公共数据安全访问模型CDSA

本文提出了一个能够保持数据访问一致性的模型CDSA,给出了本机进程间、远程进程间安全访问公用数据的方法。     

安全访问外包数据的研究

在存储外包应用中,无关RAM允许客户对不信任服务器隐藏数据存储模式。提出一种新的无关RAM结构,对客户的每个请求仅需常量级代价和少量客户端存储空间即可实现无关访问。     

C#程序与基于COM的OPC数据存取服务器交换数据研究

研究了OPC NET COM自动化包装器所封装的COM编排技术和OPC NET应用程序接口内的设计模式。在其基础上使用C#语言编写了一个基于．NET的OPC客户程序，与基于COM的OPC数据存取服务器交换数据。有效地实现了将遵循OPC规范的代码从COM平台移植到．NET平台。     

Data access in distributed data base management systems

A software organization which provides for data definition and manipulation in a distributed data base system is presented by describing the functions and interrelations of the component processes; with its methodology for access, the physical location of the data is transparent to the user program. The concepts of distributed data bases are discussed and current research is summarized as a means of establishing a method for the data placement and location mechanism. Procedures for the movement of data in a distributed data base system are presented, along with the data manipulation procedures, in terms of their performance and integrity effects. Enhancements to the mechanisms are suggested.     

XML/Java技术实现Oracle数据远程访问的探讨

随着Internet的飞速发展,信息共享和数据交换日显重要,而XML技术与Java技术的结合为这一应用需求提供了极佳的解决手段。在对XML技术与Java技术特点以及二者结合的优势进行了详细阐述的基础上,给出了一个针对Oracle数据库的具体数据远程访问的实例。     

一种基于角色和数据项的访问控制方式

当今社会,随着信息和通信技术的飞速发展,数字信息正在被广泛使用,为了进行数据分析以支撑基于信息的决策,政府、社会机构、公司和个人都可能会收集一些涉及个人的信息数据,然而伴随着大数据资源的正在进行越来越广泛的整合、分析和利用,使得数据治理问题,特别是数据隐私保护问题也越来越被人们重视,成为大数据研究的一个重点。本文针对如何保证数据资源在使用过程中的安全访问控制问题,在主流的基于角色的访问控制方式的思路之上进行了扩展,提出了一种基于角色和数据项的访问控制方式,即在数据库中增加角色对数据表中每一项的访问权限表。实践结果表明,与目前主流的几种访问控制模式相比,实现了对数据的精细化管理,对不同角色的用户访问实现了数据可控,对大数据环境下信息系统的数据隐私保护具有一定的指导意义。     

定位数据访问框架的设计与实现

目前定位应用访问定位数据的方法常和特定的技术绑定在一起,这种相关性限制了应用向新技术的移植,也将最终用户绑定在了特定的设备上.通过对现存的定位技术方案的研究,抽象出了通用的定位数据访问模型,根据模型给出了定位数据访问框架的体系结构和实现方法.框架对定位应用屏蔽各种定位数据访问的细节和定位数据接收终端硬件的差异,为定位应用提供个一个与平台、技术体制和设备独立的定位数据访问接口.     

基于.NET的通用数据访问类

为提高数据库应用程序的设计效率,基于VS．NET开发平台,利用ADO．NET的强大数据访问功能,设计了一个适应访问不同数据库且具备基本数据访问应用功能的基类。介绍了ADO．NET技术和在设计中涉及的相关概念以及设计的思路和方法,利用此基类的派生类可方便地实现多种功能的数据访问。     

基于ADO.NET的数据访问层设计

对基于ADO.NET的数据访问层设计进行探讨,提出一种多层次的、灵活可靠的设计方案,并结合实际应用介绍方案的实现及应用方式.     

Computing complete answers to queries in the presence of limited access patterns

In data applications such as information integration, there can be limited access patterns to relations, i.e., binding patterns require values to be specified for certain attributes in order to retrieve data from a relation. As a consequence, we cannot retrieve all tuples from these relations. In this article we study the problem of computing the complete answer to a query, i.e., the answer that could be computed if all the tuples could be retrieved. A query is stable if for any instance of the relations in the query, its complete answer can be computed using the access patterns permitted by the relations. We study the problem of testing stability of various classes of queries, including conjunctive queries, unions of conjunctive queries, and conjunctive queries with arithmetic comparisons. We give algorithms and complexity results for these classes of queries. We show that stability of datalog programs is undecidable, and give a sufficient condition for stability of datalog queries. Finally, we study data-dependent computability of the complete answer to a nonstable query, and propose a decision tree for guiding the process to compute the complete answer.Received: 6 December 2001, Accepted: 25 November 2002, Published online: 3 April 2003Chen Li: This article combines and integrates some content in the technical report at Stanford University [25] and the paper presented in the 8th International Conference on Database Theory (ICDT), London, UK, January, 2001 [28]. In addition to the prior materials, this article contains more results and complete proofs that were not included in the original reports.     

基于设计模式构建数据访问中间件

设计了一种两层的数据访问结构,第一层是介于数据访问层和用户之间的中间层,主要是组织数据和调用数据访问中间件;第二层是数据访问中间件,主要是同数据库交互.在设计数据访问中间件时,根据设计模式的概念,对访问数据层模式进行了比较,指出了各个类的作用、相互的关系以及如何对这个类进行扩展,最后构建出中间件.     

An ontology-based framework to support intelligent data analysis of sensor measurements

In the past years, the large availability of sensed data highlighted the need of computer-aided systems that perform intelligent data analysis (IDA) over the obtained data streams. Temporal abstractions (TAs) are key to interpret the principle encoded within the data, but their usefulness depends on an efficient management of domain knowledge. In this article, an ontology-based framework for IDA is presented. It is based on a knowledge model composed by two existing ontologies (Semantic Sensor Network ontology (SSN), SWRL Temporal Ontology (SWRLTO)) and a new developed one: the Temporal Abstractions Ontology (TAO). SSN conceptualizes sensor measurements, thus enabling a full integration with semantic sensor web (SSW) technologies. SWRLTO provides temporal modeling and reasoning. TAO has been designed to capture the semantic of TAs. These ontologies have been aligned through DOLCE Ultra-Lite (DUL) upper ontology, boosting the integration with other domains. The resulting knowledge model has a modular design that facilitates the integration, exchange and reuse of its constitutive parts. The framework is sketched in a chemical plant case study. It is shown how complex temporal patterns that combine several variables and representation schemes can be used to infer process states and/or conditions.     

数据访问对象模式在企业应用集成中的应用

在提出企业应用集成（EAI）在面对异构数据源集成和整合所出现的问题的基础上,提出以J2EE设计模式中的数据访问对象（DAO）模式来解决该问题的方法,并结合对DAO设计模式的实现,详细讨论了在EAI中应用DAO设计模式对提高系统重用性、灵活性,维护整个系统架构稳定性所起的作用。     

基于EPON技术的矿用综合数据接入网关设计

针对煤矿监测监控系统数据接口众多,无法实现数据的统一通信和共享的现状,结合EPON技术的优势,设计了一种基于EPON技术的矿用综合数据接入网关。该网关可实现煤矿井下不同接口数据的综合接入和不同系统之间的数据共享。井下实际测试结果表明,该网关主干网络通信速率达到了750Mbit/s,主干网络传输距离达15km,线路冗余切换时间小于100ms。     

OPC数据访问服务器的研究与实现

首先介绍了OPC(OLE for processcontrol)及其相关技术,提出了OPC数据访问服务器的组成模型。在分析OPC数据访问服务器两种开发模式的基础上,给出了以WTOPCSvr.DLL工具包为平台,使用工具开发模式实现其开发的主要步骤。重点阐述了基于PA150通信协议,OPC数据访问服务器中硬件驱动通信模块采用串口编程方式实现的方法,并给出了通信两端的主要配置过程,基于该方法和过程的OPC数据访问服务器已成功应用在某煤矿的计算机监控系统中,取得了良好的效果。     

OPC-SMS: a wireless gateway to OPC-based data sources

This paper describes OPC-SMS gateway, a platform that integrates IP networks with the Short Message Service (SMS), in order to deliver an integrated service for access to data sources conforming to Object Linking and Embedding for Process Control (OPC) standard specifications, through SMS-enabled mobile devices. The gateway supports pull and push services in order to support both request-based and alarm/scheduled-based notifications, respectively. The proposed architecture is based entirely on the ubiquitous HyperText Transport Protocol (HTTP), Simple Object Access Protocol (SOAP), Extensible Markup Language (XML) protocols, and the Global System for Mobile communication (GSM) network and thus exploits the network infrastructure already in place. The capability of accessing different types of OPC data sources (real-time and historical) by any SMS-enabled device consists of a highly flexible service, supporting mobility and event-based notification. A pilot implementation of our approach has been tested in a large-scale installation for accessing OPC data sources of several automation subsystems in a hospital.     

Using multiple data sources to get closer insights into user cost and task performance

This pilot study explores the use of combining multiple data sources (subjective, physical, physiological, and eye tracking) in understanding user cost and behavior. Specifically, we show the efficacy of such objective measurements as heart rate variability (HRV), and pupillary response in evaluating user cost in game environments, along with subjective techniques, and investigate eye and hand behavior at various levels of user cost. In addition, a method for evaluating task performance at the micro-level is developed by combining eye and hand data. Four findings indicate the great potential value of combining multiple data sources to evaluate interaction: first, spectral analysis of HRV in the low frequency band shows significant sensitivity to changes in user cost, modulated by game difficulty—the result is consistent with subjective ratings, but pupillary response fails to accord with user cost in this game environment; second, eye saccades seem to be more sensitive to user cost changes than eye fixation number and duration, or scanpath length; third, a composite index based on eye and hand movements is developed, and it shows more sensitivity to user cost changes than a single eye or hand measurement; finally, timeline analysis of the ratio of eye fixations to mouse clicks demonstrates task performance changes and learning effects over time. We conclude that combining multiple data sources has a valuable role in human–computer interaction (HCI) evaluation and design.     

Performance analysis of customer access to an ISDN

A simple analytical model has been developed to quantify the performance encountered by voice and data traffic during customer access to an ISDN. This enables a direct comparison of traffic capabilities of various proposed implementation schemes currently under consideration by telecommunications administrations.