89 resultados para Web-service agents


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The introduction of Web services into grids helped to address their two main obstacles to be embraced by business and industry, heterogeneity and useability. However, many problems are still open, e.g., grid reconfiguration, reliability and computing optimization. We argue here that a mechanism that could help solving these problems is Web Service migration, a part of automatic and transparent brokerage. Web service migration presents a number of new requirements not addressed in traditional process migration, being the outcome of Web services specific configuration of hosts and application servers, and availability of Web services / resources state. In this paper we report on our study into the development of a Web service migration facility focused on providing migration of services in a Service Oriented Grid environment. We present a novel approach to Web service migration, embodied in a System Management Broker, which is transparent, interoperable and flexible. We take the requirements of Web services into consideration when discovering suitable destination hosts and match services to suitable grid resources which are able to fulfil the needs of the service. We discuss a number of experiments conducted with different types of grid and Web service applications to highlight the feasibility and effectiveness of our migration facility and demonstrate how our facility significantly improves Service Oriented Grids.

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Grid Web Services are still relevantly a new to business systems, and as more systems are being attached to it, any threat to it could bring collapse and huge harm. Some of these potential threats to Grid Web services come in a new form of a new denial of service attack (DoS), called XML Denial of Service or XDOS attacks. Though, as yet, there have not been any reported attacks from the media, we have observed these attacks are actually far less complex to implement than any previous Denial of Service (DoS), but still just as affective. Current security applications for grid web services (WS-Security for example), based on our observations, and are not up to job of handling the problem. In this paper, we build on our previous work called Service Oriented Traceback Architecture (SOTA), and apply our model to Grid Networks that employ web services. We further introduce a filter defence system, called XDetector, to work in combination with SOTA. Our results show that SOTA in conjunction with XDetector makes for an effective defence against XDoS attacks and upcoming DXDoS.

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In the past decade the massive growth of the Internet brought huge changes in the way humans live their daily life; however, the biggest concern with rapid growth of digital information is how to efficiently manage and filter unwanted data. In this paper, we propose a method for managing RSS feeds from various news websites. A Web service was developed to provide filtered news items extracted from RSS feeds and these were categorized based on classical text categorization algorithms. A client application consuming this Web service retrieves and displays such filtered information. A prototype was implemented using Rapidminer 4.3 as a data mining tool and SVM as a classification algorithm. Experimental results suggest that the proposed method is effective and saves a significant amount of user processing time.

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In this chapter, we introduce an interesting type of Web services for "things". Existing Web services are applications across the Web that perform functions mainly to satisfy users' social needs "from simple requests to complicated business processes". Throughout history, humans have accumulated lots of knowledge about diverse things in the physical world. However, human knowledge about the world has not been fully used on the current Web which focuses on social communication; the prospect of interacting with things other than people on the future Web is very exciting. The purpose of Web services for "things" is to provide a tunnel for people to interact with things in the physical world from anywhere through the Internet. Extending the service targets from people to anything challenges the existing techniques of Web services from three aspects: first, an unified interface should be provided for people to describe the needs of things; then basic components should be designed in a Web service for things; finally, implementation of a Web service for things should be optimized when mashing up multiple sub Web services. We tackle the challenges faced by a Web service for things and make the best use of human knowledge from the following aspects. We first define a context of things as an unified interface. The users' description (semantic context) and sensors (sensing context) are two channels for acquiring the context of things. Then, we define three basic modules for a Web service for things: ontology Web services to unify the context of things, machine readable domain knowledge Web services and event report Web services (such as weather report services and sensor event report services). Meanwhile, we develop a Thing-REST framework to optimally mashup structures to loosely couple the three basic modules. We employ a smart plant watering service application to demonstrate all the techniques we have developed.

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With the fast growth of applications of service-oriented architecture (SOA) in software engineering, there has been a rapid increase in demand for building service-based systems (SBSs) by composing existing Web services. Finding appropriate component services to compose is a key step in the SBS engineering process. Existing approaches require that system engineers have detailed knowledge of SOA techniques which is often too demanding. To address this issue, we propose KS3 (Keyword Search for Service-based Systems), a novel approach that integrates and automates the system planning, service discovery and service selection operations for building SBSs based on keyword search. KS3 assists system engineers without detailed knowledge of SOA techniques in searching for component services to build SBSs by typing a few keywords that represent the tasks of the SBSs with quality constraints and optimisation goals for system quality, e.g., reliability, throughput and cost. KS3 offers a new paradigm for SBS engineering that can significantly save the time and effort during the system engineering process. We conducted large-scale experiments using a real-world Web service dataset to demonstrate the practicality, effectiveness and efficiency of KS3.

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At first blush, user modeling appears to be a prime candidate for straightforward application of standard machine learning techniques. Observations of the user's behavior can provide training examples that a machine learning system can use to form a model designed to predict future actions. However, user modeling poses a number of challenges for machine learning that have hindered its application in user modeling, including: the need for large data sets; the need for labeled data; concept drift; and computational complexity. This paper examines each of these issues and reviews approaches to resolving them.

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With the recent innovations in stateful web services, they are now being used to support the construction of distributed systems using software as a service. While the state of web services is preserved, the state is still hidden from clients thus searches for both functionality and state remains a two step process. Proposed in this report is the Resources Via Web Instances (RVWI) framework. RVWI grants to web services the ability to include their state and characteristics in their WSDL. This was done by allowing snapshots (instances) of a web service to be listed in the WSDL of the web service. Instances were utilised as they contain state and characteristic information directly from the web service. Thanks to the inclusion of state and characteristics, queries for web services can now be carried out on the availability of a web service and the 'dimensions' of resources..

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With the rapid development of computing technologies and network technologies, Grid technology has emerged as the solution for high-performance computing. Recently, the grid of orient-services has become a hot issue in this research area. In this paper, we propose an architecture of ChemGrid in CGSP (China Grid Support Platform). The effectiveness of the proposed architecture is demonstrated by an example which is developed as a Web service based on CGSP; the Web service is used for searching elements in the periodic table. An improvement of the user interface for applications is proposed in order to obtain results interactively. Finally, an extension of ChemGrid is discussed in order to integrate different types of resources and provide specialized services.

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A common architecture in today's development of distributed systems is the service-oriented architecture (SOA) implemented using Web services. Until recently, it was difficult to build a SOA based grid/distributed system using Web services due to the inability to learn the state of services. The state of a Web service could only be accessed through specialized clients and/or services. Should the specialized client or service fail, the state can't be accessed. This paper shows the innovative resources via Web instances (RVWI) framework. RVWI grants to web services the ability to show the state of dynamic resources in their WSDL. This was achieved via software components called connectors which watch for any changes in a resource and updates the web service. The significance of this report is the support for resources which can change state between requests and the innovation is the improvement of state updates between the service and discovery services.

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This special issue mainly focuses on the timely topic of “Data and Security in Web Service”. More specially, from the perspective of service construction, the future Web service should address issues such as how to construct an intelligent service which can effectively perceive the individual behavior, identify and satisfy individual requirements. On the other hand, from the perspective of service utilization, in the dynamic environment, Web services should address issues such as how to utilizing security-related techniques. In this JNW special issue, we select and edit 6 most relevant papers with higher reviewer scores from 16 submissions, which give effective discussion about Web service management methodologies from different perspective.

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Objective: To provide statistician end users with a visual language environment for complex statistical survey design and implementation. Methods: We have developed, in conjunction with professional statisticians, the Statistical Design Language (SDL), an integrated suite of visual languages aimed at supporting the process of designing statistical surveys, and its support environment, SDLTool. SDL comprises five diagrammatic notations: survey diagrams, data diagrams, technique diagrams, task diagrams and process diagrams. SDLTool provides an integrated environment supporting design, coordination, execution, sharing and publication of complex statistical survey techniques as web services. SDLTool allows association of model components with survey artefacts, including data sets, metadata, and statistical package analysis scripts, with the ability to execute elements of the survey design model to implement survey analysis. Results: We describe three evaluations of SDL and SDLTool: use of the notation by expert statistician to design and execute surveys; useability evaluation of the environment; and assessment of several generated statistical analysis web services. Conclusion: We have shown the effectiveness of SDLTool for supporting statistical survey design and implementation. Practice implications: We have developed a more effective approach to supporting statisticians in their survey design work.

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Objective: We want to support enterprise service modelling and generation using a more end user-friendly metaphor than current approaches, which fail to scale to large organisations with key issues of "cobweb" and "labyrinth" problems and large numbers of hidden dependencies. Method: We present and evaluate an integrated visual approach for business process modelling using a novel tree-based overlay structure that effectively mitigate complexity problems. A tree-overlay based visual notation (EML) and its integrated support environment (MaramaEML) supplement and integrate with existing solutions. Complex business architectures are represented as service trees and business processes are modelled as process overlay sequences on the service trees. Results: MaramaEML integrates EML and BPMN to provide complementary, high-level business service modelling and supports automatic BPEL code generation from the graphical representations to realise web services implementing the specified processes. It facilitates generated service validation using an integrated LTSA checker and provides a distortion-based fisheye and zooming function to enhance complex diagram navigation. Evaluations of EML show its effectiveness. Conclusions: We have successfully developed and evaluated a novel tree-based metaphor for business process modelling and enterprise service generation. Practice implications: a more user-friendly modelling approach and support tool for business end users.

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This paper explores Critical Success Factors (CSFs) in the transfer
of after-sales support-oriented knowledge from Information Technology (IT)
support organisations to enterprise customers, using Web-based self-service Systems (WSS). As it appears that best-in-class companies are ahead of the academic work in this area, we approached the topic through an exploratory CSF study of a best-in-class multinational IT services firm and identified 26 CSFs. Key findings from the study indicate that best-in-class IT service organisations may be cognisant of a range of factors relating to supporting customers, but are less aware of what is needed to support their own frontline support agents. Such organisations also lack an understanding of what is needed to provide enterprise support in the later stages of knowledge transfer, where enterprise customers can experience problems attempting to integrate resolutions. The study further showed that many aspects that might be characterised as encompassing socio-technical issues relating to the provision of web-based self-service are still poorly understood.

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Quality-of-Service is an important issue in multimedia applications; so far most of the research focuses on bandwidth guarantee, few pays attention to the server performance guarantee. In this paper we pay more attention to the server performance guarantee under the prerequisite of guaranteed bandwidth quality. We take advantage of anycast to find the "best" multimedia server among a distributed server group in terms of bandwidth, the request will be submitted to the selected server, moreover, the selected server's neighbours' (all the servers with feasible paths) addresses are delivered to the selected server simultaneously. If the selected server can not guarantee the QoS for the request in terms of server performance, then a proposed QoS-Aware Server Load Deviation (QASLD) mechanism wiII be employed, which will deliver the request to one of its neighbours until there exists a suitable server that can guarantee the server performance for the request. Our experiments show that the proposed QASLD algorithm works well.

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End-user experience with information presumably considered as one of the prominent factors shaping the adoption of web-based electronic services. User interfacing with large amount of information the rationale is to deduce the effect in the current web-based task environment. Understanding user’s perception on the basis of the prior experience with information may provide insights into what constitutes in driving those perceptions and their effect in the current and future task in web-based electronic services. The paper lays the theoretical context of end-user experience with information and proceeds further in an attempt to distinguish the role in web-based electronic services.