Database Design: Object-Oriented versus Relational

Using NNF to transform conceptual data models to object-oriented database designs

Integration of object-oriented programming languages and database systems in KOPERNIK

The issue of dependability and exception handling is very important, and it is best to address the dependability of software at the very early stage or beginning of the development life cycle. The Object-Oriented Design (OOD) phase works as a base. The object-oriented approach is used to represent the problem domain and clearly understand the design. This paper defines dependability and exception handling that must be addressed during the design phase. Dependability can be achieved through the proper placement or management of design characteristics and the establishment of relationships between them and to develop an exception-handling model that provides a distinct and transparent separation between a component's regular activity and its exceptional action.

This paper compares two approaches to meeting the data handling requirements of Intermedia, a hypermedia system developed at the Institute for Research in Information and Scholarship at Brown University. Intermedia, though written using an object-oriented programming language, relies on a traditional relational database management system for data storage and retrieval. We examine the ramifications of replacing the relational database with an object-oriented database. We begin by describing the important characteristics each database system. We then describe Intermedia and give an overview of its architecture and its data handling requirements. We explain why and how we used a relational database management system and the problems that we encountered with this system. We then present the design of an object-oriented database schema for Intermedia and compare the relational and object-oriented database management system approaches.

Since the early 1970s, the need for a special design phase at the early stage of the database or information system design process began to emerge. This phase is usually called that of conceptual modelling or conceptual design. The development of database design theory prior to the common acceptance of this design phase was much influenced by the ANSI/SPARC proposal for a three-level architecture for database systems (see, for example, Tsichritzis and Klug, 1978) and the efforts of the ISO TC97/SC5/WG3 (1982). The features of conceptual modelling that contributed most to its acceptance are: (i) it postpones the design decisions concerning the hardware configuration and the software components including the decision as to what type of database management system is to be used (for example, relational, Codasyl-like); (ii) it enables the implementation environment (hardware as well as software) to be changed without the need to repeat the design process completely — however important the change may be, the results of conceptual modelling can always serve as a starting point for the re-design of the database; and (iii) it leaves the computer-oriented way of thinking in terms of data, records, elements, files and so on — a very important feature from the viewpoint of communication between the database designers and its future users.

An active OODB system for Genome physical map assembly

Object-oriented databases (OODBs) have been used for many advanced applications requiring advanced modeling power. In this paper, a locking-based concurrency control scheme is presented for OODBs. The proposed scheme reduces locking overhead for class hierarchy which is an important property in OODBs. While existing schemes show good performance only for specific applications, the proposed scheme can incur less locking overhead for any applications. For the performance evaluation of the proposed scheme, simulation is conducted using 007 benchmark. Through the simulation, the proposed scheme is compared with the two existing techniques. The performance studies show that the proposed scheme is superior to existing works.

Computer science education is greatly affected by the object-oriented approach. This can be seen in the numerous new teachers being attracted to programming languages such as Java. Learning the object-oriented approach is however difficult for novice students, mostly because it requires a new way of thinking about computing and more depth to grasp. Thus, to promote the object-oriented approach at the introductory level, a re-examination of the teaching method is recommended. This article describes a pedagogical framework rooted in the constructivist epistemology for teaching object-oriented design and programming.

We describe the design of a multimedia database management system for a distributed news-on-demand multimedia information system. News-on-demand is an application that uses broadband network services to deliver news articles to subscribers in the form of multimedia documents. Different news providers insert articles into the database, which are then accessed by users remotely, over a broadband, asynchronous transfer-mode (ATM) network. The particulars of our design are an object-oriented approach and strict adherence to international standards, in particular the Standard Generalized Mark-up Language (SGML) and Hy-Time. The multimedia database system has a visual query facility, which is also described in this paper. The visual query interface provides three major facilities for end users: presentation, navigation, and querying of multimedia news documents. The main focus, however, is the querying of multimedia objects stored in the database.

For a hospital information system, object-oriented methodology plays an increasingly important role, especially for the management of digitized data, e.g., the electrocardiogram, electroencephalogram, electromyogram, spirogram, X-ray, CT and histopathological images, which are not yet computerized in most hospitals. As a first step in an object-oriented approach to hospital information management and storing medical data in an object-oriented database, we connected electrocardiographs to a hospital network and established the integration of ECG storage and retrieval systems with a hospital information system. In this paper, the object-oriented analysis and design of the ECG storage and retrieval systems is reported.

Impedance mismatch of data flow is the major problem in the relational database when one is using the web based application development on the computer system. It effects the development of scalable and reusable web application. Due to this, the research cost of development and maintenance increases. Therefore the present work is an attempt towards an object-oriented database system by using Db4o to overcome the impedance mismatch problem. In the current work, the development of web application for Indian Postal Services by using Db4o is demonstrated on dot NET platform. Before developing the application, the authors used a Unified Modeling Language (UML) model in the form of UML class, sequence and use-case diagrams. The Db4o is used to store the object-oriented database and the performance of Db4o is observed through several object-oriented queries and corresponding results are demonstrated.

Cyclic query processing issues in object-oriented databases are investigated. A data and cyclic query model is defined for an object-oriented database system, using a graph model. Then the efficient processing of a general object-oriented cyclic query is discussed. For efficient processing, a general cyclic query and the access plans generated for a given query are defined and a cost model is developed to determine the cost for each access plant generated. The retrieval algorithms used for actual data retrieval are also investigated. >

A practical approach for coding object-oriented design in Ada is described. Even though Ada lacks direct support for two important object-oriented constructs, inheritance and polymorphism, an object-orient design can be implemente d with existing portable Ada constructs. More lines of code will be required t o defined the implied constructs of inheritance and polymorphism, but such cod e will have side benefits such as improved readability. The extra lines of code can be minimized with the use of coding rules.This paper does not suggest how Ada can be modified to implement inheritance and polymorphism; such matters are already being addressed by the Ada 9X committee. Instead, it is concern with meeting the needs of government sponsored contracts which require object-oriented design techniques and Ada as th e coding language. Furthermore, this must be done with Ada as it exists today [LRM] and should not require the use of precompilers.Without modification, Ada cannot be as flexible as an object-oriented language; but this is not the issue. In government contracted software, design and coding are distinct phases in the software development. The flexibility of the object-oriented approach can be used in the design phase independently from the target language. The issue is how to code a relatively stable object-oriented design in Ada.

CHAPTER 8 - Modeling Object-Oriented Systems

We investigate methods to improve the performance of algorithms for automatic storage reclamation of object databases. These algorithms are based on a technique called partitioned garbage collection, in which a subset of the entire database is collected independently of the rest. We evaluate how different application, database system, and garbage collection implementation parameters affect the performance of garbage collection in object database systems. We focus specifically on investigating the policy that is used to select which partition in the database should be collected. Three of the policies that we investigate are based on the intuition that the values of overwritten pointers provide good hints about where to find garbage. A fourth policy investigated chooses the partition with the greatest presence in the I/O buffer. Using simulations based on a synthetic database, we show that one of our policies requires less I/O to collect more garbage than any existing implementable policy. Furthermore, that policy performs close to a locally optimal policy over a wide range of simulation parameters, including database size, collection rate, and database connectivity. We also show what impact these simulation parameters have on application performance and investigate the expected costs and benefits of garbage collection in such systems.