200,059 research outputs found
Specification and Verification of Context-dependent Services
Current approaches for the discovery, specification, and provision of
services ignore the relationship between the service contract and the
conditions in which the service can guarantee its contract. Moreover, they do
not use formal methods for specifying services, contracts, and compositions.
Without a formal basis it is not possible to justify through formal
verification the correctness conditions for service compositions and the
satisfaction of contractual obligations in service provisions. We remedy this
situation in this paper. We present a formal definition of services with
context-dependent contracts. We define a composition theory of services with
context-dependent contracts taking into consideration functional,
nonfunctional, legal and contextual information. Finally, we present a formal
verification approach that transforms the formal specification of service
composition into extended timed automata that can be verified using the model
checking tool UPPAAL.Comment: In Proceedings WWV 2011, arXiv:1108.208
An Abstract Formal Basis for Digital Crowds
Crowdsourcing, together with its related approaches, has become very popular
in recent years. All crowdsourcing processes involve the participation of a
digital crowd, a large number of people that access a single Internet platform
or shared service. In this paper we explore the possibility of applying formal
methods, typically used for the verification of software and hardware systems,
in analysing the behaviour of a digital crowd. More precisely, we provide a
formal description language for specifying digital crowds. We represent digital
crowds in which the agents do not directly communicate with each other. We
further show how this specification can provide the basis for sophisticated
formal methods, in particular formal verification.Comment: 32 pages, 4 figure
A Web-Based Tool for Analysing Normative Documents in English
Our goal is to use formal methods to analyse normative documents written in
English, such as privacy policies and service-level agreements. This requires
the combination of a number of different elements, including information
extraction from natural language, formal languages for model representation,
and an interface for property specification and verification. We have worked on
a collection of components for this task: a natural language extraction tool, a
suitable formalism for representing such documents, an interface for building
models in this formalism, and methods for answering queries asked of a given
model. In this work, each of these concerns is brought together in a web-based
tool, providing a single interface for analysing normative texts in English.
Through the use of a running example, we describe each component and
demonstrate the workflow established by our tool
An Integrated Methodology for Creating Composed Web/Grid Services
This thesis presents an approach to design, specify, validate, verify, implement, and evaluate composed web/grid services. Web and grid services can be composed to create new services
with complex behaviours. The BPEL (Business Process Execution Language) standard was created to enable the orchestration of web services, but there have also been investigation of
its use for grid services. BPEL specifies the implementation of service composition but has no formal semantics; implementations are in practice checked by testing. Formal methods are
used in general to define an abstract model of system behaviour that allows simulation and reasoning about properties. The approach can detect and reduce potentially costly errors at
design time.
CRESS (Communication Representation Employing Systematic Specification) is a domainindependent,
graphical, abstract notation, and integrated toolset for developing composite web service. The original version of CRESS had automated support for formal specification in
LOTOS (Language Of Temporal Ordering Specification), executing formal validation with MUSTARD (Multiple-Use Scenario Testing and Refusal Description), and implementing in
BPEL4WS as the early version of BPEL standard. This thesis work has extended CRESS and its integrated tools to design, specify, validate, verify, implement, and evaluate composed web/grid
services. The work has extended the CRESS notation to support a wider range of service compositions, and has applied it to grid services as a new domain. The thesis presents two new
tools, CLOVE (CRESS Language-Oriented Verification Environment) and MINT (MUSTARD Interpreter), to respectively support formal verification and implementation testing. New work
has also extended CRESS to automate implementation of composed services using the more recent BPEL standard WS-BPEL 2.0
An Operator-based Approach to Incremental Development of Conform Protocol State Machines
An incremental development framework which supports a conform construction of Protocol State Machines (PSMs) is presented. We capture design concepts and strategies of PSM construction by sequentially applying some development operators: each operator makes evolve the current PSM to another one. To ensure a conform construction, we introduce three conformance relations, inspired by the specification refinement and specification matchings supported by formal methods. Conformance relations preserve some global behavioral properties. Our purpose is illustrated by some development steps of the card service interface of an electronic purse: for each step, we introduce the idea of the development, we propose an operator and we give the new specification state obtained by the application of this operator and the property of this state relatively to the previous one in terms of conformance relation
A service-oriented architecture for integrating the modeling and formal verification of genetic regulatory networks
<p>Abstract</p> <p>Background</p> <p>The study of biological networks has led to the development of increasingly large and detailed models. Computer tools are essential for the simulation of the dynamical behavior of the networks from the model. However, as the size of the models grows, it becomes infeasible to manually verify the predictions against experimental data or identify interesting features in a large number of simulation traces. Formal verification based on temporal logic and model checking provides promising methods to automate and scale the analysis of the models. However, a framework that tightly integrates modeling and simulation tools with model checkers is currently missing, on both the conceptual and the implementational level.</p> <p>Results</p> <p>We have developed a generic and modular web service, based on a service-oriented architecture, for integrating the modeling and formal verification of genetic regulatory networks. The architecture has been implemented in the context of the qualitative modeling and simulation tool G<smcaps>NA</smcaps> and the model checkers N<smcaps>U</smcaps>SMV and C<smcaps>ADP</smcaps>. G<smcaps>NA</smcaps> has been extended with a verification module for the specification and checking of biological properties. The verification module also allows the display and visual inspection of the verification results.</p> <p>Conclusions</p> <p>The practical use of the proposed web service is illustrated by means of a scenario involving the analysis of a qualitative model of the carbon starvation response in <it>E. coli</it>. The service-oriented architecture allows modelers to define the model and proceed with the specification and formal verification of the biological properties by means of a unified graphical user interface. This guarantees a transparent access to formal verification technology for modelers of genetic regulatory networks.</p
CABS: a case-based and graphical requirements capture, formalisation and verification system
The use of formal specifications based on varieties of mathematical logic is becoming common in the process of designing and implementing safety critical systems and practices for hardware design. Formal methods are usually intended to include in the specification, all the important details of the final system in the specification, with the aim of proving that the specification possesses certain properties and lacks other unwanted properties. In large, complex systems, this task requires sophisticated theorem proving, which can be difficult and complicated. Telecommunications systems are large and complex, making detailed formal specification impractical given current technology. However, formal “sketches” of the behaviours the services provide can be produced, and these can be very helpful in locating which service might be relevant to a given problem.This thesis describes CABS, a case-based approach that uses coarse-grained graphical requirements specification sketches, to outline the basic behaviour of the system's functional modules (called services), thereby allowing us to identify, re-use and adapt requirements (from cases stored in a library), to construct new cases. The matching algorithm identifies similar behaviour between the input examples and the cases stored in the case library. By using cases that have already been tested, integrated and im plemented, less effort is needed to produce requirements specifications on a large scale. Using a hypothetical telecommunications system as an example, it will be shown that a comparatively simple logic can be used to capture coarse-grained behaviour and how a case-based approach benefits from this. The input from the examples is used both to identify the cases whose behaviour corresponds most closely to the designer's intentions, and also in the process of adapting, validating and, finally, verifying the proposed solution against the examples
DecSerFlow: Towards a Truly Declarative Service Flow Language
The need for process support in the context of web services
has triggered the development of many languages, systems, and standards.
Industry has been developing software solutions and proposing
standards such as BPEL, while researchers have been advocating the
use of formal methods such as Petri nets and pi-calculus. The languages
developed for service flows, i.e., process specification languages for web
services, have adopted many concepts from classical workflow management
systems. As a result, these languages are rather procedural and
this does not fit well with the autonomous nature of services. Therefore,
we propose DecSerFlow as a Declarative Service Flow Language. DecSerFlow
can be used to specify, enact, and monitor service flows. The
language is extendible (i.e., constructs can be added without changing
the engine or semantical basis) and can be used to enforce or to check the
conformance of service flows. Although the language has an appealing
graphical representation, it is grounded in temporal logic
A Multiset Rewriting Model for Specifying and Verifying Timing Aspects of Security Protocols
Catherine Meadows has played an important role in the advancement of formal methods for protocol security verification. Her insights on the use of, for example, narrowing and rewriting logic has made possible the automated discovery of new attacks and the shaping of new protocols. Meadows has also investigated other security aspects, such as, distance-bounding protocols and denial of service attacks. We have been greatly inspired by her work. This paper describes the use of Multiset Rewriting for the specification and verification of timing aspects of protocols, such as network delays, timeouts, timed intruder models and distance-bounding properties. We detail these timed features with a number of examples and describe decidable fragments of related verification problems
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