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.
A graph-orientedobject database model (GOOD) is introduced as a theoretical basis for database systems in which manipulation as well as conceptual representation of data is transparently graph-based. In the GOOD mode...
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A graph-orientedobject database model (GOOD) is introduced as a theoretical basis for database systems in which manipulation as well as conceptual representation of data is transparently graph-based. In the GOOD model, the scheme as well as the instance of an object database is represented by a graph, and the data manipulation is expressed by graph transformations. These graph transformations are described using five basic operations and a method construct, all with a natural semantics. The basic operations add and delete objects and edges in function of the matchings of a pattern. The expressiveness of the model in terms of object-oriented modeling and data manipulation power is investigated.
Hypermedia, object-oriented programming, and objectdatabases are new and promising trends in information processing. Behind each of these trends is a programming paradigm supporting a different approach in the design...
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Hypermedia, object-oriented programming, and objectdatabases are new and promising trends in information processing. Behind each of these trends is a programming paradigm supporting a different approach in the design and implementation of programs based on it. In this article, we consider possibilities to combine the most interesting features from these paradigms, and to apply the result to the development of knowledge-based systems. We call the combined paradigm hyperobjects. We have applied hyperobjects to an application performing knowledge-based condition monitoring and fault diagnosis on marine diesel engines. The application is called FAKS (Fault Avoidance Knowledge System). The prototype of the system was developed in the Technical Research Centre of Finland in cooperation with a Finnish diesel engine manufacturer Wartsila Diesel. Further development of FAKS, as a commercial product, have been made by Tiihonen Software Company Ltd and Wartsila Diesel. The first FAKS installation was delivered to a German rail ferry, Railship III, at the end of February 1990.
In object-oriented database systems, a view mechanism can extend the object paradigm by adapting object structure and object behavior to the needs of the different applications or users. In this paper we consider view...
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In object-oriented database systems, a view mechanism can extend the object paradigm by adapting object structure and object behavior to the needs of the different applications or users. In this paper we consider views with object-generating semantics which is an important construct in database environment and mediator systems (Y. Papakonstantinou, S. Abiteboul, H. Garcia-Molina, object Fusion in Mediator Systems, in: Proceedings of the International Conference on Very Large databases, New York, July 1998). We reexamine the problem of updating views according to the aspects of object-orientation, namely: object identity, inheritance and aggregation path. Furthermore, rye propose a taxonomy of virtual classes in order to define the update semantics with respect to the virtual class semantics. We present also a cost model for our update algorithms to quantify the impact of our materialization method upon updates propagation times. (C) 2000 Elsevier Science B.V. All rights reserved.
The issues of managing distributed applications are discussed, and a set of tools, the meta system, that solves some longstanding problems is presented. The Meta model of a distributed application is described. To mak...
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The issues of managing distributed applications are discussed, and a set of tools, the meta system, that solves some longstanding problems is presented. The Meta model of a distributed application is described. To make the discussion concrete, it is shown how NuMon, a seismological analysis system for monitoring compliance with nuclear test-ban treaties is managed within the Meta framework. The three steps entailed in using Meta are described. First the programmer instruments the application and its environment with sensors and actuators. The programmer then describes the application structure using the object-oriented data modeling facilities of the authors' high-level control language, Lomita. Finally, the programmer writes a control program referencing the data model. Meta's performance and real-time behavior are examined
Semantic data modelling constructs, such as relationships, composite objects and versions, are used to represent knowledge explicitly in object-oriented databases. Such constructs increase the ability of the database ...
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Semantic data modelling constructs, such as relationships, composite objects and versions, are used to represent knowledge explicitly in object-oriented databases. Such constructs increase the ability of the database to capture not only the structural aspects of data, as in traditional databases, but also the meaning of data. The modelling process can be further enhanced by supporting expressive visual representations of the constructs in a direct-manipulation interface. This paper focuses upon the development of effective visualizations for such constructs by presenting a range of sample visualizations, outlining how they can be prototyped rapidly in an integrated interface development environment, and describing how evaluation techniques can be used to assess alternative proposals.
Wrappers export the schema and data of existing heterogeneous databases and support queries on them. In the context of cooperative information systems, we present a flexible approach to specify the derivation of objec...
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Wrappers export the schema and data of existing heterogeneous databases and support queries on them. In the context of cooperative information systems, we present a flexible approach to specify the derivation of object-oriented (OO) export databases from local relational databases. Our export database derivation consists of a set of extent derivation structures (EDS) which defines the extent and deep extent of export classes. Having well-defined semantics, the EDS can be readily used in transforming wrapper queries to local queries. Based on the EDS, we developed a wrapper query evaluation strategy which handles OO queries on the export databases. The strategy is unique in that it considers the limited query processing capabilities of local database systems as well as the language constraints on the local query languages. (C) 1999 Elsevier Science B.V. All rights reserved.
The intermediate result cardinality - the number of objects satisfying a condition given in a query - is an important factor for estimating the cost of the query in query optimization. In this paper we show that an ob...
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The intermediate result cardinality - the number of objects satisfying a condition given in a query - is an important factor for estimating the cost of the query in query optimization. In this paper we show that an object-oriented query often involves partial participation of classes in a relationship. We then present a new technique for estimating the intermediate result cardinality in such a query. Partial participation has not been considered seriously in existing techniques. Since the proposed technique uses detailed statistics to accommodate partial participation, it estimates the intermediate result cardinality more accurately than existing ones. We also show that these statistics are easily obtained by using inherent properties of object-oriented databases.
This paper presents an approach to implementing production rules for object-oriented databases (OODBs). The approach builds upon earlier work on production rule algorithms for relational databases, and exploits fundam...
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This paper presents an approach to implementing production rules for object-oriented databases (OODBs). The approach builds upon earlier work on production rule algorithms for relational databases, and exploits fundamental differences in the structuring mechanisms employed by OODBs. An implementation is described whereby the production rules are mapped onto event-condition action rules for execution, It is shown how the resulting implementation has minimal space overheads, and a time performance close to that of the widely used TREAT algorithm which uses significantly more space.
In temporal contexts, information entities are not physically discarded from the database after they are modified. This non-deletion rule allows the recovery of past states of the database while a consistency history ...
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In temporal contexts, information entities are not physically discarded from the database after they are modified. This non-deletion rule allows the recovery of past states of the database while a consistency history management guarantees the data validity in each instant of time. This paper describes a data model which introduces the above mentioned time features in an object-oriented environment. In our model, called TVOO, objects and the relationships between them are time dependent and the history of the changes which occur in the database are kept in Version hierarchies. (C) 1999 Elsevier Science Inc. All rights reserved.
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