Human-computer Interface

Robert ].K. Jacob is investigating formal specification techniques for describing user-computer interaction for both the design and construction of user interfaces for computer systems. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission. © 1983 ACM 0001-0782/83/0400-0259 75¢. INTRODUCTION Formal specification techniques have been applied to many aspects of software development. Their value is that they permit a designer to describe the external behavior of a system precisely without specifying its internal implementation. However, such techniques have been applied only rarely to the specification of user interfaces, despite the fact that the user interface is increasingly being recognized as a critical element in many software systems. One is handicapped in trying to design a good user interface without a clear and precise technique for specifying such interfaces. The design of the user interface for a military message system has a special importance because of its role in maintaining the security of classified messages. Enforcement of system security requires that the user understand the security-related consequences of his or her actions, but often such consequences are not intuitively obvious. Recent experimental results indicate that communicating the security implications of an action and obtaining meaningful approval or disapproval from a user can be very difficult [18]. In the Military Message System (MMS) project at the Naval Research Laboratory, formal specification techniques are being used to construct a family of secure message systems [6, 7]. Compatible specification techniques must therefore be applied to the human-computer interfaces for such systems. Rapid prototypes of military message systems will then be constructed based on these specifications [8], and, later, full-scale prototypes will be built. This paper describes the specification of the user interface module for the family of message systems, surveys specification techniques that can be applied to human-computer interfaces, provides examples of specifications, and presents some conclusions [10].