The duality of objects and relationships is so deeply embedded in our thinking that almost all modelling languages include it as a fundamental distinction. Yet there is evidence that the two are naturally complemented by a third, equally fundamental notion: that of roles. Although definitions of the role concept abound in the literature, we maintain that only few are truly original, and that even fewer acknowledge the intrinsic role of roles as intermediaries between relationships and the objects that engage in them. After discussing the major families of role conceptualizations, we present our own basic definition and demonstrate how it naturally accounts for many modelling issues, including multiple and dynamic classification, object collaboration, polymorphism, and substitutability. <3 2000 Elsevier Science B.V. All rights reserved.

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To achieve the goal of realizing object adaptationto environments, a new role-based model Epsilon and a language EpsilonJ is proposed. In Epsilon, an environment is defined as a field of collaboration between roles and an object adapts to the environment assuming one of the roles. Objects can freely enter or leave environments and belong to multiple environments at a time so that dynamic adaptation or evolution of objects is realized. Environments and roles are the first class constructs at runtime as well as at model description time so that separation of concerns is not only materialized as a static structure but also observed as behaviors. Environments encapsulating collaboration are independent reuse components to be deployed separately from objects. In this paper, the Epsilon model and the language are explained with some examples. The effectiveness of the model is illustrated by a case study on the problem of integrated systems. Implementation of the language is also reported. 1.

The role generic relatio nship fo r co nceptualmo deling relates a classo o jects (e.g., perso s) and classeso f roz# (e.g., students, emplo yees) fo thow o bjects. The relatio ship is meant to capture tempofiz aspectso f real-wo rldo bjects while the cozwO generalizatio relatio - ship deals with theirmow static aspects. This paper presents a generic ro lemo del, where the semanticso f ro les is defined at bo th the class and the instance levels. The paperalso discusses the interactio between the ro# relatio ship and generalizatio , and it attempts to clarify sofi o f their similarities and di#erences. Keywords: Infowzfi io mo deling,roz mo del, o ject techno lob 1

Sound naming schemes for objects are crucial in many parts of computer science, such as database modeling, database implementation, distributed and federated databases, and networked and distributed operating systems. Over the past 20 years, physical pointers, keys, surrogates and object identifiers have been used as naming schemes in database systems and elsewhere. However, there are some persistent confusions about the nature, applicability and limits of these schemes. In this paper we give a detailed comparison of three naming schemes, viz. object identifiers, internal identifiers (often called surrogates) and keys. We discuss several ways in which identification schemes can be implemented, and show what the theoretical and practical limits of applicability of identification schemes are, independently from how they are implemented. In particular, we discuss problems with the recognition and authentication of identifiers. If the identified objects are persons, an additional problem is that object identification may conflict with privacy demands; for this case, we indicate a way in which identification can be combined with privacy protection.

. This paper presents a conceptual toolbox for software specification and design that contains techniques from structured and objectoriented specification and design methods. The toolbox is called TRADE (Toolkit for Requirements and Design Engineering). The TRADE tools are used in teaching informatics students structured and object-oriented specification and design techniques, but the toolkit may be of use to practicing software engineers as well. The conceptual framework of TRADE distinguishes external system interactions from internal components. External interactions in turns are divided into external functions, behavior and communication. The paper shows that structured and OO analysis offer a small number of specification techniques for these aspects, most of which can be combined in a coherent software design specification. It is also shown that the essential difference between structured and object-oriented software design approaches lies in the separation of data storage, data ...

In this work, we present an automatic codegdevB# ion process from conceptual models. This process incorporates the use of desig patterns in OO-Method, an automated software production method, which is built on a formal object-oriented model called OASIS. Our approach defines a precisemapping between conceptual patterns,desig patterns and their implementation.Desig patterns make the codegd eration process easy because they provide methodologhod g idance to g from the problem space to the solution space. In order to understand these ideas, we introduce a complete codegdevF# ion process for conceptual models that have dynamic specialization relationships. This proposal can be incorporated into CASE tools, making the automation of the software production process feasible. # 2002 Elsevier Science B.V. All rigv# reserved.

: Application environments that object-oriented database management systems support are characterized by a highly evolving nature. Two different forms of evolution can be distinguished for object-oriented databases: evolution of schema and evolution of instances. This paper deals with evolution of instances in the context of the Chimera object-oriented deductive data model. In particular, problems related to object migration, dynamic object classification and multiple class direct membership are discussed. 1 INTRODUCTION There are many aspects related to evolution in object-oriented databases. Not all of them have been investigated in sufficient depth. Generally speaking, one can distinguish between evolution of schemas - for example, modifying a class definition - and of instances - for example, the migration of an instance from one class to another. In the latter kind of evolution, an instance modifies its own structure while maintaining the same identity. In this paper we discuss ...

Abstract. In this paper we briefly present some solution strategies for situations in which it is necessary to transform multiple inheritance schemes into single inheritance or non-inheritance “equivalent ” schemes. The strategies are divided into basic strategies and combined strategies. The mechanisms presented are comparatively analyzed in the light of some ideal characteristics to be accomplished by hierarchy transformation strategies. 1

Abstract. Role is very important in ontology engineering. Although OWL has been available for ontology representation, consideration about roles is not enough. It can cause to decrease semantic interoperability of ontologies because of conceptual gaps between OWL and developers. To overcome this difficulty, this paper presents some consideration for dealing with roles using OWL. 1.