A software metric set for program maintenance management

Managers at the National Aeronautics and Space Administration's (NASA) Mission Operations Directorate (MOD) at the Johnson Space Center wanted to increase their insight into the cost, schedule, and quality of the software-intensive systems maintained for the Space Shuttle programs. We defined and imple-mented a software metrics set that contains thirteen metrics related to corrective and adaptive maintenance actions. Management support and tools were necessary for effective implementation. The start-up cost was low because much of the data is already collected by the projects. Management’s ability to make decisions and take actions to improve software quality and reduce software maintenance costs have made early results encouraging. Introduction The Assistant Director for Program Support of NASA's MOD is responsible for planning and controlling the development and maintenance of all ground-based systems used to support mission operations of the Space Shuttle program. These systems involve large software efforts: the smallest is approximately 1.1 million lines of code and the largest is over 7 million lines. The systems are a mixture of assembly, high-level, and fourth generation languages. Both the Shuttle mission control center and the Shuttle mission training facility execute in real-time. The Assistant Director and his supporting MOD management team needed an approach that would allow them clear, consistent insight into the status of each system's software maintenance activities at various levels (i.e., project, subsystem, module). MOD responded to this need by using the goal/question/metric paradigm popularized by Basili [1] to identify a set of twelve metrics for use on current and future systems. This paper is intended to assist software maintenance managers and quality assurance personnel considering developing a software maintenance metric program. The paper provides background into the MOD metrics effort and explains the approach taken in defining the maintenance metric set. Next, it describes each metric in the set, and explains the implementation process with its associated roadblocks. Finally, it discusses future plans for the MOD metric program and presents our conclusions. Background MOD initiated its software measurement program in May of 1990 to help project managers make decisions about the status of their projects [2]. This effort studied development test metrics and showed important trends in testing progress and product quality. Because of this success, MOD expanded the measurement program focus to cover the entire development cycle and documented it in a measurement handbook [3]. The development metric handbook is currently being used on five software development projects and will be included on all future MOD Requests for Proposal.