A monitoring approach for runtime service discovery

Effective runtime service discovery requires identification of services based on different service characteristics such as structural, behavioural, quality, and contextual characteristics. However, current service registries guarantee services described in terms of structural and sometimes quality characteristics and, therefore, it is not always possible to assume that services in them will have all the characteristics required for effective service discovery. In this paper, we describe a monitor-based runtime service discovery framework called MoRSeD. The framework supports service discovery in both push and pull modes of query execution. The push mode of query execution is performed in parallel to the execution of a service-based system, in a proactive way. Both types of queries are specified in a query language called SerDiQueL that allows the representation of structural, behavioral, quality, and contextual conditions of services to be identified. The framework uses a monitor component to verify if behavioral and contextual conditions in the queries can be satisfied by services, based on translations of these conditions into properties represented in event calculus, and verification of the satisfiability of these properties against services. The monitor is also used to support identification that services participating in a service-based system are unavailable, and identification of changes in the behavioral and contextual characteristics of the services. A prototype implementation of the framework has been developed. The framework has been evaluated in terms of comparison of its performance when using and when not using the monitor component.     

基于组件动态管理的Web应用框架研究

软件复用的应用需求推动了可复用应用框架和应用业务组件的研究和发展应用,在开发高度可重用性J2EE应用框架和业务组件中使用合适的设计模式,可以降低应用业务组件和应用框架组件之间的耦合,提高框架组件的重用性.讨论了通过应用MVC设计模式对J2EE应用框架组件和应用组件进行角色化处理,构造了一个可动态管理组件的J2EE应用模型,定义了应用框架组件和应用组件的功能以及它们之间的逻辑结构关系。     

Algorithms for checking channel passing in web service choreography

Web service choreography describes global models of service interactions among a set of participants. For an interaction to be executed, the participants must know the required channel(s) used in the interaction, otherwise the execution will get stuck. Since channels are composed dynamically, the initial channel set of each participant is often insufficient to meet the requirements. It is the responsibility of the participants to pass required channels owned (known) by one to others. Since service choreography may involve many participants and complex channel constraints, it is hard for designers to specify channel passing in a choreography exactly as required. We address the problem of checking whether a service choreography lacks channels or has redundant channels, and how to automatically generate channel passing based on interaction flows of the service choreography in the case of channel absence. Concretely, we propose a simple language Chor _c , a channel interaction sub-language for modeling the channel passing aspect of service choreography. Based on the formal operational semantics of Chor _c , the algorithms for static checking of service choreography and generating channel passing are also studied, and the complexity results of algorithms are discussed. Moreover, some illustrated service choreography examples are presented to show how to formalize and analyze service choreography with channel passing in Chor _c .     

Algorithms for checking channel passing in web service choreography

Web service choreography describes global mod- els of service interactions among a set of participants. For an interaction to be executed, the participants must know the required channel（s） used in the interaction, otherwise the ex- ecution will get stuck. Since channels are composed dynami- cally, the initial channel set of each participant is often insuf- ficient to meet the requirements. It is the responsibility of the participants to pass required channels owned （known） by one to others. Since service choreography may involve many par- ticipants and complex channel constraints, it is hard for de- signers to specify channel passing in a choreography exactly as required. We address the problem of checking whether a service choreography lacks channels or has redundant chan- nels, and how to automatically generate channel passing based on interaction flows of the service choreography in the case of channel absence. Concretely, we propose a sim- ple language Chorc, a channel interaction sub-language for modeling the channel passing aspect of service choreography. Based on the formal operational semantics of Chore, the algo- rithms for static checking of service choreography and gen- erating channel passing are also studied, and the complexity results of algorithms are discussed. Moreover, some illus- trated service choreography examples are presented to show how to formalize and analyze service choreography with channel passing in Chorc.     

A perspective on service orchestration

Service-oriented computing is an emerging paradigm with increasing impact on the way modern software systems are designed and developed. Services are autonomous, loosely coupled and heterogeneous computational entities able to cooperate to achieve common goals. This paper introduces a model for service orchestration, which combines a exogenous coordination model, with services’ interfaces annotated with behavioural patterns specified in a process algebra which is parametric on the interaction discipline. The coordination model is a variant of Reo for which a new semantic model is proposed.     

基于嵌入式可信平台的运行时监控方法

当前可信计算平台缺乏对自身运行时安全属性的监控,对此,提出一种针对嵌入式可信平台的运行时监控方法。通过自动化的代码插入和运行时实时监控,保证可信平台的运行时安全功能符合设计规范,并保证系统性能和运行状态符合特定条件约束,同时对相应的异常进行实时处理。实验结果表明,随着监控节点数的增长,监控的准确性和实时性提高,而监控开销和异常处理开销处于合理范围。     

基于Web日志挖掘的个性化服务技术的研究

随着互联网的迅速普及和广泛应用,网络信息资源的数量及网站设计的复杂度也呈急剧增长趋势。如今,针对用户特性并向用户提供个性化服务已经成为计算机技术的研究热点之一。本文首先简述了Web日志挖掘的相关概念和具体实现过程,然后重点讲述了Web日志挖掘的关键技术。最后采用了用户群体聚类算法与Web页面聚类算法相结合实现挖掘用户访问模式,并针对个性化服务的应用和发展方向进行了研究和分析。     

基于Web Service的空间信息服务研究

WebGIS已经成为目前空间信息大众化的有力工具,然而系统之间难以集成,无法互操作和空间数据共享等问题却严重制约了WebGIS的发展,GIS Web服务的出现为解决这一难题提供了全新思路。介绍了Web服务的基本概念、分析了Web服务与GIS结合的优势、探讨了GIS Web服务开发的基本原则,同时提出了一个GIS Web服务的模型,并进行了相关的实验。     

基于Multi-agent的实时系统运行故障监控研究

软件密集型装备中常常包含着许多担负监测和控制作用的嵌入式实时系统,它们常常属于安全关键或者任务关键系统(safety-critical/mission-critical system)。为了能够有效解决该类系统中的软件故障检测、诊断与修复任务,本文提出了基于Multi-agent的实时系统运行故障监控框架,旨在利用在多agent的协作构建运行故障监控系统来在系统运行当中验证系统是否满足时序逻辑描述的性质规约,并采用具体的算法进行故障定位和修复。     

Lightweight runtime checking of C programs with RTC

The C Programming Language is known for being an efficient language that can be compiled on almost any architecture and operating system. However the absence of dynamic safety checks and a relatively weak type system allows programmer oversights that are hard to spot. In this paper, we present RTC, a runtime monitoring tool that instruments unsafe code and monitors the program execution. RTC is built on top of the ROSE compiler infrastructure. RTC finds memory bugs and arithmetic overflows and underflows, and run-time type violations. Most of the instrumentations are directly added to the source file and only require a minimal runtime system. As a result, the instrumented code remains portable. In tests against known error detection benchmarks, RTC found 98% of all memory related bugs and had zero false positives. In performance tests conducted with well known algorithms, such as binary search and MD5, we determined that our tool has an average run-time overhead rate of 9.7× and memory overhead rate of 3.5×.     

基于Web Service的CIS设计

分析了设计临床路径管理系统的重大意义,提出了基于Web Service的系统设计模型和体系结构,既有效的提高了系统的开发效率,又实现了各种医疗信息的跨平台应用集成.对系统中基于COM 应用层重点进行了研究,给出一个切实可行的开发方法.通过比较Web Service调用的方法并结合本系统的特性,提出一个适合本系统的委托回调方法,实现了系统消息的传递.最后通过系统的正常运行验证了设计思路的正确性.     

基于Web服务的数据集成框架

为了给用户和第三方应用提供更方便的接口支持并扩展数据集成产品的功能,提出基于Web服务的数据集成(Web Services Based Data Integration,WSDI)框架,并详细描述其框架结构及关键技术.WSDI可以提高数据集成产品的内部管理和扩展能力,在数据集成产品OnceDI中进行应用,效果良好.     

Dynamic web service composition based on OWL-S

Composing existing web services for enterprise applications may enable higher level of reuse. However the composition processes are mostly static and lack of support for runtime redesign. In this paper, we describe our approach to the extension of the OWL-S ontology framework for dynamic web service composition. We raise the level of abstraction and propose an abstract service layer so that web services can be com- posed at the abstract service level instead of the concrete level. Each abstract service is attached with an instance pool including all instances of the abstract service to facilitate fail-over and dynamic compositions.     

基于网络服务的机动车排气检测监管系统实现

为提高省级环保部门机动车排气污染监管能力,并解决省内各城市间机动车监管数据统一共享的实际问题,以广东省为例研究了基于Web Service技术的省、市、站三级耦合的机动车排气检测监管系统的构建方法,并开发了相应的原型系统来测试方法的有效性.阐述了系统的总体设计、功能结构以及基于Web Service的技术实现方法.所提的建设方案可以解决异构或不同时期建设的各类市级机动车排气检测监管系统的数据集成和共享问题.     

有界模型检测在服务组合中的应用研究

大规模服务自动组合问题是Web Service技术的主要瓶颈。传统的服务组合技术灵活性差并且适用的服务规模有限。在用有限状态自动描述机服务的输入、输出、操作等活动的基础上,提出用有界模型检测技术对大规模服务进行建模,将用户请求翻译为线性时态逻辑公式,采用适定性问题求解技术快速求解限定长度的服务组合解。实验结果表明有界模型检测技术应用在自动服务组合中是可行的。     

基于Web Service的电子商务技术研究

WebServices是一种面向服务的体系结构,其突出优点是实现了真正意义上的平台独立性和语言独立性。WebServices是新一代Internet分布式应用框架,代表了下一代网络计算和企业应用的必然趋势。分析了电子商务发展现状以及存在的问题,介绍了基于WebServices电子商务技术,它们可以跨越不同应用系统的对象体系、运行平台和开发语言等的界限,并以服务的形式封装,对外对内发布应用服务接口,供其它的应用程序调用,从而形成一个基于Web的服务共享平台。由于XML语言的应用,电子商务的应用和开发将进入一个新的阶段-ebXML.     

基于Web Service的多代理系统的研究

为了更好地适应软件智能化和分布化的发展需要,在阐述了多代理系统的主要特点和Web Service的核心概念的基础上,提出了基于Web Service的多代理系统的体系架构。架构很好地融合了代理技术与Web Service各自的优点,能够更加高效地构建出应用于发布环境中的开放的、动态的、健壮的多代理系统。     

Meta web service: building web-based open decision support system based on web services

Web services are currently one of the trends in network-based business services, which intuitively will be applied to build a semantic web-based decision support system (DSS). Since web services are self-contained, modular business process applications, based on open standards, enable integration models for facilitating program-to-program interactions. Decision modules in a semantic web-based DSS can be viewed as a web service. However, according to the current features, web services know only about themselves, they are neither autonomous, nor are they designed to use ontologies; they are passive until invoked, and they do not provide for composing functionalities. These lead to the motivation on building a sophisticated web service to contain these features and to utilize web services on behalf of the user. This paper aims to propose a new concept of Meta Web Service, a web service-based DSS. The meta web service understands the user's problem statement with ontology, performs web service discovery, web service composition, and automatically generates codes for composite web service execution. Case-based reasoning is applied to quickly find past histories of successful service compositions. A prototype of research web service has been developed to show the feasibility of the proposed idea.     

基于行为描述的Web服务组合兼容性检查*

定义了服务的基调视图和行为视图,设计了将Web服务行为转换为π演算进程表达的建模方法,并给出了实现服务视图向π演算进程自动转换的算法;最后借助π演算的操作语义和形式化推理技术实现了对Web服务组合时的兼容性进行检查。