Ongoing Software Maintenance: What It Should Mean to System-Level Documentation Artifacts and Why We Should Care

Abstract

Capabilities demanded from large scale software intensive systems show trends of continually increasing levels of change and complexity. Multiple organizations may be charged with acquiring such complex systems via multiple contracts with independent programmatic boundaries for system development. The overall “system” is more likely to consist of an integration or federation of separately acquired software intensive systems. This not only complicates the specification, acquisition and development of such entities, but also creates increasingly complex issues for ongoing software maintenance. Historically, the development costs of software systems have been observed to be only about 20%-40% of their entire lifecycle amounts. Thus, the majority of the lifecycle costs for software are seen to be consumed by maintenance activities performed throughout the operational lifecycle phase. In part, this trend is due to increasing demand for enhanced software capabilities that goes beyond basic defect repairs and then implementing these enhancements over everlengthening operational periods (in many cases to 10 years or more). There is no reason to believe that these trends will significantly change in a manner which eases the challenges faced by software maintenance organizations. We can therefore anticipate that capabilityenhancing software updates may be made available multiple times per year throughout a software intensive system’s operational period. This paper explores a sampling of thoughts circulating through the software community regarding the kinds of software architecture and design information needed by software maintainers to reduce risks of unanticipated, negative consequences due to software changes and enhancements made during lengthening operational lifecycles. Considering these industry trends, acquisition organizations may want to establish a program-wide view for scope and consistency of software maintainability artifacts, particularly when multiple development contracts or organizations are involved.