Software Pin Factory

Posted in philosophy software -

I started reading Adam Smith’s The Wealth of Nations. For fun. Because I’m a big dork. Right at the beginning, he talks about division of labor and pin factories. Pins: little bits of wire with a point on on end and a knob on the other. The point is that a single craftsman, without particular skill or tools, could only make a handful of pins a day. In a pin factory, the process is divided into more than a dozen stages, each simple and specific, with its own tools. This process is literally hundreds of times more productive. Businesses have been trying to pull off this trick ever since.

It worked fantastically well in the industrial age. As we moved into more of a service economy, the principle still applied, though not as strongly. In your typical office, you have specialization of skills: Managers, admin assistants, sales, marketing, and so on. In a one person company, that one person can cover all those roles. Things will go smoother when they can divide the work up among several people, but not by a factor of hundreds.

As software development has become a bigger and bigger business, the obvious thing has been to try to apply the same assembly line model: analyze, subdivide, specialize. And so we come to Enterprise Software development, which pretty much follows the old waterfall model: Requirements, architecture, design, implementation, test, support. The business analysts don’t write code, the architect doesn’t write test plans, and the programmers don’t field support calls. The business analyst writes a requirements document, the architect writes an architecture document, and so on. Each stage does their piece and throws it over the wall to the next team. The principle is sound: The more narrowly you divide up the skill set, the more specialized each group will be, and the better at their particular task. Push this far enough and eventually you can replace them with trained monkeys. Very clean, very elegant. Very efficient? Umm… no.

The problem is that there’s a significant difference between an Enterprise Software solution and a pin. A pin is a very simple thing. Everyone knows how it works and can tell at a glance if a given pin will do its job. Unless it’s bent, blunt or missing its head, it’s good to go. If an end user finds that one pin is poorly made, they just throw it away and get another.

An Enterprise Software system is not simple or obvious. Aside from the fact that even the customer often doesn’t entirely understand how they want it to work until they start using it, the amount of information that has to be communicated from stage to stage is huge. Requirements documents can be hundreds of pages. None of the workers has any innate sense of whether the information handed to them from the previous stage is complete or accurate. Every misunderstanding is multiplied down the chain. It’s like playing “telephone” with War and Peace.

The key here is that when you divide up the labor in a process, you also incur a communications cost between each stage. It’s a trade-off: Each stage can be done more efficiently, but information about the work has to be passed between them. In the pin factory, the benefit of specialization is huge, and the communications transfer is tiny - as I said, the quality of a pin is obvious. In a software shop, the benefit of specialization may be significant, but the communications overhead is enormous. To come at it from a different angle, I’ve heard it said that a programmer is lucky if they get to spend 20% of their time actually writing code. The other 80% is communications overhead: reading documents, sitting in meetings, writing documents. Add in the time you spend on rework due to miscommunication, and that 20% starts to sound generous. Here, the assembly line is actually less efficient.

So what do you do? The development of “Agile” tools and techniques is a response to this, along with component or service oriented architectures. Break the system up into independent, well-defined pieces, and put them in front of the users as quickly as possible. The catch here is that you can’t use trained monkeys. You need people who can talk to the end users and write code, who can carry the product all the way through the process. Maybe they need help from experts like domain specialists or QA engineers, maybe they can divvy up some of the work to tech writers or programmers, but the key is to capture an end-to-end understanding of the product in as few heads as possible.

Older article
Under the Hood