In this paper we investigate some issues arising from the introduction of multiple temporal granularities in an object-oriented data model. Although issues concerning temporal granularities have been investigated in t...
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In this paper we investigate some issues arising from the introduction of multiple temporal granularities in an object-oriented data model. Although issues concerning temporal granularities have been investigated in the context of temporal relational database systems, no comparable amount of work has been done in the context of object-oriented models. Moreover, the main drawback of the existing proposals is the lack of a formal basis-which we believe is essential to manage the inherent complexity of the object-oriented data model. In this paper, we define a comprehensive temporal object-oriented data model supporting multiple temporal granularities. We formally define the main notions of the data model such as types, legal values, classes, and objects. We address issues related to inheritance, type refinement, and substitutability. Finally, we describe the implementation of the presented model on top of an ODMG compliant DBMS. (C) 2002 Elsevier Science Ltd. All rights reserved.
Flora is a functional-style language For object and relational algebra. It has been designed for efficient support of advanced database languages combining rules and objects using compilation and optimization. Flora i...
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Flora is a functional-style language For object and relational algebra. It has been designed for efficient support of advanced database languages combining rules and objects using compilation and optimization. Flora is a strongly typed language based on an OO data model and incorporating support For collection-oriented computational capabilities. In this paper, we describe the design and architecture of the Flora optimizer which is rule-based, yet doing cost-based optimization. The optimizer uniformly captures logical, semantic and implementation knowledge regarding the execution system and the applications by means of assertions. This framework eases extensibility and enables efficient query rewriting.
We proposed a temporal object system (TOS) which maintains changes to both the structure and the state of an object in a temporal fashion. objects in TOS are referred to as temporal objects and are allowed to evolve o...
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We proposed a temporal object system (TOS) which maintains changes to both the structure and the state of an object in a temporal fashion. objects in TOS are referred to as temporal objects and are allowed to evolve over time. A collection of temporal objects which share the same set of common properties is grouped into a family. A temporal object that can be defined by using the local knowledge of a family is referred to as an offstage object. We also discussed the renovations of both temporal complex objects and offstage objects. This paper is a continuation of the work reported, and now we report on the operators of the TOS and their implementation. These operators are grouped into three different modules of the TOS based on their relevant functions. These modules are: object manager (or object module), family module, and root of TOS (RTOS) module. The important module is the object manager (OM) that consists of basic operators. The modules provide a facility for defining a simple temporal object and later to add a stage in the temporal object. The other operators are grouped into the two other modules and are referred to as RTOS module and family module. We have implemented these operators using the SELF version 4.0 programming language on a SUN Sparc Workstation running Solaries 2.4. (C) 2003 Published by Elsevier Inc.
An integrated approach to the management of computer-aided control engineering projects is described. It is shown that to exploit the benefits of object-oriented modelling and design an object-oriented database is req...
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An integrated approach to the management of computer-aided control engineering projects is described. It is shown that to exploit the benefits of object-oriented modelling and design an object-oriented database is required. A dynamic system object model is developed for use in project management using an object-oriented database. A complete description of the project management facilities is given, and the graphical user interface is described. A case study is used for illustration. Open architectures are considered and it is concluded that, together with object-oriented methods, these provide the possibility for exploiting the work described.
It is widely acknowledged that clustering is a cornerstone for the performance of database management systems. In particular, object-oriented databases have special properties which make clustering even more important...
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It is widely acknowledged that clustering is a cornerstone for the performance of database management systems. In particular, object-oriented databases have special properties which make clustering even more important for them than for conventional database models. In this paper, a survey is presented for the state of the art in the field of clustering in object bases. Several design dimensions are discussed and used as a basis for comparing different systems. Moreover, a set of selection guidelines and evaluation criteria are proposed and finally, open questions and future research directions are outlined.
A knowledge base management system (KBMS) realises a combination of techniques found in database management systems and knowledge-based systems. At the data model and knowledge representation level, many systems of th...
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A knowledge base management system (KBMS) realises a combination of techniques found in database management systems and knowledge-based systems. At the data model and knowledge representation level, many systems of this kind constitute a marriage of the relational data model and the rule-based reasoning. Experience has shown that either approach is restricted in the way it can express the demanding information and knowledge structures required for applications like decision support systems. Two new technologies offer an exciting new integrated approach to knowledge management. object-oriented database management systems (OODBMS) provide an object model that supports powerful abstraction mechanisms to facilitate the modelling of highly structured information. Whereas case-based reasoning (CBR) systems are knowledge bases which organise their capabilities around a memory of past cases and the notion of similarity. Both types of system are built upon two fundamental concepts: 1) the retrieval of entities with potentially complex structure, called objects in the former, and cases in the latter type of system;2) the organisation of those entities in collections with common characteristics. In an OODBMS such collections are termed extents, and in CBR they are usually called categories. In either system, the conceptual meta notion to represent both, objects as well as extents, and cases as well as categories, is the class. Revolving around a Conceptual Case Class and extending a standard object model, this paper proposes a novel and general approach to represent case-knowledge and to build KBMSs. The work presented here is a spin-off the design of an object query language within the ESPRIT project Lynx.
Controlled Vocabularies (CVs) are networks of concepts that unify disparate terminologies and facilitate the process of information sharing within an application domain. We describe a general methodology for represent...
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Controlled Vocabularies (CVs) are networks of concepts that unify disparate terminologies and facilitate the process of information sharing within an application domain. We describe a general methodology for representing an existing CV as an object-oriented database (OODB), called an object-oriented Vocabulary Repository (OOVR). A formal description of the OOVR methodology, which is based on a structural abstraction technique, is given, along with an algorithmic description and a number of theorems pertaining to some of the methodology's formal characteristics. An OOVR offers a two-level view of a CV, with the schema-level view serving as an important abstraction that can aid in orientation to the CV's contents. While an OOVR can also assist in traversals of the CV, we have identified certain special CV configurations where such traversals can be problematic. To address this, we introduce-based on the original methodology-an enhanced OOVR methodology that utilizes both structural and semantic features to partition and model a CV's constituent concepts. With its basis in the notions of area and the recursively defined articulation concept, an enhanced OOVR representation provides users with an improved CV view comprising groups of concepts uniform both in their structure and semantics. An algorithmic description of the singly rooted OOVR methodology and theorems describing some of its formal properties are given. The results of applying it to a large existing CV are discussed.
This paper describes the activities of object-oriented (OO) analysis that were implemented in order to obtain a high part representation level and to give sets of structured and hierarchical data to the Computer Aided...
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This paper describes the activities of object-oriented (OO) analysis that were implemented in order to obtain a high part representation level and to give sets of structured and hierarchical data to the Computer Aided Process Planning (CAPP) system. The OO modeling activities were carried out by using the object-oriented System Analysis (OOSA) method which allows careful specification of all the information contained inside the system. All the models used by this method have been described in detail to show how the OO database is defined and how it can be used by a generative CAPP system. The feature model proposed is defined by taking all the part information that;can be recognized and extracted from the Computer Aided Design (CAD) model into account. The result is the design of an OO database which allows the CAPP system to use manufacturing features to define machining operation sequences of 3D workpieces. The approach proposed is generic enough to integrate any geometrical forms which can be recognized and identified from the CAD system. Hole geometry is taken as an example to show the link between the step of OO analysis and the step of knowledge representation in the Expert System which has been used to generate machining cycles. The OO database presented makes up a real solution of CAD/CAPP/CAM integration by using feature modeling. (C) 1998 Elsevier Science Ltd. All rights reserved.
Query languages are an important component of any data management system. Therefore, recent object-oriented DBMS's provide (or plan to provide) some associative query capabilities. Because of the increased complex...
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Query languages are an important component of any data management system. Therefore, recent object-oriented DBMS's provide (or plan to provide) some associative query capabilities. Because of the increased complexity of the data model, designing a suitable query language raises new issues. In this paper, we describe how the characteristics of an object-oriented data model, such as object identity, complex object structure, methods, and class hierarchies, have an impact on the design of a query language. We also point out major differences with respect to relational query languages.
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