Issues about the Adoption of Formal Methods for Dependable Composition of Web Services

Web Services provide interoperable mechanisms for describing, locating and invoking services over the Internet; composition further enables to build complex services out of simpler ones for complex B2B applications. While current studies on these topics are mostly focused - from the technical viewpoint - on standards and protocols, this paper investigates the adoption of formal methods, especially for composition. We logically classify and analyze three different (but interconnected) kinds of important issues towards this goal, namely foundations, verification and extensions. The aim of this work is to individuate the proper questions on the adoption of formal methods for dependable composition of Web Services, not necessarily to find the optimal answers. Nevertheless, we still try to propose some tentative answers based on our proposal for a composition calculus, which we hope can animate a proper discussion

Property Analysis of Composable Web services

Web services are basic components constructing a flexible business process software. By composing multiple Web services, a complicated business process across organization and departments can be formed. This paper present a formal model of composable Web services: composed service process nets (CSPNs). Properties of Composable Web services are analyzed based on CSPNs. The relation between a CSPN and its corresponding Web service process subnets are discussed. The property analysis methods of CSPNs are come up with. A dynamic property of CSPNs can be determined based on static net structures by means of the proposed methods

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 Efficient Web Service Discovery Architecture for Static and Mobile Environments

The widely adopted and implemented core web servicesstandards SOAP and WSDL have achieved extraordinaryinteroperability across highly disparate software systems. The serviceoriented architecture SOA has become widely recognized for itsimportant role in information technology (IT) projects. A SOA is a styleof design that guides an organization during all aspects of creating andusing business services (including conception, modeling, design,development, deployment and management). SOA has been the idealcombination of architecture and technology for consistently deliveringrobust, reusable services that support today’s business needs and that canbe easily adapted to satisfy changing business requirements. As systemsbecome more complex, the overall system structure-or architecture---becomes a central design problem. A system's architecture provides amodel of the system that suppresses implementation detail.Unfortunately, current representations of SOA architecture are informaland ad hoc. Currently many state of the art formal methods have beenapplied into the modeling, interoperability, dependability andtrustworthiness of web services and this could have a significant impacton the ongoing standardization efforts for services and cloudtechnologies. This paper presents a formal verification of proposed x-SOA based architecture for UDDI based web service discoveryframework. The paper attempts to establish the proposed architecture forlocating services in mobile computing environment as well. Potentially,extending the state of art formal method techniques could have asignificant impact on the ongoing standardization efforts for web servicesand cloud technologies for both fixed and mobile networks

Automated Analysis and Implementation of Composed Grid Services

Service composition allows web services to be combined into new ones. Web service composition is increasingly common in mission-critical applications. It has therefore become important to verify the correctness of web service composition using formal methods. The composition of grid services is a similar but new goal. We have previously developed an abstract graphical notation called CRESS for describing composite grid services. We have demonstrated that it is feasible to automatically generate service implementations as well as formal specifications from CRESS descriptions. The automated service implementations use orchestration code in BPEL, along with the service interfaces and data types in WSDL and XSD respectively for all services. CRESS-generated BPEL implementations currently do not useWSRF features such as implicit endpoint references for WS-Resources and interfacing to standard WSRF port types. CRESS-generated formal models use the standardised process algebra LOTOS. Service behaviour is modelled by processes, while service data types are modelled as abstract data types. Simulation and validation of the generated LOTOS specifications can be performed. In this paper, we illustrate how CRESS can be further extended to improve its generation of service compositions, specifically for WSRF services implemented using Globus Toolkit 4. We also show how to facilitate use of the generated LOTOS specifications with the CADP toolbox

Web Services: A Process Algebra Approach

It is now well-admitted that formal methods are helpful for many issues raised in the Web service area. In this paper we present a framework for the design and verification of WSs using process algebras and their tools. We define a two-way mapping between abstract specifications written using these calculi and executable Web services written in BPEL4WS. Several choices are available: design and correct errors in BPEL4WS, using process algebra verification tools, or design and correct in process algebra and automatically obtaining the corresponding BPEL4WS code. The approaches can be combined. Process algebra are not useful only for temporal logic verification: we remark the use of simulation/bisimulation both for verification and for the hierarchical refinement design method. It is worth noting that our approach allows the use of any process algebra depending on the needs of the user at different levels (expressiveness, existence of reasoning tools, user expertise)

Folksonomies : Indexing and Retrieval in Web 2.0

One of the defining principles of Web 2.0 when it first emerged was that the collective intelligence of users should be harnessed in order to enrich services for that user community (O’Reilly, 2005). This so-called ‘network effect’ principle remains as central to the Web 2.0 thesis then as it does five years on (O’Reilly and Battelle, 2009). Folksonomies, or collaborative tagging systems, have become the epitome of the network effect; using collective intelligence to organise and retrieve information on the Web. In Folksonomies: indexing and retrieval in Web 2.0, author Isabella Peters explores the use of folksonomies in ‘collaborative information services’, a catch-all term used by Peters to encompass the heterogeneous nature of the Web 2.0 services that use tagging systems. The stated purpose of Folksonomies is to provide a degree of insight into folksonomy applications, as well as discuss their strengths, weaknesses and how their problems can be ameliorated by applying recognised information retrieval models and formal knowledge representation methods