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ALGORITHMS FOR ASYNCHRONOUS PARALLEL-PROCESSING OF object-oriented databases

IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 1995年第3期7卷 487-504页

作者： THAKORE, AK SU, SYW LAM, HX UNIV FLORIDA DEPT ELECT ENGNDEPT COMP & INFORMAT SCICTR DATABASE SYST RES & DEVGAINESVILLEFL 32611

Management of large quantities of complex data is essential in many advanced application areas object-oriented (OO) database management system have been developed to effectively model and process the complex domain knowledge. They have been shown to outperform sam existing relational systems. The existing implementations of OO database management system attempt to improve the efficiency of OO queries by explicitly capturing the relationships among objects. However, the execution of complex queries involving the retrieval of objects from many classes and relationships among them causes the existing system to operate inefficiently. In this paper, we present parallel algorithms for the processing of queries against a large OO database The algorithms are based on a closed model of query processing using pattern-based access instead of the conventional value-based access. During processing, the algorithms avoid the execution of time-consuming join operations by making use of the explicitly stared object associations. Generation of large quantities of temporary data is avoided by marking objects using their identifiers and by employing a two-phase query processing strategy, A query is processed by concurrent multiple waves, thereby improving parallelism and avoiding the complexities introduced in their sequential implementation. The correctness and the performance of the parallel algorithms have been tested and analyzed by running parallel programs on a 32-node Transputer based parallel machine designed and developed at the IBM Research Center at Yorktown Heights, New York Benchmark queries of different semantic complexities are generated, and their performance is analyzed for various data and query parameters.

关键词： ASYNCHRONOUS object-oriented databases PARALLEL ALGORITHMS PERFORMANCE EVALUATION QUERY PROCESSING

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Spatial views and LOD-based access control in VRML-object databases

Spatial views and LOD-based access control in VRML-object da...

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International Conference on Worldwide Computing and Its Applications (WWCA 97)

作者： Kamiura, M Oiso, H Tajima, K Tanaka, K Kobe Univ Grad Sch Sci & Technol Kobe Hyogo 657 Japan Kobe Univ Fac Engn Kobe Hyogo 657 Japan

ISBN: (纸本)354063343X

VRML is a language to describe virtual 3D spaces. In order to achieve reuse and sharing of data described in VRML among multiple applications, we designed and implemented a VRML-object database system. In our system, we can add semantic information onto VRML data, and can issue queries by using that information. We also introduce the concepts of spatial view and level-of-detail based access control. When a user issues a query, the system produces a spatial view by reorganizing a virtual space in accordance with the user's concern and the user's access capability.

关键词： object-oriented databases

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Method transformations for vertical partitioning in parallel and distributed object databases

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3rd International Conference on Parallel Processing, Euro-Par 1997

作者： Chinchwadkar, Gajanan S. Goh, Angela School of Applied Science Nanyang Technological University Singapore 639798 Singapore

ISBN: (纸本)9783540634409

Vertical partitioning is a useful technique for performance improvement in parallel and distributed object oriented database systems (POBSs and DOBSs). Arising from partitioning, there is a need to modify methods in a user defined schema for correct execution in the partitioned domain. A partitioning scheme should also support application transparency in order to make schema definitions and vertical partitioning independent. We have followed an approach of method transformations for dealing with these problems. A complete taxonomy for the method types arising from vertical partitioning of a class is presented with transformations for each of these types. The role of the transformations in determining the cost of methods is also briefly presented.

关键词： object-oriented databases

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Security in Cyberspace: A knowledge-base approach

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DATA & KNOWLEDGE ENGINEERING 1997年第1期24卷 69-96页

作者： vandeRiet, RP Junk, A Gudes, E BEN GURION UNIV NEGEV DEPT MATH & COMP SCI IL-84105 BEER SHEVA ISRAEL

In Cyberspace, realized by the Electronic Super-highway and multimedia techniques, persons will be represented by 'things' (so called 'alter-egos') grown out of the traditional social security numbers. In this paper we will study how the object-oriented methodology can help in designing these inhabitants. By using an interesting example, namely home banking, we will study the problem of security and privacy, in general: access protection, in this world. New in this paper is the combination of Cyberspace, Alter-ego objects representing its inhabitants and protection problems. In particular, we will demonstrate the need for knowledge based capabilities for handling the complex security features which are required in the Cyberspace world.

关键词： security and database systems Cyberspace object-oriented databases active knowledge bases

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The formalisation of ROCK & ROLL: A deductive object-oriented database system

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INFORMATION AND SOFTWARE TECHNOLOGY 1997年第6期39卷 379-389页

作者： Fernandes, AAA Barja, ML Paton, NW Williams, MH HERIOT WATT UNIV DEPT ELECT & COMP ENGN EDINBURGH EH14 4AS MIDLOTHIAN SCOTLAND UNIV MANCHESTER DEPT COMP SCI MANCHESTER M13 9PL LANCS ENGLAND

This paper describes the formalisation of the deductive object-oriented database system ROCK & ROLL, This is a system which integrates the deductive and object-oriented paradigms in a way that is both clean and consistent, and that has a sound theoretical foundation. The system uses a formally defined object-oriented data model as a foundation for both a logic query language and an imperative data manipulation language in such a way that impedance mismatches are minimised. This paper introduces the facilities offered by ROCK & ROLL, and indicates how their formalisation has been achieved. (C) 1997 Elsevier Science B.V.

关键词： deductive databases logic programming object-oriented databases programming language semantics

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object-oriented database schema analysis and inheritance processing: A graph-theoretic approach

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DATA & KNOWLEDGE ENGINEERING 1997年第2期24卷 157-181页

作者： Formica, A Groger, HD Missikoff, M CNR IST ANAL SISTEMI & INFORMATI-00185 ROMEITALY SZECHENYI COLL H-9026 GYORHUNGARY

In this paper we address the inheritance process in the context of strongly typed object-oriented database (OODB) systems, allowing multiple inheritance and overriding. For such powerful systems, it is important to analyse the inheritance hierarchy to identify a number of significant properties. The first, schema consistency, is connected to the inheritance conflicts. In the presence of an unsolvable inheritance conflict there is a contradiction in the schema. The second property is related to the termination of the inheritance process. We expect that all the subtypes in the schema, if consistent, can be rewritten in expanded form, after inheritance, in a finite time. Schemas that guarantee these two formal properties will be referred to as correct schemas. In the paper a graph-theoretic method is provided, aimed at supporting the designer in checking the correctness and deriving the expanded form of a schema. Furthermore, from the analysis of the complexity of the inheritance process, a third formal property has been defined, concerning the degree of compactness achievable in a schema, by using inheritance hierarchies. In particular, a class of schemas has been defined, referred to as logarithmic schemas, whose expanded forms, after inheritance, become exponential in the size of the original schemas.

关键词： object-oriented databases multiple inheritance inheritance process inheritance conflicts recursive schemas schema consistency subtyping substitutivity database design

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Management of multi-structured hypermedia documents: A data model, query language, and indexing scheme

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MULTIMEDIA TOOLS AND APPLICATIONS 1997年第2期4卷 199-223页

作者： Lee, KC Lee, YK Berra, PB KOREA TELECOM RES & DEV GRPSEOUL 137792SOUTH KOREA SYRACUSE UNIV DEPT ELECT ENGN & COMP SCISYRACUSENY 13244

Structured documents have gained popularity with the advent of document structure markup standards such as SGML, ODA, HyTime, and HTML. Document management systems can provide powerful facilities by maintaining the structure information of documents. Since the hypermedia document is also a kind of structured document, we can apply the results of many studies, which have been performed in storing, retrieving, and managing structured documents, to the hypermedia document management. However, more factors should be considered in handling hypermedia documents because they contain multimedia data and also have multiple complex structures such as hyperlink networks and spatial/temporal layout structures as well as logical structures. In this paper, we propose an object-oriented model for multi-structured hypermedia documents and multimedia data, and a query language for retrieving hypermedia document elements based on the content and multiple complex structures. By using unique element identifiers and an indexing scheme which exploits multiple structures, we can process queries efficiently with minimal storage overhead for maintaining structure information.

关键词： structured documents hypertext multimedia object-oriented databases query languages

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CDOL: A comprehensive declarative object language

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DATA & KNOWLEDGE ENGINEERING 1997年第1期22卷 67-111页

作者： Urban, SD Karadimce, AP Dietrich, SW BenAbdellatif, T Chan, HWR Department of Computer Science and Engineering Arizona State University Tempe AZ 85287-5406 USA

In this paper we present a rule-based database language known as CDOL (Comprehensive, Declarative object Language) that is an integration of deductive, object-oriented and active database technology. CDOL provides sublanguages for the expression of derived data, constraints, updates and active rules. The rule-based query language of CDOL provides an expressive approach to extend the stored database with derived attributes and classes. The constraint sublanguage allows explicit declarative specification of integrity constraints as a basis for database consistency. The update sublanguage of CDOL enables ad-hoc declarative update requests, where updates are encapsulated in the methods associated with class definitions, thus conforming to traditional object-oriented design concepts. The active rule sublanguage provides active, user-transparent agents that support reactive behavior within CDOL applications. In particular, active rules can be used to supplement declarative updates to maintain database consistency with respect to the set of integrity constraints. Active rules in general are used to monitor the occurrence of specific events and to serve as alerters and triggers within a CDOL application. This paper presents the rule-based query language of CDOL and illustrates the manner in which the constraint, update and active rule sublanguages build on this declarative framework. The use of methods and transactions are also addressed, together with a discussion of the operational semantics of active rule processing.

关键词： object-oriented databases active rules deductive rules derived data constraints updates rule-based query language

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Implementation of a dynamic scheduler for apparel computer integrated manufacturing systems

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JOURNAL OF INTELLIGENT MANUFACTURING 1997年第2期8卷 67-81页

作者： Gracanin, D Valavanis, KP Smith, SA Williams, T Steward, A Apparel-CIM Center The University of Southwestern Louisiana Lafayette USA

A major problem faced by the typical apparel manufacturer in day-to-day operations is the need for an effective scheduler to determine actions required because of operator and/or machine non-performance. The dynamic resource allocation system (DRAS) scheduler described in this paper is the natural outgrowth of previously funded research related to the design, development, technology transfer and installation of a CIM system in an apparel plant. The already developed CIM system provides a way for the DRAS scheduler (described in this paper) to change a production process dynamically. The implementation and modeling approach of the scheduler is described. The underlying system model is based on Petri nets and object-oriented databases. Petri nets provide a dynamic model of the CIM system, while object-oriented databases provide necessary information about system components and overall system activity. The data from the CIM system is used by the scheduler in the simulation mode. The daily production plan is used as a guideline to determine how to react to and correct production problems.

关键词： computer integrated manufacturing (CIM) scheduling resource allocation Petri nets object-oriented databases

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Adaptive caching and refreshing in mobile databases

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Personal and Ubiquitous Computing 1997年第3期1卷 156-170页

作者： Si, Antonio Leong, Hong Va Department of Computing Hong Kong Polytechnic University Hung Horn Kowtoom Hong Kong

The mobile computing environment is receiving increasing attention recently. We consider a mobile environment in which a collection of mobile clients accesses a stationary database server via a wireless channel. Due to the limited bandwidth of a wireless channel and the instability of the wireless network, caching of frequently accessed data items in a client's local storage becomes especially important for improving the performance and data availability of data access queries. In this paper, we discuss the limitations of existing caching mechanisms in a mobile environment and investigate issues that need to be addressed. We propose an adaptive caching model that could cope with the nature of a mobile environment and the low-bandwidth wireless media, supporting fast data access. We describe the adaptive cache replacement and refresh mechanisms;explain the implementation in the context of object-oriented databases;and illustrate the results of some exploratory experiments to demonstrate the feasibility of the mechanisms. © Springer-Verlag London Ltd.

关键词： object-oriented databases

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