A nonblocking quorum consensus protocol for replicated data

A nonblocking quorum protocol for replica control which guarantees one-copy serializability is developed. The effects of a nonblocking protocol are analyzed, and it is shown that the gains can be substantial under certain conditions. It is demonstrated that in order for the protocol to be useful, it must be integrated with a propagation mechanism. It is also shown that the access latency can be reduced significantly in a replicated environment. An interesting aspect of the quorum protocol is that it essentially uses a read quorom/write-quorom approach for concurrency control but uses a read-one/write-all approach for replica control. It is shown that the nonblocking quorom protocol provides the same level of availability and fault tolerance as the quorum protocol proposed by D.K. Gifford (1979)     

A model of transaction blocking in databases

A simple analytic queueing model of software resource sharing in a multiprogramming environment is presented. Implicit algebraic equations for steady state mean waiting times at the various queues are developed. These equations may be solved by simple fixed point iteration. It is shown that a solution always exists and that under non-restrictive conditions the simple iteration does converge. An easily applied test for uniqueness of solution is given. Tables of results and comparison with simulation solutions are included.     

A graph grammar approach to geographical databases

This paper treats the modeling of an important class of databases, i.e. geographical databases, with emphasis on both structural (data definition) and behavioral (data manipulation) aspects. Geometric objects such as polygons, line segments, and points may have different relations among each other (such as order, adjacency, connectivity) and can be represented in a uniform spatial data structure (structure graph). The dynamic behavior is defined by a finite set of consistency-preserving state transitions (productions) where coincidence problems as well as topological properties have to be solved. Moreover, the graph grammar approach can be used to study the synchronization of several concurrent productions (Church-Rosser properties) and offers a framework for implementing a geographical database.     

Mining interesting association rules from customer databases and transaction databases

In this paper, we examine a new data mining issue of mining association rules from customer databases and transaction databases. The problem is decomposed into two subproblems: identifying all the large itemsets from the transaction database and mining association rules from the customer database and the large itemsets identified. For the first subproblem, we propose an efficient algorithm to discover all the large itemsets from the transaction database. Experimental results show that by our approach, the total execution time can be reduced significantly. For the second subproblem, a relationship graph is constructed according to the identified large itemsets from the transaction database and the priorities of condition attributes from the customer database. Based on the relationship graph, we present an efficient graph-based algorithm to discover interesting association rules embedded in the transaction database and the customer database.     

GraphLMI: A data driven system for exploring labor market information through graph databases

Multimedia Tools and Applications - Labor Market Intelligence (LMI) is an emerging field of study that has been gaining interest as it allows employing Artificial Intelligence (AI) algorithms on...     

Portable security transaction protocol

The Portal Security Transaction Protocol (PSTP) is a new signature technology that adds signature semantics to one-time password technology. PSTP was developed to secure transactions in the financial services industry; however, PSTP may be applicable to signatures in other spaces. PSTP technology provides high signature strength of mechanism without requiring asymmetric key pairs deployed to client machines. PSTP provides cryptographic after-the-fact evidence of a transaction event in a secured log.     

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。     

基于全局时标的网格事务并发机制研究

针对现有网格数据库事务并发控制协议存在的问题,提出了一种基于全局时标的网格事务并发控制协议。该协议引入全时序的概念,将网格事务在全局层面上进行了排序,实现了网格事务并发执行的可串行化。通过网格事务可串行化定理对所提出的协议进行可串行化证明,并对协议及算法的性能进行了实验测试。实验结果表明,提出的协议是可行和有效的,相对于传统的基于时标的并发控制协议具有一定的优越性。     

Coordinator log transaction execution protocol

The coordinator log transaction execution protocol proposed in this paper centralizes logging on a per transaction basis and exploits piggybacking to provide the semantics of a distributed atomic commit at a minimal cost. The protocol eliminates two rounds of messages (one phase) from the presumed commit protocol and dramatically reduces the number of log forces needed for distributed atomic commit. We compare the coordinator log transaction execution protocol to existing protocols, explain when it is desirable, and discuss how it affects the write ahead log protocol and the database crash recovery algorithm. Recommended by: Tamer Ozsu     

A graph grammars based framework for querying graph-like data

The widespread use of graph-based models for representing data collections (e.g. object-oriented data, XML data, etc.) has stimulated the database research community to investigate the problem of defining declarative languages for querying graph-like databases. In this paper, a new framework for querying graph-like data based on graph grammars is proposed. The new paradigm allows us to verify structural properties of graphs and to extract sub-graphs. More specifically, a new form of query (namely graph query) is proposed, consisting in a particular graph grammar which defines a class of graphs to be matched on the graph representing the database. Thus, differently from path queries, the answer of a graph query is not just a set of nodes, but a subgraph, extracted from the input graph, which satisfies the structural properties defined by the graph grammar. Expressiveness and complexity of different forms of graph queries are discussed, and some practical applications are shown.     

A nonrestrictive concurrency control protocol for object-oriented databases

We propose an algorithm for executing transactions in object-oriented databases. The object-oriented database model generalizes the classical model of database concurrency control by permitting accesses toclass andinstance objects, by permittingarbitrary operations on objects as opposed to traditional read and write operations, and by allowingnested execution of transactions on objects. In this paper, we first develop a uniform methodology for treating both classes and instances. We then develop a two-phase locking protocol with a new relationship between locks calledordered sharing for an object-oriented database. Ordered sharing does not restrict the execution of conflicting operations. Finally, we extend the protocol to handle objects that execute methods on other objects thus resulting in the nested execution of transactions. The resulting protocol permits more concurrency than other known locking-based protocols.     

A reversible data hiding scheme based on graph neighbourhood degree

Abstract

The perceptibility and capacity are two vital criteria of data hiding scheme. Concerning these criteria, data hiding algorithm used images as cover object based on the graph theory is proposed in this study. Images are quantised according to determined range and then quantised images are divided into n × n sized blocks. Each block is accepted as a graph and vertexes which have the same quantisation value are accepted as neighbours. Neighbourhood degrees of vertexes are calculated and indices of vertexes that have a neighbourhood degree over the threshold value are stored in the codebook. Pixel values indicated by these indices in the codebook are used for data hiding process. In this algorithm, there is no need for edge extraction because of hiding data to pixels containing vertexes having high neighbourhood degrees. The proposed method is compared with similar methods in literature in terms of the perceptibility and capacity. More successful results are provided than the others.     

一种基于RSA签名的公平交换协议的算法设计

公平性是电子商务协议的基本安全要求。在电子商务活动中,进行实时公平的文件交换具有非常重要的意义。本文利用证书机制、应用公钥密码体制RSA的加密算法和数字签名技术,设计了一种新的公平交换协议。这种算法简单、高效、易于实现。     

Inexact graph matching based on kernels for object retrieval in image databases

In the framework of online object retrieval with learning, we address the problem of graph matching using kernel functions. An image is represented by a graph of regions where the edges represent the spatial relationships. Kernels on graphs are built from kernel on walks in the graph. This paper firstly proposes new kernels on graphs and on walks, which are very efficient for graphs of regions. Secondly we propose fast solutions for exact or approximate computation of these kernels. Thirdly we show results for the retrieval of images containing a specific object with the help of very few examples and counter-examples in the framework of an active retrieval scheme.     

基于依赖图的信息流图构建方法*

信息流分析法是一种有效的隐通道搜索方法,用信息流图来描述系统中信息流的流动情况。直接基于系统源代码生成系统信息流图,由于信息流的传递关系,会引进大量系统中不存在的信息流路径。利用程序依赖图先处理系统信息流中的传递关系,然后再进行信息流图的生成,从而减少引入系统中不存在的信息流路径,减少信息流分析时的工作量。     

Compound graph based hybrid data center topologies

In large-scale data centers, many servers are interconnected via a dedicated networking structure, so as to satisfy specific design goals, such as the low equipment cost, the high network capacity, and the incremental expansion. The topological properties of a networking structure are critical factors that dominate the performance of the entire data center. The existing networking structures are either fully random or completely structured. Although such networking structures exhibit advantages on given aspects, they suffer obvious shortcomings in other essential fields. In this paper, we aim to design a hybrid topology, called R3, which is the compound graph of structured and random topology. It employs random regular graph as a unit cluster and connects many such clusters by means of a structured topology, i.e., the generalized hypercube. Consequently, the hybrid topology combines the advantages of structured as well as random topologies seamlessly. Meanwhile, a coloring-based algorithm is proposed for R3 to enable fast and accurate routing. R3 possesses many attractive characteristics, such as the modularity and expansibility at the cost of only increasing the degree of any node by one. Comprehensive evaluation results show that our hybrid topology possesses excellent topology properties and network performance.     

A high concurrency XPath-based locking protocol for XML databases

Providing efficient access to XML documents becomes crucial in XML database systems. More and more concurrency control protocols for XML database systems were proposed in the past few years. Being an important language for addressing data in XML documents, XPath expressions are the basis of several query languages, such as XQurey and XSLT. In this paper, we propose a lock-based concurrency control protocol, called XLP, for transactions accessing XML data by the XPath model. XLP is based on the XPath model and has the features of rich lock modes, low lock conflict and lock conversion. XLP is also proved to ensure conflict serializability. In sum, there are three major contributions in this paper. The proposed XLP supports most XPath axes, rather than simple path expressions only. Conflict conditions and rules in the XPath model are analyzed and derived. Moreover, a lightweighted lock mode, P-lock, is invented and integrated into XLP for better concurrency.     

A scene graph based visualization method for representing continuous simulation data

This paper proposes a scene graph based visualization method that can verify time-varying continuous analysis simulation in a virtual reality (VR) environment by using the computer-aided engineering (CAE) data of structural analysis in product development. In previous research, the use of CAE analysis data has been problematic because of the lack of any interactive simulation controls for visualizing continuous simulation data. Moreover, the research on post-processing methods for real-time evaluation of CAE analysis data has not been sufficient. We therefore propose a scene graph based visualization method for representing continuous simulation data. The method can continuously visualize static analysis data independently of any timeline; it can also continuously visualize dynamic analysis data that varies in relation to the timeline. The visualization system for continuous simulation data, which includes CAE2VR Middleware that interfaces with various formats of CAE analysis data as well as functions for visualizing continuous simulation data and operational functions, enables users to verify simulation results with more realistic scenes.     

A customer-oriented organisational diagnostic model based on data mining of customer-complaint databases

The purpose of this paper is to develop a customer-oriented organisational diagnostic model, ‘PARA’ model, based on data mining of customer-complaint databases. The proposed ‘PARA’ model, which is designed to diagnose and correct service failures, takes its name from the initial letters of the four analytical stages of the model: (i) ‘primary diagnosis’; (ii) ‘advanced diagnosis’; (iii) ‘review’; and (iv) ‘action’. In the primary-diagnosis stage, the customer-complaint database is comprehensively analysed to identify themes and categories of complaints. In the advanced-diagnosis stage, a data-mining technique is employed to investigate the relationship between the categories of customer complaints and the deficiencies of the service system. In the review stage, the identified weaknesses of the service system are reviewed and awareness of these weaknesses is enhanced among the organisation’s employees. In the action stage, a strategy of action plans for improvement is developed. An empirical case study is conducted to demonstrate the practical efficacy of the ‘PARA’ model. The paper concludes by summarising the advantages of the proposed model and the implications for future research.     

基于邻节点和关系模型优化的网络表示学习

随着图表示学习在多个领域的成功应用,针对不同图数据和问题而设计的图表示学习方法爆发式增长. 然而,图噪声的存在限制了图表示学习的能力. 为有效降低图网络中的噪声比例,首先分析了图节点局部邻接的分布特性,并理论证明在局部邻接拓扑构建时,探索高阶邻近信息能够优化增强图表示学习的性能. 其次,提出“2步骤”局部子图优化策略（local subgraph optimization strategy,LSOS）. 该策略首先根据原始图拓扑结构信息构造出具有多阶信息的局部邻接相似矩阵. 然后基于相似矩阵和图节点局部信息,对图节点进行局部子图的结构优化. 通过局部邻接的合理重构来降低网络中的噪声比例,进而达到图表示学习能力的增强. 在节点分类、链接预测和社区发现3类任务的实验中,结果表明局部子图优化策略能够提升8个基线算法的性能. 其中,在3个航空网络的节点分类任务中,提升效果最高分别达到23.11%,41.58%,24.16%.