移动网络中Web服务应用架构研究

提出一个应用于移动网络的Web服务交互通信体系架构,其将基于XML的系统通信的负担从移动客户转移到外部中间件上,该中间件像网关一样,使用快速的二进制协议以客户/服务器方式与移动设备进行轻量级通信,并同时负责解析对Web服务的请求。     

基于REST的空间信息服务互操作协议的研究

REST式的Web服务充分地利用HTTP协议的分布式特性,可以使Web服务的开发变得更加高效、简洁、 可维护。着力于REST式空间信息服务互操作协议研究,通过分离OGC Web服务定义中的动作、意图和表示的方 式,确定服务中的资源。最后将REST的“资源”概念与空间信息“数据”共享结合起来,利用H"I"I'P协议定义的操作, 设计了RES"I'式空间信息服务互操作规范REST=WMS与REST-WFS.     

一种基于CPN的运行时监控服务交互行为的方法

BPEL对Web服务组合的描述特性使得它很难表达和分析服务组合中的交互行为属性.这些行为属性需要遵循一定的交互协议.然而良定义的交互协议还是容易受到侵犯,这将导致服务组合进程产生状态不一致的问题.为了解决这类实际交互行为与其服务组合描述之间的不一致性问题,提出了一种由BPEL描述自动构造运行时监控器的方法.首先提出了一种基于有色Petri网(CPN)的形式化表示模型以及服务组合规约到模型的映射方法,用于精确表达从BPEL流程描述中提取的服务交互行为规约.然后,描述了由CPN形式化表示模型生成运行时监控器的方法.该运行时监控器能够捕获所有进出服务组合进程的交互消息,并且检测是否存在违背交互协议的行为.     

Context-aware middleware for resource management in the wireless Internet

The provisioning of Web services over the wireless Internet introduces novel challenging issues for service design and implementation: from user/terminal mobility during service execution, to wide heterogeneity of portable access devices and unpredictable modifications in accessible resources. In this scenario, there are frequent provision-time changes in the context, defined as the logical set of accessible resources depending on client location, access terminal capabilities, and system/service management policies. The development of context-dependent services requires novel middlewares with full context visibility. We propose a middleware for context-aware resource management, called CARMEN, capable of supporting the automatic reconfiguration of wireless Internet services in response to context changes without any intervention on the service logic. CARMEN determines the context on the basis of metadata, which include declarative management policies and profiles for user preferences, terminal capabilities, and resource characteristics. In addition, CARMEN exploits the mobile agent technology to implement mobile middleware components that follow the provision-time movement of clients to support locally their customized service access. The proposed middleware shows how metadata and mobile agents can favor component reusability and automatic service reconfiguration, by reducing the development/ deployment complexity.     

基于中间件的电子商务服务集成

提出了一种将CORBA、基于XML的信息交换中间件以及Web Services3种中间件相结合的方法，在松耦合和紧耙合两个层面上实现电子商务服务的集成。CORBA用于企业内部的服务集成，WebServices用于Web上的服务集成，而信息交换中间件则在内外集成系统之间起到信息及功能的桥接作用。     

一种基于扩展有限自动机验证组合Web服务的方法

为简化并自动化组合Web服务验证,提出一种基于扩展有限自动机(extended deterministic finite automata,简称EDFA)验证组合Web服务的方法.使用EDFA可以准确地描述Web服务:EDFA的状态表达Web服务在与用户交互的过程中维护的状态;EDFA的状态转移及其标注描述Web服务与用户间的消息交换.EDFA给出Web服务交互过程的所有消息交换序列,刻画出Web服务的动态行为.使用基于EDFA的组合Web服务验证方法不但可以验证组合Web服务是否满足系统需求,还可以验证组合Web服务运行过程是否有逻辑错误.与其他方法相比,该方法更适于验证开放式环境下的组合Web服务.     

Deriving Protocol Models from Imperfect Service Conversation Logs

Understanding the business (interaction) protocol supported by a service is very important for both clients and service providers: it allows developers to know how to write clients that interact with a service, and it allows development tools and runtime middleware to deliver functionality that simplifies the service development lifecycle. It also greatly facilitates the monitoring, visualization, and aggregation of interaction data. This paper presents an approach for discovering protocol definitions from real-world service interaction logs. It first describes the challenges in protocol discovery in such a context. Then, it presents a novel discovery algorithm, which is widely applicable, robust to different kinds of imperfections often present in realworld service logs, and able to derive protocols of small sizes, also thanks to heuristics. As finding the most precise and the smallest model is algorithmically not feasible from imperfect service logs, finally, the paper presents an approach to refine the discovered protocol via user interaction, to compensate for possible imprecision introduced in the discovered model. The approach has been implemented and experimental results show its viability on both synthetic and real-world datasets.     

基于网络信息搜索的Web Service 文本描述信息扩充方法

随着Web服务技术的不断成熟和发展,互联网上出现了大量的公共Web服务.在使用Web服务开发软件系统的过程中,其文本描述信息(例如简介和使用说明等)可以帮助服务消费者直观有效地识别和理解Web服务并加以利用.已有的研究工作大多关注于从Web服务的WSDL文件中获取此类信息进行Web服务的发现或检索,调研发现,互联网上大部分Web服务的WSDL文件中普遍缺少甚至没有此类信息.为此,提出一种基于网络信息搜索的从WSDL文件之外的信息源为Web服务扩充文本描述信息的方法.从互联网上收集包含目标Web服务特征标识的相关网页,基于从网页中抽取出的信息片段,利用信息检索技术计算信息片段与目标Web服务的相关度,并选取相关度较高的文本片段为Web服务扩充文本描述信息.基于互联网上的真实数据进行的实验,其结果表明,可为约51％的互联网上的Web服务获取到相关网页,并为这些Web服务中约88％扩充文本描述信息.收集到的Web服务及其文本描述信息数据均已公开发布.     

基于语义描述的Web服务工作流集成

Web服务是可以由其它软件在Internet上访问的一种软件接口。Web服务工作流则是一组按一定顺序执行的Web服务的集合。如何集成一个Web服务工作流,特别是如何运用对Web服务的语义描述来为一个工作流来自动寻找和匹配Web服务,这是目前所急需解决的问题。介绍如何用语义Web服务本体论来集成工作流,同时提出一个基于语义Web服务工作流集成的模型。     

Web services interaction models. Current practice

Each middleware approach has one or more interaction models associated with it that determine how applications built on top of the middleware interact with each other. Message-oriented middleware (MOM) applications interact rather simply, for example, by posting messages to and retrieving messages from queues. Object-oriented middleware applications such as those based on Corba or Enterprise Java Beans (EJB) interact by invoking methods on distributed objects. Because interaction models significantly influence the types of abstractions a middleware system makes available to applications, they figure prominently in determining the breadth and variety of application integration that the middleware supports. As Web services evolve, they too will acquire standard interaction models; otherwise, their use will be limited to small-scale proprietary systems, rather than providing the standards-based "middleware for middleware" for uniting disparate islands of integration. At this point, however, the industry and standards bodies have yet to reach consensus on Web services interaction models. I consider some of the problems associated with a popular current approach to Web services interaction models     

企业级Java Web服务的研究与实现

企业级Java Web 服务是一种基于Java 技术实现的企业级分布式组件技术, 解决了Web 服务访问过程中的状态保持问题, 基于HTTP 和JMS 协议支持对Web 服务的多种调用方式, 采用灵活的配置获得多种中间件服务的支持, 并利用Web 服务的包容性实现了对多种异构遗留系统的集成, 从而为将Web 服务应用到企业级的环境中提供了足够的保障。利用一个企业级Java Web 服务组件模型, 并基于此实现了一个运行时系统, 系统由客户端、消息中间件和运行时容器三部分组成, 支持业务客户端与服务端企业级     

Protocol engineering for web services conversations

Although web services aim to bring about seamless and effective communication in a wide variety of Internet applications, the interactions between them are currently limited to simple request–response exchanges. However, in the longer term we believe this is unsustainable. In particular, we believe that more complex protocols for web service conversations are necessary if the participants are to tailor their needs and offers to the prevailing context and they are to coordinate multiple services in open and realistic environments. To this end, this paper combines and extends two recent web service languages, WS-Conversation Language (WSCL) and WS-Agreement, in order to obtain a method for engineering protocols of sufficient expressiveness for the next generation of flexible and autonomous services. Specifically, we propose that the protocols include speech-acts as the individual messages and we show how to model such speech-acts as WS-Agreement schemas, which can, in turn, be imported into the specification of the protocols in WSCL. To demonstrate our approach, we express a standard contracting protocol in the extended WSCL/WS-Agreement languages. Furthermore, we use statechart notation as a visual counterpart to help developers write clients that flexibly interact with a service and to help users to better understand how to interact with a service. Finally, we show that the translation between statecharts and WSCL/WS-Agreement protocols is straightforward.     

Mobile Web services: a new agent-based framework

Mobile devices and server applications often run on different platforms, which can make integration problematic. Web services might offer a solution, but they typically include XML protocols that are too "heavy" for mobile devices. In this article, we describe agent-based mobile services framework. It uses wireless portal networks and eliminates XML processing on mobile clients. It also offers dynamic service selection and rapid application development and deployment for Web service providers.