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.
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.
The ideal query language for a knowledge base will probably never be found: easy formulation and easy evaluation of queries are two conflicting goals. Easy formulation asks for a flexible, expressive language near to ...
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The ideal query language for a knowledge base will probably never be found: easy formulation and easy evaluation of queries are two conflicting goals. Easy formulation asks for a flexible, expressive language near to human language or gestures. Easy evaluation of queries requires an effective mapping to machine code, which computes the correct answer in a finite number of steps. This article approaches the problem by a query language with three faces. The first projects queries to concepts of the knowledge representation language KL-One for easy formulation and readability. The second presents queries as rules of a deductive database with fixpoint semantics. The third presents queries as classes whose instances are the materialized answer (view) to the query. The methods for maintaining and updating the views are compiled from their deductive interpretation.
Advanced application domains such as computer-aided design, computer-aided software engineering, and office automation are characterized by their need to store, retrieve, and manage large quantities of data having com...
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Advanced application domains such as computer-aided design, computer-aided software engineering, and office automation are characterized by their need to store, retrieve, and manage large quantities of data having complex structures. A number of object-oriented database management systems (OODBMS) are currently available that can effectively capture and process the complex data. The existing implementations of OODBMS outperform relational systems by maintaining and querying cross-references among related objects. However, the existing OODBMS still do not meet the efficiency requirements of advanced applications that require the execution of complex queries involving the retrieval of a large number of data objects and relationships among them. Parallel execution can significantly improve the performance of complex OO queries. In this paper, we analyze the performance of parallel OO query processing algorithms for various benchmark application domains. The application domains are characterized by specific mixes of queries of different semantic complexities. The performance of the application domains has been analyzed for various system and data parameters by running parallel programs on a 32-node transputer based parallel machine developed at the IBM Research Center at Yorktown Heights. The parallel processing algorithms, data routing techniques, and query management and control strategies have been implemented to obtain accurate estimation of controlling and processing overheads. However, generation of large complex databases for the study was impractical. Hence, the data used in the simulation have been parameterized. The parallel OO query processing algorithms analyzed in this study are based on a query graph approach rather than the traditional query tree approach. Using the query graph approach, a query is processed by simultaneously initiating the execution at several object classes, thereby, improving the parallelism. During processing, the algorithms avoid the
A query model for object-oriented engineering design systems exhibits characteristics that are quite different from those found in relational models. An engineering query model should take into account the fundamental...
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A query model for object-oriented engineering design systems exhibits characteristics that are quite different from those found in relational models. An engineering query model should take into account the fundamental concepts and requirements of interactive engineering applications that are not found in traditional applications. For example, engineering systems deal with large volumes of data of high complexity, with recursive structures and rich semantic properties. Similarly, engineering systems require the support of 'long transactions', as opposed to the 'short transactions' found in traditional relational-database systems. These differences have an interesting effect on the complexity of and strategy for query evaluation in engineering systems. The paper provides a framework for the classification of queries in engineering design systems. Engineering queries are classified into several categories on the basis of their semantics and complexity, and the impact of these queries on the architecture of an object-oriented engineering design system is shown.
In a distributed object-oriented system-a system containing more than one object-oriented system (OOS)-different OOSs may contain classes with different definitions, different definitions but the same name, or the sam...
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In a distributed object-oriented system-a system containing more than one object-oriented system (OOS)-different OOSs may contain classes with different definitions, different definitions but the same name, or the same definition but different names. Moving an object between two OOSs includes locating a suitable class and creating an instance of the class with the value of the moved object in the destination system. This study discusses what is a suitable class for a moved object in the destination OOS and presents the algorithms for finding such a suitable class. It also discusses the activities of copying the value of the moved object into the instance of a located class in the destination site. A general object movement mechanism and its implementation for a domain specific model are then incorporated into a prototype of a distributed OOS, called DOOSPE.
The Business object Management System (BOMS) is a distributed resource manager that generalizes and extends the concepts of shared corporate information to include not only data that are structured such that the data ...
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The Business object Management System (BOMS) is a distributed resource manager that generalizes and extends the concepts of shared corporate information to include not only data that are structured such that the data can be held in relational tables but also generalized, complex business information objects. BOMS allows enterprises to store, manage, and query the totality of their documents, business transaction records, images, etc., in a uniform and consistent way. With this system, businesses can make more effective use of information that has in the past been inaccessible to thorough and systematic queries and that could not be integrated effectively into existing or new business processes. BOMS is targeted toward very large collections of information objects (on the order of a billion objects, equivalent to terabytes of data) and allows enterprises to unlock information treasures that would otherwise remain hidden in collections of that size. BOMS is influenced by theoretical concepts, such as object-orientation and hypermedia, but relies on proven relational database and transaction processing concepts. BOMS has been implemented with DATABASE 2TM (DB2(R)) and Customer Information Control System/Enterprise Systems Architecture (CICS/ESA(TM)) and has been in productive use since 1991.
In this paper we present a framework and algorithms for method evolution handling in object-oriented databases. Two levels of granularity for method evolution ate described. The first level to the evolution of methods...
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ISBN:
(纸本)3540587861
In this paper we present a framework and algorithms for method evolution handling in object-oriented databases. Two levels of granularity for method evolution ate described. The first level to the evolution of methods in the context of the class inheritance hierarchy, and concerns the semantics of the polymorphism. The second level relates to the behavioural evolution in which the chain of calling relationships between methods is considered. A graph based approach is used to achieve such behavioural consistency in order to prevent the problems of run-time errors, side-effects, and to detect redundant methods and unexpected behaviours.
Several object-oriented database management systems have been implemented without an accompanying theoretical foundation for constraint, query specification, and processing. The pattern-based object calculus presented...
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Deductive objectoriented database languages are faced with the problem of dealing with the new concepts of the objectoriented approach: object identity, inheritance, method, and complex object structure. Complex obj...
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ISBN:
(纸本)3540587861
Deductive objectoriented database languages are faced with the problem of dealing with the new concepts of the objectoriented approach: object identity, inheritance, method, and complex object structure. Complex object structures raise a consistency problem for derived objects. To the best of our knowledge, no method has been proposed to do a static check of the consistency of deductive programs dealing with complex objects. In this paper we propose a solution based on a deductive language, called ERCLog, for an object and relationship data model. ERCLog explicitly manages the cardinalities of the attributes of the objects and of the links between objects. This information allows the static checking of the consistency of the programs.
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