Software architecture

Software architecture refers to the fundamental structures of a software system, the discipline of creating such structures, and the documentation of these structures. These structures are needed to reason about the software system. Each structure comprises software elements, relations among them, and properties of both elements and relations, along with rationale for the introduction and configuration of each element. The architecture of a software system is a metaphor, analogous to the architecture of a building.

Software architecture is about making fundamental structural choices which are costly to change once implemented. Software architecture choices, also called architectural decisions, include specific structural options from possibilities in the design of software. For example, the systems that controlled the space shuttle launch vehicle had the requirement of being very fast and very reliable. Therefore, an appropriate real-time computing language would need to be chosen. Additionally, to satisfy the need for reliability the choice could be made to have multiple redundant and independently produced copies of the program, and to run these copies on independent hardware while cross-checking results.

Documenting software architecture facilitates communication between stakeholders, captures decisions about the architecture design, and allows reuse of design components between projects.

Opinions vary as to the scope of software architectures:

There is no sharp distinction between software architecture versus design and requirements engineering (see Related fields below). They are all part of a "chain of intentionality" from high-level intentions to low-level details. This duality is also referred to as the "twin peaks" of software engineering.

Software architecture exhibits the following:

Multitude of stakeholders: software systems have to cater to a variety of stakeholders such as business managers, application owners, developers, end users and infrastructure operators. These stakeholders all have their own concerns with respect to the system. Balancing these concerns and demonstrating how they are addressed is part of designing the system. This implies that architecture involves dealing with a broad variety of concerns and stakeholders, and has a multidisciplinary nature. Software architect require non-technicals skills such as communication and negotiation competencies.

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