GUARD - A RELATIVE DEBUGGER

A significant amount of software development is evolutionary, involvin g the modification of already existing programs. To a large extent, th e modified programs produce the same results as the original program. This similarity between the original program and the development progr am Is utilized by relative debugging. Relative debugging is a new conc ept that enables the user to compare the execution of two programs by specifying the expected correspondences between their states. A relati ve debugger concurrently executes the programs, verifies the correspon dences, and reports any differences found. We describe our novel debug ger, called Guard, and its relative debugging capabilities. Guard Is i mplemented by using our library of debugging routines, called Dynascop e, which provides debugging primitives in heterogeneous networked envi ronments. To demonstrate the capacity of Guard for debugging in hetero geneous environments, we describe an experiment in which the execution of two programs is compared across Internet The programs are written in different programming languages and executing on different computin g platforms. (C) 1997 by John Wiley & Sons, Ltd.