Composability Issues in Object Orientation

In the increasingly complex applications of today, the ability to select existing components and compose them into new objects is becoming more important than ever. The Workshop on Composability Issues in Object-Orientation addressed research issues such as; what is composability, why do we need it, what are the approaches to achieve it, and what are the composability problems in the current object-oriented models.

The proceedings of this workshop start by a workshop report that describes the presentations, discussions and conclusions. This is followed by a number of papers by participants of the workshop. An important selection criteria has been the attempt to describe the field of composability research and give an impression of the various directions and approaches.

We start with an invited paper by Gregor Kiczales on "Aspect Oriented Programming", which is a significantly different and innovative approach towards the composition of systems from different parts. Then a paper by Lodewijk Bergmans offers an introduction to composability, followed by a paper from Carine Lucas, Patrick Steyaert and Kim Mens, "Research Topics in Composability", which addresses three inhibitors of composability.

The 5 papers that follow each address a different aspect of composability: the paper by Christian Prehofer, "From Inheritance to Feature Interaction" present an object model that allows for the composition of objects from different functional parts called features. The paper by Jan Bosch discusses three modeling problems and argues that these can be solved by composition through superimposition. In the paper by Fernando Sanchez et.al., entitled "Issues in Composability of Synchronization Constraints in Concurrent Object-Oriented Languages" the composition of objects that incorporate synchronization constraints is discussed. Boris Bokowski addresses the issue of the interaction between objects that are composed together in his paper "Interaction Protocols for Composing Concurrent Objects". The final paper, "Class Composition in FACE, a Framework Adaptive Compsition Environment", by Theo Dirk Meijler, Serge Demeyer and Robert Engel presents an approach to the composition of objects at a meta-level.

We think that this set of papers gives a nice impression of the various research that is being conducted in this area. We have also included a list of participants with their position papers, addresses and pointers to their web pages. Finally, we would like to thank all the participants of the workshop for their cooperation and contributions.

Lodewijk Bergmans & Pierre Cointe (workshop organisers)