Abstract: Session Initiation Protocol (SIP) is a signaling layer protocol for building, adjusting and ending sessions among participants including Internet conferences, telephone calls and multimedia distribution. SIP facilitates user movement by proxying and forwarding requests to the present location of the user. In this paper, we provide a formal Specification and Description Language (SDL) and Message Sequence Chart (MSC) to model and define the Internet Engineering Task Force (IETF) SIP protocol and its sample services resulted from informal SIP specification. We create an “Abstract User Interface” using case analysis so that can be applied to identify SIP services more explicitly. The issued sample SIP features are then used as case scenarios; they are revised in MSCs format and validated to their corresponding SDL models.
Abstract: Digital reference service is when a traditional library
reference service is provided electronically. In most cases users do
not get full satisfaction from using digital reference service due to
variety of reasons. This paper discusses the formal specification of
web services applications for digital reference services (WSDRS).
WSDRS is an informal model that claims to reduce the problems of
digital reference services in libraries. It uses web services technology
to provide efficient digital way of satisfying users’ need in the
reference section of libraries. Informal model is in natural language
which is inconsistent and ambiguous that may cause difficulties to the
developers of the system. In order to solve this problem we decided
to convert the informal specifications into formal specifications. This
is supposed to reduce the overall development time and cost. We use
Z language to develop the formal model and verify it with Z/EVES
theorem prover tool.
Abstract: The web services applications for digital reference
service (WSDRS) of LIS model is an informal model that claims to
reduce the problems of digital reference services in libraries. It uses
web services technology to provide efficient way of satisfying users’
needs in the reference section of libraries. The formal WSDRS model
consists of the Z specifications of all the informal specifications of
the model. This paper discusses the formal validation of the Z
specifications of WSDRS model. The authors formally verify and
thus validate the properties of the model using Z/EVES theorem
prover.
Abstract: The importance of the formal specification in the
software life cycle is barely concealing to anyone. Formal
specifications use mathematical notation to describe the properties of
information system precisely, without unduly constraining the way in
how these properties are achieved. Having a correct and quality
software specification is not easy task. This study concerns with how
a group of rectifiers can communicate with each other and work to
prepare and produce a correct formal software specification. WBCS
has been implemented based mainly in the proposed supported
cooperative work model and a survey conducted on the existing Webbased
collaborative writing tools. This paper aims to assess the
feasibility of executing the web-based collaboration process using
WBCS. The purpose of conducting this test is to test the system as a
whole for functionality and fitness for use based on the evaluation
test plan.
Abstract: This paper provides new ways to explore the old
problem of failure of information systems development in an
organisation. Based on the theory of cognitive dissonance,
information systems (IS) failure is defined as a gap between what the
users expect from an information system and how well these
expectations are met by the perceived performance of the delivered
system. Bridging the expectation-perception gap requires that IS
professionals make a radical change from being the proprietor of
information systems and products to being service providers. In order
to deliver systems and services that IS users perceive as valuable, IS
people must become expert in determining and assessing users-
expectations and perceptions. It is also suggested that the IS
community, in general, has given relatively little attention to the
front-end process of requirements specification for IS development.
There is a simplistic belief that requirements are obtainable from
users, they are then translatable into a formal specification. The
process of information needs analysis is problematic and worthy of
investigation.
Abstract: We decribe a formal specification and verification of the Rabin public-key scheme in the formal proof system Is-abelle/HOL. The idea is to use the two views of cryptographic verification: the computational approach relying on the vocabulary of probability theory and complexity theory and the formal approach based on ideas and techniques from logic and programming languages. The analysis presented uses a given database to prove formal properties of our implemented functions with computer support. Thema in task in designing a practical formalization of correctness as well as security properties is to cope with the complexity of cryptographic proving. We reduce this complexity by exploring a light-weight formalization that enables both appropriate formal definitions as well as eficient formal proofs. This yields the first computer-proved implementation of the Rabin public-key scheme in Isabelle/HOL. Consequently, we get reliable proofs with a minimal error rate augmenting the used database. This provides a formal basis for more computer proof constructions in this area.
Abstract: As a security mechanism, authorization is to provide access control to the system resources according to the polices and rules specified by the security strategies. Either by update or in the initial specification, conflicts in authorization is an issue needs to be solved. In this paper, we propose a new approach to solve conflict by using prioritized logic programs and discuss the uniqueness of its answer set. Addressing conflict resolution from logic programming viewpoint and the uniqueness analysis of the answer set provide a novel, efficient approach for authorization conflict resolution.
Abstract: Functionalities and control behavior are both primary
requirements in design of a complex system. Automata theory plays
an important role in modeling behavior of a system. Z is an ideal
notation which is used for describing state space of a system and then
defining operations over it. Consequently, an integration of automata
and Z will be an effective tool for increasing modeling power for a
complex system. Further, nondeterministic finite automata (NFA)
may have different implementations and therefore it is needed to
verify the transformation from diagrams to a code. If we describe
formal specification of an NFA before implementing it, then
confidence over transformation can be increased. In this paper, we
have given a procedure for integrating NFA and Z. Complement of a
special type of NFA is defined. Then union of two NFAs is
formalized after defining their complements. Finally, formal
construction of intersection of NFAs is described. The specification
of this relationship is analyzed and validated using Z/EVES tool.
Abstract: Formal Specification languages are being widely used
for system specification and testing. Highly critical systems such as
real time systems, avionics, and medical systems are represented
using Formal specification languages. Formal specifications based
testing is mostly performed using black box testing approaches thus
testing only the set of inputs and outputs of the system. The formal
specification language such as VDMµ can be used for white box
testing as they provide enough constructs as any other high level
programming language. In this work, we perform data and control
flow analysis of VDMµ class specifications. The proposed work is
discussed with an example of SavingAccount.
Abstract: wind catchers have been served as a cooling system, used to provide acceptable ventilation by means of renewable energy of wind. In the present study, the city of Yazd in arid climate is selected as case study. From the architecture point of view, learning about wind catchers in this study is done by means of field surveys. Research method for selection of the case is based on random form, and analytical method. Wind catcher typology and knowledge of relationship governing the wind catcher's architecture were those measures that are taken for the first time. 53 wind catchers were analyzed. The typology of the wind-catchers is done by the physical analyzing, patterns and common concepts as incorporated in them. How the architecture of wind catcher can influence their operations by analyzing thermal behavior are the archetypes of selected wind catchers. Calculating fluids dynamics science, fluent software and numerical analysis are used in this study as the most accurate analytical approach. The results obtained from these analyses show the formal specifications of wind catchers with optimum operation in Yazd. The knowledge obtained from the optimum model could be used for design and construction of wind catchers with more improved operation
Abstract: Recent advances in both the testing and verification of software based on formal specifications of the system to be built have reached a point where the ideas can be applied in a powerful way in the design of agent-based systems. The software engineering research has highlighted a number of important issues: the importance of the type of modeling technique used; the careful design of the model to enable powerful testing techniques to be used; the automated verification of the behavioural properties of the system; the need to provide a mechanism for translating the formal models into executable software in a simple and transparent way. This paper introduces the use of the X-machine formalism as a tool for modeling biology inspired agents proposing the use of the techniques built around X-machine models for the construction of effective, and reliable agent-based software systems.
Abstract: Specification-based testing enables us to detect errors
in the implementation of functions defined in given specifications.
Its effectiveness in achieving high path coverage and efficiency in
generating test cases are always major concerns of testers. The automatic
test cases generation approach based on formal specifications
proposed by Liu and Nakajima is aimed at ensuring high effectiveness
and efficiency, but this approach has not been empirically assessed.
In this paper, we present an experiment for assessing Liu-s testing
approach. The result indicates that this testing approach may not be
effective in some circumstances. We discuss the result, analyse the
specific causes for the ineffectiveness, and describe some suggestions
for improvement.
Abstract: In this article, a formal specification and verification of the Rabin public-key scheme in a formal proof system is presented. The idea is to use the two views of cryptographic verification: the computational approach relying on the vocabulary of probability theory and complexity theory and the formal approach based on ideas and techniques from logic and programming languages. A major objective of this article is the presentation of the first computer-proved implementation of the Rabin public-key scheme in Isabelle/HOL. Moreover, we explicate a (computer-proven) formalization of correctness as well as a computer verification of security properties using a straight-forward computation model in Isabelle/HOL. The analysis uses a given database to prove formal properties of our implemented functions with computer support. The main task in designing a practical formalization of correctness as well as efficient computer proofs of security properties is to cope with the complexity of cryptographic proving. We reduce this complexity by exploring a light-weight formalization that enables both appropriate formal definitions as well as efficient formal proofs. Consequently, we get reliable proofs with a minimal error rate augmenting the used database, what provides a formal basis for more computer proof constructions in this area.
Abstract: Due to important issues, such as deadlock, starvation,
communication, non-deterministic behavior and synchronization,
concurrent systems are very complex, sensitive, and error-prone.
Thus ensuring reliability and accuracy of these systems is very
essential. Therefore, there has been a big interest in the formal
specification of concurrent programs in recent years. Nevertheless,
some features of concurrent systems, such as dynamic process
creation, scheduling and starvation have not been specified formally
yet. Also, some other features have been specified partially and/or
have been described using a combination of several different
formalisms and methods whose integration needs too much effort. In
other words, a comprehensive and integrated specification that could
cover all aspects of concurrent systems has not been provided yet.
Thus, this paper makes two major contributions: firstly, it provides a
comprehensive formal framework to specify all well-known features
of concurrent systems. Secondly, it provides an integrated
specification of these features by using just a single formal notation,
i.e., the Z language.
Abstract: Morgan-s refinement calculus (MRC) is one of the
well-known methods allowing the formality presented in the program
specification to be continued all the way to code. On the other hand,
Object-Z (OZ) is an extension of Z adding support for classes and
objects. There are a number of methods for obtaining code from OZ
specifications that can be categorized into refinement and animation
methods. As far as we know, only one refinement method exists
which refines OZ specifications into code. However, this method
does not have fine-grained refinement rules and thus cannot be
automated. On the other hand, existing animation methods do not
present mapping rules formally and do not support the mapping of
several important constructs of OZ, such as all cases of operation
expressions and most of constructs in global paragraph. In this paper,
with the aim of providing an automatic path from OZ specifications
to code, we propose an approach to map OZ specifications into their
counterparts in MRC in order to use fine-grained refinement rules of
MRC. In this way, having counterparts of our specifications in MRC,
we can refine them into code automatically using MRC tools such as
RED. Other advantages of our work pertain to proposing mapping
rules formally, supporting the mapping of all important constructs of
Object-Z, and considering dynamic instantiation of objects while OZ
itself does not cover this facility.
Abstract: The complexity of today-s software systems makes
collaborative development necessary to accomplish tasks.
Frameworks are necessary to allow developers perform their tasks
independently yet collaboratively. Similarity detection is one of the
major issues to consider when developing such frameworks. It allows
developers to mine existing repositories when developing their own
views of a software artifact, and it is necessary for identifying the
correspondences between the views to allow merging them and
checking their consistency. Due to the importance of the
requirements specification stage in software development, this paper
proposes a framework for collaborative development of Object-
Oriented formal specifications along with a similarity detection
approach to support the creation, merging and consistency checking
of specifications. The paper also explores the impact of using
additional concepts on improving the matching results. Finally, the
proposed approach is empirically evaluated.
Abstract: Probabilistic techniques in computer programs are becoming
more and more widely used. Therefore, there is a big
interest in the formal specification, verification, and development
of probabilistic programs. In our work-in-progress project, we are
attempting to make a constructive framework for developing probabilistic
programs formally. The main contribution of this paper
is to introduce an intermediate artifact of our work, a Z-based
formalism called PZ, by which one can build set theoretical models of
probabilistic programs. We propose to use a constructive set theory,
called CZ set theory, to interpret the specifications written in PZ.
Since CZ has an interpretation in Martin-L¨of-s theory of types, this
idea enables us to derive probabilistic programs from correctness
proofs of their PZ specifications.