Software Architecture: Foundations, Theory, and Practice

Chapter 9. Implementation

Implementation is the one phase of software development that is not optional. Regardless of how well the requirements have been captured or how carefully the architecture has been designed and reviewed, software systems must be implemented in code to achieve their ends. Architecture is used to capture important design decisions about a system, using sound engineering principles and knowledge to increase confidence that the target system's qualities match the expectations of its stakeholders. To imbue these qualities in the target system, the implementation must be derived from its architecture.

In terms of implementation, architecture is both prescriptive and restrictive. It is prescriptive in the sense that it gives implementers direction on what to produce—how to structure code modules, how they should be interconnected, and how they should behave. It is restrictive in the sense that its guidelines—particularly those specified in the architectural style—tell developers what they may not do: the forms of communication that are prohibited, the kinds of behaviors or system states that are not allowed, and so on.

The problem of relating architecture to implementation is one of mapping. Concepts defined at the architecture level should be directly connected to artifacts at the implementation level. This correspondence is not necessarily one-to-one. For example, in general, a software component or connector will be implemented using many code and resource artifacts. ...