Usability and UML

User Vision discusses the main issues and points arising from the Usability and UML symposium in Edinburgh on the 18th of January 2002.

Successful and usable system interfaces are built out of the co-operation of two disciplines: software engineering and human computer interaction (HCI). Both disciplines have concepts, techniques, and notations for specifying, constructing, and evaluating their respective editing objects, but they are based on two different views on user interfaces. The user-oriented view focuses on the user’s tasks and the required interactions with the system to fulfil these, while the system-oriented view defines how the software is to be implemented. Although design activities for these often occur in parallel, there are two different design spaces, and different design communities, which inevitably join each other in the user interface.

It has been widely recognised that the two disciplines should interact frequently to create a more usable user interface design. The adoption of Object Oriented development methods has been a great catalyst since these enable a move away from the rigid ‘waterfall’ design process, toward an iterative approach which can integrate information about users, their context, and preferred task methods up-front in the system life cycle. Incorporating such user-defined information has enabled archaic batch system designs and other commercial applications to better suit their end-users. This was an encouraging sign. Although the two camps did not yet speak the same language, objects, actions, classes, and interaction diagrams are recognisable terms which the HCI community recognise.

Within the Object Oriented process, UML (Unified Modelling Language) has become the de facto standard and is seen by many as the best opportunity to link the two areas. It reflects several HCI task modelling concepts, and gaps which exist between software engineering and HCI representations might even be bridged by alterations to the original UML. (At this stage it is worth noting that UML is a language and not a tool or a method, but since its usage is usually through tools such as Rational Rose as part of a systems development methodology, the rest of this article avoids being overly pedantic!)

So is UML a ‘Trojan horse’ by which we may infiltrate user-centred design principles into traditional software designers? That was a central question at the Usability and UML symposium in Edinburgh, sponsored by the British HCI Group and the ScotlandIS Usability Forum. Several leading academics and practitioners shared their views and experience to let the attendees at this sold-out event decide for themselves.

The 12 speakers covered a range of topics, beginning with a top-level introduction to UML concepts and diagrams, by Birgit Bomsdorf (FernUniversität Hagen)and Gerd Szwillus (University of Paderborn). Adding further foreign spice, Phillippe Palanque came all the way from the University of Toulouse to deliver a fast-paced tour de force presentation on applying Interactive Systems Engineering in the development of an air traffic control system interface.

Dave Roberts next gave an insight into how IBM adapts UML to achieve a more user-centred system throughout the ‘4 D’s’ (discovery, design, development and deployment), and especially facilitates communication within the design team and to the client company,

After summarising how UML can enable a synthesis between two previously distinct disciplines, Mark Van Harmelen moderated a discussion on what needs to be done technically and by the community to ensure success of UML as a ‘Trojan horse’. Dave Martin, Mark Rouncefield (Lancaster University) and Rob Proctor (Edinburgh University) then discussed how ethnographers can deliver patterns as a useful description of user behaviour in a notation that is amenable to system designers.

Perdita Stevens (Edinburgh University) predicted benefits from future UML tools that will better support user-centred design for everyday programmes and systems. She emphasised tomorrow’s UML tools must be flexible enough to support the different types of users of UML, from those that collaboratively ‘do’ a design at a whiteboard to those that record and refine a design at a computer screen. Peter Johnson of the University of Bath vividly applied UML to model the social and technical interactions that resulted in a plane accident, and finally Lachlan Mackinnon (Heriot Watt University) focused on potential extensions to UML notation and usage to make it the ‘Babel fish’ of system design.

Throughout the day it was generally recognised that UML diagrams are different than HCI task models, most significantly because there is no specific modelling of user goals and intentions in UML. However, there were opposing views on whether or not UML should be adapted to better represent HCI notations or individual development projects. Philippe Palanque and others felt that such mutations would reduce the ability of UML to serve primarily as software development notation. Others pointed out that that better synthesis between HCI and software engineering could only be achieved by modifications such as: 1) extending the basic UML notations, 2) modifying existing notations, or 3) somehow linking the UML diagrams to separate external task models.

The symposium showed that, as a way of relating the two design spaces of HCI and software engineering, UML is currently the best way of applying Object Oriented methods. Innovation and natural evolution of UML will certainly occur, and, as often stated in such symposiums, more research and case studies from practice will benefit everyone. The session ended on the encouraging note that it seemed inevitable that HCI and software engineering will move towards and learn from each other. Chair Tom McEwan (Napier University) highlighted that the equal mix at this event of researchers and practitioners, software engineers and HCI specialists, was an opportunity for all present to integrate their efforts better than was currently done.

Tom thanked organisers Alistair Kilgour (of BHCIG), Polly Purvis (ScotlandIS) and Judith Ramsay (ScotlandIS Usability Forum), and Ian Smith and Sun Hea Choi for technical support. The Symposium web-site [Sorry but this site is no longer available].

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This article was written by Chris Rourke. Chris is the Managing Director of User Vision, a usability and accessibility consultancy that helps clients gain a competitive advantage through improved ease of use.

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