A Broker based Web Service Allocation Mechanism

Los servicios web son considerados por la industria y la investigación de facto por proporcionar funcionalidad de forma distribuida que sea usable en entornos heterogéneos. En pocas palabras, los servicios web son funcionalidad empaquetada que se basa en un conjunto de estándares que facilitan la definición de los métodos de los servicios web, sus números y formatos de entrada, así como sus números y formatos de salida. En combinación con la replicación, los servicios web pueden proporcionar soluciones de optimización del rendimiento a un número ilimitado de aplicaciones de negocio de la vida real. Sin embargo, cuando se habla de replicación es necesario plantearse cómo asignar o elegir las réplicas para proporcionar el mejor rendimiento posible. Esta tesis está dedicada a responder a esta pregunta. La tesis se titula "Un mecanismo de asignación de servicios web basado en Broker" donde un paradigma de ejecución (Proteus) es presentado, y varios algoritmos de asignación son también presentados, examinados y analizados para mostrar el óptimo. La tesis se centra en el componente broker del paradigma de ejecución. Este componente tiene embebido el algoritmo de asignación. Por otra parte, la tesis se centra en el Algoritmo de menor tiempo de servicio (LRT), el cual funciona asignando las réplicas del servicio web que proporcionan un tiempo de respuesta más rápido. La tesis ofrece todo el trabajo de fondo necesario, así como toda la investigación relacionada. Contiene una parte simulada, así como una descripción de un sistema de la vida real (Proteus). Contiene también una sección dedicada a analizar los resultados de los registros de ejecución y analizar las diferentes variaciones de los entornos (homogéneos y heterogéneos), el número de replicas y el nivel de paralelismo. Los registros son examinados y las conclusiones expuestas.Alwagait, EAK. (2011). A Broker based Web Service Allocation Mechanism [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/12500Palanci

Distributed Web Service Coordination for Collaboration Applications and Biological Workflows

In this dissertation work, we have investigated the main research thrust of decentralized coordination of workflows over web services. To address distributed workflow coordination, first we have developed “Web Coordination Bonds” as a capable set of dependency modeling primitives that enable each web service to manage its own dependencies. Web bond primitives are as powerful as extended Petri nets and have sufficient modeling and expressive capabilities to model workflow dependencies. We have designed and prototyped our “Web Service Coordination Management Middleware” (WSCMM) system that enhances current web services infrastructure to accommodate web bond enabled web services. Finally, based on core concepts of web coordination bonds and WSCMM, we have developed the “BondFlow” system that allows easy configuration distributed coordination of workflows. The footprint of the BonFlow runtime is 24KB and the additional third party software packages, SOAP client and XML parser, account for 115KB

Semantic Service Description Framework for Efficient Service Discovery and Composition

Web services have been widely adopted as a new distributed system technology by industries in the areas of, enterprise application integration, business process management, and virtual organisation. However, lack of semantics in current Web services standards has been a major barrier in the further improvement of service discovery and composition. For the last decade, Semantic Web Services have become an important research topic to enrich the semantics of Web services. The key objective of Semantic Web Services is to achieve automatic/semi-automatic Web service discovery, invocation, and composition. There are several existing semantic Web service description frameworks, such as, OWL-S, WSDL-S, and WSMF. However, existing frameworks have several issues, such as insufficient service usage context information, precisely specified requirements needed to locate services, lacking information about inter-service relationships, and insufficient/incomplete information handling, make the process of service discovery and composition not as efficient as it should be. To address these problems, a context-based semantic service description framework is proposed in this thesis. This framework focuses on not only capabilities of Web services, but also the usage context information of Web services, which we consider as an important factor in efficient service discovery and composition. Based on this framework, an enhanced service discovery mechanism is proposed. It gives service users more flexibility to search for services in more natural ways rather than only by technical specifications of required services. The service discovery mechanism also demonstrates how the features provided by the framework can facilitate the service discovery and composition processes. Together with the framework, a transformation method is provided to transform exiting service descriptions into the new framework based descriptions. The framework is evaluated through a scenario based analysis in comparison with OWL-S and a prototype based performance evaluation in terms of query response time, the precision and recall ratio, and system scalability

An Investigation into Dynamic Web Service Composition Using a Simulation Framework

[Motivation] Web Services technology has emerged as a promising solution for creat- ing distributed systems with the potential to overcome the limitation of former distrib- uted system technologies. Web services provide a platform-independent framework that enables companies to run their business services over the internet. Therefore, many techniques and tools are being developed to create business to business/business to customer applications. In particular, researchers are exploring ways to build new services from existing services by dynamically composing services from a range of resources. [Aim] This thesis aims to identify the technologies and strategies cur- rently being explored for organising the dynamic composition of Web services, and to determine how extensively each of these has been demonstrated and assessed. In addition, the thesis will study the matchmaking and selection processes which are essential processes for Web service composition. [Research Method] We under- took a mapping study of empirical papers that had been published over the period 2000 to 2009. The aim of the mapping study was to identify the technologies and strategies currently being explored for organising the composition of Web services, and to determine how extensively each of these has been demonstrated and assessed. We then built a simulation framework to carry out some experiments on composition strategies. The rst experiment compared the results of a close replication of an ex- isting study with the original results in order to evaluate our close replication study. The simulation framework was then used to investigate the use of a QoS model for supporting the selection process, comparing this with the ranking technique in terms of their performance. [Results] The mapping study found 1172 papers that matched our search terms, from which 94 were classied as providing practical demonstration of ideas related to dynamic composition. We have analysed 68 of these in more detail. Only 29 provided a `formal' empirical evaluation. From these, we selected a `baseline' study to test our simulation model. Running the experiments using simulated data- sets have shown that in the rst experiment the results of the close replication study and the original study were similar in terms of their prole. In the second experiment, the results demonstrated that the QoS model was better than the ranking mechanism in terms of selecting a composite plan that has highest quality score. [Conclusions] No one approach to service composition seemed to meet all needs, but a number has been investigated more. The similarity between the results of the close replication and the original study showed the validity of our simulation framework and a proof that the results of the original study can be replicated. Using the simulation it was demonstrated that the performance of the QoS model was better than the ranking mechanism in terms of the overall quality for a selected plan. The overall objectives of this research are to develop a generic life-cycle model for Web service composition from a mapping study of the literature. This was then used to run simulations to replicate studies on matchmaking and compare selection methods

Atomic service-based scheduling for web services composition

With the rapid development of Internet technologies and widespread of Internet applications, Web Services has become an important research issue of World Wide Web Consortium (W3C). In order to cope with various requirements from service users, services need to be thoroughly and precisely described, thus improvement needs to be made in describing services as more properties should be added to the current service description model based on OWL-ร, an ontology structure consisting of service profiles and operations. Semantics is widely considered as one of the core supplements, which is able to provide the metadata of services, so as to better match requirements with services in the service repository. On the other hand, Web Services has attracted people from various fields to perform relevant experiments on how to cope with users' requirements. Service providers tend to coordinate service implementation by means of interacting with available resources and reconstructing existing service modules. The integration of self-contained software components becomes a key step to meet service demands. This thesis makes contributions to current service description. The introduction of the term "Atomic Service" is not only considered to be a more refined service structure, but also serves as the fundamental component for all service modules. Based on this, the thesis will discuss issues including composition and scheduling, with the purpose of building interoperations among composable service units and setting up the mechanism of realising business goals with composite services under the guidance of the service scheduling language. This notion is illustrated in a demonstration system to justify the manageable interrelationship between service modules and the way of composition

Services State of Play - Compliance Testing and Interoperability Checking

The document contains an inventory of existing solutions for compliance testing and interoperability checking of services, the assumption being that the services are web services. Even if the emphasis is on geographical information and therefore on Geographical Information Systems, the document describes applicable solutions outside the geographical Information System domain.JRC.H.6-Spatial data infrastructure

Business rules based legacy system evolution towards service-oriented architecture.

Enterprises can be empowered to live up to the potential of becoming dynamic, agile and real-time. Service orientation is emerging from the amalgamation of a number of key business, technology and cultural developments. Three essential trends in particular are coming together to create a new revolutionary breed of enterprise, the service-oriented enterprise (SOE): (1) the continuous performance management of the enterprise; (2) the emergence of business process management; and (3) advances in the standards-based service-oriented infrastructures. This thesis focuses on this emerging three-layered architecture that builds on a service-oriented architecture framework, with a process layer that brings technology and business together, and a corporate performance layer that continually monitors and improves the performance indicators of global enterprises provides a novel framework for the business context in which to apply the important technical idea of service orientation and moves it from being an interesting tool for engineers to a vehicle for business managers to fundamentally improve their businesses