• Journal of Internet Computing and Services
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• v.19 no.5
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• pp.107-113
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• 2018

Object-oriented databases (OODBs) canbe used for many non-traditional database application areas such as computer-aided design, etc. Usually those application areas require advanced modeling power for expressing complicated relationships among data sets. OODBs have more distinguished features than the traditional relational database systems. One of the distinguished characteristics of OODBs is class hierarchy (also called inheritance hierarchy). A class hierarchy in an OODB means that a class can hand down the definitions of the class to the subclass of the class. In other words, a class is allowed to inherit the definitions of the class from the superclass. In this paper, we present performance evaluation metrics for class hierarchy in OODBs from a concurrency control perspective. The proposed performance metrics are developed to determine which concurrency control scheme in OODBs can be used for a given class hierarchy. In this study, in order to develop performance metrics, we use class hierarchy structure (both of single inheritance and multiple inheritance), and data access frequency for each class. The proposed performance metrics will be also used to compare performance evaluation for various concurrency control techniques.

• Journal of Korea Multimedia Society
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• v.9 no.6
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• pp.693-699
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• 2006

Object-oriented databases (OODBs) have been adopted for managing non-standard applications such as computer-aided design (CAD), office document management and many multimedia applications. One of the major characteristics of OODBs is class hierarchy where a subclass is allowed to inherit the definitions defined on its superclasses. In this paper, I present the evaluation metrics for class hierarchy quality in OODBs. These metrics are developed to determine if a concurrency control scheme can achieve good performance or not on a given class hierarchy. I first discuss the existing concurrency control schemes for OODBs. Then I provide evaluation metrics based on structural information and access frequency information in class hierarchies. In order to discuss significance of the proposed performance metrics, an analytical model is developed. Analysis results show that the performance metrics are important factor in concurrency control performance. I consider both single inheritance and multiple inheritance. The proposed metrics can be used to provide guidelines on how to design class hierarchy of an OODB for maximizing the performance of concurrency control technique.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.4
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• pp.328-333
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• 2002

The deeper the hierarchy of a inheritance structure is, the better the reusability of the structure is, but the more difficult the understandability and the maintainability of it is. On the contrary, the shallower the hierarchy is, the worse the abstraction of the inheritance structure is, but the better the understandability and modifiability of it is. Therefore, it is to be desired that a deep hierarchy of a inheritance structure should be split to be shallow for the maintainability of a system. This paper proposed a complexity metric that is based on DIT and NOC of Chidamber and Kemerer, and solved the ambiguity of the metrics of them, which was pointed out by Li. The metric is a simple and heuristic one for measuring the complexity of class inheritance structures by considering the number of ancestor classes and descendant classes and the depth of inheritance hierarchy. This provides a quantitative information for assessing the complexity of a inheritance structure in splitting it.

• Journal of Electrical Engineering and information Science
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• v.1 no.1
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• pp.164-172
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• 1996

The partitioning of related objects should be performed before clustering for an efficient access in object-oriented databases. In this paper, a horizontal partition of related objects in object-oriented databases is presented. All subclass nodes in a class inheritance hierarchy of a schema graph are shrunk to a class node in the graph that is called condensed schema graph because the aggregation hierarchy has more influence on the partition than the class inheritance hierarchy. A set function and an accessibility function are defined to find a maximal subset of related objects among the set of objects in a class. A set function maps a subset of the domain class objects to a subset of the range class objects. An accessibility function maps a subset of the objects of a class into a subset of the objects of the same class through a composition of set functions. The algorithm derived in this paper is to find the related objects of a condensed schema graph using accessibility functions and set functions. The existence of a maximal subset of the related objects in a class is proved to show the validity of the partition algorithm using the accessibility function.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.6
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• pp.537-542
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• 2002

We propose new metrics for understandability and modifiability of class inheritance structures based on the object-oriented metrics suggested by Chidamber and Kemerer. The metrics are evaluated using the results of Gursaran s experiments which validated the empirical relation of DIT(Depth of Inheritance Tree) and NOC(Number of Children) metrics of Chidamber and Kemerer.

• The KIPS Transactions:PartD
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• v.8D no.6
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• pp.853-860
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• 2001

In the object-oriented software development, redesigning of classes and reorganizing of class hierarchy structures should be necessary to reduce many of the headaches of object-oriented software design and maintenance. To support this task, in this paper, we propose a theoretical foundation for class hierarchy reorganizations that is relatively complete, correct, formal and easy to understand and use. We introduce the flattened class hierarchy that characterizes the class hierarchy structures in object-oriented software evolution. And we also present an algorithm which transforms a given class hierarchy into the normalized form. The flattened class hierarchy helps us map the inheritance and aggregation paths in a class hierarchy to paths in an object hierarchy that is an instance of the class hierarchy. By applying the algorithm into a given class hierarchy, we can make a new, object-preserved, and flattened class hierarchy that is the cornerstone for reorganization of class hierarchy structure and plays an important role as a bridge on the incremental evolutionary changes and reuse of object-oriented software to reorganize class hierarchies.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2000.05a
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• pp.226-231
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• 2000

객체지향 패러다임의 상속성은 코드 재사용 및 확장을 용이하게 하여 소프트웨어 생산성을 높여준다. 그러나 상속을 남용하여 상속 계층구조(class inheritance hierarchy)의 상속 깊이가 깊게 되면 프로그램을 이해하는데 어려움을 준다. 이러한 관점에서 볼 때 상속성의 이용에 제한을 둘 필요가 있다. 본 논문은 상속 계층구조의 상속 깊이에 대한 기준을 세우기 위하여 인지실험을 행하고 그 결과를 보고한다. 본 논문의 목적은 객체지향의 특성 중 상속성의 장점을 잘 이용하면서 이해하기 쉬운 객체지향 소프트웨어 개발을 돕는 것이다.

• Journal of KIISE:Software and Applications
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• v.28 no.9
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• pp.612-628
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• 2001

This paper presents a methodology to extract classes and inheritance relations from procedural software. The methodology is based on the idea of generating all groups of class candidates, based on the combinatorial groups of object candidates, and their inheritance with all possible combinations and selecting a group of object candidates, and their inheritance with all possible combinations and selecting a group with the best or optimal combination of candidates with respect to the degree of relativity and similarity between class candidates in the group and classes in a domain model. The methodology has innovative features in class candidates in the group and classes in a domain model. The methodology has innovative features in class and inheritance extraction: a clustering method based on both static (attribute) and dynamic (method) clustering, the combinatorial cases of grouping class candidate cases based on abstraction, a signature similarity measurement for inheritance relations among n class candidates or m classes, two-dimensional similarity measurement for inheritance relations among n class candidates or m classes, two-dimensional similarity measurement, that is, the horizontal measurement for overall group similarity between n class candidates and m classes, and the vertical measurement for specific similarity between a set of classes in a group of class candidates and a set of classes with the same class hierarchy in a domain model, etc. This methodology provides reengineering experts with a comprehensive and integrated environment to select the best or optimal group of class candidates.

• Journal of Internet Computing and Services
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• v.15 no.1
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• pp.63-71
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• 2014

Currently many non-traditional application areas such as artificial intelligence and web databases require advanced modeling power than the existing relational data model. In those application areas, object-oriented database (OODB) is better data model since an OODB can providemodeling power as grouping similar objects into class, and organizing all classes into a hierarchy where a subclass inherits all definitions from its superclasses. The purpose of this paper is to develop an OODB concurrency control scheme dealing with multiple inheritance. The proposed scheme, called Multiple Inheritance Implicit Locking (MIIL), is based on so-called implicit locking. In the proposed scheme, we eliminate redundant locks that are necessary in the existing implicit locking scheme. Intention locks are required as the existing implicit locking scheme. In this paper, it is shown that MIIL has less locking overhead than implicit locking does. We use only OODB inheritance hierarchies, single inheritance and multiple inheritance so that no additional overhead is necessary for reducing locking overhead.

• Journal of the Korean Society for information Management
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• v.31 no.2
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• pp.41-56
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• 2014

The necessity of the raw data management and reuse is issued by diffusion of the recognition that research data is a national asset. In this paper, a metadata design model by schema class inheritance and a metadata integrated search model by schema objects are suggested for a structural management of the data. A data architecture in which an schema object has an 1 : 1 relation to the data collection was designed. A suggested model was testified by creation of a virtual schema class and objects which inherit the schema class. It showed the possibility of implement systematically. A suggested model can be used to manage the data which are produced by government agencies because schema inheritance and integrated search model present way to overcome the weak points of the 'Top-dow Hierarchy model' which is being used to design the metadata schema.