This book presents recent worldwide results in both the theory and practice of the testing of communicating systems. Through a range of selected papers, this volume provides a forum in which the substantial volume of research on the testing of communicating systems, spanning from conformance testing through interoperability testing to performance testing, is brought together. The following topics are discussed in detail: types of testing; phases of the testing process; classes of systems to be tested, and theory and practice of testing. It contains the selected proceedings of the International Workshop on the Testing of Communicating Systems, formerly the International Workshop on Protocol Test Systems, sponsored by the International Federation for Information Processing, and held in Darmstadt, Germany in September 1996.