On Architecture

The other day, a coworker told me that they want to improve their architectural skills. That brought up a number of questions for me. What is architecture and how does it differ from programming? What are traits of a good architecture? What about a good architect? Am I a good architect?

"Traits of a good architecture" is something that gets covered in a lot of CS textbooks: extensibility, security, resilience, and so on. However, concentrating on those traits won't make you a better architect.

I don't know what will improve your architectural skills, but I do know what I think about when I'm working on architecture. I don't necessarily architect by reason. I have "good code" values, and I evaluate all the code that I write or encounter against them. For example, I think that exceptions (if available) should be used to signal the presence of and to recover from erroneous conditions. Status codes are straight out, and "fixups"[1] are a bad idea, too. Only in rare performance-critical areas are other mechanisms appropriate.

Where did I get my "good code" values? I've built them up from my personal and professional experience. I've been writing toy programs for 18 years. A lot of that is useless today, but some of those experiences have taught me valuable lessons. Just like a master carpenter didn't acquire his skills overnight, a software architect needs to develop his skills over a period of time. Trying, failing, reading, watching, discussing, and reflecting are all useful for developing this sense.

Just like other developers, I like to program. In fact, for an architect, it's essential to get one's hands dirty. However, it's also important to know when to step back and look at the big picture. For me, it's all about relying on that design "sense". When people talk about code smells, it's because something smells rank to their design sense. On the other hand, it's important not to get paralyzed by that sense. If you're unsure what direction you should be heading, it might be time to try something. Commit your current work (or, if using Git or Mercurial, create a new branch) and try going down a path. Keep your eyes open along the way, and learn what works and what does not. If you have time, try the other path. It might also make sense to start a new "toy" project to try some ideas without being burdened by the current code base. Also, be ready to revert all of your changes. Most of the work in programming is wrapped up in the thinking. Once you know how to do something, it should be reasonably simple to reproduce your work[2].

Finally, I'm a big fan of deciding on a direction and pursuing it. Sometimes, you don't know what to do, and it's too much work to mock up or try out even one approach. In this case, I ask myself how I would want it to work, and I try to do that. I ignore technical constraints unless they are insurmountable. Blindly following a path because it is "right" can get you into a lot of trouble, but so can meandering about without any goal in sight.

What do other people think? What is architecture to you, and how do you improve those skills?

[1] In this case, I'm talking about code which detects invalid input or state (which is a good thing), but then changes the input or state to be valid. An example would be a function with a parameter whose value needs to be in the range [1, 1000], but which will assume 0 for any invalid value. This makes the function always terminate normally (after all, there are no longer any invalid inputs), but it doesn't necessarily ensure correctness of the program. Who's to say that 24124142 and 0 are equivalent, anyway? Exceptions are better because they allow the caller, not the callee, to determine the result in the case of an invalid condition.

[2] If, on the other hand, most of your programming effort is spent on pushing keys on a keyboard, you're in a difficult position. Programming is primarily a thinking man's game, not a typing man's game. Your goal should not be to generate the most code in a day, but rather to generate the most value per line of code. Partially, then, your goal should be to keep the number of lines of code to a minimum. Removing code while retaining functionality, flexibility, and performance is always a good thing.