基于云仿真的Web服务选择研究

针对当前Web服务海量增加,而现有的Web服务选择算法低效、缓慢的问题,提出了一种基于云计算的粒子群优化算法的Web服务选择方法。该方法在云平台下对粒子分群映射、相似分群并行化简、适时更新分群,并且寻找与用户需求最相似、服务质量最好的策略。实验表明,该方法能有效减少流程执行过程中Web服务选择导致的时间开销,并提高Web服务选择的可靠性。     

语义Web服务——Web服务的扩展

语义Web服务是应用语义Web技术对Web服务的扩展.使信息具有语义就是用计算机内的Ontology中的概念作标记符对信息进行标记,对该过程予以支持的就是语义Web技术,即Ontology的构建技术、Ontology的使用技术(语义推理技术)和信息的语义标记技术.语义Web技术对Web服务的扩展可具体化为两项任务:服务提供者、服务请求者和服务注册处三类服务主体均内置Ontology;发布、查找和绑定三种交互信息均采用语义标记.     

Integrating Internet telephony services

Cost savings and the ease of developing and adding new services have motivated great interest in Internet telephony, which integrates services provided by the Internet with the public switched telephone network (PSTN). Internet telephony relies on several protocols, including the real-time transport protocol (RTP) for multimedia data transport and the session initiation protocol (SIP) or H.323 for establishing and controlling sessions. SIP can integrate with other Internet services, such as email, the Web, voice mail, instant messaging, conference calling, and multimedia collaboration. We have implemented a SIP-based software suite called the Columbia Internet extensible multimedia architecture (Cinema), which we installed and integrated with the existing private branch exchange (PBX) infrastructure in the computer science department at Columbia University. The Cinema environment provides interoperability with the PSTN, programmable Internet telephony services, and IP-based voice mail. It also integrates Web access and e-mail for unified messaging and supports multiparty multimedia conferencing. The setup lets us extend our PBX capacity and will eventually let us replace it while keeping our existing phone numbers. It also provides an environment in which we can easily add new services and features, including interoperation with existing multimedia tools, e-mail access from standard. telephones, network appliance control, and instant messaging support     

Personalised e-learning through an educational virtual reality game using Web services

This paper describes how a personalised educational game architecture has been used in conjunction with Web services to provide remote access to the system. The educational game is a virtual reality adventure game that performs affective user modelling by measuring emotional characteristics of users. Virtual reality (VR) games are so popular among children and adolescents that can be used for the purposes of educational software to render it more attractive and motivating. The benefits of such an application can be maximised if it is available over the Web. Software applications that operate over the Web are targeted to a wide range of users. Hence they need a high degree of adaptivity and dynamic individualisation to each user that interacts with the application. This should include the students’ emotional state that affects their learning. However, the environment of a Web-based VR-game that performs user modelling is so demanding that the technology of Web services is necessary for its effective operation and interoperability. Moreover, reusability may be achieved for the user modelling component.

Web services push

Industry heavyweights Hewlett-Packard, IBM, Microsoft, Oracle, Sun Microsystems, BEA Systems and webMethods, have signed on to support VeriSign’s open standard-based framework that will let these vendors and others add security and authentication services to their Web services development tools.     

Web services notifications

As Web services have matured, they've also acquired the need for asynchronous push capabilities. Early Web services, such as those for getting traffic or weather reports or for performing currency exchange-rate calculations, were seemingly all remote procedure calls-oriented. In an RPC system, the receiver typically performs the requested service and sends a response back to the caller over the same connection on which the request arrived, which means the details required by the service for sending a reply are implicit in the RPC network connection. Unfortunately, these kinds of implied communication details are wholly inadequate for asynchronous push Web services.     

Web services policies

In addition to the basic Web services architecture, various specifications already exist for adding security, reliable messaging, and transaction mechanisms to Web services messages. All of these include numerous options to let them meet various application requirements. Specifying option choices for Web services in basic communication areas such as security, reliable messaging, privacy, and transactions is the immediate goal underlying efforts to define Web services policies.     

Semantic Web services

The authors propose the markup of Web services in the DAML family of Semantic Web markup languages. This markup enables a wide variety of agent technologies for automated Web service discovery, execution, composition and interoperation. The authors present one such technology for automated Web service composition.     

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     

Emerging research areas in SIP-based converged services for extended Web clients

The convergence of Next Generation Networks and Internet-based rich applications are generating relevant industrial opportunities in the market of mobility-enabled services. Even if this trend is widely recognized, there are still a few industrial-level solutions that effectively support session mobility in a transparent way and with the capability of openly integrating with existing and legacy applications. In this paper we propose a SIP-based hybrid architecture for Web session mobility that offers content sharing and session handoff between Web browsers. In addition, its technical originality includes integrating a SIP stack into a Web browser, thus offering the advantage of extending a Web browser to act as a SIP client. Lastly, a rich set of control services that prevent abuse of content sharing and session handoff are introduced into the proposed system. The implemented solution uses SIP in a standard way to migrate Web sessions between Web browsers; it is made up of a SIP integrated Web client and a converged (SIP and HTTP) Application Server that can be easily used to enable session mobility in any kind of Web-based application. In addition, the implemented system has recently evolved to a framework for developing different kinds of converged services over the Internet, analogously to what is possible with Google Wave and the existing telephony APIs. Finally, the paper reports the evaluation of the proposed framework and of the employed technologies, together with directions of future work, in terms of both extension to other application domains and exploration of research areas/models that can benefit form the adoption of SIP and Web-related solutions.     

Integrating knowledge on the Web

The World Wide Web provides a ubiquitous medium for seamlessly integrating distributed applications, formats and content, making it well-suited for enterprise knowledge management. In this article, we discuss a framework for characterizing knowledge management technology. We identify the desirable attributes of a knowledge management system and describe how Web-centric approaches can support these requirements. We also review related research in enterprise knowledge management     

Putting the "Web" into Web services. Web services interaction models.2

For pt.1 see ibid., vol.6, no.3, p. 89-91 (2002). As I discussed in my previous column, each different style of middleware promotes one or more interaction models that determine how applications based on that middleware communicate and work with each other. It is difficult to say what the best interaction models would be for Web services, mainly because the World Wide Web Consortium (W3C) is still developing the architecture. The author considers the use of remote procedure calls, Web services and messaging and interface complexity.     

Integrating Web caching and Web prefetching in client-side proxies

Web caching and Web prefetching are two important techniques used to reduce the noticeable response time perceived by users. Note that by integrating Web caching and Web prefetching, these two techniques can complement each other since the Web caching technique exploits the temporal locality, whereas Web prefetching technique utilizes the spatial locality of Web objects. However, without circumspect design, the integration of these two techniques might cause significant performance degradation to each other. In view of this, we propose in this paper an innovative cache replacement algorithm, which not only considers the caching effect in the Web environment, but also evaluates the prefetching rules provided by various prefetching schemes. Specifically, we formulate a normalized profit function to evaluate the profit from caching an object (i.e., either a nonimplied object or an implied object according to some prefetching rule). Based on the normalized profit function devised, we devise an innovative Web cache replacement algorithm, referred to as Algorithm IWCP (standing for the Integration of Web Caching and Prefetching). Using an event-driven simulation, we evaluate the performance of Algorithm IWCP under several circumstances. The experimental results show that Algorithm IWCP consistently outperforms the companion schemes in various performance metrics.     

语义Web和Web服务标准集成的研究

首先提出基于本体的增强Web服务描述能力的方法,即将语义添加到Web服务的标准WSDL和UDDI中。然后,提出一种基于语义的Web服务发现算法。基于语义的Web服务发现过程比原有的基于服务属性的服务发现过程更为准确和有效。     

基于三层组织模型的一种Web服务组合策略

在研究Web服务三层组织模型和有限状态自动机的基础上,提出了一种新的Web服务组合策略,给出了一个服务的可组合性定理,并证明了定理的正确性。该策略以Web服务三层组织模型为基础,简化了BPEL中基于有限状态自动机的Web服务自动组合,精简了服务组合流程。最后对这种新的组合策略的优缺点作了分析。     

Web services interoperability specifications

A proposed conceptual framework for analyzing Web services interoperability issues provides a context for studying existing standards and specifications and for identifying new opportunities to provide automated support, for this technology. Web services are becoming the technology of choice for realizing service-oriented architectures (SOAs). Web services simplify interoperability and, therefore, application integration. They provide a means for wrapping existing applications so developers can access them through standard languages and protocols.