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CONSISTENCY AND ORDERABILITY - SEMANTICS-BASED CORRECTNESS CRITERIA FOR databases

ACM TRANSACTIONS ON DATABASE SYSTEMS 1993年第3期18卷 460-486页

作者： AGRAWAL, D ELABBADI, A SINGH, AK Department of Computer Science University of California

The semantics of objects and transactions in database systems are investigated. User-defined predicates called consistency assertions are used to specify user programs. Three new correctness criteria are proposed. The first correctness criterion consistency is based solely on the users' specifications and admits nonserializable executions that are acceptable to the users. Integrity constraints of the database are maintained through consistency assertions. The second correctness criterion orderability is a generalization of view serializability and represents a weak notion of equivalence to a serial schedule. Finally, the third correctness criterion strong orderability is introduced as a generalization of conflict serializability. Unlike consistency, the notions of orderability allow users to operate in isolation as maintenance of the integrity constraints now becomes the responsibility of the database system.

关键词： DESIGN THEORY VERIFICATION CONCURRENCY CONTROL object-oriented databases SEMANTICS SERIALIZABILITY THEORY

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Enhancing OODB semantics to support browsing in an OODB vocabulary representation

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2003年第9期15卷 845-869页

作者： Liu, LM Geller, J Perl, Y New Jersey Inst Technol Dept Comp Sci Newark NJ 07102 USA Chung Yuan Christian Univ Dept Math Appl Chungli Taiwan

In previous work, we have modeled a vocabulary given as a semantic network by an object-oriented database (OODB). The OODB schema thus obtained provides a compact abstract view of the vocabulary. This enables the fast traversal of the vocabulary by a user. In the semantic network vocabulary, the IS-A relationships express the specialization hierarchy. In our OODB modeling of the vocabulary, the SUBCLASS relationship expresses the specialization hierarchy of the classes and supports the inheritance of their properties. A typical IS-A path in the vocabulary has a corresponding shorter SUBCLASS path in the OODB schema. In this paper we expose several cases where the SUBCLASS hierarchy fails to fully correspond to the IS-A hierarchy of the vocabulary. In these cases there exist traversal paths in the semantic network for which there are no corresponding traversal paths in the OODB schema. The reason for this failure is the existence of some IS-A relationships between concepts of two classes, which are not connected by a SUBCLASS relationship. This phenomenon weakens the accuracy of our modeling. To rectify the situation we introduce a new OODB semantic relationship IS-A' to represent the existence of IS-A relationships between concepts of a pair of classes which are not connected via a SUBCLASS relationship. The resulting schema contains both SUBCLASS relationships and IS-A' relationships which completely model the IS-A hierarchy of the vocabulary. We define a mixed-class level traversal path to contain either SUBCLASS or IS-A' relationships. Consequently, each traversal path in the semantic network has a corresponding mixed traversal path in the OODB schema. Hence the introduction of the semantic OODB IS-A' relationship improves the modeling of semantic network vocabularies by OODBs. Copyright (C) 2003 John Wiley Sons, Ltd.

关键词： object-oriented databases object-oriented models object-oriented systems knowledge representation database models vocabulary systems object-oriented hierarchical relationships object-oriented semantic relationships

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All Your Database Are Belong to Us

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COMMUNICATIONS OF THE ACM 2012年第9期55卷 54-60页

作者： Meijer, Erik TUDelft Delft Netherlands

In the big open world of the cloud, highly available distributed objects will rule.

关键词： DATABASE design object-oriented databases object-oriented methods (Computer science) CLOUD computing ABSTRACT data types (Computer science) DATA DEVELOPMENT of application software

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Distributed data integration by object-oriented mediator servers

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2001年第11期13卷 933-953页

作者： Risch, T Josifovski, V Uppsala Univ Dept Informat Sci SE-75120 Uppsala Sweden

Integration of data from autonomous, distributed and heterogeneous data sources poses several technical challenges. This paper overviews the data integration system AMOS II based on the wrapper-mediator approach. AMOS II consists of. (i) a mediator database engine that can process and execute queries over data stored locally and in several external data sources, and (ii) object-oriented (OO) multi-database views for reconciliation of data and schema heterogeneities among sources with various capabilities. The data stored in different types of data sources is translated and integrated using OO mediation primitives, providing the user with a consistent view of the data in all the sources. Through its multi-database facilities many distributed AMOS II systems can interoperate in a federation. Since most data reside in the data sources, and to achieve high performance, the core of the system is a main-memory DBMS having a storage manager, query optimizer, transactions, client-server interface, disk backup, etc. The AMOS II data manager is optimized for main-memory access and is extensible so that new data types and query operators can be added or implemented in some external programming language. The extensibility is essential for providing seamless access to a variety of data sources. Copyright (C) 2001 John Wiley & Sons, Ltd.

关键词： heterogeneous data integration mediator systems distributed databases object-oriented databases

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Incremental computation of complex object queries

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ACM SIGPLAN NOTICES 2001年第11期36卷 156-165页

作者： Nakamura, H IBM Japan Ltd Tokyo Res Lab Yamato Kanagawa 2428502 Japan

The need for incremental algorithms for evaluating database queries is well known, but constructing algorithms that work on object-oriented databases (OODBs) has been difficult. The reason is that OODB query languages involve complex data types including composite objects and nested collections. As a result, existing algorithms have limitations in that the kinds of database updates are restricted, the operations found in many query languages are not supported, or the algorithms axe too complex to be described precisely. We present an incremental computation algorithm that can handle any kind of database updates, can accept any expressions in complex query languages such as OQL, and can be described precisely. By translating primitive values and records into collections, we can reduce all query expressions into ones composed of only one kind of operation, namely comprehension. This makes the problems with incremental computation less complicated and thus allows us to describe the algorithm precisely. Our incremental algorithm consists of two parts: one is to maintain the consistency in each comprehension occurrence and the other is to update the value of an entire expression. The algorithm is so flexible that we can use strict updates, lazy updates, and their combinations. By comparing the performance of applications built with our mechanism and that of equivalent hand written update programs, we show that our incremental algorithm can be implemented efficiently.

关键词： object-oriented databases

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USING AN object-oriented DATABASE SYSTEM TO CONSTRUCT A SPATIAL DATABASE KERNEL FOR GIS APPLICATIONS

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COMPUTING SYSTEMS 1992年第2期7卷 100-121页

作者： CHOI, A LUK, WS SIMON FRASER UNIV SCH COMP SCIBURNABY V5A 1S6BCCANADA

In this Paper we show how a generic object-oriented database system can be extended into some domain-specific object-oriented database systems by building additional software layers on top of it. With each lower layer supporting the constructs and views provided by the upper layers, a high-level interface to the system is provided to the user, without having him/her to know about the details of the underlying database system. Specifically, the design of a spatial database kernel for GIS (Geographic Information System) applications which sits on top of a generic object-oriented database system is presented here. Bi-level data modelling approach is used as a methodology for its design and implementation. This data model consists at the top level the geographic object data model, and the geometric object data model at the bottom level The former consists of geographic objects, semantic spatial functions and non-spatial functions, whereas the geometric object data model consists of geometric objects and geometric functions. Geometric objects (e.g. polygons, lines, points) are the spatial representations of the geographic objects (e.g. countries, roads, rivers). Geometric functions directly support the implementation of the semantic spatial functions of the geographic object data model Furthermore, super-functions can be built using the existing functions in the kernel to build more specialized GIS domain-specific functions. Users can invoke these superfunctions, just like calling any other functions in the kernel, in writing GIS application programs that run on top of the kernel With this extensible set of application-oriented and domain-specific functions, a high-level query language called OFQL or the object-oriented Functional Query Language, is designed to allow user to pose spatial and non-spatial queries of a geographic nature. High-level query Processing and optimization issues, which are among the major concerns in the design of the spatial database kernel, are

关键词： object-oriented databases DATABASE KERNEL GIS APPLICATIONS

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AN object-oriented REPRESENTATION OF STRUCTURED PROCESS MODELS

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COMPUTERS & CHEMICAL ENGINEERING 1992年第suppl.期16卷 S329-S336页

作者： MARQUARDT, W Institut für Systemdynamik und Regelungstechnik Universität Stuttgart Pfaffenwaldring 9 D-7000 Stuttgart 80

Efficient process modeling is a key requirement for widespread use of model-based techniques for process design and operation in an industrial environment. It can only be met by advanced knowledge based software tools to cut down the effort for model development and maintenance. A suitably designed model base providing generic modeling knowledge as well as a validated family of models of varying degree of detail for a certain process is one of the main components of such a modeling system. This contribution focuses on the design of the model base which is treated as a database design problem. Proper process model structuring, formalization of the modeling knowledge by means of an object-oriented data model, and some implementational issues are considered.

关键词： PROCESS MODELING COMPUTER-AIDED MODELING object-oriented DATA MODEL object-oriented databases

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AN object-oriented APPROACH TO TEMPORAL MULTIMEDIA DATA MODELING

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 1995年第11期E78D卷 1477-1487页

作者： MASUNAGA, Y Univ of Library and Information Science Tsukuba-shi Japan

This paper discusses an object-oriented approach to temporal multimedia data modeling in OMEGA;a multimedia database management system under development at the University of Library and Information Science, An object-orientated approach is necessary to integrate various types of heterogeneous multimedia data, but it has become clear that current object-oriented data models are not sufficient to represent multimedia data, particularly when they are temporal. For instance, the current object-oriented data models cannot describe objects whose attribute values change time-dependently. Also, they cannot represent temporal relationships among temporal multimedia objects. We characterize temporal objects as instances of a subclass of class TimeInterval with the temporal attributes and the temporal relationships. This temporal multimedia data model is designed upward compatible with the ODMG-93 standard object model. To organize a temporal multimedia database, a five temporal axes model for representing temporal multimedia objects is also introduced. The five temporal axes - an absolute, an internal, a quasi-, a physical, and a presentation time axis- are necessary to describe time-dependent properties of multimedia objects in modeling, implementing and use. A concrete example of this organization method is also illustrated.

关键词： MULTIMEDIA databases TEMPORAL databases object-oriented databases TEMPORAL objectS SOUND VIDEO TEMPORAL ATTRIBUTES TEMPORAL RELATIONSHIPS DATA MODELING ODMG-93 OMEGA

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Share-kno : Knowledge Sharing Mechanism of the Temporal object System

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Journal of King Saud University - Computer and Information Sciences 1999年 11卷 25-43页

作者： Abad Shah Farshad Fotouhi William Grosky Computer Science Department King Saud University P.O. Box 51178 Riyadh 11543 Saudi Arabia Computer Science Department Wayne State University Detroit Michigan 48202 U.S.A

Temporal object System (TOS) handles the structural and stature changes to an object in a uniform and temporal fashion. The TOS takes a hybrid approach of the class-based and prototype-based approaches in modeling the real-word objects and knowledge sharing among the objects. This hybrid approach makes it flexible than the two approaches, i.e., the class-based approach and the prototype-based approach. In this paper, we propose a model of knowledge sharing mechanism, Share-kno (SK) for object hierarchy of the TOS. We also formally prove that the Share-kno (SK) model encapsulates more knowledge than the inheritance hierarchy and delegation hierarchy models proposed by Stein.

关键词： object-oriented databases Temporal Database Temporal objects Knowledge Sharing Mechanism Inheritance Delegation Modeling

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Ontology of object-oriented database evolution

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COMPUTER SYSTEMS SCIENCE AND ENGINEERING 1999年第6期14卷 371-377页

作者： Hines, ML Univ Missouri Software Architecture Dept Kansas City MO 64110 USA

The need for expanded data representation and semantic capture has resulted in the emergence of object-oriented databases. Representation of relationships beyond inheritance relationships, provision of separate development and working environments, and control of evolution for developing database systems are areas not yet adequately addressed in current object-oriented database research(1). This work defines: a specification hierarchy which provides expanded relationship representation and a separate, yet connected, development environment for database systems;and an ontological system which constrains the migration of classes and relationships from the development environment to the working environment.

关键词： object-oriented databases semantic capture specification hierarchy

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