4,933 research outputs found
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
Specifying and Analysing SOC Applications with COWS
COWS is a recently defined process calculus for specifying and combining service-oriented applications, while modelling their dynamic behaviour. Since its introduction, a number of methods and tools have been devised to analyse COWS specifications, like e.g. a type system to check confidentiality properties, a logic and a model checker to express and check functional properties of services. In this paper, by means of a case study in the area of automotive systems, we demonstrate that COWS, with some mild linguistic additions, can model all the phases of the life cycle of service-oriented applications, such as publication, discovery, negotiation, orchestration, deployment, reconfiguration and execution. We also provide a flavour of the properties that can be analysed by using the tools mentioned above
A Calculus for Orchestration of Web Services
Service-oriented computing, an emerging paradigm for distributed computing based on the use of services, is calling for the development of tools and techniques to build safe and trustworthy systems, and to analyse their behaviour. Therefore, many researchers have proposed to use process calculi, a cornerstone of current foundational research on specification and analysis of concurrent, reactive, and distributed systems. In this paper, we follow this approach and introduce CWS, a process calculus expressly designed for specifying and combining service-oriented applications, while modelling their dynamic behaviour. We show that CWS can model all the phases of the life cycle of service-oriented applications, such as publication, discovery, negotiation, orchestration, deployment, reconfiguration and execution. We illustrate the specification style that CWS supports by means of a large case study from the automotive domain and a number of more specific examples drawn from it
Reasoning About a Service-oriented Programming Paradigm
This paper is about a new way for programming distributed applications: the
service-oriented one. It is a concept paper based upon our experience in
developing a theory and a language for programming services. Both the
theoretical formalization and the language interpreter showed us the evidence
that a new programming paradigm exists. In this paper we illustrate the basic
features it is characterized by
Microservice Transition and its Granularity Problem: A Systematic Mapping Study
Microservices have gained wide recognition and acceptance in software
industries as an emerging architectural style for autonomic, scalable, and more
reliable computing. The transition to microservices has been highly motivated
by the need for better alignment of technical design decisions with improving
value potentials of architectures. Despite microservices' popularity, research
still lacks disciplined understanding of transition and consensus on the
principles and activities underlying "micro-ing" architectures. In this paper,
we report on a systematic mapping study that consolidates various views,
approaches and activities that commonly assist in the transition to
microservices. The study aims to provide a better understanding of the
transition; it also contributes a working definition of the transition and
technical activities underlying it. We term the transition and technical
activities leading to microservice architectures as microservitization. We then
shed light on a fundamental problem of microservitization: microservice
granularity and reasoning about its adaptation as first-class entities. This
study reviews state-of-the-art and -practice related to reasoning about
microservice granularity; it reviews modelling approaches, aspects considered,
guidelines and processes used to reason about microservice granularity. This
study identifies opportunities for future research and development related to
reasoning about microservice granularity.Comment: 36 pages including references, 6 figures, and 3 table
POLICY BASED THIRD PARTY WEB SERVICE MANAGEMENT
Service-oriented computing potentially can help businesses respond more quickly and more cost-effectively to changing market-conditions. Web services are the basic building elements of service-oriented architecture. There are often expectations expected from services that are related to non-functional aspects (i.e. response time, availability) of the web service. The non-functional requirements are referred to as Quality of Service (QoS) requirements. Service Level Agreements (SLAs) are contracts between service providers and service consumers by which the service providers are bound to maintain a certain level of the Quality of Service. SLAs specify conditions on metrics, that represent some aspect of run-time behaviour, that are to be satisfied at run-time. Monitoring of services is needed to determine when SLAs are vio
lated. Adaptive recovery actions are taken to maintain the quality of the service promised on the SLAs. Policies are used to guide the decision making process to determine the appropriate action.
In this work a new system architecture which uses policies to manage web services is pro posed and a prototype is implemented to validate the architecture. In this system policies could be added, modified or deleted at system run time. The management task is totally handled by the third party and so, management tasks on the client end are reduced.
The results of the conducted experiments validates the functionality of our proposed archi tecture and proves that the overhead of using the architecture is less
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