While preparing a talk on module systems and architectures I remembered some old talks I listened to talking about architectures and arguing why an explicit software architect is necessary within professional projects. Many of them used the analogy of building a dog-house versus building a cathedral. For a small dog house, you don't need an architecture. But for the cathedral you do. Hm, agree, but where is the point?
I think the world has changed. Today for most software systems the analogy of building something like a cathedral is no longer a good choice. And I hope that people no longer have a cathedral in mind when designing software. We have learned that building software is a learning process, that requirements change all the time, that we need a short time-to-market, and most of all that we need feedback all the time - and react to this feedback quickly. Agile methods reflect this and allows us to move forward to modern ways of software development.
But our view on architectures need to reflect this. Modern software architectures need to be build for flexibility, for changing requirements all the time, for changing even fundamental layers of our software in a flexible way without causing tremendous costs. Having a cathedral in mind don't help you here. But if you still like the analogy of building real buildings (even though I think this is not always a good analogy to building software at all), you should take a look at some modern office buildings. Maybe they are not as beautiful as some of the old cathedrals, but they are built for flexibility.
But building flexible architectures is not an easy task. We need to build a flexible architecture and at the same time just what we need without designing all possible stuff upfront. Sounds like contradictory goals, eh? Hm, in some way, they are. I think modularity can help you to solve this conflict. Modularity (and I mean modularity on a higher level than individual classes or packages, but more something like Bundles in OSGi) helps you to think about dependencies, coupling, cohesion, and many of these nice design principles. And I think we all agree on having a good, decoupled design makes life easier when things change - and they will change.
