of agile development, this shouldn't scare or even surprise us (though our non-technical stakeholders may initially be less sanguine). Good agile architecture says that everything in your app other than the raw business rules is an implementation detail that should be testable and fully replaceable in isolation.

Novice to journeyman Rails developers may be forgiven at this point for saying "but that's the way Rails is; it all works together, even though you can swap pieces out as you like". A majority of Rails developers have at least experimented with swapping out Test::Unit for RSpec, or erb for Haml or Slim. More adventurous still are the folks who swap out the ORM, replacing ActiveRecord with, say, DataMapper or the aforementioned Erector for ActionView. Why are they trying such things? Because they're asking (quoting Wynne again), "what does a modular Rails architecture look like?" Or, "we know we've hit the wall with our current (connected) architecture; everything we touch introduces new tech debt if not outright breakage, but we don't know how to do anything else and stay true to The Rails Way."

That "wall" you've hit has nothing to do with the number of lines of code you've written nor the number of unique visitors your production app serves per day nor the revenue your app is bringing in the door. You've realised that your ability to keep bringing in that revenue, let alone increasing it, is dependent on you somehow reconciling your understanding of "agile development" and "software engineering-style practices" with "the Rails Way". One of these things is not like the others. If you haven't yet, watch both of those videos. Particularly in Matt Wynne's talk from about 5:30 where he talks about the crossover point between a "connected" architecture being cheaper/faster/better giving way to a "modular" one… that rings a lot of bells for me. Likewise when Uncle Bob rails against Rails apps screaming "I'm a Rails app, never mind what I do". I've done several projects, never mind how many, where I've gotten to that point (which Wynne describes as "hang on; I don't want to work on that application anymore. Something's seriously wrong with it") and my reaction to the realisation that "something is seriously wrong" has been to stop, look at everything I'm doing and evaluating how well I'm following convention, "best practice" and so on, come to the conclusion that I'm doing everything exactly the way I've been taught it should be done, and deciding that that proves the fault is in my understanding of the problem, so I start over, from scratch, trying to figure out where I fell off the cliff. With one application, that involved at least five restarts over the course of a year and a half… and I must have always "fallen off the cliff" at the same spot, because I never saw it coming before I realised I was at the bottom of that cliff once again. "Uncle Bob" Martin's keynote (from Ruby Midwest 2011) does a great job of explaining why an experienced OO software developer like me has always felt uncomfortable with Rails' interpretation of the "Model-View-Controller" architecture. By writing your app centred on what the app is for rather than how the app presents itself on the Web, you make your life a lot easier and more enjoyable. Looking back at my commit history over the last year and a half, I see that well over 2/3 of the times I was "stuck" for more than a couple of hours had more to do with "how do I adapt what I'm trying to do to how Rails wants me to do things" than "how do I implement (this feature)". That should, and has been, setting off all kinds of alarm bells; I'd just drank enough of the Flavor Aid to think that pain level was "normal" for Rails. It shouldn't be.

Going forward, my strategy for Rails development is going to work something like this:

  1. Model the domain objects (Martin's "interactors", "entities", "boundaries" and "entity gateways", after Jacobsen "control objects") as POROs (Plain Old Ruby Objects);
  2. Wrap those up in Gems whose use can be demonstrated by specs, supplemented by a simple (Web or JSON or command-line; doesn't matter) example or set of examples.
  3. Plug those into a Web app using the current framework of choice (Rails, Padrino, JoeBobsAwesomeFramework, or whatever), whose sole purpose is to implement the "client" side of the boundary layer and present what comes back over the fence.

Now we're back to something more closely approximating classical agile development that focuses on delivering business value, not playing mind games with a tool that insists on making most of the important decisions for you, and makes them in ways that make it harder for your app to be scalable, performant, or fun to work on. Or even for your app to be finished.


P.S. Oh, and as far as InheritedResources::Base, that truly useful tool for Rails app development I mentioned before? We'll continue to use it as a default, but if we choose to use tools that "get in the way" (like wisper) by wanting all your methods explicitly defined, we'll switch back to ApplicationController, on the theory that making the puzzle one piece smaller without affecting how the other pieces fit together is a Good Thing™. But that's another decision we want to defer as long as possible; "good architecture" is all about deferring as many decisions as possible as long as possible, while still getting business value done.