基于对象存储的新型元数据管理策略

在对已有对象存储元数据管理策略进行研究的基础上,提出一种基于对象存储的新型元数据管理策略。该策略将命名空间的目录子树分割为等粒度的中子树,将中子树的根目录名和文件名的组合作为哈希参数进行哈希运算,元数据服务器根据其所得哈希值确定存储路径。实验结果表明,该策略在处理元数据重命名操作和修改文件名时,可以避免大量元数据迁移及网络开销问题。     

Incentivized provision of metadata, semantic reasoning and time-driven filtering: Making a puzzle of personalized e-commerce

e-Commerce recommender systems select potentially interesting products for users by looking at their purchase histories and preferences. In order to compare the available products against those included in the user’s profile, semantics-based recommendation strategies consider metadata annotations that describe their main attributes. Besides, to ensure successful suggestions of products, these strategies adapt the recommendations as the user’s preferences evolve over time. Traditional approaches face two limitations related to the aforementioned features. First, product providers are not typically willing to take on the tedious task of annotating accurately a huge diversity of commercial items, thus leading to a substantial impoverishment of the personalization quality. Second, the adaptation process of the recommendations misses the time elapsed since the user has bought an item, which is an essential parameter that affects differently to each purchased product. This results in some pointless recommendations, e.g. including regularly items that the users are only willing to buy sporadically. In order to fight both limitations, we propose a personalized e-commerce system with two main features. On the one hand, we incentivize the users to provide high-quality metadata for commercial products; on the other, we explore a strategy that offers time-aware recommendations by combining semantic reasoning about these annotations with item-specific time functions. The synergetic effects derived from this combination lead to suggestions adapted to the particular needs of the users at any time. This approach has been experimentally validated with a set of users who accessed our personalized e-commerce system through a range of fixed and handheld consumer devices.     

Providing access to satellite imagery through OGC catalog service interfaces in support of the Global Earth Observation System of Systems

The Global Earth Observation System of Systems (GEOSS) architecture requires supporting discovery and access to large volumes of Earth Observation data. To support this application requirement in a polar ecosystem scenario, the project constructed a metadata catalog service for pre-collected orthorectified Landsat satellite images with global coverage. This study investigates the characteristics and challenges in building Open Geospatial Consortium Inc. (OGC) catalog service. It further presents a general lightweight XML adapter for relational tables, followed by a general OGC catalog service solution based on this adapter. This adapter relies on two configuration files to make the core software modules independent of the underlying metadata database structure. One configuration file identifies how XML schema is mapped into relational schema, and the other represents the XML output template. At runtime, this adapter internally employs a two-step mechanism: XQuery processing and XML publication. In the XQuery processing step, metadata discovery requests are interpreted, resulting in an SQL query clause. In the XML publication step, this SQL query and other dynamically generated queries are executed to generate the output according to the predefined XML template. Successful application of this OGC catalog service solution in the GEOSS AIP-2 polar ecosystem scenario is presented, followed by an analysis on its advantages and limitations.     

一种定制的、更高效的C++RTTI实现方法

RTTI(Run-Time Type Information,运行时类型识别)是C++等面向对象编程语言的一种重要语言机制。目前流行的C++编译器中的RTTI实现机制在应用中存在一些不足,主要体现在动态类型转换操作的低效率和RTTI实现机制的不可定制性。本文通过分析研究标准C++的RTTI机制,提出一种基于元数据和宏,以可定制和高效率为目标的RTTI实现方法。在文章的最后仿真这种RTTI实现方法,证明其可行性和高效性(仿真数据其效率比为5.8)。     

基于元数据的电子政务发布系统的设计与实现

由于政府各职能部门独立的系统间缺乏统一的规划和标准,使得各部门间大量的异构数据难以共享,导致信息孤岛的产生。为了解决问题的同时有效整合现有资源、减少重复建设、降低政府投资成本,提出使用J2EE技术,基于元数据的电子政务发布系统,该系统有效解决了信息共享与发布难的问题。从总体框架、元数据库的设计出发,对系统的主要模块进行了分析和实现,最后对该系统进行详细深入的讨论。     

一种面向下一代互联网的广域网智能存储系统

广域网智能存储系统针对下一代互联网数据急剧增长、网络资源难以管理和使用的问题,采用多层次、可扩展的分布式存储模式,从改进体系结构着手来提高网络存储系统的性能。其存储管理遵循存储管理计划规范(SMIS),并针对复杂网络环境下的元数据管理和数据传输问题,提出了有效的负载均衡策略和高速安全的存储中间件解决方案,不仅降低了存储管理开销,加快了数据传输速度,同时也实现了命令与数据分流、扩容与增速同步的目标,从而大大提高了整个存储系统的性能。     

System support for exploration and expert feedback in resolving conflicts during integration of metadata

A critical reality in integration is that knowledge obtained from different sources may often be conflicting. Conflict-resolution, whether performed during the design phase or during run-time, can be costly and, if done without a proper understanding of the usage context, can be ineffective. In this paper, we propose a novel exploration and feedback-based approach [FICSR (Pronounced as “fixer”)] to conflict-resolution when integrating metadata from different sources. Rather than relying on purely automated conflict-resolution mechanisms, FICSR brings the domain expert in the conflict-resolution process and informs the integration based on the expert’s feedback. In particular, instead of relying on traditional model based definition of consistency (which, whenever there are conflicts, picks a possible world among many), we introduce a ranked interpretation of the metadata and statements about the metadata. This not only enables FICSR to avoid committing to an interpretation too early, but also helps in achieving a more direct correspondence between the experts’ (subjective) interpretation of the data and the system’s (objective) treatment of the available alternatives. Consequently, the ranked interpretation leads to new opportunities for exploratory feedback for conflict-resolution: within the context of a given statement of interest, (a) a preliminary ranking of candidate matches, representing different resolutions of the conflicts, informs the user about the alternative interpretations of the metadata, while (b) user feedback regarding the preferences among alternatives is exploited to inform the system about the expert’s relevant domain knowledge. The expert’s feedback, then, is used for resolving not only the conflicts among different sources, but also possible mis-alignments due to the initial matching phase. To enable this feedback process, we develop data structures and algorithms for efficient off-line conflict/agreement analysis of the integrated metadata. We also develop algorithms for efficient on-line query processing, candidate result enumeration, validity analysis, and system feedback. The results are brought together and evaluated in the Feedback-based InConSistency Resolution (FICSR) system. This research has been funded with NSF Grant, AOC: Archaeological Data Integration for the Study of Long-Term Human and Social Dynamics, 2007–2009. This work was done while the M. L. Sapino was at ASU for sabbatical.     

Regia: a metadata editor for audiovisual documents

Although the Metadata Editor is an important part of any digital library, it becomes fundamental in the presence of audiovisual content. This is because the metadata produced by automated support tools (such as speech recognizers and shot detection procedures) is error-prone and often needs correction. In addition, scenes are manually annotated. This paper describes Regia, a prototype application for manually editing metadata for audiovisual documents developed in the ECHO project. Regia allows the user to manually edit textual metadata and to hierarchically organize the segmentation of the audiovisual content. An important feature of this metadata editor is that it is not hard-wired with a particular metadata attributes set. To achieve this feature the XML schema of the metadata model is used by the editor as a configuration file.

数据仓库原形系统设计

文章系统地研究了数据仓库的理论体系和设计准则,实际设计完成了一个具体的数据仓库原形系统,并对其总体框架以及关键环节进行了较为详细的探讨和阐述,对推动数据仓库理论的实用化和系统化有一定的借鉴意义.     

一种基于Internet的Web资源获取方法与实现

本文介绍了一个基于 Ｉｎｔｅｒｎｅｔ的 Ｗｅｂ资源获取系统原型,阐述了 Ｗｅｂ的数据 特征及其资源的获取方法,并分析该系统的实现原理和策略。