基于异构集成的元数据及其多表动态查询算法

基于企业内多个分布异构关系数据库的集成需求,设计了一个向上支持集成访问界面,向下表述数据库网络位置、数据模式、数据内容的元数据字典模式。给出了面向集成环境和各异构数据库的通用查询请求表示。基于元数据字典,提出了一种因访问需求变化而引起相关数据库关系表动态变化的动态查询语句构造算法,并对算法进行了论证。     

一种基于元数据的Web通用查询系统(GQS)

提出了一种基于元数据的Web通用查询系统（GQS），GQS引入元数据概念,并结合JDO、Servlet、JSP等技术手段,实现了一些通用性较强的查询模块,同时能够根据查询对象动态生成查询页面元素，此外GQS还扩展了查询定制等功能，相对于传统的查询系统,GQS的功能性、通用性、移植性大幅提高,并且很大程度地降低了系统维护量。     

一种面向SaaS应用多级定制模型的缓存技术研究

对共享架构共享存储的SaaS应用来说,如何实现SaaS应用数据低代价高速查询一直是其中的焦点问题之一.在元数据驱动的SaaS应用多级定制模型中,定制元数据存在层次关系,查询代价较高,普通的数据查询优化机制不足以实现SaaS应用的性能优势.采用元数据传递闭包策略解决该问题,针对多级定制的SaaS应用的特点,提出面向租户的...     

基于XML的地理信息元数据系统

首先对地理信息元数据的内容从不同角度进行了研究：地理信息元数据内容由描述数据自身的元数据信息和描述数据之间关系的元数据信息构成;根据地理信息元数据的规范程度对地理信息元数据进行分类,随规范程度递减分为标准元数据、共识元数据和用户元数据;同时还分析了利用XML来表示地理信息元数据方法．最后,设计了一个基于XML的地理信息元数据系统GeoMeta,对其体系结构和各个部分的功能进行了分析,并详细介绍了基于XML的地理信息元数据存储和查询策略．     

元数据管理系统的设计与实现

大规模并行数值模拟程序通常会被运行十几次甚至上百次,每次运行都会输出几十、上百、甚至上千时间步的数据,每个时间步会产生几十、上百、甚至上千个数据文件.传统的数据管理方法是使用记事本记录数值模拟结果相关的元数据信息,这种方法的缺点是大量的信息需要手工录入,同时也不方便数据查询和共享.元数据管理系统的设计目标是通过自动提取元数据来减少需要录入的元数据信息,通过集成管理与结果数据相关的各种数据来方便数据查询与共享.该系统包含5个组成部分:层次化自描述通用数据存储模型、科学计算元数据、元数据自动提取、对象数据库系统、Web界面元数据管理系统.通过用户试用,验证了元数据管理系统实现了预期的目标.     

基于XML的信息集成虚拟方法研究与应用

在分析XML与信息集成相融合的优势基础上,提出了一种利用元数据支持进行信息集成的框架,利用解析器和Wrapper技术向用户提供统一的查询接口和数据视图,借助于元数据的支持来判断查询操作的有效性.采取Xquery语言对XML文档进行集成操作,利用XSL将查询结果提交给用户浏览,较好地解决了信息集成过程中透明访问、联合查询和数据转换等问题,实现了多个民构数据源的快捷查询和快速结果展现.     

一种基于元数据的分布式数据源定位算法

随着Internet和数字图书馆这两种基础信息资源的大量涌现,用户在检索信息之前,如何选择合适的目标站点来提交查询,从而降低查询代价、提高查询效率,已经成为一个重要任务。这个问题更加一般的说法是“数据源定位”或“数据库发现”。元数据是关于数据的数据,数字图书馆中,每个数据文档由其元数据描述,元数据是数字图书馆管理、检索数据以及在各个层面上实现互操作的重要手段。文章提出了一种基于元数据的数据源发现算法,并在召回率、检索精度等方面对这种算法作了评价。     

基于元数据的通用数据维护框架设计

针对数据维护程序代码重复、对需求变化适应性差等问题,提出一种以数据库表的元数据为核心的通用数据维护框架。该元数据模型能描述表之间的一般关系和基于面向对象的继承关系。框架实现了数据操纵SQL语句和数据维护程序界面的自动生成,并能自适应表结构的变化。实际应用验证了该框架的可行性和高效性。     

BESⅢ分布式计算的元数据管理

北京谱仪III(BESIII)高能物理实验产生PB量级的实验数据,海量数据的处理和分析对计算资源提出较大挑战。分布式计算是整合异构计算资源和解决计算资源短缺的可行方案。根据BESIII实验需求对分布式计算所需的元数据管理进行研究,提出数据文件的元数据模型,利用中间件软件DIRAC的目录服务设计并实现元数据管理系统。该系统利用树型目录结构、物理文件名动态构建和虚拟数据集等技术,组织和存储各种类型的元数据,实现查询请求、逻辑文件以及物理文件之间的映射,使用数字证书和开放安全套接层协议保证系统安全。将该系统应用于实验数据分析和处理中,测试结果表明,当并发用户访问量为300时,查询时间仅为0.3 s,证明该系统性能较好,可以满足BESIII实验的应用需要。     

图书馆元数据信息发布平台及其应用

文中研究了图书馆信息服务。信息服务呈现多元化、个性化的趋势,根据需求定制服务十分重要,图书馆信息可以重复利用是服务定制的保障。提出元数据信息发布平台设计方案,发布平台利用中国机读目录抽取信息,并结合互熵一信息检索方法提高抽取信息的正确性,抽取的信息以元数据形式存储,通过OAI协议发布。给出发布平台的应用实例,说明信息发布平台如何为毕业设计过程管理系统提供数据服务。     

The end of zero-hit queries: query previews for NASA’s Global Change Master Directory

The Human-Computer Interaction Laboratory (HCIL) of the University of Maryland and NASA have collaborated over three years to refine and apply user interface research concepts developed at HCIL in order to improve the usability of NASA data services. The research focused on dynamic query user interfaces, visualization, and overview + preview designs. An operational prototype, using query previews, was implemented with NASA’s Global Change Master Directory (GCMD), a directory service for earth science datasets. Users can see the histogram of the data distribution over several attributes and choose among attribute values. A result bar shows the cardinality of the result set, thereby preventing users from submitting queries that would have zero hits. Our experience confirmed the importance of metadata accuracy and completeness. The query preview interfaces make visible the problems or gaps in the metadata that are undetectable with classic form fill-in interfaces. This could be seen as a problem, but we think that it will have a long-term beneficial effect on the quality of the metadata as data providers will be compelled to produce more complete and accurate metadata. The adaptation of the research prototype to the NASA data required revised data structures and algorithms. Received: 12 December 1997 / Revised: June 1999     

QMDS: a file system metadata management service supporting a graph data model-based query language

File system metadata management has become a bottleneck for many data-intensive applications that rely on high-performance file systems. Part of the bottleneck is due to the limitations of an almost 50-year-old interface standard with metadata abstractions that were designed at a time when high-end file systems managed less than 100 MB. Today's high-performance file systems store 7–9 orders of magnitude more data, resulting in a number of data items for which these metadata abstractions are inadequate, such as directory hierarchies unable to handle complex relationships among data. Users of file systems have attempted to work around these inadequacies by moving application-specific metadata management to relational databases to make metadata searchable. Splitting file system metadata management into two separate systems introduces inefficiencies and systems management problems. To address this problem, we propose QMDS: a file system metadata management service that integrates all file system metadata and uses a graph data model with attributes on nodes and edges. Our service uses a query language interface for file identification and attribute retrieval. We present our metadata management service design and architecture and study its performance using a text analysis benchmark application. Results from our QMDS prototype show the effectiveness of this approach. Compared to the use of a file system and relational database, the QMDS prototype shows superior performance for both ingest and query workloads.     

A Statistical Metadata Model for Simultaneous Manipulation of both Data and Metadata

There is a growing demand for more cost-efficient production processes in Statistical Institutes. One way to address this need is to equip Statistical Information Systems (SIS) with the ability to automatically produce statistical data and metadata of high quality and deliver them to the user via the Internet. Current approaches, although provide for the storage of appropriate metadata, do not use process metadata for guiding the production process. In this paper we present an approach on creating SISs that permits metadata-guided statistical processing based on an object-based, statistical metadata model. The model is not domain specific and can accommodate both microdata and macrodata. We have equipped the model with a set of transformations that can be used to automatically manipulate data and metadata. We show the applicability of transformations with some examples using actual statistical data for R&D expenditures. Finally, we demonstrate how the presented framework can be exploited for the construction of a web site that offers ad hoc query capabilities to the users of statistical data.     

基于用户需求的产品深度个性化定制

为解决现有产品个性化定制中用户需求分析复杂、需求契合度低与用户参与度不 足的问题,提出一种基于用户需求的产品深度个性化定制方法。通过结合用户个性需求表达模 型与质量功能展开(QFD)将用户需求映射为定制需求,运用实例检索与匹配进行产品配置求解。 用户通过可视界面对定制方案进行实时反馈与调整,并结合变型设计加深产品个性化定制程度, 最后通过优度评价将最优方案提供给用户,实现用户高参与度、高满意度的定制。以披肩定制 为例,验证该方法的可行性,为产品深度个性化定制提供了一种有效方法。     

多意象驱动下的产品造型个性化定制系统研究

构建了一种基于多意象驱动下的产品个性化定制系统,增加用户对个性化定制的体验度,从而实现智能的产品个性化定制设计。通过对当下三种产品个性化定制模式的比较研究和分析,提出了个性化定制系统的构架模型和系统流程。然后通过用户参与模式、感性意象挖掘、关联方法建立多意象驱动机制,并结合感性工学的相关研究方法、BP神经网络以及多目标粒子群算法构建了面向产品意象造型的智能设计模型,实现了多意象驱动下的产品造型个性化定制。最后以人形卡通文具的个性化定制进行了实例验证。结果表明多意象驱动的产品造型个性化定制系统更加丰富了消费者对产品造型意象风格的体验,满足了消费者日益迫切的个性化设计需求,符合智能时代对产品设计开发的需要。     

Browsing large online data tables using generalized query previews

Companies, government agencies, and other organizations are making their data available to the world over the Internet. They often use large online relational tables for this purpose. Users query such tables with front-ends that typically use menus or form fillin interfaces, but these interfaces rarely give users information about the contents and distribution of the data. Such a situation leads users to waste time and network/server resources posing queries that have zero- or mega-hit results. Generalized query previews enable efficient browsing of large online data tables by supplying data distribution information to users. The data distribution information provides continuous feedback about the size of the result set as the query is being formed. Our paper presents a new user interface architecture and discusses three controlled experiments (with 12, 16, and 48 participants). Our prototype systems provide flexible user interfaces for research and testing of the ideas. The user studies show that for exploratory querying tasks, generalized query previews can speed user performance for certain user domains and can reduce network/server load.     

A web content manipulation technique based on page Fragmentation

Web portals today offer a variety of content and services to their users. This content can be split into various categories and usually content semantically related is placed in the same area. In this paper, a software technique is presented that allows the viewers of web sites to build their own personalized portals, using specific areas of their preferred sites. This technique saves users’ time and reduces the cost of browsing the web by minimizing the volume of data that has to be downloaded. It is based on an algorithm, which fragments a web page in discrete fragments using the page's internal structure. Users utilize a web interface to define which parts of selected web pages they desire to appear in their personalized portal. No additional software needs to be installed on the users’ personal computers, since this technique is designed to function centrally as a data source for a Web Server. In addition, usage of this technique reduces user perceived latency during browsing sessions, since less data must be transferred to users’ personal computers.