Web Services have become the de-facto standard for architecting and implementing business collaborations within and across organization boundaries. Web service composition refers to the creation of new (Web) services ...
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ISBN:
(纸本)9783764384470
Web Services have become the de-facto standard for architecting and implementing business collaborations within and across organization boundaries. Web service composition refers to the creation of new (Web) services by combining the functionalities provided by existing ones. A processoriented language for service composition has been proposed as BPEL4WS. BPEL4WS specification defines an XML based formal language and provides a general overview of the framework. However no design and implementation issues are described in it. Most of the available BPEL4WS compliant process engines are heavy weight, complex and not extensible. This paper describes the design and implementation of an embeddable, scalable and extensible BPEL4WS compliant process engine. This paper highlights the concepts and strategies that were followed during the design and implementation. Primary contribution of this paper is the design of stateless process model and the design of run time core engine using a multi-processor scheduler.
Making mobile phones capable of consuming Web services over wireless networks is a challenging task because of the different issues to be addressed and the limited resources of mobile devices. In this paper, we focus ...
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ISBN:
(纸本)9783764384470
Making mobile phones capable of consuming Web services over wireless networks is a challenging task because of the different issues to be addressed and the limited resources of mobile devices. In this paper, we focus on the issue of how to perform dynamic discovery and invocation of Web services from mobile phones when a J2ME wireless middleware is used. In order to solve the limitations of the middleware platform when mobile phones act as Web services requester we propose a Web service based dynamic proxy between service providers and mobile consumers. With this approach, we provide the following features to mobile devices: (1) support of dynamic binding, (2) support of UDDI specification, (3) support of SOAP messages with encoded representation and (4) handling of complex data types. The paper includes the description of the dynamic proxy, implementation and experimental results with the performance of the approach proposed.
In order for service-oriented architectures (SOAs) to deliver their true value for the business, e.g. flexibility and transparency, a holistic service management needs to be set up in the enterprise. To perform all th...
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ISBN:
(纸本)9783764384470
In order for service-oriented architectures (SOAs) to deliver their true value for the business, e.g. flexibility and transparency, a holistic service management needs to be set up in the enterprise. To perform all the service management tasks efficiently heavy support by automated processes and tools is necessary. This article describes a service description approach that is based on OWL-S (Web Ontology Language for Services) and focuses on nonfunctional criteria. lt starts with the necessary service management tasks and explains non-functional data elements and statements for its automated support. After covering related work it explains the proposed flexible extension to OWL-S. This extension is twofold. Firstly, simple service lifecycle elements are added using the normal extension mechanism. Secondly for adding QoS (Quality of Service) capabilities, the approach combines this extension mechanism with UML (Unified Modeling Language) Profile for QoS. A prototype delivers the proof-of-concept.
Service Level Agreements (SLAs) are commonly prepared and signed agreements that form the contracts between a service provider and its customers, defining the obligations and liabilities of the parties. Naturally, SLA...
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ISBN:
(纸本)9783764384470
Service Level Agreements (SLAs) are commonly prepared and signed agreements that form the contracts between a service provider and its customers, defining the obligations and liabilities of the parties. Naturally, SLAs should reflect the business needs of both customer and supplier. SLAs are usually formed through either the adoption of a boilerplate agreement from the provider, or through a mediation/negotiation process between the parties. With the increasing adoption of software supply being implemented as a network service, such schemes are rigid or slow and costly, This paper proposes a system that the parties can use to facilitate both fast and flexible agreements. It proposes automation of SLA creation from a set of Service Level Objectives (SLOs), making use of softwareagents and adopting a social order function by incorporating it into the decision process.
This paper presents a suite of software code metrics, developed specifically for service-oriented systems with a well-defined methodology, which can be used as indicators of runtime efficiency. Existing literature on ...
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ISBN:
(纸本)9783764384470
This paper presents a suite of software code metrics, developed specifically for service-oriented systems with a well-defined methodology, which can be used as indicators of runtime efficiency. Existing literature on software metrics is mainly focused on centralized systems, while work in the area of distributed systems, particularly in service-oriented systems, is scarce. Firstly, a critical analysis of the problem domain identifies a number of software attributes which are likely to have an impact on efficiency. Secondly, concrete metrics are defined and evaluated (theoretically and empirically) for all identified attributes, with results showing that these software metrics are strongly correlated to typical efficiency metrics. Finally, a simple algorithm, which facilitates the runtime adaptation of service-oriented systems via service redeployment, illustrates a practical application of the metrics.
The design of Web Services is nowadays emerging as one of the most important tasks in the development of a Service Oriented Application. Web service designers need some guidelines to achieve a design of quality. In th...
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ISBN:
(纸本)9783764384470
The design of Web Services is nowadays emerging as one of the most important tasks in the development of a Service Oriented Application. Web service designers need some guidelines to achieve a design of quality. In this paper we provide a methodological guide in the context of a Web engineering method called OOWS. Our approach allows identifying the operations of Web services following a model driven approach, taking the OO-Method / OOWS conceptual models as the source. To document our approach, we apply our ideas to a real case study of a Web application to manage University Research Groups.
The development of composite Web Services is being specified in a more declarative way than imperative programming. In this context, conceptual modeling has been the most accepted solution. Conceptual modeling of Web ...
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ISBN:
(纸本)9783764384470
The development of composite Web Services is being specified in a more declarative way than imperative programming. In this context, conceptual modeling has been the most accepted solution. Conceptual modeling of Web services has been done using behavioral models (like activity diagrams) considering mainly the dynamic view. We believe that, besides the dynamic aspects, the models should capture structural requirements between web service operations. In this way, behavioral models could be complemented with a structural model. In this paper we introduce a Web service composition modeling solution, following the MDA approach, considering both -structural and dynamic properties-enriched with semantic constraints in order to automatically generate composite Web services implemented in BPEL.
An increasing amount of applications are currently built as Web Service compositions based on the TCP/IP+HTTP protocol stack. In case of any deviations from desired runtime-behavior, problematic Web Services have to b...
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ISBN:
(纸本)9783764384470
An increasing amount of applications are currently built as Web Service compositions based on the TCP/IP+HTTP protocol stack. In case of any deviations from desired runtime-behavior, problematic Web Services have to be substituted and their execution plans have to be updated accordingly. One challenge is to detect deviations as early as possible allowing timely adaption of execution plans. We advocate a cross-layer approach to detect bad performance and service interruptions much earlier than by waiting for their propagation through the full protocol stack. This position paper describes an approach to gain detailed real-time information about Web Service behavior and performance based on a cross-layer analysis of the TCP/IP+HTTP protocols. In this paper we focus especially on TCP. The results are used to make decisions supporting service selection and replanning in service-oriented computing scenarios. Furthermore, generic architectural components are proposed implementing the functionality needed which can be used in different web-based scenarios.
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