一个演绎对象数据库SD-DOOD的设计与实现

通过探寻面向对象数据库与知识库技术相结合的途径，研究演绎对象数据库系统实现的关键技术。以基于演绎数据库系统SD-DDBS，设计实现了一个演绎对象数据库系统原型SD-DOOD。系统支持类、类层次、对象、属性、方法、继承和封装等面向对象数据库系统的核心概念，支持演绎对象等演绎数据库的概念，提供了图形用户接口(GUI)，便于用户进行创建、查询等操作。     

An object-based architecture for biomedical expert database systems

Objects play a major role in both database and artificial intelligence research. In this paper, we present a novel architecture for expert database systems that introduces an object-based interface between relational databases and expert systems. We exploit a semantic model of the database structure to map relations automatically into object templates, where each template can be a complex combination of join and projection operations. Moreover, we arrange the templates into object networks that represent different views of the same database. Separate processes instantiate those templates using data from the base relations, cache the resulting instances in main memory, navigate through a given network's objects, and update the database according to changes made at the object layer. In the context of an immunologic-research application, we demonstrate the capabilities of a prototype implementation of the architecture. The resulting model provides enhanced tools for database structuring and manipulation. In addition, this architecture supports efficient bidirectional communication between database and expert systems through the shared object layer.     

Query processing over object views of relational data

This paper presents an approach to object view management for relational databases. Such a view mechanism makes it possible for users to transparently work with data in a relational database as if it was stored in an object-oriented (OO) database. A query against the object view is translated to one or several queries against the relational database. The results of these queries are then processed to form an answer to the initial query. The approach is not restricted to a ‘pure’ object view mechanism for the relational data, since the object view can also store its own data and methods. Therefore it must be possible to process queries that combine local data residing in the object view with data retrieved from the relational database. We discuss the key issues when object views of relational databases are developed, namely: how to map relational structures to sub-type/supertype hierarchies in the view, how to represent relational database access in OO query plans, how to provide the concept of object identity in the view, how to handle the fact that the extension of types in the view depends on the state of the relational database, and how to process and optimize queries against the object view. The results are based on experiences from a running prototype implementation. Edited by: M.T. ?zsu. Received April 12, 1995 / Accepted April 22, 1996     

基于内容的多媒体数据库系统引擎CDB

CDB(Content-based DataBase)是一种基于内容的多媒体数据库引擎，可以嵌入到通用的对象一关系数据库中，使数据库系统综合支持对多媒体数据的常规和基于内容的壹询．本文首先阐述CDB的体系结构，它把信息检索和数据检索结合到数据库中，支持多媒体数据库的基于内容的建立、操纵和维护；然后给出其层次型内容模型，描述多媒体内容的时空结构特征以及信息线索；最后描述用于CDB的基于内容信息检索技术及其设计和实现的用户壹询和操纵接口，包括示例壹询、主观颜色壹询、视频概要和浏览、扩展SQL内容壹询等．     

地理信息系统与数据库结合研究

鉴于地理信息系统需要对外提供灵活高效的地理信息访问途径,因此采用数据库管理地理信息是发展趋势,目前存在关系型,对象-关系型,面向对象型3类数据库产品,在讨论它们与地理信息系统结合可行性的基础上,重点介绍了纯关系模型,空间扩展模型,包装模型3种结合方案,还通过对这3种方案实现原理的分析及其优缺点的比较,指出了各方面的应用前景,并由此归纳出,在GIS与数据库结合中需要注意的问题及解决这些问题的关键技术。     

A framework for object migration in object-oriented databases

This article presents a framework developed for accomodating various object migrations in ‘statically-typed’ object databases. Requirements for supporting object migrations are stipulated, and a conceptual model for describing and facilitating different kinds of migrations is described. Associated issues of controlling such migrations are then addressed, along with an initial investigation on the interence of implied migration paths and the completeness of migration operators. Some guidelines are then given to help users conduct migrations more effectively. An implementation prototype on top of an object-oriented database system was built, which embodies full support of all migration types specified in the migration model.     

DOOL程序语义等价转换为Datalog 程序的转换规则

演绎对象数据库(DOOD)是演绎数据库与面向对象数据库两者优点相结合的产物。笔者设计实现了一个演绎对象数据库系统原型SD-DOOD,它是基于演绎数据库系统SD-DDBS的。然而,它使用的是演绎对象库语言DOOL,而演绎数据库语言是基于Datalog的,因此该文提出了应用一些转换规则来将DOOL程序转换为Datalog,通过规则转换,能求出DOOL程序的最小不动点(即程序值),从而使得系统的查询操作全都由SD-DDBS最终得出结果。文中详细介绍了转换规则的具体内容。     

An expert-system shell using structured knowledge: anobject-oriented approach

An architecture for an expert-system shell that mixes declarative nd procedural knowledge, overcoming a major problem of conventional shells, is presented. The prototype shell uses structured knowledge representations and its built-in database interface not only allows automatic extraction of data from a database management system but also provides a fuzzy database query facility. The shell's object-oriented approach to knowledge representation supports data and knowledge acquisition and management. Another feature is encapsulation which prevents object manipulation except by defined operations. A comparison of representation methods and two case studies showing System X-I's power and flexibility are included     

持久对象框架中基于多级访问模式的对象预取技术研究与实现

在基于关系数据库和对象关系映射的持久对象框架中,对象之间通常通过对象引用和各种集合属性将对象相互关联起来,组合成更为复杂的复合对象。应用程序对这些复合对象的访问则是通过使用这些属性逐个访问成员对象来完成。这种在多个成员对象之间的导航操作导致了客户端和后端数据库系统之间的获取操作大幅度增加,从而导致严重的性能问题。对象预取技术根据某种策略,将应用程序可能访问到的对象成组或批量地预先从数据库中装载到客户端,从而减少了应用程序对后端数据库系统进行查询的次数。本文对现有各种对象预取技术并对其进行分析分类,在此基础上,提出了一种基于多级访问模式的对象预取技术。最后,介绍了该算法在软件构件平台StarC-CM的持久对象框架中的实现。     

The Design, Implementation and Evaluation of an ODMG Compliant, Parallel Object Database Server

This paper describes the design, implementation and evaluation of a parallel object database server. While a number of research groups and companies now provide object database servers designed to run on uniprocessors, there has been surprisingly little work on the exploitation of parallelism to provide scalable performance in Object Database Management Systems (ODBMS). The work described in this paper takes as its starting-point the Object Database Management Group (ODMG) standard for object databases, thereby allowing the project to focus on research into parallelism, rather than on the ODBMS interfaces. The system is designed to run on a distributed memory parallel machine, and the paper describes the key issues and design decisions including: parallel query optimisation and execution, flow control, support for user-defined operations in queries, object distribution, cache management and navigational client access. The work shows that the significant differences between the object and relational database paradigms lead to significant differences in the designs of parallel servers to support these two paradigms. The paper presents an extensive performance analysis of the prototype systems which shows that good performance can be achieved on a cluster of linux PCs.     

多处理机并行主存数据库管理系统PRISMA／DB

ＰＲＩＳＭＡ／ＤＢ是一并行的主存关系数据库管理系统，其设计思想主要有两个：第一，将整个数据库存入主存从而获得高性能；第二，系统使用一种面向对象的程序设计语言以模块方式实现，使得这种灵活的组织结构适应于功能和性能方面的分析和试验。目前其原型系统已实现，运行在一个具有１００个结点的多处理机上。本文将对其设计和实现细节做一初步介绍。     

Lite/2中基于数据同步对象的事务性同步技术

数据同步技术是移动数据库系统中消除移动客户机与数据库服务器之间数据不一致和冲突的主要方法.给出了"小金灵"移动数据库系统Lite/2中所采用的基于数据同步对象的事务性数据同步方法,它能够保持数据的语义一致性.此外,Lite/2将同步失败恢复和队列技术相结合来优化事务性同步过程的总通信代价.实验结果表明,Lite/2中的同步方案是高效合理的.     

MDARTS: a multiprocessor database architecture for hard real-timesystems

Complex real time systems need databases to support concurrent data access and provide well defined interfaces between software modules. However, conventional database systems and prior real time database systems do not provide the performance or predictability needed by high speed, hard real time applications. The authors designed, implemented, and evaluated an object oriented database system called MDARTS (Multiprocessor Database Architecture for Real Time Systems). MDARTS avoids the client server overhead of most prior real time database systems and object oriented, real time systems by moving transaction execution into application tasks. By eliminating these sources of overhead and focusing on basic data management services for control systems (data sharing, serializable transactions, and multiprocessor support), the MDARTS prototype provides hard real time transaction times approximately three orders of magnitude faster than prior real time database systems. MDARTS ensures bounded locking delay by disabling preemption when a transaction is waiting for a lock, and hence, allows for the estimation of worst case transaction execution times. Another contribution of MDARTS is that it supports explicit declarations of real time requirements and semantic constraints within application code. The MDARTS library examines these declarations at application initialization time and attempts to construct objects that are compatible with the requirements. Besides local shared memory transactions with hard real time response time guarantees, MDARTS also supports remote transactions that use remote procedure calls for data access with less stringent timing constraints. The MDARTS prototype is implemented in C++ and it runs on VME based multiprocessors and Sun workstations     

An experimental object-based sharing system for networked databases

An approach and mechanism for the transparent sharing of objects in an environment of interconnected (networked), autonomous database systems is presented. An experimental prototype system has been designed and implemented, and an analysis of its performance conducted. Previous approaches to sharing in this environment typically rely on the use of a global, integrated conceptual database schema; users and applications must pose queries at this new level of abstraction to access remote information. By contrast, our approach provides a mechanism that allows users to import remote objects directly into their local database transparently; access to remote objects is virtually the same as access to local objects. The experimental prototype system that has been designed and implemented is based on the Iris and Omega object-based database management systems; this system supports the sharing of data and meta-data objects (information units) as well as units of behavior. The results of experiments conducted to evaluate the performance of our mechanism demonstrate the feasibility of database transparent object sharing in a federated environment, and provide insight into the performance overhead and tradeoffs involved. Edited by Georges Gardarin. Received October 29, 1992 / Revised May 4, 1994 / Accepted March 1, 1995     

面向对象数据库无缝的C^＋＋应用编程界面

关系数据库与程序设计语言之间的松散耦合存在着编程范型及类型系统两方面的失配，是提高数据库应用软件之质量和生产率的极大障碍，面向对象数据库（ＯＯＤＢ）与程序设计语言（ＰＬ）的无缝结合旨在消除这种失配，本文以面向对象数据库管理系统原型ＯＳＣＡＲ为背景，提出ＯＯＤＢ与ＰＬ无缝结合的基本准则，ＯＯＤＢ无缝Ｃ＾＋＋应用编程界面的对象持久性模型，以及实现ＯＯＤＢ无缝Ｃ＾＋＋应用编程界面的关键技术。     

一种Linux数据库应用定制引擎LADE的设计

针对用户需求变化导致程序代码大量修改这一难题,本文在可视化开发、永久对象及设计模式等技术基础上,采用面向对象的分析设计和实现方法,设计了一个基于Linux平台,由数据库所驱动,可进行简单数据库应用可视化定制以及动态生成的数据库应用定制引擎--LADE(Linux Application Designer Engine),以快速构造可适应用户需求有限变更的原型系统.基于这种设计思路,我们使用Delphi for Linux作为开发工具,对LADE的大部分功能进行了实现.     

View operations on objects with roles for a statically typeddatabase language

To deal with the evolution of data and applications and with the existence of multiple views for the same data, the object data model needs to be extended with two different sets of operations: object extension operations, to allow an object to dynamically change its type; and object viewing operations, to allow an object to be seen as if it had a different structure. Object extension and object viewing operations are related in that they are both identity-preserving operations, but different in that object extension may modify the behavior of the original object while object viewing creates a new view for the original object without modifying its behavior. A set of object viewing operations is defined in the context of a statically and strongly typed database programming language which supports objects with roles, and the relationships with object extension and role mechanisms are discussed. We then show how the object viewing operations can be used to give the semantics of a higher level mechanism to define views for object databases. Examples of the use of these operations are given with reference to the prototype implementation of the language Galileo 97     

Introduction

We describe an SQL relational database schema for representing the objects in HyperCard, along with a technique for automatically populating this schema from a HyperCard stack using the facilities in HyperTalk with calls to the database manager. The standard relational database query language SQL can then be used to perform more general hypertext searches than are possible with the string search feature found in most hypertext browsing environments. Semiautomatic updates of the content of a hypertext are also possible using SQL updates on the object representations in the database to trigger corresponding HyperCard updates on the objects themselves. We describe a prototype implementation and present several example queries and updates to motivate this approach. These techniques, although demonstrated here specifically using HyperCard and Oracle for Macintosh, are generally applicable to a wide range of hypertext systems and relational databases.     

Composition and Retrieval of Visual Information for Video Databases

This paper presents a new visual aggregation model for representing visual information about moving objects in video data. Based on available automatic scene segmentation and object tracking algorithms, the proposed model provides eight operations to calculate object motions at various levels of semantic granularity. It represents trajectory, color and dimensions of a single moving object and the directional and topological relations among multiple objects over a time interval. Each representation of a motion can be normalized to improve computational cost and storage utilization. To facilitate query processing, there are two optimal approximate matching algorithms designed to match time-series visual features of moving objects. Experimental results indicate that the proposed algorithms outperform the conventional subsequence matching methods substantially in the similarity between the two trajectories. Finally, the visual aggregation model is integrated into a relational database system and a prototype content-based video retrieval system has been implemented as well.