Hussein Zedan

Using formal specifications to support testing

Formal methods and testing are two important approaches that assist in the development of high-quality software. While traditionally these approaches have been seen as rivals, in recent years a new consensus has developed in which they are seen as complementary. This article reviews the state of the art regarding ways in which the presence of a formal specification can be used to assist testing.

Augmenting semantic web service descriptions with compositional specification

Current ontological specifications for semantically describing properties of Web services are limited to their static interface description. Normally for proving properties of service compositions, mapping input/output parameters and specifying the pre/post conditions are found to be sufficient. However these properties are assertions only on the initial and final states of the service respectively. They do not help in specifying/verifying ongoing behaviour of an individual service or a composed system. We propose a framework for enriching semantic service descriptions with two compositional assertions: assumption and commitment that facilitate reasoning about service composition and verification of their integration. The technique is based on Interval Temporal Logic(ITL): a sound formalism for specifying and proving temporal properties of systems. Our approach utilizes the recently proposed Semantic Web Rule Language.

Why Moodle

Using the Internet to enhance e-learning has become a trend in modern higher education institutes. E-learning systems are increasingly becoming an important part of the strategy for delivering online and flexible e-learning. The main advantage of e-learning is the opportunity for students to interact electronically with each other and their teachers during forums, on discussion boards, by e-mail and in chat rooms. Though recognizing that the world at large will continue to use terminology in different and often ambiguous ways, the term of virtual learning environments (VLE) is used to refer to the on-line interactions of a variety of kinds that take place between learners and instructors. There are many pieces of software available that provide VLE systems, both commercial and open source software (OSS). One such system that has been gradually gaining worldwide popularity is known as Moodle. This paper focuses on this platform and on a comparison between VLE (Moodle) and other VLE systems in order to discover their strengths and limitations. The comparative study is in two phases. The first phase is based on the features and capabilities of VLE tools and the second phase is based on the technical aspects of the VLE platforms.

Context-Aware Driver Behavior Detection System in Intelligent Transportation Systems

Vehicular ad hoc networks (VANETs) have emerged as an application of mobile ad hoc networks (MANETs), which use dedicated short-range communication (DSRC) to allow vehicles in close proximity to communicate with each other or to communicate with roadside equipment. Applying wireless access technology in vehicular environments has led to the improvement of road safety and a reduction in the number of fatalities caused by road accidents through development of road safety applications and facilitation of information sharing between moving vehicles regarding the road. This paper focuses on developing a novel and nonintrusive driver behavior detection system using a context-aware system in VANETs to detect abnormal behaviors exhibited by drivers and to warn other vehicles on the road to prevent accidents from happening. A five-layer context-aware architecture is proposed, which is able to collect contextual information about the driving environment, to perform reasoning about certain and uncertain contextual information, and to react upon that information. A probabilistic model based on dynamic Bayesian networks (DBNs) in real time, inferring four types of driving behavior (normal, drunk, reckless, and fatigue) by combining contextual information about the driver, the vehicle, and the environment, is presented. The dynamic behavior model can capture the static and the temporal aspects related to the behavior of the driver, thus leading to robust and accurate behavior detection. The evaluation of behavior detection using synthetic data proves the validity of our model and the importance of including contextual information about the driver, the vehicle, and the environment.

The Calculus of Context-aware Ambients

We present the Calculus of Context-aware Ambients (CCA in short) for the modelling and verification of mobile systems that are context-aware. This process calculus is built upon the calculus of mobile ambients and introduces new constructs to enable ambients and processes to be aware of the environment in which they are being executed. This results in a powerful calculus where both mobility and context-awareness are first-class citizens. We present the syntax and a formal semantics of the calculus. We propose a new theory of equivalence of processes which allows the identification of systems that have the same context-aware behaviours. We prove that CCA encodes the @p-calculus which is known to be a universal model of computation. Finally, we illustrate the pragmatics of the calculus through many examples and a real-world case study of a context-aware hospital bed.

A compositional framework for access control policies enforcement

Despite considerable number of work on authorization models, enforcing multiple polices is still a challenge in order to achieve the level of security required in many real-world systems. Moreover current approaches address security settings independently, and their incorporation into systems development lifecycle is not well understood. This paper presents a formal model for the specification of access control policies. The approach can handle the enforcement of multiple policies through policies composition. Temporal dependencies among authorizations can be formulated. Interval Temporal Logic (ITL) is our underlying formal framework an policies are modeled as safety properties expressing how authorizations are granted over time. The approach is compositional, and can be used to specify other systems properties such as functional and temporal requirements. The use of a common formalism eases the integration of security requirements into system requirements so that they can be reasoned about uniformly throughout the development lifecycle. Furthermore specification of policies are executable in <i>Tempura,</i> a simulation tool for ITL.

Refining Interval Temporal Logic Specifications

Interval Temporal Logic (ITL) was designed as a tool for the specification and verification of systems. The development of an executable subset of ITL, namely Tempura, was an important step in the use of temporal logic as it enables the developer to check, debug and simulate the design. However, a design methodology is missing that transforms an abstract ITL specification to an executable (concrete) Tempura program. The paper describes a development technique for ITL based on refinement calculus. The technique allows the development to proceed from high level “abstract” system specification to low level “concrete” implementation via a series of correctness preserving refinement steps. It also permits a mixture of abstract specification and concrete implementation at any development step.

Slicing as a program transformation

The aim of this article is to provide a unified mathematical framework for program slicing which places all slicing work for sequential programs on a sound theoretical foundation. The main advantage to a mathematical approach is that it is not tied to a particular representation. In fact the mathematics provides a sound basis for any particular representation. We use the WSL (wide-spectrum language) program transformation theory as our framework. Within this framework we define a new semantic relation, semirefinement, which lies between semantic equivalence and semantic refinement. Combining this semantic relation, a syntactic relation (called reduction), and WSLs remove statement, we can give mathematical definitions for backwards slicing, conditioned slicing, static and dynamic slicing, and semantic slicing as program transformations in the WSL transformation theory. A novel technique of “encoding” operational semantics within a denotational semantics allows the framework to handle “operational slicing”. The theory also enables the concept of slicing to be applied to nondeterministic programs. These transformations are implemented in the industry-strength FermaT transformation system.

Generating OWL Ontology for Database Integration

Today, databases provide the best technique for storing and retrieving data, but they suffer from the absence of a semantic perspective, which is needed to reach global goals such as the semantic web and data integration. Using ontologies will solve this problem by enriching databases semantically. Since building an ontology from scratch is a very complicated task, we propose an automatic transformation system to build Web Ontology Language OWL ontologies from a relational model written in Structured Query Language SQL. Our system also uses metadata, which helps to extract some semantic aspects which could not be inferred from the SQL. Our system analyzes database tuples to capture these metadata. Finally, the outcome ontology of the system is validated manually by comparing it with a conceptual model of the database (E/R diagram) in order to obtain the optimal ontology.

Non-intrusive speech quality prediction in VoIP networks using a neural network approach

Measuring speech quality in Voice over Internet Protocol (VoIP) networks is an increasingly important application for legal, commercial and technical reasons. Any proposed solution for measuring the quality should be applicable in monitoring live-traffic non-intrusively. The E-Model proposed by the International Telecommunication Union-Telecommunication Standardisation Sector (ITU-T) achieves this, but it requires subjective tests to calibrate its parameters. In this paper a solution is proposed to extend the E-Model to any new network conditions and for newly emerging speech codecs without the need for the time-consuming, expensive, hard to conduct subjective tests. The proposed solution is based on an artificial neural network model and is compared against the E-Model to check its prediction accuracy.