Beyond the Interface: Modelling the Interaction in a Visual Development Environment

Chris Scogings1and Chris Phillips 2

1 Institute of Information & Mathematical Sciences Massey University
Albany Campus
Auckland
New Zealand

2 Institute of Information Sciences & Technology Massey University
Turitea Site
Palmerston North
New Zealand

ABSTRACT
A shortcoming of current user interface building tools is that while they permit the designer to construct an interface made up of a set of screens, they provide no model of the interaction. Interface builders could be extended to produce such a model as an automatic by product of the construction of the interface. This research examines such an extension to Delphi. The interaction model is specified in Lean Cuisine+, a semi- formal graphical notation for describing the behaviour of direct manipulation GUIs.

KEYWORDS

interface development tools, interaction model, Lean Cuisine+

INTRODUCTION
A variety of tools and techniques are available to support the development of interactive systems, from pencil and paper mockups to full scale interface development environments (Myers, 1993; Szekely, 1994). Interface builders, such as Visual Basic and Delphi are capable of producing industrial strength applications, and are commonly based on general purpose (often object-oriented) programming languages. They provide access to a toolkit of widgets, and support visual programming, which provides designers with immediate feedback on the look and feel of the interface.
A shortcoming of current interface builders is that while they permit the designer to construct a set of screens, they provide no model of the interaction. The interface exists and can be exercised, but no specification or description of the interaction exists outside the code produced. The focus is on the interfacerather than the interaction. Interface builders could be extended to produce a model of the interaction as a byproduct of the construction of the interface. This research explores such an extension to Borland's Delphi, and briefly reviews its utility. The interaction model is specified in Lean Cuisine+ (Phillips, 1995).
MODELLING THE INTERACTION
Delphi is a visual development tool which can be used to create PC Windows applications. Delphi supports a 'drag-and-drop' approach to creating interfaces. Using Delphi, the designer can define the appearance of screens, and also the behaviour of menus, buttons etc in linking screens. Thus both the look and feel of the user interface can be created. A Delphi prototype has been developed for an Automatic Teller Machine (ATM) based on a touch screen. Numeric data, eg, the PIN number, is entered using touch keys. Six Delphi screens (Forms) have been defined, including those for Card Entry, Deposit, Account Balance, and Withdrawal. The interaction model for the Delphi ATM application has been produced via a conversion process which makes use of a prototype Lean Cuisine+ software support environment (Phillips, 1994). Lean Cuisine+ is a semi-formal graphical notation for specifying the behaviour of GUIs in terms of the constraints and dependencies which exist between selectable dialogue primitives. For the ATM, the conversion process

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