Deening Composition Operators for Object Interaction Deening Composition Operators for Object Interaction

Note: Most SVRC technical reports are available via anonymous ftp, from ftp.cs.uq.edu.au in the directory /pub/SVRC/techreports. Abstract Operations in object-oriented systems are often a composition of other operations, deened across multiple objects. The aim of this paper is to formally develop a suite of composition operators for specifying object interaction through operation composition. Experience with using Object-Z to design a range of object-oriented systems has suggested that four composition operators, conjunction, parallel, choice and sequential composition, are necessary and, at least for commonly occurring architectures, suu-cient. In this paper, an abstract model of operations in object-oriented systems is rst developed and used as the basis for deening the formal semantics of these composition operators.