This paper attempts to define an object-oriented database system. It describes the main features and characteristics that a system must have to qualify as an objectoriented database system. We have separated these characteristics into three groups: ffl Mandatory, the ones the system must satisfy in order to be termed an objectoriented database system. These are complex objects, object identity, encapsulation, types or classes, inheritance, overriding combined with late binding, extensibility, computational completeness, persistence, secondary storage management, concurrency, recovery and an ad hoc query facility. ffl Optional, the ones that can be added to make the system better, but which are not mandatory. These are multiple inheritance, type checking and inferencing, distribution, design transactions and versions. ffl Open, the points where the designer can make a number of choices. These are the programming paradigm, the representation system, the type system, and uniformity. We...

Bayesian networks provide a modeling language and associated inference algorithm for stochastic domains. They have been successfully applied in a variety of medium-scale applications. However, when faced with a large complex domain, the task of modeling using Bayesian networks begins to resemble the task of programming using logical circuits. In this paper, we describe an object-oriented Bayesian network (OOBN) language, which allows complex domains to be described in terms of inter-related objects. We use a Bayesian network fragment to describe the probabilistic relations between the attributes of an object. These attributes can themselves be objects, providing a natural framework for encoding part-of hierarchies. Classes are used to provide a reusable probabilistic model which can be applied to multiple similar objects. Classes also support inheritance of model fragments from a class to a subclass, allowing the common aspects of related classes to be defined only once. Our language h...

Schema versioning is one of a number of related areas dealing with the same general problem- that of using multiple heterogeneous schemata for various database related tasks. In particular, schema versioning, and its weaker companion, schema evolution, deal with the need to retain current data and software system functionality in the face of changing database structure. Schema versioning and schema evolution offer a solution to the problem by enabling intelligent handling of any temporal mismatch between data and data structure. This survey discusses the modelling, architectural and query language issues relating to the support of evolving schemata in database systems. An indication of the future directions of schema versioning research are also given.

ODE is a database system and environment based on the object paradigm. It offers one integrated data model for both database and general purpose manipulation. The database is defined, queried and manipulated in the database programming language O++ which is based on C++. O++ borrows and extends the object definition facility of C++, called the class. Classes support data encapsulation and multiple inheritance. We provide facilities for creating persistent and versioned objects, defining sets, and iterating over sets and clusters of persistent objects. We also provide facilities to associate constraints and triggers with objects. This paper presents the linguistic facilities provided in O++ and the data model it supports. 1. INTRODUCTION The object paradigm is a natural way of organizing data as it allows users to structure, retrieve and update data in terms of the application domain. ODE is a database system and environment based on the object paradigm. The database is defined, queri...

This paper presents an overview of EXODUS, an extensible database system project that is addressing data management problems posed by a variety of challenging new applications. The goal of the project is to facilitate the fast development of high-performance, application-specific database systems. EXODUS provides certain kernel facilities, including a versatile storage manager. In addition, it provides an architectural framework for building application-specific database systems; powerful tools to help automate the generation of such systems, including a rule-based query optimizer generator and a persistent programming language; and libraries of generic software components (e.g., access methods) that are likely to be useful for many application domains. We briefly describe each of the components of EXODUS in this paper, and we also describe a next-generation DBMS that we are now building using the EXODUS tools. 1.

A language for databases with sets, tuples, lists, object identity and structural inheritance is proposed. The core language is logic-based with a fixpoint semantics. Methods with overloading and methods evaluated externally providing extensibility of the language are considered. Other important issues such as updates and the introduction of explicit control are discussed. 1 INTRODUCTION The success of the relational database model [19, 38, 27] is certainly due to technological advances such as fast query processing or reliable concurrency control. However, we believe that a major factor in that success has been the existence of simple-to-use languages allowing the definition and manipulation of data. This has to be remembered while considering future generations of database systems. Object-oriented database systems are now being developed, e.g., [15, 12, 22, 39, 36]. An object-oriented approach [24] is used to answer the needs of a much wider variety of applications. Most of th...

Abstract A multidatabase system (MDBS) is a confederation of pre-existing distributed, heterogeneous, and autonomous database systems. There has been a recent proliferation of research suggesting the application of object-oriented techniques to facilitate the complex task of designing and implementing MDBSs. Although this approach seems promising, the lack of a general framework impedes any further development. The goal of this paper is to provide a concrete analysis and categorization of the various ways in which object orientation has affected the task of designing and implementing MDBSs.

Abstract not found

When a database is shared by many users, updates to the database schema are almost always prohibited because there is a risk of making existing application programs obsolete when they run against the modified schema. This paper addresses the problem by integrating schema evolution with view facilities. Each user is assigned his or her own database view, and develops application programs against the view. When new requirements necessitate schema updates for a particular user, then the user specifies schema changes to his personal view rather than to the shared base schema. Our view schema evolution approach then computes a new view schema that reflects the semantics of the desired schema change, and replaces the old view with the new one. This approach provides the means for schema change without affecting other views (and thus without affecting existing application programs). The persistent data is shared by different views of the schema, i.e. by both old as well as newly developed app...

The object-oriented paradigm has gained popularity in various guises not only in programming languages, but in user interfaces, operating systems, databases, and other areas. We argue that the fundamental object-oriented concept is encapsulation, and that all object-oriented mechanisms and approaches exploit this idea to various ends. We introduce the most important of these mechanisms as they are manifested in existing object-oriented systems, and we discuss their relevance in the context of modern application development.