Asmir Mustafic has kicked off a new series on his site with an introduction to modular application architectures. In the series he will work through the creation and management of modular applications as inspired by a session he attended in 2011.

When developing a software, one of the most common steps is taking care that the resulting application is extensible and modular.

Let's suppose we have our application or library. If we see it from outside, often it looks as a single thing. [...] As the application grows we can continue adding components... but this comes with a price. Components often knows too much of our application and there is a delicate equilibrium of dependencies between them and our application. When not handled carefully, a small change in one component might require changes in many other.

As a rule of thumb, I personally try to follow as much as possible the Acyclic dependencies principle Another way to allow extensibility but keeping the application "clean" is to introduce modules.

He starts by talking about modules and the major part they'll play in the overall architecture. He explains why modules are so key to the overall structure and what kind of advantages they bring along with their use. He spends the remainder of the post looking at some of the main challenges they'll face including the file/directory structure definitions, module registration methods and the configuration of each of the modules.