Visualizing an algebra of objects

Visual languages provide syntactic features to depict graphs explicitly: they offer an alternative to text for the denotation of structures of relations. The language viz was therefore devised to provide a means for visualizing relational specifications and programs. The increased understanding of object-oriented program design makes it sensible to enhance viz to cope with this style, and so provide a single notation for small and large applications. An object is modelled as a graph, linking interfaces (methods) with internal components (the state). Each interface is itself a graph: structure can be introduced into links among objects. Links may be streams of events. An interface may be exclusive, such that one link prevents other connections (as in claiming a resource); or it may be inclusive, with a link creating a copy of the interface (as in a function invocation)