Robert L. Probert

Synthesis of communication protocols: survey and assessment

Eleven methods for the synthesis of communication protocols are described. Based on particular features of the synthesis process, these methods are classified and compared. In particular, it is noted that interactive methods allow flexibility in the design process; as a result, communication patterns are not prespecified but may be constructed interactively. Methods that only consider the synchronous mode of behavior of communicating entities exclude a wide range of real-life protocols. Methods that make no reference to service requirements do not guarantee the semantic correctness of the synthesized protocol and therefore require the application of a semantic verification procedure. Most methods concentrate on the synthesis of the control part of the protocol entities, which mainly consists of the exchange of synchronization messages. The data part is not adequately treated by any of the synthesis methods. Other than the exchange of synchronization messages, some methods have been extended to deal with unreliable media by synthesizing error-recovery patterns. Some new research directions for enhancing the applicability of the synthesis approach to the design of real-life protocols are obtained. >

Relative-clock-based specification and test result analysis of distributed systems

A model employing totally ordered events of a distributed system based on a logical clock has been presented by L. Lamport (1978). The authors propose a new interpretation and extension of Lamports notion of concurrency by introducing the concept of relative concurrency to capture the nature of concurrency of distributed systems by means of a relative (or logical) clock. They then derive a totally ordered global events model based on the relative clock. Based on this model, they represent and interpret timing (ordering) information from observable scenarios, including collision scenarios of the system, expressed in an extended trace assertion language (ETAL) specification. Finally, a new approach is illustrated with a realistic example for test result analysis including timing information based on the global events model.<<ETX>>

CORBA-based e-commerce application testing architecture

E-commerce systems are specialized instances of distributed processing systems. The Common Object Request Broker Architecture (CORBA) provides a sophisticated infrastructure to develop and deploy distributed objects. As systems become more complex and geographically distributed, it is becoming increasingly difficult to conduct cost-effective, systematic and comprehensive testing on such systems. Using CORBA to facilitate the development and testing of e-commerce systems can greatly improve testability and directly shorten the time-to-market cycle by decreasing the test effort. This paper proposes a practical CORBA-based approach called CDATA (e-Commerce Development And Testing Approach), which supports both functional and performance testing of multiple distributed CUTs (components under test). The approach is illustrated by the implementation of an experimental e-commerce system and the corresponding testing architecture.

Formalization of ISDN LAPD for conformance testing

Usefulness of a formalization of the specification of ISDN LAPD is demonstrated for designing and developing a comprehensive set of conformance tests. Since many protocol standards are specified in a natural language (i.e., English), a method for formalizing protocol specifications with a view to a number of validation activities, including conformance testing, is also presented. In particular, it is shown how to utilize the state-transition-oriented approach to automatically generate a major component of standard conformance test suites. The use of formalized specifications is also illustrated for verifying the specification by selective executions, and for validating conformance test cases against the specification.<<ETX>>

An application of explanation-based learning to protocol conformance testing

A method that employs a machine learning technique for the semiautomatic generation of protocol-conformance test-sequence requirements is described. Given a protocol knowledge representation and some high-level nonexecutable descriptions of protocol behavior, a learning algorithm based on extended explanation-based generalization produces conformance test-sequence requirements for a protocol implementation under test. The role of learning is to compile relevant parts of protocol knowledge into behaviors, consequently inferring executable protocol behaviors. This inference makes explicit constraints that are implicit in both the protocol knowledge and the behaviors. It is shown that the approach facilitates the derivation of new operational constraints on protocol behavior. The new constraints lead to new types of protocol behavior, thereby yielding potentially valuable new conformance test cases. An application of the method to the Alternating Bit Protocol (ABP) (a canonical example in protocols research literature) is described.<<ETX>>