In this paper we present a method of code imple-mentation that works in conjunction with collab-oration and responsibility based analysis model-ing techniques to achieve better code reuse and resilience to change. Our approach maintains a closer mapping from responsibilities in the analy-sis model to entities in the implementation. In so doing, it leverages the features of flexible design and design reuse found in collaboration-based de-sign models to provide similar adaptability and reuse in the implementation. Our approach re-quires no special development tools and uses only standard features available in the C++ language. In an earlier paper we described the basic mech-anisms used by our approach and discussed its advantages in comparison to the framework ap-proach. In this paper we show how our approach combines code and design reuse, describing spe-cific techniques that can be used in the develop-ment of larger applications. 1

Taxonomies are an important part of conceptual modeling. They provide substantial structural information, and are typically the key elements in integration efforts, however there has been little guidance as to what makes a proper taxonomy. We have adopted several notions from the philosophical practice of formal ontology, and adapted them for use in information systems. These tools, identity, essence, unity, and dependence, provide a solid logical framework within which the properties that form a taxonomy can be analyzed. This analysis helps make intended meaning more explicit, improving human understanding and reducing the cost of integration.

A common problem of ontologies is that their taxonomic

When modelling a domain, it is often the case that certain individuals are represented as belonging to multiple categories, generating therefore "tangled " hierarchies: 1. A physical object can be seen as an amount of matter 2. A hole can be seen as a region of space

For decades, the notion of roles has been discussed and applied in various fields of computer science in a number of different ways, but apparently no consensus at an integrative definition has been reached yet. Therefore, roles qualify for a comprehensive analysis with the aim of covering and generalizing recurrent understandings and uses of roles. Regarding ontology development, this would further allow to relate or integrate this notion into top-level ontologies. For these purposes, this paper extends and refines an earlier analysis of roles which is primarily based on the notions of role, player, and context and their interrelations (Loebe 2003). In particular, the classification of roles therein is refined in the light of recent papers and discussions on recurrent role issues. We argue that roles can be understood in two distinct ways which are mixed in the literature. Firstly, abstract roles provide a means of viewing something in a context, whereas social roles are complex social objects for which a relation to players (frequently referring to material objects) is of primary interest.

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.

COCA (Collaborative Objects Coordination Architecture) was proposed as a novel means to model and support collaborations over the Internet. Our approach separates coordination policies from user interfaces and the policies are specified in a logic-based language. Over the past year, both the collaboration model and the specification language have been substantially refined and evaluated through our experience in building real-life collaboration systems. This paper presents the design of the specification language and illustrates the main ideas with a few simple design examples. Semantics, implementation, runtime support, and applications are also covered but not as the focus of this paper.

Traditional object-oriented programming languages do not support the dynamic type change of an object so as to model the behavior of real world entities which change their status over time. This is a severe limitation in the context of a database programming language. Moreover, traditional object-oriented languages do not model the fact that the behavior of real world entities may depend on the role that they play. This paper describes the data model for DOOR, a dynamic object-oriented database programming language with role extension, which addresses these problems. We distinguish object classes from role classes by defining roles (instances of role classes) as parts of objects (instances of object classes). Objects are represented by globally unique and unchangeable identifiers while roles are represented by the names of their role classes as well as their values. The data model described in this paper emphasizes the role representation as well as the player qualification for the rol...

. In most object-oriented languages and systems, objects must belong to a single most specific class. Relaxing this requirement, also known as role modeling, has been proposed by several research groups independently. To shed some light on the similarities and differences of the proposed solutions we provide an overview and comparison thereof in this paper. 1. Introduction Object-oriented modeling and development has left research laboratories and is widely used in industry. Not least since Aksit's and Bergmans' paper at OOPSLA'92 [Aksi92] several problems, however, with object-oriented modeling are known and solutions thereof are sought. One of the problems, the lack of adequate object evolution mechanisms - also known as role modeling - has attracted the attention of several research groups. Meanwhile different proposals for extending the traditional object model with role mechanisms have been published. To be able to reason about the different approaches an overview and comparison ...

: 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 ...