Copyright 2001 IEEE. Published in the Proceedings of 2003 IEEE Human-Centric Computing Conference, Auckland, New Zealand, October 2003. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the IEEE. Contact: Manager, Copyrights and Permissions / IEEE Service Center / 445 Hoes Lane / P.O. Box 1331 / Piscataway, NJ 08855- 1331, USA. Telephone: + Intl. 732-562-3966. An E-whiteboard Application to Support Early Design-Stage Sketching of UML Diagrams Qi Chen1, John Grundy1, 2 and John Hosking1 Department of Computer Science1 and Department of Electrical and Electronic Engineering2, University of Auckland, Private Bag 920, Auckland, New Zealand {qche013@ec.|john-g@cs.|john@cs.}auckland.ac.nz Abstract We describe a Unified Modelling Language (UML) diagramming tool that uses an E-whiteboard, pen-based sketching interface to support collaborative design. Our tool allows designers to sketch UML visual modelling language constructs, mixing different UML diagram components, free-hand annotations and hand-written text. A key novelty of our approach is the preservation of hand- drawn diagrams and support for manipulation of the diagrams using pen-based actions. UML sketches can be ���formalized��� to computer-recognised and drawn diagrams, and exported to a 3rd party CASE tool. 1. Introduction One of the most common tools used by software designers when doing collaborative design work is a whiteboard. This is used to collaboratively sketch software design ideas (for example as whole or partial UML diagrams), explore architectural solutions, capture high level code fragments, organise design teams, schedule events, etc, as shown in Figure 1 [5, 11]. Three partial UML diagram types are shown in the whiteboard sketches on the right ��� (1) ���use cases��� (stick figure and oval), describing actors (users) interacting with a system (2) ���classes��� (box with horizontal lines inside and arrowed lines between), describing classes of types and their relationships and (3) ���sequences��� (boxes with vertical lines underneath and horizontal arrowed lines between), denoting message sequence flow between objects. Some key advantages of using whiteboards for sketching such UML (and other) designs include: ��� Immediacy: there is very little effort required to make a whiteboard ���available���, and it is very easy to create diagrams, capture text, delete or extend information. ��� Versatility: a whiteboard can be used to sketch diagrams of multiple (even mixed) notations, as well as supporting a variety of secondary notations, such as comments, arrows, highlighting, and colour. Sketches do not have to be precise nor complete in any formal manner. ��� Size: a whiteboard is generally big enough to hold several significant sketches and to allow several people to easily collaborate. ��� Collaboration: a whiteboard allows multiple designers to gather around and discuss evolving designs, including taking turns at sketching and annotating designs on the whiteboard Disadvantages of conventional whiteboards for such tasks are a lack of data persistency, an inability to readily transfer information to electronic design tools (eg CASE tools), difficulty making some changes (eg repositioning parts of diagrams), lack of collaboration support at a distance, and ink dust on your clothing. For these reasons much recent work has focussed on the development and use of large electronic whiteboards [19, 15, 3, 11]. We describe an electronic whiteboard-based early design phase sketching tool. This allows UML diagrams to be sketched, recognised, and integrated with a conventional CASE tool. Key novelties of our approach include the preservation of hand-sketched design elements, provision of various pen-based manipulation facilities on sketches, and ability to formalise sketches to computer-drawn diagrams for export to CASE tools. 2. Related Work Electronic whiteboards have become a popular way of support a wide range of activities. These include meeting support with collaborative document display, review and annotation [21] education [3] presentation control and annotation [1] and (early) design [11]. The previously listed input advantages of conventional whiteboards are partially replicated with E-whiteboard applications, with additional advantages of digital data capture and display, distributed work support and control via sketching/gesture-based interfaces [1, 3, 19].