Isolating faults in complex COTS-based systems

Government policies on the acquisition of software-intensive systems have recently undergone a significant shift in emphasis toward the use of existing commercial products. Some Requests for Proposals (RFPs) now include a mandate concerning the amount of COTS (commercial off-the-shelf) products that must be included. This interest in COTS products is based on a number of factors, not least of which is the spiraling cost of software. Given the current state of shrinking budgets and growing need, it is obvious that appropriate use of commercially available products is one of the remedies that might enable the government to acquire needed capabilities in a cost-effective manner. In systems where the use of existing commercial components is both possible and feasible, it is no longer acceptable for the government to specify, build, and maintain a large array of comparable proprietary products. However, like any solution to any problem, there are drawbacks and benefits: significant tradeoffs exist when embracing a commercial basis for the government's software systems. Thus, the policies that favor COTS use must be implemented with an understanding of the complex set of impacts that stem from use of commercial products. Those implementing COTS products must also recognize the associated issues—system distribution, interface standards, legacy system reengineering, and so forth—with which a COTS-based approach must be integrated and balanced. In response to this need, a set of monographs is being prepared that addresses the use of COTS software in government systems. Each monograph will focus on a particular topic, for example: the types of systems that will most benefit from a COTS approach; guidelines about the hard tradeoffs made when incorporating COTS products into systems; recommended processes and procedures for integrating multiple commercial products; upgrade strategies for multiple vendors' systems; recommendations about when not to use a commercial approach. Since these issues have an impact on a broad community in DoD and other government agencies, and range from high-level policy questions to detailed technical questions, we have chosen this modular approach; an individual monograph can be brief and focused, yet still provide sufficient detail to be valuable. This monograph provides an overview of a method for isolating and overcoming faults in COTS-based systems. It provides a method and mechanisms that are useful for engineers and integrators who are tasked with assembling complex systems from heterogeneous sources. While other readers may find value in this report, it is specifically written for a technical …