Investigating the readability of state-based formal requirements specification languages

The authors present a framework for developing and verifying knowledge-based systems (KBSs). In this framework, they propose FRORL (frame-and-rule oriented requirements specification language) as a formal requirements specification language which exploits knowledge representation techniques as an aid in the specification, analysis, and development of a knowledge-based system. FRORL uses a combination of resolution refutation, anomaly detection matrix, and algorithm methods to verify a number of properties which might exist in KBSs. Incorporating FRORL and its verification methods in the proposed framework lays a solid foundation for coping with the current issues in KBS verification. >

The Live Sequence Charts (LSC) language is a formally rigorous variant of the well-known scenario language Message Sequence Charts (MSC). LSCs yield expressive power by means to distinguish mandatory and scenario behaviour, means to characterise by another scenario the context in which a specification applies, and means to distinguish required from possible progress, i.e. to require liveness. From the original proposal by Damm & Harel [1], two slightly different dialects emerged, one in the context of LSC play-in and -out [2] and one for the use of LSCs as formal requirements specification language in formal, model-based approaches to software development [3]. In this paper, we investigate the expressive power of LSCs in the sense of [3]. That is, we first (constructively) show that for each LSC there is an equivalent CTL * formula. Complementing existing work, we show that the containment is strict, that is, not each CTL* formula has an equivalent LSC. To complete the discussion, we present for the first time a way back, from a syntactically characterised fragment of CTL* to the subset of bonded LSC specifications, thereby establishing an equivalence.

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.

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.

Specification of software process measurement

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.

Implementing specification freedoms

Requirements Engineering is more and more considered as a central phase in the development and implementation of computer systems. Within the context of CIM, the CIMOSA project proposes a set of models based on adequate concepts for expressing requirements. In this paper, we suggest how these models can be supported by the use of a fully formal requirements specification language called ALBERT and based on an agent-oriented real-time temporal logic framework.

Standardization of Formal Specification Languages

This paper deals with experience with specification languages at AEROSPATIALE Aircraft, Systems and Avionics Division. We describe first the current avionics development environment. Then, we present our results and viewpoints on the use of the three specification languages: LOTOS, ESTEREL, and B. The evaluation studies we performed, showed that each of these languages does not cover in a complete way our needs in specification, validation, and development of avionics. Afterwards, we propose and illustrate an investigation approach that allows to structure and compose different formal specification languages in the same environment.

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.

SOFL is a formal language and method for system specification and design. It was developed by integrating Petri Nets, Data Flow Diagrams, and VDM-SL. As the major feature of the original SOFL method is to use structured techniques for analysis and specification, and object-oriented techniques for design and implementation, SOFL has its own implementation language that is similar to C++. However during our recent work of applying SOFL to software systems, the transformation of structured specifications to object-oriented implementations creates some difficulties, simply because of paradigms mismatch. In this paper we extend SOFL to a formal object-oriented language and method while keeping its structured features. This will allow powerful object-oriented reuse mechanisms, such as class inheritance and object composition, to be utilized in the early phases, and transformation from SOFL specifications to commercial object-oriented programming languages to be readily achieved.

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.