Historically, architecture has been about the structure of the solution, focused on the components that make up a system and the connectors which enable their coordinated interaction. Given this solution focus, systems, enterprise, and software architecture evolved in different directions. During the past 15+ years, architectural theory and practice have been undergoing a gradual, but significant, shift in focus. Five trends which highlight this shift are: decision rationale, challenges vs. requirements, systems-of-systems, contextual analysis, and design cognition. Each of these trends facilitates a necessary shift from the architecture of the solution to the architecture of the problem. In addition to enabling a clearer link between the problem and solution, these trends also help to unify systems, enterprise, and software architecture by providing a common foundation for collaboration on complex problems.
TopBackground
For over 20 years, enterprise, systems, and software architecture each have been making significant contributions to the development of complex systems that enrich our lives every day. These three disciplines share a similar mission, as evidenced by their common adoption of the architecture definition in IEC 42010 (2007, pg. 10), “the fundamental organization of a system embodied in its components, their relationships to each other, and to the environment, and the principles guiding its design and evolution.”
While these disciplines share a common mission, their focus and practice differ in important ways. Maier (2009, pg. 425) defines a system as “a collection of things or elements that, working together, produce a result not achievable by the elements alone.”
These definitions of system and architecture lead to a broad view of systems architecture, as shown in Figure 1.
Figure 1. Enterprise, systems, and software architecture domains
With its focus on managing business information and enabling business processes, enterprise architecture is a specialization of systems architecture according to problem focus. By contrast, with its focus on manipulating computational abstractions which represent real world entities, software architecture is a specialization of system architecture on a different axis: solution mechanism.
Software, systems and enterprise architecture intersect in the region where computational abstractions manage the storage and flow of business information and model the behavior of business processes and workflows. Realtime control systems, such as medical devices, automotive and avionics are areas where software and systems architecture overlap, with a somewhat lesser concern for enterprise architecture. However, all one need do is step outside the boundary of a medical device and strong evidence of electronic medical records and hospital information systems (enterprise architecture) will be present. Virtually the same statement can be made for any other realtime control system.