High level architecture [closed]

Question

Even if you are using Agile, you would need a high level architecture before you can start implementing the project.

By high level architecture, I mean dividing project into small parts, infrastructure stuff, distributed/web-based/thick client etc...

Are there any books/articles on this topic??

Answer 1

I've had this argument with Kent Beck on more than one occasion, and he would say that you're just wrong, that you don't need to make these architectural decisions, or rather that you should choose the Simplest Thing That Could Possibly Work and proceed from there.

The problem I see is that you can be a long way down the tracks before you discover that the STTCPW won't, in fact, work, and leave you with a lot of rework. Now, if you're doing things properly incrementally, or even better with a risk-driven model so you examine the riskiest decisions first, then hopefully you will have spotted these things relatively early, but there's certainly no guarantee.

The other side of that is that a whole lot of Agile projects are in contexts where most of the architecture is pre-determined, eg, Ruby on Rails or J2EE. Those systems reduce the risk considerably, because you have a decided environment.

I don't know of any particular books on the topic, although I'm thinking of writing one; this is still pretty much up for debate in the Agile Community.

Probably my favorite fora for this are Martin Fowler's bliki, and InfoQ, with the caveat that I'm about to start posting to infoQ and so may be prejudiced.

Answer 2

A good article on the topic is "Who needs an architect?" by Martin Fowler.

My personal take is that you probably need to make much less architectural decisions up front than you might think. If you just do enough to come up with reasonable estimates, you should do well.

You will need to pay close attention to design forces, and get good at refactoring, though. You will want to start practicing it as early as possible. Not having come up with an architecture up front should give you many opportunities. ;)

Will you make wrong decision? Yes. Will it take time to change the architecture. Sure.

But you also saved a lot of time by not trying to dream up an architecture up front. And, because at the beginning of the project you have the least amount of information, the up front architecture wouldn't be really "right", anyway. With some luck, it will "just" be overkill, more likely, there will also be decisions made that you'd better change later, too.

Regarding risk, remember that you should start developing the most important features first. That way, your architecture will in fact be build to support the most important features best, which is exactly the way it should be.

A good book you might enjoy on the topic is Robert Martin's "Agile Software Development - Principles, Patterns, Practices".