Design Principles and Design Patterns

What is software architecture? The answer is multi-tiered. At the highest level, there are the architecture patterns that define the overall shape and structure of software applications. Down a level is the architecture that is specifically related to the purpose of the software application. Yet another level down resides the architecture of the modules and their interconnections. This is the domain of design patterns, packages, components, and classes. It is this level that we will concern ourselves with in this paper.