1,990 research outputs found

    A Calculus for Orchestration of Web Services

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    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

    A Programming Language for Web Service Development

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    There is now widespread acceptance of Web services and service-oriented architectures. But despite the agreement on key Web services standards there remain many challenges. Programming environments based on WSDL support go some way to facilitating Web service development. However Web services fundamentally rely on XML and Schema, not on contemporary programming language type systems such as those of Java or .NET. Moreover, Web services are based on a messaging paradigm and hence bring forward the traditional problems of messaging systems including concurrency control and message correlation. It is easy to write simple synchronous Web services using traditional programming languages; however more realistic scenarios are surprisingly difficult to implement. To alleviate these issues we propose a programming language which directly supports Web service development. The language leverages XQuery for native XML processing, supports implicit message correlation and has high level join calculus-style concurrency control. We illustrate the features of the language through a motivating example

    On Synchronous and Asynchronous Monitor Instrumentation for Actor-based systems

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    We study the impact of synchronous and asynchronous monitoring instrumentation on runtime overheads in the context of a runtime verification framework for actor-based systems. We show that, in such a context, asynchronous monitoring incurs substantially lower overhead costs. We also show how, for certain properties that require synchronous monitoring, a hybrid approach can be used that ensures timely violation detections for the important events while, at the same time, incurring lower overhead costs that are closer to those of an asynchronous instrumentation.Comment: In Proceedings FOCLASA 2014, arXiv:1502.0315

    Recovery within long running transactions

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    As computer systems continue to grow in complexity, the possibilities of failure increase. At the same time, the increase in computer system pervasiveness in day-to-day activities brought along increased expectations on their reliability. This has led to the need for effective and automatic error recovery techniques to resolve failures. Transactions enable the handling of failure propagation over concurrent systems due to dependencies, restoring the system to the point before the failure occurred. However, in various settings, especially when interacting with the real world, reversal is not possible. The notion of compensations has been long advocated as a way of addressing this issue, through the specification of activities which can be executed to undo partial transactions. Still, there is no accepted standard theory; the literature offers a plethora of distinct formalisms and approaches. In this survey, we review the compensations from a theoretical point of view by: (i) giving a historic account of the evolution of compensating transactions; (ii) delineating and describing a number of design options involved; (iii) presenting a number of formalisms found in the literature, exposing similarities and differences; (iv) comparing formal notions of compensation correctness; (v) giving insights regarding the application of compensations in practice; and (vi) discussing current and future research trends in the area.peer-reviewe

    Analysis and Verification of Service Contracts

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    A compensating transaction example in twelve notations

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    The scenario of business computer systems changed with the advent of cross-entity computer interactions: computer systems no longer had the limited role of storing and processing data, but became themselves the players which actuated real-life actions. These advancements rendered the traditional transaction mechanism insufficient to deal with these new complexities of longer multi-party transactions. The concept of compensations has long been suggested as a solution, providing the possibility of executing “counter”-actions which semantically undo previously completed actions in case a transaction fails. There are numerous design options related to compensations particularly when deciding the strategy of ordering compensating actions. Along the years, various models which include compensations have emerged, each tackling in its own way these options. In this work, we review a number of notations which handle compensations by going through their syntax and semantics — highlighting the distinguishing features — and encoding a typical compensating transaction example in terms of each of these notations.peer-reviewe

    Recent Advanced Computing Methods Employed in Web Service Automation - A Survey

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    Web Service Automation gains momentum for the past two decades. So, various computational algorithms have been developed on different aspects of web service categorization and resource allocation. Research activities are more on comparing the algorithms over time and space complexity. Web designers and service providers make their contribution to enrich the IT products in this area. In this paper, a detail study is attempted on the above aspects of web service Automation. We open an area of web technology for implementation of newer algorithms. Keywords - Web Service Allocation, Zero Knowledge Authentication, Logic Programming, Service Computing, Distributed Algorithms, Cloud computing
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