PadSpace: A new framework for the service federation of web resources

End-users need a simple and interactive tool for service composition development. A PadSpace proposes an extension of a typical Linda-like coordination model (tuplespace) to provide mechanisms for the interoperation among Web applications, Web services and end-users’ local functional resources. First, a PadSpace provides an end-user supporting tool for composing Web applications, Web services, and local visual resources based on the meme media architecture without writing any program codes. It enables end-users to directly manipulate visual components, and to create new composite components for the creation of services that use Web applications, Web services, and local functional resources. Second, a PadSpace provides a spreadsheet-based service-coordination tool for end-users to orchestrate multiple Web applications, Web services, and local functional resources. Finally, we show some new applications of service composition and service orchestration.     

XML-based specification for Web services document security

The Internet and related technologies have seen tremendous growth in distributed applications such as medicine, education, e-commerce, and digital libraries. As demand increases for online content and integrated, automated services, various applications employ Web services technology for document exchange among data repositories. Web services provide a mechanism to expose data and functionality using standard protocols, and hence to integrate many features that enhance Web applications. XML, a well-established text format, is playing an increasingly important role in supporting Web services. XML separates data from style and format definition and allows uniform representation, interchange, sharing, and dissemination of information content over the Internet. XML and Web services provide a simplified application integration framework that drives demand for models that support secure information interchange. Providing document security in XML-based Web services requires access control models that offer specific capabilities. Our XML-based access control specification language addresses a new set of challenges that traditional security models do not address.     

Improving the Dependability of Web Services Integration

The WS-Mediator framework employs an off-the-shelf mediator architecture and resilience-explicit computing in pursuit of dependable, dynamic Web services integration. Web services and service-oriented architectures (SOAs) represent a new paradigm for building distributed computing applications. Web services offer advantages over conventional distributed computing middleware platforms. Web services' loosely coupled architecture, combined with their standardized interoperability, lead to a new computing paradigm that supports the construction of more flexible and dynamic distributed applications     

Understanding Web services

Web services are a new breed of Web applications. These independent application components are published on to the Web in such a way that other Web applications can find and use them. They take the Web to its next stage of evolution, in which software components can discover other software components and conduct business transactions. Examples of Web services include a credit card service that processes credit card transactions for a given account number, a market data service that provides stock market data associated with a specified stock symbol, and an airline service that provides flight schedule, availability, and reservation functionalities. Major vendors like IBM, Microsoft, Hewlett-Packard, and Sun, among others, are investing heavily in Web services technology. Ranging from simple to complex, Web services bring the promise of flexible, open-standards-based, distributed computing to the Internet     

Opening web applications for third-party development: a service-oriented solution

Web applications are nowadays prevalent software systems in our everyday’s life. A lot of these applications have been developed for end users only. Thus, they are not designed by considering future extensions that would be developed by third parties. One possible and interesting solution for opening these applications for such kind of extension development is to create and deploy Web services starting from these applications. In this paper, we present a method and a tool for semiautomatically creating Web service implementations from applications having Web interfaces. The proposed method generates operations that are published in Web services for each functionality provided by a Web application. In addition, it generates new operations starting from Web interfaces. Our approach goes further in the creation of services by generating executable orchestrations, as BPEL processes, starting from navigations in the Web interfaces of these applications and by providing BPMN choreography specifications starting from the collaborations between the generated Web services. We implemented and experimented our solution in the migration of three real-world Web applications toward Web service-oriented systems.     

Efficient execution of composite Web services exchanging intensional data

Web service technologies provide a standard means of integrating heterogeneous applications distributed over the Internet. Successive compositions of new Web services using pre-existing ones usually create a hierarchical structure of invocations among a large number of Web services. For the efficient execution of these composite Web services, we propose an approach which exploits intensional XML data, i.e. an XML document that contains special elements representing the calls to Web services, in order to delegate the invocations of the external Web services to some relevant nodes. We formalize an invocation plan for composite Web services in which intensional data is used as their parameters and results, and define a cost-based optimization problem to obtain an efficient invocation plan for them. We provide an A∗ heuristic search algorithm to find an optimal invocation plan for a given set of Web services and also present a greedy method of generating an efficient solution in a short time. The experimental results show that the proposed greedy method can find a close-to-optimal solution efficiently and has good scalability for a complex call hierarchy of Web services.     

A layered architecture for flexible Web service invocation

Web service composition is emerging as an interesting approach to integrate business applications and create intra‐organizational business processes. Single Web services are combined to create a complex Web service that will realize the process business logic. Once the process is created, it is executed by an orchestration engine that invokes individual Web services in the correct order. However, Web services composing the workflow sometimes become unavailable during the run‐time phase, blocking process execution. This paper describes an architecture that allows the flexible orchestration of business processes. With this approach, Web services composing the process can be automatically substituted with other compatible Web services during process execution. A methodology is defined to evaluate Web service compatibility based on interface matching, in order to select substitutable Web services. Copyright © 2005 John Wiley & Sons, Ltd.     

Discovering semantic associations among Web services based on the qualitative probabilistic network

In recent years, the intelligent management and decision of Web services have attracted more and more attention due to the wide applications in various aspects of the real world. With the increase of Web services in an organization, the desired on-line services should be located rapidly requiring not only the syntactic but also the semantic techniques. In addition, aiming at fulfilling complex applications by discovering and composing available services automatically and precisely, it is indispensable to develop an underlying model and the corresponding measure for semantic associations among given Web services. In this paper, by mining the historical invocations of component services, we first construct a semantic model to describe their behavior rules based on the qualitative probabilistic network. Further, we propose a distance measure and the approach to discovering semantic associations among Web services. Preliminary experiments and performance studies show that our methods are feasible. Moreover, high recall and precision can be achieved when our methods are applied to Web service search.     

SOAW2 for Managing the Web 2.0 Framework

Web 2.0 predicates an improved and seamless user interaction and management of Web environment and resources, guaranteeing required services and a flexible generation of user applications. This occurs via an agile composition of services from available application (foundation) tools. Hence, Web 2.0 developers merely create the core of these applications, while the boundaries dynamically change and expand in accordance with user interaction (a use model). In other words, the resources, tools, and services act as plug-in entities that users can add or remove from the application's operational framework according to their needs. In this article we propose a service-oriented architecture, or SOA, model for managing the operation of Web 2.0 platform actors, improving the services provided to consumers     

基于BTP的Web服务事务协调研究与实现

Web服务技术为异构应用之间的集成和互操作提供了有效的解决手段。目前的Web服务还缺乏全局的事务环境,传统的事务模型不再适用于新的Web环境下的要求。针对Web服务中事务处理的协调问题,分析现有的事务处理模型和协议,设计实现了一个基于BTP协议的Web服务事务原型系统,把用于Web服务事务处理的BTP协议和用于传统事务的两阶段提交协议相结合来协调Web服务中的事务。通过运行应用实例,验证了原型系统的可行性,该系统具备协调短期事务与长事务的能力。     

Web服务提供方安全模型的设计、建模与分析

随着Web服务应用的迅速发展,Web服务提供方的安全问题已成为制约其实际应用的主要障碍之一。文中着重讨论了Web服务提供方面临的安全问题,引入了一种基于安全策略与实现分离的信息安全解决模型,并根据Web服务的实际情况进行了改进,方便了Web服务提供方动态地制定安全策略、灵活地实现策略指导下的各种安全措施。最后,采用投影时序逻辑(PTL,Projection Temporal Logic)形式化描述了该模型中资源访问决策部分的规范说明。     

Web services: problems and future directions

Recently, Web services have generated great interests in both vendors and researchers. Web services, based on existing Internet protocols and open standards, can provide a flexible solution to the problem of application integration. With the help of WSDL, SOAP, and UDDI, Web services are becoming popular in Web applications. However, the current Web services architectures are confronted with a few stubborn problems, for instance, security. In this paper, we shall give an overview of these problems. We believe that solving these problems will become crucial to success of Web services. In the end, we predict distinct advances in semantic Grid services.     

A novel real-time scheduling algorithm and performance analysis of a MapReduce-based cloud

MapReduce, a popular programming model for processing data-intensive tasks, has achieved great success in a wide range of applications such as search indexing, social network mining, collaborative recommendation, and spam detection. However, the ability of MapReduce is limited in two respects by its default schedulers. First, it does not support concurrent services sharing a cloud datacenter and second, it fails to guarantee response time for deadline-constrained services. This paper proposes the Paused Rate Monotonic (PRM) algorithm for scheduling hard real-time tasks on a MapReduce-based cloud. The scheduling performance is analyzed theoretically. We prove a bound on cluster utilization, which can be used as a sufficient condition to test whether a given task set can be scheduled. Both the theoretical analysis and experimental evaluation show that the PRM algorithm outperforms traditional real-time ones by improving the probability that a real-time task set can be scheduled on a MapReduce-based cloud.     

Integrating biological research through Web services

Web services might be a way to solve the integration problem because Web services technology provides a higher layer of abstraction that hides implementation details from applications. Using this technology, applications invoke other applications' functions through well-defined, easy-to-use interfaces. To test the potential of a Web services solution, we implemented a microarray data-mining system that uses Web services in drug discovery - a research process that attempts to identify new avenues for developing therapeutic drugs. Although our implementation focuses on a problem within the life sciences, we strongly believe that Web services could be a boon to any research field that requires analyzing volumes of data and conducting complex data mining.     

一个基于自管理单元支持差分服务的Web容器

随着Internet的飞速发展,符合J2EE规范的Web容器已经成为部署企业Web应用的主流平台.同时,企业Web应用的多样化和复杂性的增长,迫切地要求Web容器提供差分服务的支持.然而,传统的Web容器采用尽力而为的服务模型,无法提供差分服务支持.已有的研究采用准入控制、优先级调度等方法来为Web容器提供差分服务支持,但是它们只能提供单调、静态的差分服务策略.提出了一个基于自管理单元的Web容器DSWC,它能够根据SLA定义提供两级差分服务支持.此外,提出了一个自适应差分服务策略选择算法,它能够根据动态变化的运行环境自适应地选择差分服务策略.原型系统的实验结果显示,DSWC能够有效地为请求提供符合SLA定义的细粒度的差分服务支持.     

Web服务事务处理应用模型

本文利用Web服务的应用程序组件特性,配合分布式事务处理的两阶段提交机制,建立了一个Web服务与事务处理协调操作的应用模型。实际应用不需修改Web服务内部代码,特别有利于企业应用的后期维护和系统升级。     

新一代分布式计算模型--XML Web Services

从Windows DNA多层体系结构出发,简单回顾了Internet及分布式计算模型的发展历程,讨论了支撑XML WebServices的几种标准协议。郑重论述了XML Web Services的基础结构,联网形式,解决方案,生存期以及XML Web Services的平台Microsoft.NET平台,并给出了一个用Microsoft.NET构建的基于XML Web Services的典型实例。     

Web服务图及其在服务发现中的应用研究

Web服务是一种崭新的Web应用。随着Web环境下服务数量的快速增长,在海量的待选服务中发现所需的服务将十分耗时。UDDIV2增加了一个新特征Publisher Assersion来描述UDDI注册中心中商业实体间的关系,类似于网页之间的超链接,由此可产生Web服务图。本文首先研究Web服务的新特征,然后提出与分析了Web服务图的构建原理和构建算法,最后利用Web服务图进行服务发现,提出了基于Web服务图的服务发现匹配算法,并对其进行了仿真实验。从仿真实验结果可以看出,本文提出的Web服务图对组合的Web服务发现是有效的。     

Ws-AC: A Fine Grained Access Control System for Web Services

The emerging Web service technology has enabled the development of Internet-based applications that integrate distributed and heterogeneous systems and processes which are owned by different organizations. However, while Web services are rapidly becoming a fundamental paradigm for the development of complex Web applications, several security issues still need to be addressed. Among the various open issues concerning security, an important issue is represented by the development of suitable access control models, able to restrict access to Web services to authorized users. In this paper we present an innovative access control model for Web services. The model is characterized by a number of key features, including identity attributes and service negotiation capabilities. We formally define the protocol for carrying on negotiations, by specifying the types of message to be exchanged and their contents, based on which requestor and provider can reach an agreement about security requirements and services. We also discuss the architecture of the prototype we are currently implementing. As part of the architecture we propose a mechanism for mapping our policies onto the WS-Policy standard which provides a standardized grammar for expressing Web services policies.     

Toward an agent-based and context-oriented approach for Web services composition

This paper presents an agent-based and context-oriented approach that supports the composition of Web services. A Web service is an accessible application that other applications and humans can discover and invoke to satisfy multiple needs. To reduce the complexity featuring the composition of Web services, two concepts are put forward, namely, software agent and context. A software agent is an autonomous entity that acts on behalf of users and the context is any relevant information that characterizes a situation. During the composition process, software agents engage in conversations with their peers to agree on the Web services that participate in this process. Conversations between agents take into account the execution context of the Web services. The security of the computing resources on which the Web services are executed constitutes another core component of the agent-based and context-oriented approach presented in this paper.