Software Architecture in Practice, 4th Edition

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.

If you want your implementation to conform to an architecture, then it must conform to the design decisions prescribed by the architecture. It must have the set of elements prescribed by the architecture, these elements must interact with each other in the fashion prescribed by the architecture, and each element must fulfill its responsibility to t... See more

Architecture represents a common abstraction of a system that most, if not all, of the system’s stakeholders can use as a basis for creating mutual understanding, negotiating, forming consensus, and communicating with each other. The architecture—or at least parts of it—are sufficiently abstract that most nontechnical people can understand it to th... See more

The software development community is coming to grips with the fact that roughly 80 percent of a typical software system’s total cost occurs after initial deployment. Most systems that people work on are in this phase. Many programmers and software designers never get to work on new development—they work under the constraints of the existing archit... See more

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

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

once the architecture has been agreed upon, it becomes very costly—for managerial and business reasons—to significantly modify it. This is one argument (among many) for analyzing the software architecture for a large system before settling on a specific choice.

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.

• If your system requires high performance, then you need to pay attention to managing the time-based behavior of elements, their use of shared resources, and the frequency and volume of their interelement communication.


• If modifiability is important, then you need to pay attention to assigning responsibilities to elements and limiting the interaction

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