software architecture

Once an architecture has been defined, it can serve as the basis for incremental development. The first increment can be a skeletal system in which at least some of the infrastructure—how the elements initialize, communicate, share data, access resources, report errors, log activity, and so forth—is present, but much of the system’s application fun... See more

This point follows from the previous two: Architecture not only imbues systems with qualities, but does so in a predictable way.

A system’s ability to meet its desired (or required) quality attributes is substantially determined by its architecture. If you remember nothing else from this book, remember that.

The fidelity of the system increases as extensions are added, or early versions are replaced by more complete versions of these parts of the software. In some cases, the parts may be low-fidelity versions or prototypes of the final functionality; in other cases, they may be surrogates that consume and produce data at the appropriate rates but do li... See more

Every architecture, no matter what it is, partitions possible changes into three categories: local, nonlocal, and architectural.

• A local change can be accomplished by modifying a single element—for example, adding a new business rule to a pricing logic module.


• A nonlocal change requires multiple element modifications but leaves the underlying archite

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Decisions at all stages of the life cycle—from architectural design to coding and implementation and testing—affect system quality. Therefore, quality is not completely a function of an architectural design. But that’s where it starts.

Many systems are built as skeletal systems that can be extended using plug-ins, packages, or extensions. Examples include the R language, Visual Studio Code, and most web browsers.