Security requirements deal with the protection of assets against unauthorized access (disclosure or modification) and their availability to authorized users. Temporal constraints of history-based access control policies are difficult to express naturally in traditional policy languages. We propose a compositional formal framework for the specification and verification of temporal access control policies for security critical systems in which history-based policies and other temporal constraints can be expressed. In particular, our framework allows for the specification of policies that can change dynamically in response to time or events enabling dynamic reconfiguration of the access control mechanisms. The framework utilizes a single well-defined formalism, interval temporal logic, for defining the semantics of these policies and to reason about them. We illustrate our approach with a detailed case study of an electronic paper submission system showing the compositional verification of their safety, liveness and information flow properties.

Every day, the growing number of viruses causes major damage to computer systems. Existing antivirus products do not provide a full solution to the problems associated with viruses. One of the most encouraging recent developments in virus research is the use of logic formulae to model the behaviour of viruses, which provides alternatives to classic virus detection methods. The proposed research uses temporal logic and behaviour-based detection mechanism to detect viruses. Interval Temporal Logic (ITL) will be used to generate virus specifications, properties and formulae based on the analysis of the behaviour of computer viruses. The detection mechanism will use Tempura, the executable subset of ITL, i.e., satisfaction of a Tempura formula means a virus has been detected. The process will also use AnaTempura, an integrated workbench tool for ITL that supports our system specifications. AnaTempura will offer validation of the ITL specifications and detects whether a virus has occurred or not.

Usage Control (UCON) Models, similar to Access Control Models, control and govern the users' access to resources and services that are available in the system. One of the major improvements of UCON over traditional access control models is the continuity of the control and the concept of attribute mutability. In this paper we provide an alternative formalisation of the UCON model that relaxes many of the assumptions made in earlier formalisations of the model. We question the enforceability of UCON policies as described by previous formalisations and improve on it.

A Service oriented system emerges from composition of services. Dynamically composed reactive Web services form a special class of service oriented system, where the delays associated with communication, unreliability and unavailability of services, and competition for resources from multiple service requesters are dominant concerns. As complexity of services increase, an abstract design language for the specification of services and interaction between them is desired. In this paper, we present ASDL (Abstract Service Design Language), a wide spectrum language for modelling Web services. We initially provide an informal description of our computational model for service oriented systems. We then present ASDL along with its specification oriented semantics defined in Interval Temporal Logic (ITL): a sound formalism for specifying and reasoning about temporal properties of systems. The objective of ASDL is to provide a notation for the design of service composition and interaction protocols at an abstract level.

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.

Business processes and goals change rapidly due to the turbulent environment in which they operate. Their supporting and underpinning technologies may, as a result, require to change. Meanwhile, technological advances are being made at an increasing rate. This may trigger changes in business goals and processes to exploit these new advances; a notable example is e-commerce and e-learning. Understanding and analyzing the interplay and the dual effect between these two entities, technologies and business, is vital both for the prosperity of business and the success and further development of the technologies themselves. This paper proposes the K-Mediator framework together with its underpinning theory to facilitate the co-evolution between businesses and their supporting technologies.

Abstract. A dense temporal logic development method for the specification, refinement, composition and verification of reactive systems is introduced. A reactive system is specified by a pair consisting of a machine and a condition that indicate the valid computations of this machine. Compositionality is achieved by indicating whether each step is an environment step, a system step, or a communication step. Refinement can be expressed straightforwardly in the logic because the stutter problem is elegantly solved by using the dense structure of the logic. Compositionality enables us to break refinement between complex systems into refinement between small and simple systems. The latter can then be verified by existing proof rules for refinement which are reformulated in our formalism.

We propose a sound and practical approach, based on a formal method (known as interval temporal logic), to cope with 'change' and analyse its effect. The approach allows lows to capture a snapshot of system's behaviour over which various interesting properties, such as liveness, timeliness and safety properties, can be validated compositionally. These properties may include invariants that are required to be valid after changes have taken place. We also present and evaluate the design and implementation of a formal tool, AnaTempura, which supports the developed approach. A case study is presented to illustrate our approach and the tool.

We present a calculus which can transfer specifications to objects for the development of real-time systems. The object model is based on a practical OO development technique-HRT-HOOD. A real-time logic is specified by extending a sound formal method for real-time systems-TAM, to formalise the object model. With integration of HRT-HOOD and TAM, the advantages of object-oriented structured methods with the stepwise refinement techniques are combined. The result is illustrated on a case study.