Understanding Architecture

"Software architecture encompasses the significant decisions about the organization of a software system. The selection of the structural elements and their interfaces by which the system is composed together with their behavior as specified in the collaboration among those elements. The composition of the structural and behavioral elements into progressively larger subsystems, the architectural style that guides this organization, these elements, and their interfaces, their collaborations, and their composition. Software architecture is concerned not only with structure and behavior but also with usage, functionality, performance, resilience, reuse, comprehensibility, economic and technology constraints and trade-offs, and aesthetic issues."

Rational Unified Process

"Architecture is a set of structuring principles that enables a system to be comprised of a set of simpler systems each with its own local context that is independent of but not inconsistent with the context of the larger system as a whole."

SunTone Architecture Methodology