Prof. T.H. Tse (The University of Hong Kong),
Prof. T.Y. Chen (Swinburne University of Technology, Australia) and
Dr W.K. Chan (City University of Hong Kong)

* Supported in part by the General Research Fund of the Research Grants Council of Hong Kong (Project No. 717308).

In service computing, a service usually collaborates with other services. It may also comprise other services and self-offering actions. The testing of a service is complex and needs to address both the concurrent and sequential dimensions of service composition. As service compositions may be complicated, it is attractive to apply compositional testing, which means the assurance of the overall quality of an entire service composition based on the testing of individual (or groups of) services. Previous work focuses on addressing the concurrent dimension, since the sequentiality aspect is thought of as relatively easy. However, we have identified quite a number of non-trivial problems in the latter aspect that cannot be handled satisfactorily by existing techniques. We propose, therefore, to address the sequential dimension in this project.

We conduct a formal analysis of conformance testing in the context of sequential service composition. We propose to use process algebra as the platform to handle the issue and model a service as a process. We have identified a number of counterexamples to show that there are subtle problems to hinder compositional testing in sequential composition of services. We propose the notion of sequential extension as the basis for tackling such difficulties. A service which sequentially extends another service will enable the latter to be decomposed sequentially into component services. These component services can be abstracted individually and compositionally and, at the same time, the former service should conform to the resultant service composition thus constructed. We target to produce a series of mathematical theorems to show that the notions support compositional conformance testing. To show the practicality of our formal framework, we shall then implement it in a testing tool and conduct experimentation to verify the viability of our proposal.

Prof. T.H. Tse (The University of Hong Kong),
Prof. T.Y. Chen (Swinburne University of Technology, Australia) and
Dr W.K. Chan (City University of Hong Kong)

* Supported in part by the General Research Fund of the Research Grants Council of Hong Kong (Project No. 716507).

Program debugging aims at localizing faults and removing them. Through instrumented executions, dynamic fault localization techniques provide a candidate set of faulty positions in a program.

Pervasive computing is of emerging importance in today's applications. The debugging of such complex systems is crucial for assuring their quality, but the task is difficult because of context-sensitive issues in a volatile and unpredictable environment.

In this project, we propose to study fault-localization techniques for conventional programs and further develop them for pervasive computing. We shall investigate the dynamic properties of program executions and design statistical fault localization techniques for both conventional and context-aware applications. Behavioral statistics are derived from successful and failed runs. We shall contrast not only the former against the latter, but also the changing trends in both situations. Through detailed analyses and modeling of the statistical footprints of how faults diverge and propagate, the project aims at integrating our model with a data-centric approach to effectively and robustly rank the fault-relevance of program predicates, with a view to reducing the number of candidate faulty positions. In particular, footprints specific to pervasive applications will be explored. The integration of testing and debugging tools for wireless sensor network applications will also be studied.

Prof. T.H. Tse (The University of Hong Kong) and
Prof. T.Y. Chen (Swinburne University of Technology, Australia)

* Supported in part by the General Research Fund of the Research Grants Council of Hong Kong (Project No. 717506).

Ubiquitous computing means computing anywhere and at any time. Context-sensitive ubiquitous software dynamically adapts its operations according to the changing environment. One of the strategic directions of Hong Kong is to become a world-class base for supply chain management. Ubiquitous middleware-based sensor network systems are envisaged to be an essential enabling technology. Nevertheless, many researchers have emphasized the difficulties in assuring the quality of such software, because context-sensitive applications operate in a highly volatile and unpredictable environment. We were the first research group to embark on their testing techniques. We propose a major project to comprehensively address both the integration and unit testing of these systems.

In integration testing, we propose a model in Communicating Sequential Processes to generate test cases that conform to the components in a ubiquitous environment. We make use of a notion of anti-extension, which can help to alleviate the state-explosion problem in test case generation.

Context detections and function activations are the duties of the middleware. In unit testing, test oracles may not be immediately available for a component under test. We propose the application of metamorphic testing to solve the problem, focusing on isotropic context properties. They can reveal failures not identifiable by conventional testing methods.

This project has important theoretical and practical implications. It will solve the major difficulties in testing complex context-sensitive middleware-based ubiquitous software. It will also illustrate the usefulness of formal approaches to software testing in practical situations.