Object-oriented Database Management System Research Articles

Utilizing information and knowledge models to support global manufacturing co-ordination decisions

In recent years, researchers have devoted great attention to global manufacturing co-ordination (GMC). The focus of GMC is on integrating the activities across both functions (supply, manufacturing, distribution) and geographic areas, that is not only on synchronising and smoothing production operations but also on product shifting. Successful international co-ordination and collaboration requires information integration and sharing. Representation and provision of a common source of high quality information, through information models, is one of the fundamental requirements of effective information integration and sharing. This paper proposes an approach that utilizes a combination of information and knowledge models to support GMC decision-making. Three models have been identified and their structures have been defined and modelled using Rational Rose UML. An experimental system, based on the object-oriented DBMS ObjectStore and Visual C + + , has been constructed and used to explore the approach taken. This has shown that the new structures of the three models defined in this paper can capture the required information and knowledge, and that these provide effective information and knowledge support for GMC decisions.

A web-enabled PDM system in a collaborative design environment

For manufacturers, profitability always depends upon the orderly and efficient development, production and distribution of their products. Product Data Management (PDM) is a unique technology, which integrates and manages all applications, information and processes that define a product, from design to manufacture, and to end-user support. The recent advance in Web-based technologies has the potential to greatly enhance PDM's functionality and capability, and to overcome the obstacles that many traditional PDM systems are confronted. It is found in this research that a multi-tiered, collaborative environment with advanced Web technologies is well suited for a PDM system to operate in. In this research, the overall architecture of a Web-enabled PDM system in the Collaborative Design environment is proposed. The architecture is based on the use of open data standards to allow users on a wide variety of platforms to access the product data and other related information. It enables product visualisation using interactive 3-D graphics by the disparate members of a collaborative PDM team. Integral elements of the proposed architecture include object-oriented database (OODB), object-oriented DataBase management system, common gateway interface script and visualisation applications. The use of standard for the exchange of product model data standard effectively integrates different CAD and PDM systems. The advantage of OODB is its efficiency and effectiveness in handling complex data structures often found in engineering applications. Virtual reality modelling language provides a 3-D dynamic visualisation capability. The system, which is implemented using Microsoft Visual Basic, runs in the Windows environment with the basic Internet connections.

Encapsulation of geometric functions for ship structural CAD using a STEP database as native storage

It is difficult to support collaborative design with a conventional ship CAD system that manages design information using files. The file storage, however, can be replaced with a commercial database management system. This paper describes OpenDIS, which is an interface between the geometric modeling kernel and the DBMS. The main purpose of OpenDIS is to implement a CAD system that has the STEP database as the native storage. A prototype CAD system has been implemented using the OpenCascade geometric modeling kernel and ObjectStore, a commercial object-oriented DBMS. The STEP methodology is used for the database schema. This CAD system has been applied to the hull design process of a ship in order to verify the usefulness of the interface.

An XML Storage System for Object-Oriented/Object-Relational DBMSs.

As XML has become popular as a document standard in the World Wide Web, a lot of research has been done on the XML storage systems for storing and managing XML documents using existing DBMSs. Most of the research activities, however, assume a relational DBMS instead of an object-oriented/object-relational (OO/OR) DBMS, which offers more powerful modeling capabilities. In this paper, we present the design and implementation of an XML storage system designed for an OO/OR DBMS. Specifically, we first analyze the mapping from an XML document structure to OO/OR database schema. Second, we propose a method for describing the mapping using a standard language called the XML Schema Language. Third, we propose system catalog classes for storing the mapping information specified by users in the database. Fourth, we propose a detailed algorithm for storing XML documents in an OO/OR database, based on the mapping information. We believe the proposed system is practically usable for object-oriented programmers and DBMS implementors.

PrefetchGuide: capturing navigational access patterns for prefetching in client/server object-oriented/object-relational DBMSs

In prefetching, the objects that are expected to be accessed in the future are fetched from the server to the client in advance. Prefetching reduces the number of round-trips and increases the system performance. To prefetch object effectively, we need to correctly predict the future navigational patterns. In this paper, we propose the PrefetchGuide, a novel data structure that captures the navigational access patterns. We also formally define the notion of the attribute access log set and analyze the navigational access patterns that can be captured by the PrefetchGuide. We then present an prefetching algorithm using the PrefetchGuide. To show effectiveness of our algorithm, we have conducted extensive experiments in a prototype object-relational database management systems (DBMS). The results show that our method significantly outperforms the state-of-the-art prefetching method. These results indicate that our approach provides a practical method that can be implemented in commercial object-oriented/object-relational DBMSs. We believe our method is practically usable for object-oriented programmers and DBMS implementors.

SAMOS in hindsight: experiences in building an active object-oriented DBMS

Active object-oriented database management systems incorporate object-oriented database technology and active mechanisms such as event-condition-action rules (ECA-rules). SAMOS has been among the first representatives of this class of systems. During the development of SAMOS, numerous then open research questions have been addressed. In this paper, we present a “historical” perspective of the SAMOS project and report on lessons and experiences we have gained in the project. We identify requirements, present feasible solutions, and report on experiences we have drawn from this project. In particular, we describe the rule model of SAMOS, which represents a smooth integration of ECA-rules into an object-oriented data model. We also discuss the implementation and architecture of the SAMOS prototype on top of a passive object-oriented database management system (OODBMS). Furthermore, we report on performance and usability issues. In order to analyze performance, we have developed a benchmark; we discuss the experiences (and improvements) we have made by running the benchmark on SAMOS and by comparing the results to those obtained for other systems. Usability issues have been investigated with respect to tool support for designing SAMOS applications and analyzing rule systems. Finally, we discuss our experiences in implementing SAMOS and the conclusions we have drawn for the implementation of other types of event-based persistent systems as well as a development method for active systems in general.

File and Object Replication in Data Grids

Data replication is a key issue in a Data Grid and can be managed in different ways and at different levels of granularity: for example, at the file level or object level. In the High Energy Physics community, Data Grids are being developed to support the distributed analysis of experimental data. We have produced a prototype data replication tool, the Grid Data Mirroring Package (GDMP) that is in production use in one physics experiment, with middleware provided by the Globus Toolkit used for authentication, data movement, and other purposes. We present here a new, enhanced GDMP architecture and prototype implementation that uses Globus Data Grid tools for efficient file replication. We also explain how this architecture can address object replication issues in an object-oriented database management system. File transfer over wide-area networks requires specific performance tuning in order to gain optimal data transfer rates. We present performance results obtained with GridFTP, an enhanced version of FTP, and discuss tuning parameters.

A Sequence-Based Object-Oriented Model for Video Databases

Structuration, annotation and composition are amidst the most crucial modeling issues that video editing and querying in the context of a database entail. In this paper, we propose a sequence-based, object-oriented data model that addresses them in an unified, yet orthogonal way. Thanks to this orthogonality, the interactions between these three aspects are properly captured, i.e., annotations may be attached to any level of video structuration, and all the composition operators preserve the structurations and annotations of the argument videos. We also propose to query both the structuration and the annotations of videos using an extension of ODMG's OQL which integrates a set of algebraic operators on sequences. The overall proposal is formalized and implemented on top of an object-oriented DBMS.

Consistency management in object‐oriented databases

AbstractThe 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 © 2001 John Wiley & Sons, Ltd.

Event indexing systems for efficient selection and analysis of HERA data

The design and implementation of two software systems introduced to improve the efficiency of offline analysis of event data taken with the ZEUS Detector at the HERA electron–proton collider at DESY are presented. Two different approaches were made, one using a set of event directories and the other using a tag database based on a commercial object-oriented database management system. These are described and compared. Both systems provide quick direct access to individual collision events in a sequential data store of several terabytes, and they both considerably improve the event analysis efficiency. In particular the tag database provides a very flexible selection mechanism and can dramatically reduce the computing time needed to extract small subsamples from the total event sample of the experiment.

Modeling Accounting Processes Using UML: The Drifters Example

This paper includes a comprehensive case that details a simplified business system for the Drifters Snowboard Company. We include a description of the business processes of Drifters relative to the data needs which includes an entity-relationship (ER) dia-gram and a unified modeling language (UML) diagram. Both diagrams are con-structed to compare and contrast each method and to give those that perform modeling tasks a sense of some of the real world issues that are involved.In the past ten years, object-orientation has become viable and important in both the modeling and implementation arenas. Programming languages such as C++ and Java incorporate object-oriented (O-O) features and database management systems (DBMS) such as O2, ObjectStore, Poet, etc. and are advertised as "pure" O-O DBMS. Conversely, some systems such as Oracle, DB2, Sybase, SQL Serve,r etc. have incorporated some O-O features into essentially relational database technology in order to remain competitive.On the modeling dimension, the entity-relationship (E/R) diagramming method with its notable variants has been dominant for more than 20 years. This is probably due to its simplicity and its power to accurately represent the data needs of nearly all applica-tions. In the last 10 years however, O-O modeling has become increasingly popular because it correlates nicely to O-O implementations and because its modeling power is requisite for the greater complexity inherit in contemporary information systems. Re-cently, UML has become the de facto O-O modeling variant, so hence, we illustrate UML in the same case we use ER diagramming. The comparison and contrast is useful to those who are migrating to UML data modeling.

A Syntax-based Gateway between SQL3 and ODMG Languages

Object-oriented technology is an emerging information technology. Object-oriented database technology represents a breakthrough from the dominant relational model. Lacking the similar popularity and acceptance of SQL, object-oriented database management systems, however, are going through a difficult period of standardization. Due the complexity of object-oriented technology and the sophistication of distributed (Internet) computing, object database systems need an efficient and effective way to tackle the issue of heterogeneity and incompatibility. In this paper, we propose a syntax-based gateway model to bridge two key object standards of SQL3 and ODMU. The gateway model is methodological and systematic. The basic belief is that a real representation of the real world has to be discovered to resolve the middleware issue. In this method, we employ a set of general and generic components and constructs that compose a real world object system. We use the set to compare and contrast the composition of SQL3 and ODMG. We devise a limited set of conversion rules to convert the compositions one at a time. A transformation model is built. This approach is traceable and reversible because it is based on analysis design constructs. We have implemented the gateway model. The prototype is composed of an analyzing module, lexical scanner, and grammar parser.

A Spatio-Temporal Model for the Manipulation of Lineage Metadata

Nowadays one of the most successful applications of GIS is the management of a land-use cadastre. A lot of corporate GIS databases are in development, they support the legal management and distribution of cadastral maps. However, the propagation of geographical updates toward cadastral databases is still a methodological and technical problem to address in the context of large applications with many different users. This paper proposes a model based on lineage metadata that supports the management of geographical changes in the context of a corporate cadastre application. Geographical and cadastral changes are identified from an analysis of the French cadastre which acts as a case study for the development of our model. The lineage metadata model is based on the application of a direct acyclic graph that permits the management of the evolution of geographical objects and the generation of historical queries. The proposed model is specified and validated with the O_{2} object-oriented database management system.

Dynamic Updates of Inheritance Hierarchy for Object-Oriented Database Schema

Most current object-oriented database management systems (OODBMs) support a few types of dynamic schema change operations that include adding or dropping a class, and inserting or deleting an inheritance relationship to an existing schema. Although these operations can strengthen the update of OODB schema for various application purposes, they easily lead to redundant inheritance and cyclic inheritances. The former suffers from data redundancy and data inconsistency, and the latter suffers from self-inheritance, all of which increase the difficulties of class hierarchy query. In this paper, the authors explain how the changes of schema would lead to redundant and cyclic inheritance, and give a concrete example of the problems that arise. They propose a new concept called minimal class hierarchy to detect the two problems. Furthermore, a formal checking mechanism based on logical implication (often called inference rules) is proposed. A theoretical analysis shows that this checking mechanism is precise and easily implemented.

SEED-Config: A case-based reasoning system for conceptual building design

A case-based design functionality is a natural and intuitive addition to a design tool that can augment human capabilities and help designers remember and retrieve appropriate cases. SEED-Config, a design environment for conceptual building design, was developed to incorporate a case-based reasoning functionality to provide designers with initial potential solutions. The case representation in SEED-Config is the BENT information model, which records design knowledge, supports the hierarchical decomposition of design cases, offers multiple views, and encapsulates the outcome of the design in addition to the problem specification and the design solution. The case library was implemented in an object-oriented database management system to accumulate cases automatically and to provide efficient query facilities. The case retrieval aspect of SEED-Config offers three different methods to find the most useful cases stored in the case library: task-based, lineage-based, and customized. Case retrieval responds to the exploratory nature of the design process and supports versatile case retrieval by providing multiple paths to each case. The case adaptation aspect, which adjusts the selected case to the new problem to provide a complete solution, uses an adaptation method called derivational replay. The case-based design capabilities are completely integrated within the design environment from which the cases originate.

Development of SDAI-Based Common Access Interface for Object-Oriented DBMS

The objective of this research is to construct a data access implementation at the database level using the specifications de fined in the ISO 10303 Standard Data Access Interface (SDAI). This paper documents the process of implementing the SDAI on a specific object-oriented database management system (OODBMS), called Web-based Object Oriented-DataBase (WOO-DB). WOO-DB is devel oped by the Institute for Information Industry and uses a proprietary object definition language (ODL) and object manipulation language (OML) to describe and manipulate data. The implementation is achieved by mapping the functions and schemata between the SDAI data model and WOO-DB ODL and OML. This research concludes a number of basic features that an OODBMS should support when con structing the SDAI access mechanism. Once the data access interface is independent of data storage technologies, the integration of ap plications in a computer-aided Concurrent Engineering environment can be achieved under a common data accessing protocol.

Development of SDAI-Based Common Access Interface for Object-Oriented DBMS

Development of SDAI-Based Common Access Interface for Object-Oriented DBMS

Object-oriented data handling and OODB operation of LHD mass data acquisition system

The new data acquisition system of large helical device (LHD) diagnostics, i.e. LABCOM system, has successfully started its operation in March 1998. It has a simple but massive parallel-processing (MPP) structure by means of multiple PC/Windows NT environment, and the most significant methodology adopted for it is the object-oriented (OO) data handling through the whole system. The functions and data substances of the acquisition system are described in autonomous objects with the corresponding C++ class definitions. The object-oriented database management system (ODBMS) will be the only solution to provide a vast and virtual storage space for storing an enormous number of archiving data objects. Commercial ODBMS product ‘O2’ are installed on each diagnostic acquisition computer. Practical O2 investigations showed 300–400 kB/s as the data storing rate, whereas the data transfer rate from CAMAC digitizers to the computer is up to 700 kB/s in this system. Applying the GNU project's ‘zlib’ compression library for the data size reduction compensates this rate gap. Through the first and second (∼#7132) LHD experimental campaigns, the LABCOM system acquired about 400 GB raw data, with maximum 120 MB per shot. These experiences proved that OO technology has great promise for the next generation of the data acquisition and storage system in fusion research experiments.

Structured storage and retrieval of SGML documents using Grove

SGML standardized in ISO 8879 [ International Organization for Standardization (1986)] has been proliferated because it can provide various styles and transform documents on different platforms. The SGML document has logical structure information in addition to the contents. As SGML documents are widely used, there is an increasing demand for a storage and retrieval system to use the logical structure of documents efficiently. However, traditional retrieval systems based on document indexes cannot exploit the logical structure appropriately. In this paper, we have developed a document storage and retrieval system based on structure information, where the SGML document is transformed into Grove, which is the document model for DSSSL and HyTime, and stored at an element level by an object-oriented DBMS, Object Store. It supports structured documents and provides a query interface to retrieve information contained in the structures.

Simplifying the Formulation of a Wide Range of Object-Oriented Complex Queries

We present a model that simplifies the formulation of a wide range of complex, mainly selection-based, object-oriented queries, including linear recursive queries. They are complex because it is almost impossible for naive users to predict the formulation of their predicate expressions. Naive users are mainly decision makers who are most probably not computer professionals. Therefore, it is necessary to provide them with a straightforward and easy-to-handle approach to retrieve the information required for the decision making process. To achieve this, the definition of the selection operation and the predicate definition are adjusted to make it possible to have in the output only a subset of the objects from the actual result of a linear recursive query. Otherwise, it is infeasible to achieve the same output without an additional selection with a complicated predicate. We also define an operation that facilitates applying aggregate functions on objects. The two operations proved to be very useful and necessary to study the characteristics of trees and directed graphs. The presented model has been implemented as a part of our object-oriented database management system prototype.