Making Software

Context of the Study

The system discussed in this chapter is a very large-scale (that is, a million lines or more), distributed, real-time system written in the C programming language (with additional domain-specific languages as needed) in a Unix-based, multiple machine, multiple location environment.

The organizational structure is typical with respect to projects for systems of this size and for the number of people in each organization. Not surprisingly, different organizations are responsible for various parts of the system development: requirements specification; architecture, design, coding and capability testing; system and system stability testing; and alpha testing.

The process of development is also typical with respect to projects of this size. Systems engineers prepare informal and structured documents defining the requirements for the changes to be made to the system. Designers prepare informal design documents that are subjected to formal reviews by 3 to 15 peers, depending on the size of the unit under consideration. The design is then broken into design units for low-level design and coding. The products of this phase are subjected both to formal code reviews by three to five reviewers and to low-level unit testing. As components are available, integration and system testing is performed until the system is completely integrated.

The release considered here is a “non-initial” release—one that can be viewed as an arbitrary point in the evolution of this class of systems. ...