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A tunable class hierarchy index for object-oriented databases using a multidimensional index structure

INFORMATION AND SOFTWARE TECHNOLOGY 2001年第5期43卷 309-323页

作者： Lee, JH Whang, KY Han, WS Cho, WS Song, IY Catholic Univ Taegu Dept Comp Engn Taegu South Korea Chungbuk Natl Univ Management Informat Dept Seoul South Korea Drexel Univ Coll Informat Sci & Technol Philadelphia PA 19104 USA

This paper presents a tunable two-dimensional class hierarchy indexing technique (2D-CHI) for object-oriented databases. We use a two-dimensional file organization as the index structure. 2D-CHI deals with the problem of clustering objects in a two-dimensional domain space consisting of the key attribute domain and the class identifier domain. In conventional class indexing techniques using one-dimensional index structures such as the B+-tree, the clustering property is owned exclusively by one attribute. These indexing techniques do not handle the queries that address both the attribute keys and the class identifiers efficiently. 2D-CHI enhances query performance by adjusting the degree of clustering between the key value domain and the class identifier domain based on the precollected usage pattern. For performance evaluation, we first compare 2D-CHI with the conventional class indexing techniques using an analytic cost model based on the assumption of uniform object distribution, and then, verify the cost model through experiments using the multilevel grid file as the two-dimensional index. We further perform experiments with nonuniform object distributions. The experiments show that our proposed method builds optimal class index structures in terms of the total number of page accesses for given the precollected usage pattern regardless of query types and object distributions. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： object-oriented databases class hierarchy multidimensional structures self-tunable database systems

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Bottom-up design of active object-oriented databases -: Top-down design approaches give database designers little guidance with transforming a conceptual model into an active object-oriented database schema.: A bottom-up design approach may provide a better perspective.

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COMMUNICATIONS OF THE ACM 2001年第4期44卷 99-104页

作者： Kappel, G Rausch-Schott, S Retschitzegger, W Sakkinen, M Univ Linz Dept Informat Syst Inst Appl Comp Sci A-4040 Linz Austria Univ Jyvaskyla Dept Comp Sci & Informat Syst Jyvaskyla Finland

This article focuses on the bottom-up design approach used for software development. As top-down design approaches give database designers little guidance with transforming a conceptual model into an active object-oriented database schema. A bottom-up design approach may provide a better perspective. Using this approach to Active object-oriented databases (AOODB) two subtasks are needed, specifying application classes, and identifying business policies, which are generally spread over different classes. This approach enhance sequential message passing, so interactions are specifiable in a concurrent object-oriented (OO) environment based on multiple threads of control. Although such interaction mechanisms are built-in primitives in some concurrent OO systems, they must usually be defined by programmers. Two interaction rule patterns are, the abstraction from a single application-specific rule to a primitive rule pattern, and a composite rule pattern abstracting from more than one rule. To successfully apply rule patterns, they must include a proper design and development tool.

关键词： Computer software development Information storage & retrieval systems object-oriented databases object-oriented methods (Computer science) Computer programming management Computer simulation

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Refinements of complexity results on type consistency for object-oriented databases

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JOURNAL OF COMPUTER AND SYSTEM SCIENCES 2001年第4期62卷 537-564页

作者： Ishihara, Y Shimizu, S Seki, H Ito, M Osaka Univ Grad Sch Engn Sci Dept Informat & Math Sci Toyonaka Osaka 5608531 Japan Nara Inst Sci & Technol Grad Sch Informat Sci Nara 6300101 Japan

The method invocation mechanism is one of the essential Features in object-oriented programming languages. This mechanism contributes to data encapsulation and code reuse, but there is a risk of a run-time type error. In the case of object-oriented databases (OODBs), a run-time error causes rollback. Therefore, it is desirable to ensure that a given OODB schema is consistent;i.e., no run-time type error occurs during the execution of queries under any database instance of the OODB schema. This paper discusses the computational complexity of the type-consistency problem. As a model of OODB schemas, we adopt update schemas introduced by R. Hull cr rrl.. which have all of the basic features of OODBs such as class hierarchy. inheritance. and complex objects. Fur several subclasses of update schemas, the complexity of the type-consistency problem is presented. Importantly, it turns out that nonflatness of the class hierarchy, recursion in the queries:, and update operations in the queries each make the problem difficult. (C) 2001 Academic Press.

关键词： Legal Executions Refining schema object oriented programming languages Software reuse object-oriented databases data encapsulation

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Consistency management in object-oriented databases

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2001年第11期13卷 955-985页

作者： Oakasha, H Conrad, S Saake, G Univ Munich Inst Informat D-80538 Munich Germany Cairo Univ Fayoum Branch Fac Sci Al Fayyum Egypt Univ Magdeburg Fak Informat D-39016 Magdeburg Germany

The paper presents concepts and ideas underlying an approach for consistency management in object-oriented (OO) databases. In this approach constraints are considered as first class citizens and stored in a meta-database called constraints catalog. When an object is created constraints of this object are retrieved from the constraints catalog and relationships between these constraints and the object are established. The structure of constraints has several features that enhance consistency management in OO database management systems which do not exist in conventional approaches in a satisfactory way. This includes: monitoring object consistency at different levels of update granularity, integrity independence, and efficiency of constraints maintenance;controlling inconsistent objects;enabling and disabling constraints, globally to all objects or locally to individual objects;and declaring constraints on individual objects. All these features are provided by means of basic notations of OO data models. Copyright (C) 2001 John Wiley & Sons, Ltd.

关键词： object-oriented databases constraint management constraint maintenance database integrity integrity constraints

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Operators of the temporal object system and their implementation

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INFORMATION SCIENCES 2004年第1-4期158卷 37-68页

作者： Shah, A Fotouhi, F Grosky, W Al-Muhtadi, J King Saud Univ Dept Comp Sci Riyadh 11543 Saudi Arabia Wayne State Univ Dept Comp Sci Detroit MI 48202 USA Univ Michigan Dept Comp & Informat Sci Dearborn MI 48128 USA

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.

关键词： object-oriented databases temporal database temporal objects object manager

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Separating adaptable persistence attributes through computational reflection

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IEEE SOFTWARE 2004年第6期21卷 41-+页

作者： Ortin, F Lopez, B Perez-Schofield, JBG Univ Oviedo Oviedo Spain Univ Vigo Vigo Spain

A prototype persistence system based on the nitrO reflective system demonstrates that computational reflection is a suitable technique for dynamically and transparently adapting any application's persistence attributes, following the separation-of-concerns principle. Because computational reflection offers the runtime customization of language semantics, it lets developers combine programming language and database management systems into a single computational model.

关键词： Java SQL object-oriented databases object-oriented programming persistent objects relational databases software maintenance software metrics software quality adaptable persistence attributes computational reflection database management systems object que Relational databases object oriented programming Software measurement SQL Software maintenance object-oriented databases database management systems Java programming language software quality tangling

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A reusable graphical user interface for manipulating object-oriented databases using Java and XML 01

A reusable graphical user interface for manipulating object-...

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32nd SIGCSE Technical Symposium on Computer Science Education

作者： Dietrich, SW Suceava, D Cherukuri, C Urban, SD Arizona State Univ Dept Comp Sci & Engn Tempe AZ 85287 USA

ISBN: (纸本)1581133294

This paper describes the design and functionality of a graphical user interface (GUI) written in Java Swing that is used to support instructional activities associated with teaching object-oriented database (OODB) concepts. The GUI supports the manipulation of objects in an OODB, assuming the implementation of a specified interface for interacting with an OODB. By using the interface, students can focus on object-oriented design and programming concepts associated with OODB concepts rather than the development of a user interface. Since the GUI uses the Extensible Markup Language (XML) for defining the database schema and data import/export, the use of the GUI provides the added benefit of demonstrating the manner in which XML interacts with database technology.

关键词： object-oriented databases graphical user interfaces extensible markup language Java Java programming language User Interface Device Component database schema object-oriented design

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Closed external schemas in object-oriented databases 12th

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12th International Conference on Database and Expert Systems Applications (DEXA)

作者： Torres, M Samos, J Univ Almeria Dept Lenguajes & Computac Almeria 04120 Spain Univ Granada Dept Lenguajes & Sistemas Informat E-18071 Granada Spain

ISBN: (纸本)3540425276

Schema closure is a property to guarantee that classes in a schema have not references to classes that are not included into it (external references). The existing methodologies solve this point including referenced classes into the schema. In this paper, a new kind of schema closure (reduction closure) is put forward. Reduction closure is based on the transformation of classes with external references, removing these references to fulfil the schema closure 14 property. The main benefit of reduction closure is that it can be used as a method to simplify the external schema definition process, because explicit definition of derived classes for hiding external references is avoided. In addition, the explicit definition of derived classes to update the references to modified classes is also avoided. This closure algorithm is part of an external schema generation system for ODMG databases that we are developing, which is also briefly described in this paper.

关键词： object-oriented databases

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Dynamic clustering in object-oriented databases:: An advocacy for simplicity

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International Symposium on objects and databases

作者： Darmont, J Fromantin, C Régnier, S Gruenwald, L Schneider, M Univ Lyon 2 ERIC F-69676 Bron France Univ Clermont Ferrand LIMOS F-63177 Clermont Ferrand France Univ Oklahoma Sch CS Norman OK 73019 USA

ISBN: (纸本)3540416641

We present in this paper three dynamic clustering techniques for object-oriented databases (OODBs). The first two, Dynamic, Statistical & Tunable Clustering (DSTC) and StatClust, exploit both comprehensive usage statistics and the inter-object reference graph. They are quite elaborate. However, they are also complex to implement and induce a high overhead. The third clustering technique, called Detection & Reclustering of objects (DRO), is based on the same principles, but is much simpler to implement. These three clustering algorithm have been implemented in the Texas persistent object store and compared in terms of clustering efficiency (i.e., overall performance increase) and overhead using the object Cluslering Benchmark (OCB). The results obtained showed that DRO induced a lighter overhead while still achieving better overall performance.

关键词： object-oriented databases dynamic object clustering performance comparison

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Utilizing object-oriented databases for concurrency control in virtual environments

Utilizing object-oriented databases for concurrency control ...

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25th Annual International Computer Software and Applications Conference (COMPSAC 2001)

作者： Turgut, D Aydin, N Elmasri, R Turgut, B Univ Texas Dept Comp Sci & Engn Arlington TX 76019 USA

ISBN: (纸本)0769513727

Virtual Reality Modeling Language (VRML) is widely used to represent, create, and display virtual reality, objects and their environment. Some VRML applications require concurrent interaction by multiple users in a real-time distributed fashion. Such applications need a method for users to share and update the VRML objects in real-time. To allow concurrent shared real-time access, our approach is to store the VRML objects in an object-oriented database system (objectStore) in order to utilize the concurrency control mechanisms of the system. In this paper we present an architecture that allows multiple users to interact in a non-trivial way in such a shared VRML environment. We outline how the VRML world can be saved in objectStore and implement a series of test cases demonstrating concurrency issues arising from simultaneous updates. Our architecture uses ordinary Java enabled web browsers with a VRML plug-in. A commercial web server routes client requests to a custom application server which interacts with the object-oriented database. As users change the VRML world, our application server orders the requests and updates the master copy in the database.

关键词： object-oriented databases concurrency control virtual environments

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