National IVHS Architecture Development Strategy

National information and control systems are emerging that require system architectures for deployment across the nation, e.g., air traffic control systems, military command and control systems, and other national information systems. The required characteristics for the national level architectures include modularity, openness, and evolvability. Modularity permits a variety of system configurations. Each may be designed to size a community’s system with a level of functionality commensurate with the community’s needs. Openness enables system interoperability with other systems at both horizontal and vertical levels. Evolvability requires the system to permit functionality and scope changes as the community and technology evolves. Achieving these characteristics necessitates a formal strategy for developing architectures, for information and control systems, at the national level. A national level, information and control system is a system that is made up of systems, e.g., a supersystem. Developing an architecture is the modern approach for developing very large systems and supersystems. Formal system engineering and software engineering methodologies for developing national information and control system architectures do not exist. Most existing systems and software development methodologies need to be adapted to increase emphasis on front-end systems and software engineering methodologies. New system development methodologies for large information and control systems are emerging. Most do not support both the front-end systems engineering, i.e., defining system mission, and front-end software engineering, i.e., information modeling. Many of these methodologies are still implementation-oriented, resulting in premature commitment to system design solutions, prior to ensuring the design will satisfy all of the customer’s needs. architectural roots. Further these system designs are usually limited by their We have developed a formal strategy for supersystem architecture development, which includes newer methodologies such as Strategies for Real-Time System Specification by D. J. Hatley and I. A. Pirbhai, current United States General Accounting Office policy and the NASA Systems Engineering Handbook. Our strategy focuses on top level systems engineering methodologies by developing a mission definition document to: portray a vision of the mission, identify the operational, identify the security concepts, and develop the operational requirements needed to achieve the mission. The mission definition is used to generate a set of system functional requirements using functional analysis. The functional requirements are used to create a purely logical architecture (technology-free) capable of satisfying the system’s mission. This Logical Architecture is modeled against mission scenarios and fine tuned to achieve the required functionality. Then the Logical Architecture is allocated to physical subsystems to enable the evaluation of alternative technologies in hardware and software configuration against mission scenarios. The best solution becomes the Candidate Architecture. The entire process is then iterated through several cycles until the optimal candidate architecture is obtained. The result becomes the Physical Architecture. This is the implementation blueprint. The perspective for this paper is a survey of new system development concepts to identify the strategy to develop a national level architecture. Version: Corrected Final 01/27/94