Building Evolutionary Architectures

Chapter 1. Software Architecture

Developers have long struggled to coin a succinct, concise definition of software architecture because the scope is large and ever-changing. Ralph Johnson famously defined software architecture as “the important stuff (whatever that is).” The architect’s job is to understand and balance all of those important things (whatever they are).

An initial part of an architect’s job is to understand the business or domain requirements for a proposed solution. Though these requirements operate as the motivation for utilizing software to solve a problem, they are ultimately only one factor that architects should contemplate when crafting an architecture. Architects must also consider numerous other factors, some explicit (e.g., performance service-level agreements) and others implicit to the nature of the business (e.g., the company is embarking on a mergers and acquisition spree). Therefore, the craft of software architecture manifests in the ability of architects to analyze business and domain requirements along with other important factors to find a solution that balances all concerns optimally. The scope of software architecture is derived from the combination of all these architectural factors, as shown in Figure 1-1.

Figure 1-1. The entire scope of architecture encompasses requirements plus “-ilities”

As seen in Figure 1-1, business and domain requirements ...