39.tex

Context is King

I feel there is a certain irony in trying to impart something about architectural ideals, when the very premise I wish to begin with is that effectively there are no ideals. If this is indeed the case, then surely there is nothing to write, I am a contradiction and by doing this I run the risk of the universe imploding or something like that.

But alas, ceci n'est pas une pipe.

One of the most valuable lessons that I have learned as a software architect is that context is king, and simplicity its humble servant. What this means in practical terms is that context is the only force that trumps simplicity when making architectural decisions.

When I say context, I refer not only to high-level, immediate forces such as key business drivers, but also to elements in the periphery, such as emerging technologies and thought leadership on diverse topics. Indeed, good architects keep track of several fast-moving targets.

What constitutes good architecture? It is the product of decisions made within a context usually tainted with multiple competing priorities. Those competing priorities mean that sometimes the most important decisions are not about what you put in, but rather what you omit. The currency of good architecture is simply astute decision-making (while the products are all only about communicating your intent).

Historically, there have been some fascinating examples of the influence that context can have on architecture. A favorite example involves the database selected to support an ambitious new software system for a modern battlefield tank [1]. (Deciding what database to use is not usually architecturally significant; this example merely serves to illustrate a point).

When it came time to choose the database, the team assessed many. They found that while the tank was moving quickly over undulating terrain while tracking a target, the majority of the databases were capable of supporting this maximal throughput required of the navigation and targeting systems. But they were taken by surprise when they discovered that firing the main gun on the tank caused such a strong electromagnetic pulse that it totally crashed the on-board systems and of course the database along with it! On a modern battlefield, a tank without its software running is quite literally in the dark. In this context, recovery time was the overwhelming factor in the choice of database, and no database did that better at the time than InterBase [2], and that is why it was chosen for the M1 Abrams tank.

So, while newsgroups rage with the flames of technology debates of X vs Y, it is idle amusement. The reason these debates rage is often not because of huge disparities in their technical merits, but rather because there are more subtle differences between them, and what features individuals value more than others when there is no guiding context to act as a trump card.

Your team should be free of ideals, reflect on context in the first instance, and reach for the simplest solutions from there.

By Edward Garson