基于语义约束的资源工作流并发正确性保证

控制流结构中并发变迁的正确性是工作流模型正确性的基础．为保证模型的正确性，提出了资源语义约束工作流网的基本概念，丰富了控制流的数据语义，给出了两方面的控制流并发正确性：并发控制流与其数据语义的一致性检测算法及改正原则，保证了模型中的并发控制流结构的正确性；实例中基于数据语义约束的并发变迁正确性保证机制，提出了申请锁和释放锁的算法，保证了工作流实例中并发执行的正确性。     

用DELPHI开发基于SQL server2000的多客户应用程序

本文详细分析数据库的并发机制,以及使用DELPHI的数据导航条与数据集组件来解决多客户并发的问题。     

移动数据库中数据更新与广播的并发控制

移动数据库系统中数据更新与数据广播并发处理,导致移动客户读取的数据可能不一致,本文分析了在移动数据库中数据更新与数据广播并发处理中可能出现的三类数据冲突,并提出了基于UFBL0原则的并发控制策略来解决上述的问题。该策略具有较好的独立性,对服务器和移动客户机的影响都较小,并且可以较大限度地提高广播给用户的数据项当前性。     

大规模数据中心监控数据并发处理

在大规模数据中心场景下,采集系统要实时并发处理大规模数据来保证监控数据的实时性。论文首先描述了大规模数据中心监控数据的规模,并指出监控数据的并发处理中存在的问题,然后针对问题提出关键技术和解决方案,进而基于上述研究结果进行架构设计。经过实验验证Storm应用于大规模数据中心监控数据的并发处理业务,可以保证监控数据的实时性,并且系统具备一定的扩展性。     

移动数据库中数据广播与数据更新并发执行的数据一致性维护

移动数据库系统中数据更新与数据广播并发处理,导致移动客户读取的数据可能不一致。文章分析了并发处理中的数据冲突并提出了基于ECA原则的并发控制策略。     

典型数据并发访问问题的探讨

掌握好数据并发访问技术是保障数据库正确性、一致性所必需的。文章在实践的基础上总结出了并发事务设计原则，通过使用反复实验与测试的方法，对典型并发问题、自定义锁应用等作了深入探讨，进而得到了四种典型并发问题及两种典型并发应用的有效解决办法，为今后解决好各类数据库的并发访问问题起到积极的作用。     

实时数据库数据特征对事务处理的影响

实时数据库系统事务调度一般只考虑事务的截止期,这对保证满足事务访问数据的时间正确性是不够的。文中针对时序数据的特点给出了同时考虑事务的截止及“数据截止期”的事务优先级分派、调度及并发控制方法。     

移动数据访问系统中的事务管理

针对移动数据访问系统中事务处理的并发控制和数据访问问题，提供了一种分层的并发控制算法。另外，在弱连接或者断开连接的情况下复制的数据可以提供数据的可访问性。本文提供一个新的模式来解决带宽和数据库自治问题的限制。     

Scalaris:Web 2.0服务的可扩展、事务型数据中心

构建一个分布式的、能支持每秒满足数千、甚至百万并发数据访问的键/值式存储结构。让这个系统在节点崩溃、高并发数据写入等条件下强力保证数据的一致性。     

实时数据库并发控制

可串行化的并发控制对传统应用是适合的,它旨在确保数据库的一致性,提高系统的吞吐量及减小事务平均响应时间,而在实时数据库中,一方面系统追求的主要目标是单个事务定时限制（典型地为截止期）的满足,另一方面,系统中的数据库是外部环境在逻辑世界中的映射,局部的数据库不一致能够随下一次数据采样恢复而不会大规模扩散,这些都为有利于传统严格一致的可串化并发控制的并发控制协议的采用提供了必要性和可能性,本文首先给出了数据库“相似性”的形式化定义,接着提出了“视图一致性”的概念,然后提出了一种新的并发控制协议,它考虑了数据的相似性,并使只读事之间并不满足传统的严格可串行化的标准,但并没有破坏数据库的一致性,事务执行的并发度有了提高,有利于实时事务定时限制的满足,最后我们将这种并发控制协议的性能与有名的H2PL协议的性能进行了比较。     

数据广播环境下移动实时事务的有效并发控制

在无线数据广播环境下,从移动客户机到数据库服务器的上行带宽非常有限.传统的并发控制协议不适合这种不对称通讯环境.本文结合乐观并发控制协议和时标排序协议提出一种并发控制协议.只读事务满足弱一致性,包含所有更新事务和一个移动只读事务的可串行化图是非循环的.使用本文提出的并发控制协议,移动只读事务能够自主执行,移动更新事务能够较早地检测到数据冲突.模拟试验显示,我们提出的协议相对其它已经存在的并发控制协议来说,能够更好地满足事务截止期.     

基于XML的数据访问组件的研究与实现

提出一个基于XML技术的数据访问接口模型。该模型采用一种高效的线程池结构，利用XML相关技术解决了数据集成过程中涉及的接口定义、数据交换、格式转换、动态验证以及并发等通用性问题。     

设计偶尔连接的智能客户端

目前网络化程度越来越高，但是，在很多情况下我们的客户端应用程序仍然无法获得网络连接．或者需要显示地进行脱机工作。偶尔连接的智能客户端在无法连接到网络资源时，能够让用户继续工作，然后在以后某个时间能够获得网络连接后再同步数据。本文讨论了设计和生成偶尔连接到网络的智能客户端应用程序所面临的问题，以及解决方案。这些解决方案包括网络连接状态的监测、客户端数据的缓存、数据的同步和数据并发处理。     

BlobSeer: Next-generation data management for large scale infrastructures

As data volumes increase at a high speed in more and more application fields of science, engineering, information services, etc., the challenges posed by data-intensive computing gain increasing importance. The emergence of highly scalable infrastructures, e.g. for cloud computing and for petascale computing and beyond, introduces additional issues for which scalable data management becomes an immediate need. This paper makes several contributions. First, it proposes a set of principles for designing highly scalable distributed storage systems that are optimized for heavy data access concurrency. In particular, we highlight the potentially large benefits of using versioning in this context. Second, based on these principles, we propose a set of versioning algorithms, both for data and metadata, that enable a high throughput under concurrency. Finally, we implement and evaluate these algorithms in the BlobSeer prototype, that we integrate as a storage backend in the Hadoop MapReduce framework. We perform extensive microbenchmarks as well as experiments with real MapReduce applications: they demonstrate that applying the principles defended in our approach brings substantial benefits to data intensive applications.     

广播环境中的Q可串行化实时并发控制

研究了实时广播中的数据一致性问题。传统冲突可串行化并发控制协议对非对称通信的广播环境来说过于严格且不必要。为此,提出使用Q可串行化：形式化定义了Q可串行化,证明了它虽比传统冲突可串行化宽松但能始终保证数据一致性,基于可动态调整串行化顺序的时标段排序方法给出了相应的并发控制协议。实验结果表明：新协议可显著降低平均响应时间,使更多移动实时事务满足截止期要求。     

DFL: A Data Flow Language

Many novel computer architectures like array and multiprocessors which achieve high performance through the use of concurrency exploit variations of the von Neumann model of computation. The effective utilization of the machines makes special demands on programmers and their programming languages, such as the structuring of data into vectors or the partitioning of programs into concurrent processes. In comparison, the data flow model of computation demands only that the principle of structured programming be followed. A data flow program, often represented as a data flow graph, is a program that expresses a computation by indicating the data dependencies among operators. A data flow computer is a machine designed to take advantage of concurrency in data flow graphs by executing data independent operations in parallel. In this paper, we discuss the design of a high level language (DFL: Data Flow Language) suitable for data flow computers. Some sample procedures in DFL are presented. The implementation aspects have not been discussed in detail since there are no new problems encountered. The language DFL embodies the concepts of functional programming, but in appearance closely resembles Pascal. The language is a better vehicle than the data flow graph for expressing a parallel algorithm. The compiler has been implemented on a DEC 1090 system in Pascal.     

数据驱动的批作业执行自动机模型

模块化的状态自动机实现了作业的执行。以数据库为中心的配置信息存储与模块间参数传递,构建了整个系统的接口与框架。基于临界区的代理事件处理模型实现了数据流驱动。系统支持并发、流水,易于扩展。     

Stores clustering using a data mining approach for distributing automotive spare-parts to reduce transportation costs

Clustering of retail stores in a distribution network with specific geographical limits plays an important and effective role in distribution and transportation costs reduction. In this paper, the relevant data and information for an established automotive spare-parts distribution and after-sales services company (ISACO) for a 3-year period have been analyzed. With respect to the diversity and lot size of the available information such as stores location, order, goods, transportation vehicles and road and traffic information, three effecting factors with specific weights have been defined for the similarity function: 1. Euclidean distance, 2. Lot size 3. Order concurrency. Based on these three factors, the similarity function has been examined through 5 steps using the Association Rules principles, where the clustering of the stores is performed using k-means algorithm and similar stores are allocated to the clusters. These steps include: 1. Similarity function based on the Euclidean distances, 2. Similarity function based on the order concurrency, 3. Similarity function based on the combination of the order concurrency and lot size, 4. Similarity function based on the combination of these three factors and 5. Improved similarity function. The above mentioned clustering operation for each 5 cases addressed in data mining have been carried out using R software and the improved combinational function has been chosen as the optimal clustering function. Then, trend of each retail store have been analyzed using the improved combinational function and along with determining the priority of the depot center establishment for every cluster, the appropriate distribution policies have been formulated for every cluster. The obtained results of this study indicate a significant cost reduction (32%) in automotive spare-parts distribution and transportation costs.     

TDMA scheduling for event-triggered data aggregation in irregular wireless sensor networks

Multi-hop wireless sensor networks often use a TDMA schedule to collect data periodically from multiple locations within a large area. If the measurements from neighboring sensors are cross-correlated, they can be aggregated and compressed as they travel to the data sink. In order for data aggregation to occur quickly, the TDMA schedule must arrange time slot assignments in a certain order. The existing scheduling protocols cannot quickly obtain a schedule with this order, high concurrency, and no collisions. We propose a distributed TDMA scheduling protocol for data aggregation called DATP. In DATP, the sensor nodes transmit dummy packets in order to determine whether they can tolerate the interference from the other nodes that are assigned the same time slot. In this way, time slot allocations are empirically verified to be collision-free. In contrast, the existing protocols obtain schedules with collisions because they use unrealistic interference models such as neglecting interference generated more than two hops away. Furthermore, our simulations reveal that DATP achieves similar concurrency and lower execution time than comparable protocols. These simulations are executed for different network sizes, node densities, and data compression models. In addition, we show that, in networks with fluctuating links, DATP’s main advantage is its execution speed.     

Alternation and Bounded Concurrency Are Reverse Equivalent

Numerous models of concurrency have been considered in the framework of automata. Among the more interesting concurrency models are classical nondeterminism and pure concurrency, the two facets of alternation, and the bounded concurrency model. Bounded concurrency was previously considered to be similar to nondeterminism and pure concurrency in the sense of the succinctness of automata augmented with these features. In this paper we show that, when viewed more broadly, the power (of succinctness) of bounded concurrency is in fact most similar to the power of alternation. Our contribution is that, just like nondeterminism and pure concurrency are “complement equivalent,” bounded concurrency and alternation are “reverse equivalent” over finite automata. The reverse equivalence is expressed by the existence of polynomial transformations, in both directions, between bounded concurrency and alternation for the reverse of the language accepted by the other. It follows, that bounded concurrency is double-exponentially more succinct than DFAs with respect to reverse, while alternation only saves one exponent. This is as opposed to the direct case where alternation saves two exponents and bounded concurrency saves only one. An immediate corollary is that for languages over a one-letter alphabet, bounded concurrency and alternation are equivalent. We complete the picture of succinctness results for these languages by considering the different combinations of the concurrency models using additional lower bounds.