Traceability for Complex Systems Engineering

Improved requirements traceability would result in significant cost savings since more requirements problems are due to failures in requirements management than failures in technical functions. Without adequate requirements traceability, errors are found late in system development and are expensive to repair. Our research identifies problems with industry's capability to trace product and process information, and offers some solutions. We have defined a unique 1 method, Concurrent Stimulus-Response Threads (CSRT), that traces complex system behavior. Based on CSRT and Entity-Relationship modeling, we make recommendations that will improve traceability in two requirements methods, Requirements Driven Design (RDD), and Real-Time Structured Analysis (RT-SA). ISSUES IN TRACING SYSTEM INFORMATION The complexity of DOD systems is enormous and engineers developing these systems require traceability. System engineers need the capability to control change, control the process, and control risk. Maintenance engineers need traceability to better understand the product, and the process used to develop the system. All engineers need quick access to information, and since the information is vast and complex, engineers need information abstraction and visualization techniques that help promote understanding. Unfortunately tracing is difficult with current technology, and minimally supported. It is expensive to capture information. Tools cross disciplines and do not have the same lexicon. We cannot measure the benefits of traceability, and the cost is high. We do not know the level of granularity at which to trace, and how to represent much of the information that should be traced (e.g., behavior, non-functional requirements). In most cases, DOD customers are not asking for software traceability except for that covered in DOD-STD 2167A. traceability of unit Software Development Folders to component Software Development Folders. Engineers need greater capability for traceability. They must be notified of changes, and should rigorously trace their impact. Change can affect cost, schedule and feasibility, system design and implementation, system tests, and support software and hardware. Engineers need traceability to assess system artifacts during development. They should assess whether the system is under or over designed, specifications contradict each other, lower level decisions are consistent with higher level decisions, test cases cover requirements, detailed behavior and high level behavior are consistent, and non-functional requirements are met. Current traceability aids are reasonably good for product functions, but are limited for tracing system behavior and product attributes (Director of Defense, Research and Engineering '91). Behavior is difficult to trace using current methods, as behavior is specified by stimulus-response statements that cross …