A policy enforcement framework for verification and control of service collaboration

This paper proposes a policy enforcement framework to dynamically verify and control the collaboration process in Service-Oriented Architecture (SOA). Dynamic SOA collaboration is different from traditional service collaboration where the workflow is pre-defined at design time while the services used can be discovered at runtime. In dynamic collaboration, both the workflows and services can be determined at runtime. As they will be determined at runtime, many verification activities can be performed at runtime. This paper proposes a dynamic policy enforcement framework that follows the dynamic SOA collaboration process to ensure that various system constraints can be enforced at runtime. The framework includes a policy specification language, a policy completeness and consistency checking, and distributed policy enforcement. Finally, this paper presents the construction of a sample example to illustrate these features with quantitative performance data.     

基于模型的云应用动态配置框架

云应用是云计算技术在应用层的一种重要体现形式,通常由分布式异构组件构成,且组件相互依赖,配置参数众多。组件依赖导致配置参数间存在关联,使应用运行时弹性扩展难以确定组件实例的配置顺序并保证关联参数的一致性,导致应用扩展后的系统故障和服务不可用。针对这一问题,提出了一种基于模型的云应用动态自配置方法,实现运行时组件实例配置顺序的自动协调,保障配置参数的一致性,提高应用运行时弹性扩展的可靠性。首先提出一种部署配置模型STM(Service-based Topology Model),该模型采用声明式的方法刻画云应用的部署拓扑结构,并基于服务的方式描述组件信息,实现组件间关联关系的分离,涵盖运维部署、扩展、运行时服务状态的监测。 然后 基于该模型,提出了一个云应用动态自配置协议,其基于服务注册发现机制实现组件间强依赖关系的解耦,保证动态调整应用实例时组件配置变化的一致性,实现组件部署配置的并行化。基于上述方法实现了一个原型系统,通过对分布式应用BookStore-TPCW的部署配置和运行时弹性扩展来验证方法的有效性。     

Model-based services convergence and multi-clouds integration

With the development of cloud computing, IT users (individuals, enterprises and even public services providers) are transferring their jobs or businesses to public online services provided by professional information service companies. These information service companies provide applications as public resources to support the business operation of their customers. However, no cloud computing service vendor (CCSV) can satisfy the full functional information system requirements of its customers. As a result, its customers often have to simultaneously use services distributed in different clouds and do some connectivity jobs manually. Services convergence and multi-clouds integration will lead to new business models and trigger new integration technologies that provide solutions to satisfy IT users’ complicated requirements. This paper firstly reviews the development of cloud computing from business and technical viewpoints and then discusses requirements and challenges of services convergence and multi-clouds integrations. Thirdly, a model based architecture of multi-clouds integration is provided. Business logic modelling for cross-organizational collaboration, service modelling and operation modelling methods with relative model mapping technology are discussed in detail. Some key enabling technologies are also developed. At last, case studies are presented to illustrate the implementation of the technologies developed in the paper.     

Web Services动态合成技术的研究

为了提高Web Services合成的效率,减少用户查询时过多的人工干预,提出了一个Web Services最佳路径动态合成框架.在该框架下以产生式的形式建模,构建一个适合于最佳路径算法的DAG图,以参数级本体解决合成过程中的语义冲突问题,并通过最佳路径算法进行合成.通过分析比较,该框架特别适合于对同样的用户输入和Web Services进行多次合成以生成相同的或者不同的输出,同时也避免了回溯和对合成方案的优化.     

关于改进Web Services调用机制的研究

现行的Web Services技术的服务调用过程是基于XML的SOAP协议.随着Web Services应用范围的扩展,对其服务性能提出了更高的要求,但由于XML的自身特性,限制了Web Services作为分布式计算技术在事务级领域的应用.首先概述了Web services的总体框架,然后基于Web Services的性能评判标准,分析了Web Services的性能现状,并结合EJB技术、数字证书技术和紧耦合集成技术,从系统调用机制角度对Web Services加以改进.最后阐述了改进调用机制的特点和适用范围.     

Model-based Runtime Verification Framework for Self-optimizing Systems

This paper describes a novel on-line model checking approach offered as service of a real-time operating system (RTOS). The verification system is intended especially for self-optimizing component-based real-time systems where self-optimization is performed by dynamically exchanging components. The verification is performed at the level of (RT-UML) models. The properties to be checked are expressed by RT-OCL terms where the underlying temporal logic is restricted to either time-annotated ACTL or LTL formulae. The on-line model checking runs interleaved with the execution of the component to be checked in a pipelined manner. The technique applied is based on on-the-fly model checking. More specifically for ACTL formulae this means on-the-fly solution of the NHORNSAT problem while in the case of LTL the emptiness checking method is applied.     

基于Web Services的语义异构数据集成设计与实现

高校在信息化建设过程中积累了大量异构、异质的数据源,如何将这些异构数据源中相关的数据资源进行有效整合是当前急需解决的问题.为此,提出了一种新的基于Web Services的异构数据集成解决方案,利用Web Services技术在异构数据集成中的优势,采用虚拟数据库法设计思想,通过设计领域字典表及字段映射表,有效地解决了异构数据集成中最难解决的语义异构问题,并从数据模型转换、全局查询等方面阐述了该方案的可行性.实验结果表明,该方案具有可用性和高效性.     

Web服务应用标准化研究

Web服务为软件系统间的互操作和应用系统集成提供了技术规范.分析Web服务的技术特性和目前的Web服务开发方式存在的不足,提出了用Web服务接口文档为依据开发标准化Web服务的思想,描述了Web服务接口文档模型的组成元素及其在提高Web服务质量特性上的作用.     

一种策略驱动的Web服务质量保障框架

随着面向服务计算技术的发展和应用,提供非功能属性保障能力成为服务在企业应用中获得成功的关键因素.同传统的分布式计算技术不同的是,服务是动态发现和绑定的,这要求服务双方必须动态协商并保障各种非功能属性.使用WS-Policy语言来显式描述Web服务的非功能性的能力和需求,并提出了一种策略驱动的服务保障框架来完成非功能属性的动态保障,最后在SOAP引擎SOAPExpress中实现了这一框架,结果表明它可以有效满足企业应用对Web服务质量的需求.     

基于Web服务的局数据管理系统

由于移动通信网络的不断扩容和业务的不断扩展,网络上网元的类型和数量都在不断增加,这就对局数据的管理提出了更高的要求。如果采用Web服务技术和用正则表达式来描述数据解析规则的方法,设计出来的局数据管理系统可以通过简单的配置来动态地将新增的网元添加到系统中,并能够以通用的接口提供解析与核查服务。通过实际运行证明,该系统具有通用性、可扩展性和较高的效率,能够保障移动网络的稳定运行。     

利用J2EE实现Web Services模型与应用

WebServices是一种新颖的系统应用开发与集成技术并得到了越来越多的企业以及开发人员的青睐。该文简要阐述了WebServices的基本概念、模型以及在企业信息系统中的应用模型与实现,并以实例详细论述了WebServices系统的建立、设置与相关程序的编制。     

Formal enforcement and management of obligation policies

Obligations are generally actions that users are required to take and are essential for the expression of a large number of requirements. For instance, obligation actions may represent prerequisites to gain some privilege (pre obligations), to satisfy some ongoing or post requirement for resource usage (ongoing and post obligations), or to adhere to some privacy or availability policy. Obligations may also define states of affairs which should be maintained. An example of such obligations is the obligation “doctors should remain alert while in the operating room”. In this paper, we introduce a formal framework for the management and enforcement of obligation policies. The framework is formalized using concepts from action specification languages and the Event Condition Action paradigm of active databases. Therefore, our framework allows reasoning about change in the state of obligations and, at the same time, provides declarative formal semantics for their enforcement. In this framework, we support many types of obligations and show how to manage obligation activation, fulfillment and violation.     

Model-based quality monitoring of batch and semi-batch processes

In this paper, a model-based inferential quality monitoring approach for a class of batch systems is investigated. Given the appropriate model form, the batch quality monitoring problem can be reduced to the problem of state estimation for batch and semi-batch processes. Because feed upsets are often a major source of disturbance in this type of system, it is shown that estimating the initial conditions can lead to improved state estimates throughout the batch as well as improved monitoring and control of end-use quality in many cases. The approach taken in this paper is to reduce the effects of the initial uncertainty resulting from feed disturbances by using algorithms designed to perform on-line smoothing of the initial conditions. First, an Extended Kalman Filter-based fixed-point smoothing algorithm is presented and compared to a popular approach to estimating the initial conditions. Subsequently, a nonlinear optimization-based approach is introduced and analyzed. A sub-optimal on-line approximation to the optimization problem is developed and shown to be directly related to the Extended Kalman Filter-based results. Finally, some practical implementation aspects are discussed, along with simulation results from an industrially relevant example application.     

Web Services在构建企业信息化平台中的应用研究

企业信息化建设一直是企业比较关心的课题之一,但是随着网络技术和通信技术的飞速发展,在企业内部或不同企业间如何实现信息共享和数据集成,成为构建企业信息化平台中所必须解决的关键问题。讨论了Web Services的基本概念和体系架构,根据Web Services与企业信息化的特点,提出了利用Web Services构建企业信息化平台,并结合企业实际运营中的相关服务,给出了Web Services在构建企业信息化平台中的具体应用。     

Aggregated search of data and services

From a user perspective, data and services provide a complementary view of an information source: data provide detailed information about specific needs, while services execute processes involving data and returning an informative result as well. For this reason, users need to perform aggregated searches to identify not only relevant data, but also services able to operate on them. At the current state of the art such aggregated search can be only manually performed by expert users, who first identify relevant data, and then identify existing relevant services.     

基于整合模式的EMS/SAS监控系统研究与设计

针对IEC61970EMS系统与IEC61850变电站模型的差异,介绍了将两个标准整合集成,以实现通信和信息交互方案。根据CORBA和Web Services各自存在的优缺点,阐述了将CORBA与Web Services整合的设计思想,从而实现监控系统更大范围的应用集成。     

Collective intelligence in law enforcement - The WikiCrimes system

Collaboration is on the rise, primordially leveraged by the Web 2.0 in which the difference between information producer and consumer decreases significantly. In this paper we describe WikiCrimes, an example of a Web 2.0 application that offers a collaborative environment based on the use and direct manipulation of maps, in order to register and research criminal events. WikiCrimes is driven by three goals: (i) to give more transparency and publicity to criminal information, (ii) to provide means for citizen prevention, and (iii) to reduce the phenomenon of under-reporting (crimes that are not notified to authorities). In the paper we pay particular attention to the fact that in this context, finding the equilibrium between people’s participation and information credibility is crucial. Anonymous mass collaboration is the easiest way to receive information; however, the credibility of the received information is depreciated, because the source of information is unknown. We particularly concentrate on the ways we have created to keep the “participation vs. reliability of information” trade-off at good level. The reputation model is the main component created with this purpose. The experiences and the obstacles we are facing in the implementation of the project are the subjects of discussion and analyses.     

基于参与者上下文概念意图的语用Web服务发现

为了使得语义Web服务的发现结果与服务请求者的意图更加一致,提高服务发现的准确性,改善服务发现和选择的自动化性能。在服务描述中增加了对于服务提供者和服务请求者的上下文知识的表示,使用规划的方法完成服务参与者之间对于私有的上下文本体概念意图的理解。实验表明,该方法能够有效提高发现的准确性,在使用标准服务测试集进行服务发现实验时,尽管概念规划使得服务发现时间有所增加,但服务发现的准确性得到很大提高,尤其对于描述服务领域本体语义差异较大的情况,服务发现的结果更为准确。     

J2EE平台上基于Web Services的数据集成研究

数据集成是共享分布的异构数据资源的核心问题.在分析常用数据集成技术的基础上,结合Web Services技术和组件技术,提出了基于Web Services和组件技术实现Mediated系统的数据集成方案.最后,以J2EE为平台给出了一种面向服务的低偶合的数据集成框架,中介器和包装器由EJB组件实现,由组件部署的Web服务为用户提供一个透明的统一的接口,实现异地异构数据资源的共享和整合.