Almost every software developer I know is fascinated by software architecture and design. High-level architecture and design patterns are concepts that beginner developers least understand. For most of us, programming is relatively easier to learn; usually good aptitude and decent logical skills are enough to be a good programmer. But architecture is altogether a different beast to handle. It is more of an art, and usually takes years of experience to master.
In this chapter, we will focus on:
Understanding architecture and design from a practical viewpoint
Architectural styles
What Design patterns are
Different stages of a project lifecycle
Difference between tiers and layers
There are many different definitions of software architecture scattered across the web, in reference materials, and in books. In the wide world of programming, many of the definitions you may find are most likely going to be extremely technical in the language they use, and can be difficult for a beginner to fully grasp and understand. There are even places on the web that list thousands and thousands of different definitions by leading software architects, engineers, doctors, philosophers, and professors. (Reference: http://www.sei.cmu.edu/architecture/community_definitions.html).
To begin with, let's start with a technical definition:
Software architecture is an abstraction, or a high-level view of the system. It focuses on aspects of the system that are most helpful in accomplishing major goals, such as reliability, scalability, and changeability. The architecture explains how you go about accomplishing those goals.
Now we will translate this definition into something simple, generic, and easy to understand:
Software architecture is a blueprint of your application.
To elaborate more on the "blueprint" part, let us try to understand software architecture with a simple analogy—the process of casting.
Casting is a manufacturing process in which a liquid material is poured into a mold that contains a hollow cavity of a desired shape. The liquid is then allowed to cool and solidify, taking the shape of the mold it was poured into. The mold is the guide that shapes the liquid into the intended result. Keep in mind that the mold can be of any shape, size, or dimension, and is separate or unrelated to the liquid that is poured in.
Now, think of software architecture as the mold and think of your project as the liquid that is poured into this mold. Just like casting, software architecture is the guide that shapes your project into the intended result. The architecture of a software system has no strict relation to the actual code that is written for this system. The architecture simply makes sure that the development process stays within certain defined limits.