服务网格中的事务服务及基于Petri网的正确性分析

面向服务的架构(SOA)推动着网格技术从科学计算走向商业领域,大部分商业应用需要事务的支持．该文提出了服务网格环境下用于事务管理的网格事务服务,它能够动态地发现执行子事务的网格服务;根据事务类型调用原子事务或聚合事务协调算法以保证这些服务在行动上实现期望的一致性．通过Petri网分析技术,将两种协调算法模型化为Petri网并验证了它们的正确性．网格事务服务可以提供较强的事务管理能力并将复杂的处理过程对用户透明,为网格技术的商业化提供了有效的支持．     

网格环境下的一种事务协调机制及其补偿技术

事务处理是网格计算能否投入实际应用尤其是商业应用的关键技术之一，用于网格环境下的事务处理必须同时提供协调短时操作和长时间的商业活动的能力，基于Gtobus Toolkit和代理技术，提出了一种能够同时管理原子事务和聚合事务的事务协调机制，研究了相应的可以容错各种失败的协调算法，通过自动产生和执行补偿事务，聚合事务协调机制可以满足网格计算中对长事务的处理要求。     

数据网格中面向服务的事务技术

讨论了数据网格的背景以及目前国内外的研究状况.并根据应用的需求,提出了数据网格中面向服务的事务管理观点.定义了服务事务在数据网格体系结构中的位置、功能和实现方案,阐述了原子事务和业务事务两类事务的实现协议,最后以一个原子事务的例子说明了一个服务事务的执行过程.     

Web Services and Business Transactions

Process oriented workflow systems and e-business applications require transactional support in order to orchestrate loosely coupled services into cohesive units of work and guarantee consistent and reliable execution. In this paper we introduce a multi-level transaction model that provides the necessary independence for the participating resource managers, e.g., local database and workflow servers, of organisations engaging in business transactions that are composed of interacting web services. We also present a taxonomy of e-business transaction features such as unconventional atomicity criteria, the need for support for business conversations and the need for distinguishing between three basic business transaction phases. In addition, we review current research and standard activities and outline the main ingredients of a business transaction framework necessary for building flexible e-business applications.     

On scheduling transactions in a grid processing system considering load through Ant Colony Optimization

Load balanced transaction scheduling problem is an important issue in distributed computing environments including grid system. This problem is known to be NP-hard and can be solved by using heuristic as well as any meta-heuristic method. We ponder over the problem of the load balanced transaction scheduling in a grid processing system by using an Ant Colony Optimization for load balancing. The problem that we consider is to achieve good execution characteristics for a given set of transactions that has to be completed within their given deadline. We propose a transaction processing algorithm based on Ant Colony Optimization (ACO) for load balanced transaction scheduling. We modify two meta-heuristic along with ACO and three heuristic scheduling algorithms for the purpose of comparison with our proposed algorithm. The results of the comparison show that the proposed algorithm provides better results for the load balanced transaction scheduling in the grid processing system.     

一种基于补偿代价的长事务调度算法

服务组合应用中的事务具有较长的生命周期,一个事务被划分成多个分布的子事务.补偿机制是保证长事务原子性的一种有效方法,允许在语义上逆转一个已提交子事务的结果.然而,补偿的代价可能是巨大的.针对该问题,在分析并定义事务补偿代价的基础上,提出一种子事务延迟提交算法――STCD(subtransactions committingdelay)算法,与传统子事务执行后立即提交的方法相比,STCD 算法允许某个全局事务的子事务在提交前根据自身的补偿代价和全局事务的运行状态动态确定提交时间,使可能的补偿操作变更为回滚操作.算法的正确性得以证明.模拟实验结果表明,在事务失败时,STCD 算法可以有效地减少补偿活动的数目,降低补偿代价.     

银行业务集中式分组交易核心平台研究与应用

银行核心系统是以处理银行最基本的存款、贷款业务为主的IT系统,其中的交易平台体现了银行核心乃至整体IT服务能力.为了提高集中式架构的核心系统在交易高峰期的服务能力,本文设计了一种具备交易分组能力的核心平台.该平台涵盖了交易服务器、交易分发器、交易处理器三层架构,通过交易分组服务算法实现处理作业按交易分组以及动态分配系统资源.实验结果表明,相较于传统的监听-分发两层结构,本文设计的具备交易分组能力的三层结构的核心平台,具备较高的并发处理能力,系统资源使用情况也比较平稳.     

网格服务环境下的一种事务处理模型

提出了网格服务环境下的一种可行性事务处理模型.首先提出了事务协调框架,在此基础上提出适用于该框架的针对特定事务类型尤其是长事务的协调协议,并对长事务的恢复技术进行了一定讨论.     

A Reservation-Based Extended Transaction Protocol

With the advent of the new generation of Internet-based technology, in particular, web services, the automation of business activities that are distributed across multiple enterprises becomes possible. Business activities are different from traditional transactions in that they are typically asynchronous, loosely coupled, and long running. Therefore, extended transaction protocols are needed to coordinate business activities that span multiple enterprises. Existing extended transaction protocols typically rely on compensating transactions to handle exceptional conditions. In this paper, we identify a number of issues with compensation-based extended transaction protocols and describe a reservation-based extended transaction protocol that addresses those issues. Moreover, we define a set of properties, analogous to the ACID properties of traditional transactions that are more appropriate for business activities that span multiple enterprises. In addition, we compare our reservation protocol with other extended transaction protocols for coordinating business activities and present performance analyses and results.     

Context-adaptive and energy-efficient mobile transaction management in pervasive environments

Pervasive computing is a user-centric, scalable, parallel, and distributed computing paradigm, allowing users to access to their preferred services even while moving around. Transaction management for pervasive environments has to provide mobile users with reliable and transparent services anytime anywhere. To make such a vision a reality, the communication of pervasive transaction processing should be context-aware for adapting to dynamically changing execution environments, and energy-efficient for prolonging the lifetime of battery-powered mobile devices. In this paper, we propose a context model and a context-aware transaction model for pervasive transactions, and present a c\underline{\mathrm{c}} ontext-adaptive and e\underline{\mathrm{e}} nergy-efficient t\underline{\mathrm{t}} ransaction m\underline{\mathrm{m}} anagement mechanism (CETM) that can dynamically adjust transaction execution behaviors in terms of current context information. Moreover, we model and verify the correctness of the CETM through Petri nets. The simulation results have demonstrated that our transaction management mechanism CETM can significantly reduce the failed probability of concurrent pervasive transactions.     

Toward a business process grid for utility computing

Existing grid computing technologies take advantage of underused computing capacity to solve business problems and provide IT-level infrastructure to support business applications. A business grid's ultimate goal, however, is to apply the utility model of grid computing to business applications; that is, provide support services for charging users on a pay-per-use basis, much as a utility company charges for electricity. That way, the vendor takes the responsibility for application maintenance and upgrade. Thus, a business grid provides a virtualized infrastructure to support the transparent use and sharing of business functions on demand.     

满足原子事务的QoS感知的自适应服务选择

随着云计算的兴起,服务计算成为其实现的一种关键技术,学术领域对服务组合有新的思考。提出了满足原子事务的服务质量（quality of service,QoS）感知的自适应服务选择方法,既考虑QoS约束,也考虑服务间的事务约束,在进行全局优化选择时结合适当的协调模式选择策略,以进一步提高可靠性。首先制定自适应规则和建立QoS模型,并引用其他学者关于事务构建和规约规则的模型。接着分析事务与QoS约束下自适应服务选择算法机制。最后通过实验评价了方法的有效性和健壮性。     

taTHP：一种THP的改进事务模型

随着电子商务的迅速崛起,Web服务逐渐成为Web领域一个崭新的分布式计算模型.在自治的、松耦合的Web服务事务环境中,由于事务参与者不能提供长时排它的资源锁定模式,因而无法继续采用传统的ACID事务结构.换而言之,Web服务事务处理必须具备针对松散耦合事务环境及自治资源提供策略的协调能力.本文在THP(TentativeHoldProtocol)事务模型的基础上,进一步发展了资源的“准”占用思想,提出了一种具备“事务意识”的新型资源协调算法,从而使系统性能有了较大提升.     

组合服务事务的异常处理机制研究

服务组合目前已成为业界研究的热点,它为组织问应用集成提供了一种新的解决方案.在完全开放的Internet环境中,组合服务需要Web服务事务处理机制来保证其可靠性,而Web服务事务处理需要一种异常处理机制的支持.针对节点故障引起的异常给出多种异常处理策略,对其进行形式化描述,并给出了异常处理的算法.最后在此基础上提出一个可定制补偿操作及相关补偿规则的灵活的组合服务事务异常处理模型,并对其实现.     

基于数据库事务的不变式推导

作为数据处理和并发控制的基本单位,数据库事务被广泛应用于软件系统的业务逻辑中。通过收集运行时数据库事务中的数据,推导这些数据之间满足的不变式,建立相应的数据契约关系,是软件维护过程中对系统的内部状态进行监控的重要方法之一。目前,在不变式推导领域,主要的方法和工具都是基于代码进行分析的,缺少与基于数据分析相关的研究和成果。为了解决这一问题,首先提出了基于数据的推导代数等式形式的不变式的算法,然后设计并实现了基于数据库事务的不变式推导的原型工具,最后通过相关实验分析和验证了原型工具的有效性。实验结果表明,原型工具有良好的推导准确率和运行性能,能够弥补现有工具和方法在基于数据的分析领域的不足。     

ESB事务模型的设计与实现

企业服务总线中,传统事务处理模型、扩展事务处理模型和Web服务事务处理模型都无法满足该环境下服务流程的事务处理需求.提出一种以流程进行事务注册、以事务性消息进行事务划分的面向流程的事务处理模型来解决企业服务总线环境下具有服务松耦合、运行时间长短不确定,服务类型多样以及服务流程的静态编制等特性的服务流程的事务需求.该事务处理模型已在企业服务总线产品中得到了成功应用.     

具有隐私保护的安全电子交易协议

电子交易的普及在给用户带来便利的同时,其在交易支付中所暴露出的隐私保护和安全性问题也受到不同程度的挑战。针对此问题,提出一个安全的电子交易协议。协议中,优化后的签密算法可保证交易的安全性;同时支付服务商具有去匿名性功能,可以在保护用户隐私的基础上进行追责。经性能分析,本协议在提高通信性能的基础上,满足消息的机密性和不可否认性、购买者的匿名性和可追踪性以及电子交易的公平性。     

基于社会网络动态反馈的Web服务信任度计算

在当前服务计算背景下,针对用户难以获得满足需求的可信服务问题,提出基于社会网络动态反馈的Web服务信任度模型.基于用户使用经验设计服务直接信任度算法,对服务交易情况进行动态跟踪和监测.当用户缺乏使用某服务的直接经验时,基于社会网络中服务使用者信任度,聚合其他服务使用者对服务的直接信任度,计算该服务的间接信任度.采用修正因子进行修正,以提高社会网络节点及关联服务可信性.算法分析表明,该方法是可行和有效的.     

Towards flexible compensation for business transactions in Web service environment

Recently, many business applications embrace Web services as their implementation technologies. Due to the long duration and loosely coupled properties, Web service based applications require more transactional supports beyond traditional transactions. Some initial work has been done to deal with the transaction aspect of Web service applications, in form of standards or protocols. Among these efforts, compensation is commonly used for backward recovery. However, the compensation mechanism adopted is too fixed and cannot satisfy the various requirements of different applications. In this paper, we propose a flexible compensation mechanism which enables flexible compensation schemes for a single failed case. Based on a thorough analysis of current Web service compensation protocols and standards, we extend the flexible compensation mechanism to the Web service computing environment. The implementation of the extended compensation mechanism is discussed and the incorporation of the mechanism into current standards is also addressed.