Object Oriented Database

The object-oriented approach is being used in several areas of computing, including programming, databases, computer-aided design, and office information systems. The paper is a tutorial introduction to object-oriented databases, which is a new application in this field, although object-oriented programming has been under development since the late 1960s. The paper describes the background to object-oriented databases and outlines the rationale for this approach. It concludes with a possible application, in this case a cartographic database, explaining why the object-oriented approach is more appropriate to this application than traditional database approaches, such as the relational approach.

ODB-Tools is a integrated environment for the object oriented database (OODB) validation, preserving taxonomy coherence and performing taxonomic inferences, and semantic query optimization. Semantic query optimization uses problem-specific knowledge (e.g. integrity constraints) for transforming a query into an equivalent one (i.e. with the same answer set) that may be answered more efficiently. The approach of the tool is based on two fundamental ingredients. The first one is the OCDL description logics proposed as a common formalism to express class descriptions, a relevant set of integrity constraints rules (IC rules) and queries. The second one are Description Logics inference techniques, exploited to evaluate the logical implications expressed by IC rules and thus to produce the semantic expansion of a given query. The optimizer tentatively applies all the possible transformations and delays the choice of beneficial transformation till the end. ODB-Tools is a ODMG 93 [1] compliant tool, both for the schema definition (ODL language) and for the query language (OQL), The tool is available in internet at http://sparc20.dsi.unimo.it and supports an on-line graphical interface developed in Java language.

Horizontal partitioning is a logical database design technique which facilitates efficient execution of queries by reducing the irrelevant objects accessed. Given a set of most frequently executed queries on a class, the horizontal partitioning generates horizontal class fragments (each of which is a subset of object instances of the class), that meet the queries requirements. There are two types of

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 dis- tributed fashion. Such applications need a method for users to share and update the VRML objects in real-time. To al- low concurrent shared real-time access, our approach is

Systems for the integration of data in molecular biology are becoming more and more important because scientists as well as applications can not always find all relevant data in one database. Another advantage of data integration is the possibility to derive information of a new quality using semantic relations between the integrated data of various databases. With the requirement to feed an application for the simulation of metabolic pathways with necessary data we are developing a system for the integration which is based on a hybrid approach. As a first possibility a datawarehouse is used for an easy and fast access. The storage system of this datawarehouse is an object oriented database system. The second possibility of our hybrid approach of integration is the capability of a homogeneous online access to various data sources such as database systems and flat file based systems via the internet. The components for the data access are modular. Thus they can be created and modifie...

This paper describes a design methodology for an object oriented database, based on a semantic network. This approach is based on the assumption that semantic data models are more powerful and more easy to use than current proposed object oriented data models. They are especially more powerful in representing integrity constraints and various relationships. Object oriented data models are generally based only on class hierarchies and inheritance, plus their ability to represent the behaviour of objects. But this latter capability is generally provided through an algorithmic language which cannot be considered as a conceptual language. In this paper, we combine the two categories of data models and give a procedure on how to translate the conceptual model to the logical model.

The Horizontal Fragmentation (HF) is a process for reducing the number of disk access to execute a query by reducing the number of irrelevant objects accessed. In this paper, we present horizontal fragmentation based on a set of queries, and develop strategies for two versions of HF: primary and derived. Primary horizontal fragmentation of a class is performed using predicates