Formal object-oriented user-interface design

A notation is presented for formally describing the design of a user interface. A specification of a system is given using the Object-Z formal specification language and then extended to describe presentation (user interface design) using the User Action notation (UAN). The semantics for the design are described using an Object-Z class library. The Object-Z notation is extended to enable designs to be described by adding UAN annotations to the specification. The extended Object-Z notation supports a design philosophy of abstract specification of functionality prior to development of a concrete user interface design. By focusing attention on functionality initially, premature design effort may be avoided. Such formal specifications and designs are useful for documenting a user interface design and enable analysis of the usability and safety of interactive systems.