Using the system architecture as the starting point

Essential to developing and maintaining high-quality software is the definition of the system architecture. The Rational Unified Process states that defining and using a system architecture is one of the best practices to follow in developing software. A system architecture is the highest level concept of a system in its environment. The Rational Unified Process states that a system architecture encompasses the following:

• The significant decisions about the organization of a software system
• The selection of the structural elements and their interfaces of 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