A Formal Framework for Policy-Governed Institutional Agency

Traditional structured analysis and design methods have been criticized because the methods lack formality to provide a design for rigorous development. Several approaches have been developed for verifying a design by integrating traditional structured analysis and design methods with formal specification languages. However, the integration of traditional structured analysis and design methods with formal specification languages may confuse the problem definition and understanding with the attempt to define system structures and algorithms in the design phase. In addition, formal specification languages may add complexity to the design due to the complexity of the language syntax and semantics. In this paper, we are presenting an approach to verification of a structured design in HOS without using formal specification languages. Rules for the partial and total correctness of the design are also discussed.

PurposeSmart grid can be considered as the next step in the evolution of power systems. It comprises of different entities and objects ranging from smart appliances, smart meters, generators, smart storages, and more. One key problem in modeling smart grid is that while currently there has previously been a considerable focus on the proof of concept aspect of smart grid, there have been very few modeling attempts and even lesser attempts at formalization. To the best of our knowledge, formal specification has not been applied previously in the domain of smart grid.MethodsUsing a state-based formal specification language namely Z (pronounced as ‘Zed’), we present a novel approach to formally modeling and specify smart grid components.ResultsThe modeling exercise clearly demonstrates that Z is particularly suited for modeling various smart grid components.ConclusionsThe presented formal specification can be considered as a first step towards the modeling of smart grid using a Software Engineering formalism. It also demonstrates how formal specification can be used to model complex systems in general, and the smart grid, in particular.

In Wide Area Networks (WANs)inconsistencies among the security policies of Administrative Domains (ADs) may cause severe security flaws. Recently, security policies are written in natural language and as they get more complicated, even for an expert it might be impossible to detect such inconsistencies. However, when a formal language is used, it might be possible to make verification of security policies by automated theorem proving tools. Due to the existence of mobile devices such as laptops, PDAs and mobile agents, we need a formal language that is capable of defining the concept of mobility. In this paper, we extend Mob adtl [1] according its refinement methodology to obtain a formal policy specification language for an 802.11 WLAN with enhanced security network.

This paper presents a solution to bridging the abstract and concrete syntax of a Web rule languages by using model transformations. Current specifications of Web rule languages such as Semantic Web Rule Language (SWRL) or RuleML define their abstract syntax (e.g., metamodel) and concrete syntax (e.g., XML schema) separately. Although the recent research in the area of Model-Driven Engineering (MDE) demonstrates that such a separation of two types of syntax is a good practice (due to the complexity of languages), one should also have tools that check validity of rules written in a concrete syntax with respect to the abstract syntax of the rule language. In this study, we use the REWERSE I1 Rule Markup Language (R2ML), SWRL, and Object Constraint Language (OCL), whose abstract syntax is defined by using metamodeling, while their textual concrete syntax is defined by using either XML/RDF schema or Extended Backus-Naur Form (EBNF) syntax. We bridge this gap by a bi-directional transformation defined in a model transformation language (ATLAS Transformation Language, ATL). This transformation allowed us to discover a number of issues in both web rule language metamodels and their corresponding concrete syntax, and thus make them fully compatible. This solution also enables for sharing web rules between different web rule languages.

Multi-Party agent conversations occur frequently in multi-agent systems, for example in brokering. However, clear, formal and unambiguous specifications of the semantics of such conversations are essential for open implementation by different developers. We address this issue by generalizing a protocol-based semantic framework for expressing the semantics of Agent Communication Languages. This is used to give formal specifications of brokerage protocols, which are implemented on top of an agent-oriented middleware system. We conclude that an emphasis on design and formal specification languages in agent communication leads to clearer interfaces, improved development prospects, better re-use and with a potentially significant impact on standardisation efforts.

Standardization of Formal Specification Languages

Formal software development begins with formal specification of the user requirements or design of a system. Hence, formal specification languages are used to resolve ambiguities in user requirements or detect design errors at the early software life cycle. Furthermore, specification-based functional testing derives test inputs from its formal specification. However, formal specifications are expressed using set theory or predicate logics which are non-executable. Thus, functional test execution over abstract expressions would be impossible. Therefore, there is a need to refine abstract specification into a form that can be executable. In this paper, an automatic functional testing framework using object constraint language (OCL) formal specification has been proposed. The major objective of this paper is to describe how the refinement processes are integrated into the specification-based testing framework.

The complexity of designing concurrent and highly-evolving interactive systems has grown to a point where system verification has become a hurdle. Fortunately, formal verification methods have arrived at the right time. They detect errors, inconsistencies and incompleteness at early development stages of a system formally modeled using a formal specification language. -calculus (Milner, 1999) is one such formal language which provides strong mathematical base that can be used for verifying system specifications. But manually verifying the specifications of concurrent systems is a very tedious and error-prone work, especially if the specifications are large. Consequently, an automated verification tool would be essential for efficient system design and development. In addition, formal verification tools are vital ingredient to fully harness the potential of component-based software composition. The authors developed such an automated verification tool which is highly portable and seamlessly integrates with the visualization, reduction and performance evaluation tools introduced (Ahmad & Rahimi, 2008; Rahimi, 2006; Rahimi et al., 2001, 2008) to provide a comprehensive tool for designing and analyzing multi process/agent systems. Open-Bisimulation (Sangiorgi, 1996) concept is utilized as the theoretical base for the design and implementation of the tool which incorporates an expert system implemented in Java Expert System Shell (JESS) (Friedman-Hill, 2003).

The Unified Modeling Language (UML) has become a widely adopted standard in the software development industry. Unfortunately, the UML is a semi-formal language which lacks precisely defined constructs. Z language is a formal specification language. Formal languages are used to ensure that systems meet regulations and standards. This paper aims to reduce risks associated with software development and increase safety and reliability. This goal is achieved by formalizing the syntax of (a sub-set of the popular UML diagrams (Use Case diagram, Class diagram, and State Machine diagram) using Z specifications.

Often the most effective diagrams are those which are very simple. However there is a strong tendency, particularly prevalent in visual formal modelling and specification languages, to take a diagrammatic language which at core is very simple, and then add many extensions and features to make it more expressive - often making it so expressive that the diagrams produced in the language are no longer readable; or at least, the diagrams are no longer obviously a more effective form of representation than a text-based one. Both the design of effective visual formal modelling and specification languages, and the effective formalisation of (the semantics of) such visual languages requires the unification of results from visual language theory, cognitive science, empirical psychology and graphic design. Integrating results from such diverse fields is a non-trivial task, which may be approached through a decomposition of the study of issues of effectiveness in diagrammatic languages according to analogous understandings of (written and spoken) natural languages.

The readability of formal requirements specification languages is hypothesized as a limiting factor in the acceptance of formal methods by the industrial community. An empirical study was conducted to determine how various factors of state-based requirements specification language design affect readability using aerospace applications. Six factors were tested in all, including the representation of the overall state machine structure, the expression of triggering conditions, the use of macros, the use of internal broadcast events, the use of hierarchies, and transition perspective (going-to or coming-from). Subjects included computer scientists as well as aerospace engineers in an effort to determine whether background affects notational preferences. Because so little previous experimentation on this topic exists on which to build hypotheses, the study was designed as a preliminary exploration of what factors are most important with respect to readability. It can serve as a starting point for more thorough and carefully controlled experimentation in specification language readability.

In this work the protocol WorldFIP for industrial communication networks, is specified with the formal specification language LOTOS. This specification is the foundation of new work lines such as efficiency analysis of WorldFIP performance with simulations in critical applications, the generation of benchmark patterns for conformance tests of WorldFIP communications equipment, and the proposal of new advances in the fieldbus area. Standardization institutions can benefit largely by this implemented methodology of formal specification, because some uncertainties in their description issues can be detected easily during the standard development, if a formal specification language is used at this stage.

This paper studies two methods of interconnecting heterogeneous local area networks (LANs) such as Carrier-Sense Multiple-Access (CSMA) and token ring networks in an open systems environment, and evaluates the associated system performance. The first interconnecting method is to link the two LANs through gateways; the second is to use an architecture in which some stations on the ring LAN are also linked to the CSMA LAN via a multiplexer. Through such interconnected LANs, the Department of Defense end users can process data and applications seamlessly in an open systems environment. It has been shown that the second method (a type of dual interface) gives better performance in minimizing the response time and token rotation time, causing less traffic congestion. By allowing routing at the stations on the ring, the comparison becomes rather arbitrary. An optimal traffic routing ratio is determined for the second interconnection method. Moreover, a threshold routing ratio, beyond which the first interconnection is superior in performance, is computed. >

We present an example of a construction of an embedded software system-a controller-from the formal specification to executable code. The CO-OPN (Concurrent Object Oriented Petri Net) formal specification language is used for modelling the controller and the associated hardware system with the inherent limitation of its physical components. CO-OPN formal language is based on coordinated algebraic Petri nets. The CO-OPN model can be used to verify some properties of the controller in the concrete physical environment. This is achieved by constrained animation of the valid prototype produced by automatic code generation. The possibility to incrementally refine the generated code can be used to obtain a more efficient implementation.

A methodology for continuously monitoring a program for specification consistency during program execution is described. Prior development of the formal specification and program is assumed. The program is annotated with constructs from a formal specification language, and the formal specification constructs are transformed into checking code, which is then inserted into the underlying program. Calls to this checking code are inserted into underlying program wherever it can potentially become inconsistent with its specification. If an inconsistency does in fact occur, diagnostic information is provided. The implementation of such a system for Anna (annotated Ada) subtype annotations is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>