IEEE TRANSACTIONS ON MULTIMEDIA, VOL. 8, NO. 3, JUNE 2006 529 Interactive Dialogue Model: A Design Technique for Multichannel Applications Davide Bolchini, Member, IEEE, and Paolo Paolini, Member, IEEE Abstract—Multichannel applications deliver the same content and a “similar interactive experience” using different devices and different technologies (e.g., web sites, palm held devices, car navigators, or interactive TVs). Various channels imply a number of differences, including screen (size), keyboard (size), pointing devices, output devices, performances, and the context of use (standing, sitting, walking, etc.). In most cases, today, applications for different channels are designed and implemented almost “independently,” with ineffectiveness for the developers (high costs) and ineffectiveness for the users (loss of consistency across the different channels and the perception that they are “different applications”). This paper presents an interactive dialogue model (IDM), a novel design model specifically tailored for multichannel applications. The background research, moving from linguistic theories and practices, has led us to the develop- ment of a “channel-independent” design model (based on dialogue primitives). Design can start in a “conceptual,” channel-indepen- dent fashion, and then proceed into a further “logical” design oriented toward specific channels of communication. Designing an interactive application in two steps (channel-independent first, and channel-dependent later) allows a number of advantages without making more cumbersome the overall design process. Beside the emphasis on multichannel, IDM has additional distinc- tive features: it is lightweight, providing a few set of primitives (and a simple graphic notation) which are easy to learn and teach. Moreover, it is suitable for brainstorming and generating ideas at early stage during design (or during the shift from requirements to design); finally, it is cost-effective (it requires little effort from designers) and modular (designers can take the part they wish, not being forced to “all or nothing”). IDM has been validated both in the academic and industry en- vironments, providing excellent results so far. Index Terms—Design methodology, interactive systems, user centered design, user interfaces. I. INTRODUCTION L IGHTWEIGHT design processes and usability are being recognized, more and more, as relevant for all the design methodologies, and for the design of interactive applications in particular. Different factors are being implied here. 1) It must be easy to teach the design methodology (and the design model) to anyone (from students to practitioners). Professionals, especially, do not have time and resources to Manuscript received July 6, 2004; revised May 9. 2005. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Ryoichi Komiya. D. Bolchini is with the TEC-Lab, Faculty of Communication Sciences, Uni- versity of Lugano, 6900 Lugano-TI, Switzerland (e-mail: davide.bolchini@lu. unisi.ch). P. Paolini is with the Hypermedia Open Centre (HOC), Department of Electronics and Informatics (DEI), Politecnico di Milano, 20120 Milano, Italy (e-mail: paolo.paolini@polimi.it). Digital Object Identifier 10.1109/TMM.2006.870733 invest for learning new methodologies; one of the success factors of “Entity Relationship” (probably the most suc- cessful design model, ever) stems from the fact that it was very easy to transmit its basic concepts, both in academia and professional environment. 2) It must be possible to use the design model for brain- storming, i.e., for generating and discussing ideas among developers, with stakeholders, and with potential users. It is of little use to have a design model capable of representing only fully developed solutions. 3) It must require little time to write down design ideas: de- velopers do not like to spend too many resources in pre- liminary activities. 4) It must be possible to move, smoothly, from a general de- sign, to more detailed design, without need for excessive reworking and without need for completeness; in other words, even an incomplete design document must be useful and understandable. Other factors could be added to the above list. That is enough to set the scene for this work. The complexity and the “rich- ness” of the design model is not what we are aiming for. Sim- plicity and “usability” of the design model itself, and of the cor- responding design methodology, is our goal. Even with the above requirements, there is apparently no need for further design models or methodologies: the literature about design models is (over)abundant, as it is discussed in the “Re- lated Work” section. Besides technical (minor) differences, however, current de- sign models share a common feature: they are all based upon an information-navigation paradigm to describe the user inter- action. Especially in the field of web application design, this legacy is due to the conceptual background underlying the ori- gins of the World Wide Web, which derive from the Hypertext and the Data Base field: a network of links interconnects pieces of information (nodes). In this scenario, it should not surprise that the nature of the technology available strongly influenced (if not determined) the concepts used to describe, design and eval- uate the applications. Consider, for instance, concepts such as nodes, units, information pieces, entities, slots, links, or classes. In this perspective, current design models consider interaction design as the activity in which the application behavior and the interface/navigation components are described. II. MOTIVATION Why should designers be forced to design the user experience in terms of how the application behaves? If the user is the focus of the design effort, we should shape the user’s interaction experience first and first most from her perspective, and not from 1520-9210/$20.00 © 2006 IEEE