Saturday, 26 February 2011

True Names, and Other Dangers: What Dr. Seuss Can Teach Us About SoA

Did I ever tell you that Mrs. McCave, Had twenty-three sons, and she named them all Dave?

Well, she did. And that wasn't a smart thing to do; You see, when she wants one, and calls out "Yoo-Hoo!
Come into the house, Dave!" she doesn't get one; All twenty-three Daves of hers come on the run!

- from “Too Many Daves” by Dr. Seuss

They say there’s only two hard problems in software – cache invalidation, naming things, and off-by-one errors. Cache invalidation’s hard because it’s difficult to clarify requirements. Off-by-one errors are hard because the joke wouldn’t work without them. But naming things? How hard can that be?

The If you’ve ever worked in IT support, you’ll have had calls saying “the system is down”. Sometimes, a more enlightened caller will helpfully tell you that it’s ‘the network’ or ‘the database’ that’s broken. I once started at a job where everybody referred to everything as “sequel.” There had been a big database migration a few years earlier, resulting in a new website and new desktop software, and the whole process had been referred to as “upgrading to SQL Server”. Everyone kept hearing the techies talk about “upgrading to sequel”, and so when they got something new on their desktops, they conclude “Ah – this must be that sequel thing that everyone’s been talking about!”. Two days later, they call you up and say there’s a problem with ‘sequel’ – and in this context, ‘sequel’ could refer to just about anything. The name was overloaded to the point of uselessness.

“Ah yes - but it’s
services
all the way down!”

What’s scary is that this happens all over the industry. People talk about “Software as a Service”, when what they’re actually dealing with is an XML web service, that’s connecting to a WCF service hosted in a Windows service to provide a business service. Like dear old Mrs. McCave, we’re finding out that names are great if they’re unique, but when different things start laying claim to the same names, you’re going to end up cross-eyed.

So, as my team start teasing apart our proverbial big ball of mud, I’m trying out a new naming policy for the new components and modules we’re building. Pick a word that sounds nice and doesn’t mean anything within our business.

The last three projects I worked on were called Rosemary, Tarragon and Kamogelo. No namespace conflicts, no semantic overloading and no clashing with reserved keywords. Rosemary’s almost like an employee – it has an event log, and a mailbox, and a sufficiently clear sense of identity that people seem to get it. When they say there’s a problem with Rosemary, they’re right; it doesn’t take 15 minutes to work out what they mean, and that’s a good thing. It also encourages clear separation of concerns, and facilitates good discussion thereof – lots of “does this feature belong in Rosemary or Tarragon?” instead of just adding another class to the legacy codebase.

So it’s goodbye, “customer e-mail service” and “accounts system” and “web shop”, and hello to Sundance, Monolith and Aquarius. And before too long, Moonface and PuttPutt and Shadrack, in recognition of dear old Mrs. McCave.

1 comment:

HolyTshirT said...

We code name projects too, find it works well. Ours are generals, ike ()Eisenhower, apache (Geronimo), monty (montgomery). Once spend so much time finding a name, I called it Bob and it stuck.