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1.
Practical agent languages and their corresponding architectures have often relied on a static plan library with more or less direct trigger-response activation mechanisms as a source for agent behaviours for the sake of runtime efficiency. Although efficient, such a language design choice severely limits an agent’s ability to reason about its goals and adapt to unforeseen circumstances after being deployed. This effectively delegates the task of planning to the designers themselves, who must design plan libraries able to cope with every foreseeable situation an agent might find itself in by designing plans to deal with any contingency. In this paper we develop a formal conversion process from traditional BDI agent languages into declarative planning. Using this conversion process, we show how to integrate domain independent planning algorithms into the BDI interpreter, allowing a designer to program an agent not only through the trigger-response mechanism used in traditional languages, but also in terms of declarative goals. Our contribution here is twofold: firstly we increase an agent’s ability to cope with unforeseen situations and secondly we unburden an agent designer from having to define multiple plan combinations that could be easily generated by a planner. 相似文献
2.
D. Ballis M. Falaschi C. Ferri J. Hernndez-Orallo M.J. Ramírez-Quintana 《Electronic Notes in Theoretical Computer Science》2003,86(3):85-104
Diagnosis methods in debugging aim at detecting bugs of a program, either by comparing it with a correct specification or by the help of an oracle (typically, the user herself). Debugging techniques for declarative programs usually exploit the semantical properties of programs (and specifications) and generally try to detect one or more “buggy” rules. In this way, rules are split apart in an absolute way: either they are correct or not. However, in many situations, not every error has the same consequences, an issue that is ignored by classical debugging frameworks. In this paper, we generalise debugging by considering a cost function, i.e. a function that assigns different cost values to each kind of error and different benefit values to each kind of correct response. The problem is now redefined as assigning a real-valued probability and cost to each rule, by considering each rule more or less “guilty” of the overall error and cost of the program. This makes possible to rank rules rather than only separate them between right and wrong. Our debugging method is also different from classical approaches in that it is probabilistic, i.e. we use a set of ground examples to approximate these rankings. 相似文献
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随着电子商务的迅速发展及用户对企业服务质量和及时信息反馈的要求越来越高,企业内及企业间各个系统之间的交互对企业的发展越来越重要.结合Web服务技术和流程建模技术,设计并初步实现了支持Web服务动态组合和执行的原型系统,给出了comFlow的系统架构,并描述它的组成部分. 相似文献
5.
传统Web服务的复合由于缺乏足够的语义信息而大大降低了服务复合的效率和准确率。语义Web弥补了传统Web语义不足的缺点。但是,面对语义Web上分布的海量知识,如何有效地利用语义信息实现Web服务复合成为一个迫切需要解决的问题。文章针对这一问题,提出一种基于多维用户模型的动态服务复合机制。该机制在Web服务语义标识的启发下通过语义匹配算法能够实现Web服务的顺序复合和并行复合。采用这种服务复合机制将会在一定程度上提高语义Web服务复合的效率和准确率。 相似文献
6.
Modern society increasingly relies on mobile devices. This explains the growing demand for high quality software for such devices. To improve the efficiency of the development life-cycle, shortening time-to-market while keeping quality under control, mobile applications are typically developed by composing together ad-hoc developed components, services available on-line, and other third-party mobile applications. Applications are thus built as heterogeneous compositions, whose characteristics strongly depend on the components and services they integrate. To cope with unpredictable changes and failures, but also with the various settings offered by the plethora of available devices, mobile applications need to be as adaptive as possible. However, mainstream adaptation strategies are usually defined imperatively and require complex control strategies strongly intertwined with the application logic, yielding to applications that are difficult to build, maintain, and evolve. We address this issue by proposing a declarative approach to compose adaptive heterogeneous mobile applications. The advantages of this approach are demonstrated through an example inspired by an existing worldwide distributed mobile application, while the implementation of the proposed solution has been validated through a set of simulations and experiments aimed at illustrating its performance. 相似文献
7.
Overlay networks have emerged as a powerful and flexible platform for developing new disruptive network applications. The
attractive characteristics of overlay networks such as routing flexibility and overlay topology dynamics bring to overlay
fault diagnosis new challenges, which include the dynamical overlay symptom-fault correlation, multi-layer (i.e., underlay
vs. overlay) abstraction, and unregulated overlay symptoms. To address these challenges, we propose a novel user-level probabilistic
and reactive fault diagnosis technique, called ProFis for overlay networks, which can seamlessly integrate passive and active fault reasoning to develop an optimal fault diagnosis
framework. ProFis uses observable overlay symptoms as reported by overlay applications to dynamically correlate overlay symptoms and faults.
ProFis diagnoses overlay faults passively and selects optimal actions (i.e., with the least cost) to enhance the passive diagnosis
whenever necessary. Our evaluation study shows that ProFis can efficiently (i.e., low latency) and accurately localize the root causes of overlay faults, even when symptom loss rate
is high. 相似文献
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自动地根据用户请求进行服务的动态组合是目前Web服务领域的关键问题.针对该问题,提出了一种基于本体的服 务动态组合方法,设计并实现了一个服务动态组合原型.首先Web服务按照一定规则被抽象为本体模型,然后通过分析所 构造服务的模型来实现服务的匹配,最后利用BPEL4ws对匹配生成的服务组合序列来进行自动的组合.实验结果表明,该 方法细化了服务接口的语义,并且在发现结果上有更高的准确性. 相似文献
9.
This paper discusses a particular issue in the context of disappearing computing, namely, user mobility. Mobile users may carry with them a variety of wireless gadgets while being immersed in a physical environment encompassing numerous computing devices. In such a situation, it is most likely that the number and type of devices may dynamically vary during interactions. The Voyager development framework supports the implementation of ambient dialogues, i.e., dynamically distributed user Interfaces, which exploit, on-the-fly, the wireless devices available at a given point in time. This paper describes the Voyager implementation, focusing on: device discovery and registry architecture, device-embedded software implementation, ambient dialogue style and corresponding software toolkit development, and a method for dynamic interface adaptation, ensuring dialogue state persistence. Additionally, this paper presents two ambient dialogue applications developed using Voyager, namely, a game and a navigator. 相似文献
10.
Computing compatibility in dynamic service composition 总被引:1,自引:1,他引:1
Dynamically composing services requires mechanisms to ensure component services compatible with each other both at all of
the syntax, semantic and behavioral level. This paper focuses on the issue of behavioral compatibility in a service composition.
It adopts the π-calculus to model service behaviors and interactions in a formal way. Based on the formalization, it proposes a method to
automatically check the behavioral compatibility in a qualitative way. Furthermore, it presents an algorithm to compute the
compatibility degree in a quantitative way. The algorithm is implemented in a prototype and its performance analysis is also
carried out to show that it can help composing services on the fly and ensure the services compatible with each other to provide
functions with newly-added values.
相似文献
Jian WuEmail: |
11.
针对动态网络的间断连通性破坏了组合服务的安全性和可靠性的问题,设计动态网络环境下高延时组合服务网络密钥管理方案(key management in delay and disruption tolerant ad hoc network,KMDTAN).以稳定性、聚集度、网络规模和连通度作为密钥管理选择标准,在连通区域内根据网络密度设计不同密钥交互协议协商共享密钥,根据稳定性选择共享密钥协商范围,以提高动态网络环境下组合服务的可靠性.理论分析和实验验证了该方案具有较好稳定性和效率性. 相似文献
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目前基于工作流的Web服务组合方法大多要求预先定义流程结构,不能适应现代企业业务流程复杂多变的需求.提出了一种Web服务动态组合方法,将流程中动态部分用黑盒子流程进行封装,在执行时根据预定义规则和用户需求将黑盒子流程自动组合展开为实际运行流程.对具体服务、抽象服务、黑盒子流程等概念和服务选取规则、服务组合规则进行了定义,详细描述黑盒子流程展开算法,并设计了一个实现动态服务流程组合的框架结构. 相似文献
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With the advance of various wireless access technologies, the demand for a mobile user equipped with multiple air interfaces simultaneously executing diverse applications emerged. In such network environments, per-application mobility management is a key to allow each application of an end user device to dynamically and fully take advantage of the most suitable access technology. In this paper, we devised a comprehensive architectural platform with cross-layer techniques to realize this disruptive technology, i.e., per-application mobility management. The proposed platform enables the triggering of vertical handover decisions based on the dynamic measurements from the entire protocol stack. For per-application, the handover decision as well as the mobility management and the transport/application protocol control adaptation for handover performance optimization are made with cross-layer techniques. Through the simulation results, it is shown that multi-layer handover triggering of the proposed platform enhances the QoS of the application services by making handover decisions when the QoS requirements of an application is not satisfied as well as when a mobile user moves out of the current access network in overlay network environments. It is also presented that per-application handover based on the proposed platform enhances the QoS of the application services compared to the handover approaches which make every on-going service flows handover together to the same access network. 相似文献
14.
Hubert Pham Justin Mazzola Paluska Umar Saif Chris Stawarz Chris Terman Steve Ward 《Pervasive and Mobile Computing》2009,5(6):676-696
We present a middleware platform for assembling pervasive applications that demand fault-tolerance and adaptivity in distributed, dynamic environments. Unlike typical adaptive middleware approaches, in which sophisticated component model semantics are embedded into an existing, underlying platform (e.g., CORBA, COM, EJB), we propose a platform that imposes minimal constraints for greater flexibility. Such a tradeoff is advantageous when the platform is targeted by automatic code generators that inherently enforce correctness by construction.Applications are written as simple, single-threaded programs that assemble and monitor a set of distributed components. The approach decomposes applications into two distinct layers: (1) a distributed network of interconnected modules performing computations, and (2) constructor logic that assembles that network via a simple block-diagram construction API. The constructor logic subsequently monitors the configured system via a stream of high-level events, such as notifications of resource availability or failures, and consequently provides a convenient, centralized location for reconfiguration and debugging. The component network is optimized for performance, while the construction API is optimized for ease of assembly. Microbenchmarks indicate that our runtime incurs minimal overhead.In addition to describing the programming model, platform implementation, and a variety of pervasive applications built using our system, this paper also extends our previous work with a thorough analysis of remote objects and tracking techniques, new contributions in distributed component liveness-monitoring approaches, and expanded microbenchmarks. 相似文献
15.
基于语义的动态服务组合的改进 总被引:1,自引:0,他引:1
Web服务应用已经广泛深入,而已存在的服务也越来越不满足客户的需求,解决应用服务之间的共享和应用协作问题成为关键.基于语义的Web服务的动态组合无疑可以很好的解决这个问题,但是OWL-S还有许多方面需要完善特别是在服务质量、花费、可靠性等问题上.本论文通过对OWL-S的扩充解决了其中部分问题,并且通过描述并实现一个动态服务组合框架来验证. 相似文献
16.
The location predictions of the nodes are the key issues in mobile environment. The applications like video sharing, voice over IP and other online applications offer better results with stable nodes. In mobile scenario, connectivity and quality of service are critical issues. To overcome these issues dynamic overlay approaches are proposed in this work namely, 1.Mobile Peers-Unstructured, 2.Structured Peer, 3.MANET Structure and 4.Mesh Backbone. These structures are obtained from the network, during the requirement of connectivity or quality of service. The performance of the proposed methods are analyzed in stable and mobile conditions by analyzing power consumption, hop stretch, packet delivery ratio, network life time and other QoS parameters. 相似文献
17.
《Journal of Network and Computer Applications》2012,35(6):1990-2002
Traditional peer-to-peer technologies and systems assume that people operate with desktop computers in fixed broadband networks. When people with modern mobile devices now access Internet and Web services much in the manner they used to on desktop computers, the classical peer-to-peer overlay models can be vulnerable in wireless and mobile networks. This paper proposes a hierarchical overlay architecture based on partially central and semi-structured overlay models for the deployment of peer-to-peer systems in dynamic network environments. To keep up system scalability and efficacy, this architecture design exploits peer locality and network proximity, and contends with several problems of peer churn, peer mobility, search redundancy and traffic overhead that become much stickier in dynamic network environments. This design also integrates the reputation notion to mitigate the free-riding problem in peer-to-peer systems. According to a special cluster-based reputation tree, the hierarchical overlay is adjustable to moderate unfair or imbalanced resource utilization over the system. Furthermore, the cluster hierarchy is resilient to any points of failure at peer clusters in the overlay topology. Therefore, the effort of this study achieves an efficient and robust overlay architecture in dynamic network environments. Simulation results show that the proposed architecture is not only scalable to peer population, but also sustainable to peer- and network-initiated dynamics and influences in peer-to-peer systems. 相似文献
18.
Min-Xiou ChenAuthor Vitae Tze-Chin TzengAuthor Vitae 《Computer Standards & Interfaces》2011,33(3):271-279
This paper describes the service discovery and interaction for home network devices using heterogeneous standards and protocols. OSGi was proposed to allow several kinds of services coming from different providers to be loaded and run on a gateway. We present a residential gateway based on the OSGi architecture for a smart home network. We combine the SLP SA/DA, the UPnP control point and the SIP UA into the gateway to achieve automated device discovery, registry, and management. Application examples are introduced and the implementation results show that our gateway can provide automatic heterogeneous service or device discovery, registry, and management. 相似文献
19.
The Web has undergone a tremendous change from a primarily publication platform towards a participatory and"programmable"platform,where a large number of heterogeneous Web-delivered services(including SOAP and RESTful Web services,RSS and Atom feeds)are emerging.It results in the creation of Web mashup applications with rich user experiences.However,the integration of Web-delivered services is still a challenging issue.It not only requires the developers’tedious eforts in understanding and coordinating heterogeneous service types,but also results in the time-consuming development of user interfaces.In this paper,we propose the iMashup composition framework to facilitate mashup development and deployment.We provide a unified mashup component model for the common representation of heterogeneous Web-delivered service interfaces.The component model specifies necessary properties and behaviors at both business and user interface level.We associate the component model with semantically meaningful tags,so that mashup developers can fast understand the service capabilities.The mashup developers can search and put the proper mashup components into the Web browser based composition environment,and connect them by data flows based on the tag-based semantics.Such an integration manner might prevent some low-level programming eforts and improve the composition efciency.A series of experimental study are conducted to evaluate our framework. 相似文献
20.
Development of several computing and communication technologies is enabling the widespread availability of pervasive systems. In smart home applications, household appliances—such as security alarms, heating systems, doors and windows—are connected to home digital networks. These applications offer features that are typically developed by disparate vendors, and when composed together, these features are expected to work together harmoniously. Engineering these systems poses two main challenges. The first challenge is: how can developers of individual features specify the features in order to make them composable with other hitherto unknown features? The second challenge is: when composition of features does not produce the desired behaviour, what can be done to resolve this non-intrusively? This article argues that the two issues are intrinsically related, and proposes an approach that addresses the first challenge in a way that makes the second challenge manageable. In particular, we describe a way of writing feature specifications in which assumptions about the problem world are made explicit. These feature assumptions can then be evaluated at runtime in order to preserve the desired system behaviour to the extent possible. Our approach is illustrated with examples from smart home applications. 相似文献