This is a progress report on an experiment to build a compile-time metaobject protocol for Scheme. The compilation setting raises issues not present in runtime oriented MOP's, due to the complexity of the domain and the coupling between different parts. To address the complexity of the domain, wehave developed a structure that decomposes the description of an implementation into a combination of many small, partially interacting, choices. To address the coupling, we have developed a decision making process that allows implementation choices to be made by a collaboration between user interventions and default decision making.

We describe the TIGUKAT objectbase management system that is under development at the Laboratory for Database Systems Research at the University of Alberta. TIGUKAT has a novel object model whose identifying characteristics include a purely behavioral semantics and a uniform approach to objects. Everything in the system, including types, classes, collections, behaviors, functions as well as meta-information, is a first-class object with well-defined behavior. In this way, the model abstracts everything, including traditional structural notions such as instance variables, method implementation and schema definition, into a uniform semantics of behaviors on objects. Our emphasis in this paper is on the object model, its implementation, the persistence model and the query language. We also (briefly) present other database management functions that are under development such as the query optimizer, the version control system and transaction manager.

. The decomposition of a software application into components and connectors at the design stage has been promoted as a way to describe and reason about complex software architectures. There is, however, surprisingly little language support for this decomposition at implementation level. Interaction relationships which are identified at design time are lost as they get spread out into the participating entities at implementation. In this paper, we propose first-class connectors in an object-oriented language as a first step towards making software architecture more explicit at implementation level. Our connectors are run-time entities which control the interaction of components and can express a rich repertoire of interaction relationships. We show how connectors can be reused and how they enhance the reuse of components. 1 Introduction In modeling software architectures Allen and Garlan distinguish between implementation relationships and interaction relationships of ...

We propose a reflective model to express and to automatically manage dependencies between objects. This model describes reflective facilities which enable the changing of language semantics. Although the importance of inter-object dependencies is well accepted, there is only limited object-oriented language support for their specification and implementation. In response to this lack of expressiveness of object models, the flo language integrates dependency management into the object oriented paradigm. Dependencies are described as first class objects and flo automatically maintains the consistency of the dependency graph.

Design patterns are becoming increasingly popular as a way to describe solutions to general design problems. However, the implementation of design patterns has received only little attention so far. Traditional object models do not provide explicit support for design patterns. This situation leads to problems: design patterns are lost during the implementation creating a gap between software design and the implementation, and the software engineer has to implement a large number of methods or classes with trivial behavior. In this paper, we present how the interaction first class entities of the FLO language that represent interaction among object support explicit representation of design patterns at the implementation level. ...

Object models strive for a high degree of semantics in order to capture and formalize the requirements of the real-world application. Aggregation is one of the high-level semantic primitives in object-oriented design and knowledge representation. Intuitively, it relates a composite object to its components. Most modern object-oriented methods integrate it as one of the central concepts of their object model since part-whole lattices can be designed in various advanced modeling domains such as object-oriented database, hypertext, multimedia, WWW or CAD/CAM. This paper aims to examine the problem of extending an open system such as the Common Lisp Object System (CLOS) with this kind of modeling abstraction.

Contents 1 Le mod#le de donn#es sous-jacent 3 2 Structure du prototype 7 2.1 Architecture de Samovar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.1 La biblioth#que de classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1.2 Le moteur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.1.3 Le serveur et les clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 Vue fonctionnelle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3 Interfaces de Samovar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.4 Am#liorations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3 Le Langage de D#nition de Donn#es 15 3.1 Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.2 Roles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .