Object views: Extending the vision

A mechanism for producing views in an object-oriented system is presented. The results are analogous to database views in traditional database systems, except that the object views presented hide or expose methods as well as data. The mechanism is based on the object model´s built-in facilities for defining data and procedural abstractions and for constructing new types and objects. It uses the type system and the query language of the model to support arbitrary transformations of the underlying representations in defining database views, without introducing any new mechanism specifically to support views. Careful use of the query language allows one to define updatable views. Also indicated are how abstraction and view mapping capabilities can be used to support federation of heterogeneous software and databases