During the last decade, there has been progress within the object-oriented community in agreeing on what object-orientedness means. The role of object identity, specialization, inheritance, and dynamic binding have been examined. However, a careful look at articles written by people with a theory, programming language, database, and software engineering background shows that the semantical understanding of the same features still differs considerably. A well-known example is the feature of inheritance, which has quite a different meaning for persons from the database community with a semantic data model background and persons from the programming language community with a compiling technique background. This observation also applies to the literature on object-oriented software development methods. Here, object-oriented analysis and design methods are often heavily influenced by semantic data modelling concepts. An implementation of an object-oriented design by an object-oriented programming language usually causes more difficulties than expected although the "same" object-oriented paradigm is used.

Even when there is agreement on terminology, there are legitimate differences in perspective among different object-oriented research communities. It was the intention of this seminar to clarify differences in terminology as well as to clarify legitimate differences in perspective. The seminar brought together an approximately equal number of researchers from each of these four areas and was being jointly organized by four organizers representing each of the four areas:

• theoretical foundations of object-orientedness (H.-D. Ehrich)
• object-oriented programming languages (P. Wegner)
• object-oriented database systems (J. Paredaens)
• object-oriented software development methods (G. Engels)

This gathering of experts, working in the "same" field within computer science, offered an excellent opportunity to discuss and understand the differences, similarities, and commonalities of basic notions within the object-oriented world. In addition, the specific atmosphere of Schloß Dagstuhl gave new impulses to already existing cooperations and stimulated new "interdisciplinary" research in the whole range of object-orientedness.

The Dagstuhl-Seminar-Report summarizes the presentations and discussions during the seminar. It comprises the final seminar program, abstracts of all (morning) talks, summaries of all (afternoon) workshops, as well as a list of the participants.

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