Fundamentals of Software Architecture, 2nd Edition

Chapter 7. The Scope of Architectural Characteristics

Software architects’ thinking must evolve with our ecosystem, and nowhere is that more apparent than in scoping architectural characteristics. Many of the outdated frameworks for determining architectural characteristics had a fatal flaw: assuming one set of architectural characteristics for the entire system. While that is sometimes still true, many modern architectures, like microservices, contain different architectural characteristics at the service and system levels.

The scope of architectural characteristics is a useful measure for architects, especially in determining the most appropriate architecture style to use as a starting point for implementation. When we were writing our book Building Evolutionary Architectures, we needed a technique to measure the structural evolvability of particular architecture styles. None of the existing measures offered the correct level of detail. The section “Structural Measures” discusses a variety of code-level metrics that allow architects to analyze structural aspects of an architecture—but none of these metrics reflects scope. They reveal low-level details about the code, but can’t evaluate dependent components outside the code base (such as databases) that affect many architectural characteristics, especially operational ones. No matter how much effort an architect puts into designing a code base to be performant or elastic, if the system’s database doesn’t match those characteristics, ...