This paper presents a methodology for handling an important step of database migration. The methodology is based on a set of techniques: (i) semantic clustering, (ii) metamodeling, and (iii) knowledge-based schema tra...
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This paper presents a methodology for handling an important step of database migration. The methodology is based on a set of techniques: (i) semantic clustering, (ii) metamodeling, and (iii) knowledge-based schema transformation. Semantic clustering (i.e., grouping based on semantic cohesion) is mainly used to facilitate the process of translating an extended entity relationship schema into a schema of complex objects. Meta modeling is used to define the data models involved in the process of schema transformation. Finally, transformation rules are defined and used for mapping a schema from a source model into a schema expressed in a target model. In this paper, we limit ourselves to the mapping of an extended entity relationship diagram into an object-oriented database schema using the object model supported by the ODMG standard. (C) 1998 Elsevier Science B.V.
In agriculture as in other domains, there exists a need for multifaceted and comprehensive decision support frameworks enabling the integration and use of different types of knowledge and information processing tools....
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In agriculture as in other domains, there exists a need for multifaceted and comprehensive decision support frameworks enabling the integration and use of different types of knowledge and information processing tools. The object-oriented paradigm provides a foundation for the construction of such general decision support frameworks. The objective of the described project was to build an object-oriented framework (called SAGE) for knowledge management and decision support in the area of agro-ecosystem management. The Smalltalk object-oriented programming system was the basic technology used to build the SAGE system. A Smalltalk-based object-oriented database management system was also used to provide persistence for Smalltalk objects. The result of the design and implementation effort is a library of Smalltalk classes that constitutes a framework onto which developers can build systems to represent agroecosystems and support the management of these systems. These classes are described and their design and implementation issues are discussed.
The objectoriented Functional Data Language (O²FDL) is an interactive strongly-typed database programming language that integrates the object-oriented and functional programming paradigms. It was designed for ad...
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The objectoriented Functional Data Language (O²FDL) is an interactive strongly-typed database programming language that integrates the object-oriented and functional programming paradigms. It was designed for advanced applications such as computer-aided design, statistical computing, and multimedia systems that require a powerful and uniform database programming language supporting the software engineering principles of these two paradigms. To this end, the O²FDL supports inheritance and encapsulation of object-oriented languages, and an equational notation and strong typing of functional programming. Strong typing is extended with type restrictions to constrain the instantiations of type variables in function interfaces, while inheritance is augmented with a monotonic subtype rule for function redefinition. To facilitate convenient and concise expressions for both database and general purpose computation, the O²FDL supports novel features including 1) functions of indefinite nesting levels that simplify nested list processing; 2) system-defined functions that provide a concise and convenient notation for filtering, aggregating, and combining objects; and 3) path expressions that allow a flexible graphical correspondence for database queries. We define these features informally through examples and formally through a two pad semantics. For the core of the O²FDL we provide a denominational semantics based on an extended A-calculus. For selected system-defined functions, we provide an operational semantics and demonstrate that a subset of the O²FDL is at least as expressive as the relational algebra. [ABSTRACT FROM AUTHOR]
object-oriented (OO) technology has been heralded as a solution to the problems of software engineering. The claims are that OO technology promotes understandability, extensibility, evolvability, reusability, and main...
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object-oriented (OO) technology has been heralded as a solution to the problems of software engineering. The claims are that OO technology promotes understandability, extensibility, evolvability, reusability, and maintainability of systems and that OO systems are easy to understand and use. However, this technology has not been as successful as expected. An analysis of experiences and empirical studies reveals that the problem is not the technology per se but that the technology provides no support to software developers in performing the processes the technology requires. We present a cognitive model of software development that details the challenges software developers face in using OO technology. The model focuses on three aspects of software development-evolution, reuse and redesign, and domain orientation. We motivate this model with a variety of firsthand experiences and use it to assess current OO technology. Further, we present tools and evaluations that substantiate parts of this model. The model and tools indicate directions for future software development environments, looking beyond the technological possibilities of OO languages and beyond the context of individual developers and projects.
A concurrent design can be used to improve productivity and quality by means of shortening product development time and sharing design information. In order to share information among designers, an object-oriented dat...
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A concurrent design can be used to improve productivity and quality by means of shortening product development time and sharing design information. In order to share information among designers, an object-oriented database management system, which has shown promising capabilities in engineering data processing, is used as a foundation for building a concurrent design architecture in this research. The architecture allows multiple designers to work on the design concurrently, store multiple versions of the design, integrate design information, and evolve the design structure. A procedure of plastic filling injection moulding is used to demonstrate the process of concurrent design, and is compared with the process of C-MOLD, a simulation analysis software package for plastic injection moulding, to show the superiority of the proposed concurrent design architecture.
Herein we extend the object-oriented database model via the concept of object inheritance, and call the resulting model, the extended object-oriented database model. We then formalize this model and thereafter we inve...
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Herein we extend the object-oriented database model via the concept of object inheritance, and call the resulting model, the extended object-oriented database model. We then formalize this model and thereafter we investigate path functional dependencies, inequality dependencies and general dependencies. General dependencies subsume both path functional dependencies and inequality dependencies.
A database application generation system. Data Base 4th Generation Language (DB4GL), incorporating an object-oriented self-describing data model, has been developed at Sheffield City Polytechnic, UK. A recent extensio...
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A database application generation system. Data Base 4th Generation Language (DB4GL), incorporating an object-oriented self-describing data model, has been developed at Sheffield City Polytechnic, UK. A recent extension to the DB4GL research has been an investigation into a possible parallel implementation of DB4GL on transputer hardware, and a prototype Parallel-DB4GL (P-DB4GL) system has been designed and implemented. The paper briefly describes both the original DB4GL system and the prototype P-DB4GL implementation, and a classification of object-oriented database approaches is presented. Results obtained from the prototype P-DB4GL are reported, and based on these results, directions for further research are discussed.
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 st...
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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.
Requirements imposed on both the object data model and object management by the support of complex objects are outlined. The basic concepts of an object-oriented data model are discussed. They are objects and object i...
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Requirements imposed on both the object data model and object management by the support of complex objects are outlined. The basic concepts of an object-oriented data model are discussed. They are objects and object identifiers, aggregation, classes and instantiation mechanisms, metaclasses, and inheritance. object-oriented models are compared with semantic, relational, and Codasyl models. object-oriented query languages and query processing are considered. Some operational aspects of data management in object-oriented systems are examined. Schema evolution is discussed
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