Applied Computing. Springer-Verlag London Ltd.

Transcription

1 Applied Computing Springer-Verlag London Ltd.

2 The Springer-Verlag Series on Applied Computing is an advanced series of innovative textbooks that span the full range oftopics in applied computing technology. Books in the series provide a grounding in theoretical concepts in computer science alongside real-world examples of how those concepts can be applied in the development of effective computer systems. The series should be essential reading for advanced undergraduate and postgraduate students in computing and information systems. Books in this series are contributed by international specialist researchers and educators in applied computing who draw together the full range of issues in their specialist area into one concise authoritative textbook. Titles already available: Deryn Graham and Anthony Barrett Knowledge-Based Image Processing Systems X Linda Macaulay Requirements Engineering Derrick Morris, Gareth Evans, Peter Green, Colin Theaker Object Orientated Computer Systems Engineering John Hunt Java and Object Orientation: AnIntroduction David Gray Introduction to the Formal Design ofreal-time Systems Mike Holcombe and Florentin Ipate Correct Systems: Building A Business Process Solution Jan Noyes and Chris Baber User-Centred Design ofsystems Arturo Trujillo Translation Engines: Techniques for Machine Translation Ulrich Nehmzow Mobile Robotics: A Practical Introduction Available in the Advanced Perspectives in Applied Computing series: Sarah Douglas and Anant Mithal The Ergonomics ofcomputer Pointing Devices

3 Fabio Paterno Model-Based Design and Evaluation of Interactive Applications, Springer

4 Fabio Paterna PhD CNUCE - CNR, Pisa, Italy Series Editors Professor Ray J. Paul, BSc MSc PhD Department ofinformation Systems and Computing, Brunel University, Uxbridge, Middlesex UB8 3PH, UK Professor Peter J. Thomas, MIEE MBCS CEng FRSA Centre for Personal Information Management, U niversity of the West of England, Frenchay Campus, Bristol BSI61QY, UK Dr Jasna Kuljis, PhD MS Dipl Ing Department of Mathematical and Computing Sciences, Goldsmiths College, University of London, New Cross, London SEl4 6NW, UK ISBN British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Paterna, Fabio, Mode1-based design and evaluation of interactive applications / Fabio Paterna. p. cm. - (Applied computing) Inc1udes bibliographical references. ISBN ISBN (ebook) DOI / User interfaces (Computer systems) 2. Human-computer interaction. 3. Software engineering. 1. Title. II. Series. QA76.9.U83P '28-dc21 CIP Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may on1y be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms shou1d be sent to the publishers. Springer-Verlag London 2000 Origina1ly published by Springer-Verlag London Berlin Heidelberg in 2000 The use of registered names, trademarks etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Typesetting: Camera ready by author 34/ Printed on acid-free paper SPIN

5 Background of author Fabio Paterno received his Laurea Degree in Computer Science from the University ofpisa (Italy) and a Ph.D. in Computer Science from the University ofyork (UK). Since 1986 he has been a researcher at CNUCE-C.N.R., Pisa, where he is head of the HCI group. He has worked in various national and international projects on user interfaces-related topics. He has been the coordinator of the MEFISTO (Modelling Evaluating and Formalising Interactive Systems Using Tasks and Interaction Objects) Long Term Esprit European Project. He has developed the ConcurTaskTrees notation for specifying task models, which has been used in various industries and universities, and related methods for supporting the design and evaluation of interactive applications. His current research interests include Methods and Tools for User Interface Design and Usability Evaluation, Formal Methods for Interactive Systems, and Design of User Interfaces for Safety Critical Interactive Systems. He has published more than sixty papers in refereed international conferences or journals. He was the chair of the first International Workshop on Design, Specification, Verification of Interactive Systems. He is co-editor of a book on Formal Methods in Human-Computer Interaction. He has been a member of the Programme Committee of the main international HCI conferences. He is a member of the IFIP Technical Committee 13 on Human Computer Interaction. He has been Papers Co-Chair of the ACM CHI 2000 conference. v

6 Preface This book aims to be a bridge. A bridge between science and practice, creativity and engineering, human-computer interaction and software engineering, with possible links to artificial intelligence and formal methods. Bridges are important because they allow communication between worlds which were previously separated, thus enabling new results to be obtained. Ponte di Mezzo, Pisa. The increasing diffusion of interactive software-based applications in an increasing number of contexts, possible purposes and types of users, requires new methods for improving the design cycle of interactive applications and obtaining more usable artefacts. This stimulated the need to bring together aspects such as task modelling, dialogue design, reuse patterns, and usability evaluation with the purpose of explaining the basic ideas and concepts and discussing the possible results. The logical structure of the book focuses on reporting recent thinking in this area vii

7 viii Model-Based Design and Evaluation of Interactive Applications showing the connections between the various parts. It makes accessible work which has previously mainly appeared only in research-oriented publications. I hope it will prove useful to help the reader understand issues concerning the use of models in design and evaluation of interactive applications, to indicate possible solutions, and to foster new work able to improve previous solutions. A lot of work needs still to be done to improve current methods and tools to design and develop usable interactive applications. Fabio Paterno August 1999, Pisa, Italy ACKNOWLEDGEMENTS Over the years I have discussed the topics considered in this book with many people. It is difficult to mention all of them. In particular, I wish to thank for their help: Cristiano Mancini, Carmen Santoro, Giulio Ballardin, Simone Bellani, Andreas Lecerof, lise Breedvelt-Schouten, Nicole de Koning, Silvia Meniconi, my students, and the researchers who discussed with me some of the issues addressed in this book in the MEFISTO ( and GUITARE ( projects. I also want to acknowledge the support received from the European Commission through these projects. Last, but not least, I would like to thank Claudia, Linda and PierPaolo for their continuos support.

8 Contents 1 INTRODUCTION Why model-based design and evaluation of interactive applications? Basic concepts Structure ofthe book arid intended audience Other sources of information Conferences Journals Books Associations 10 2 MODEL-BASED APPROACHES Task-oriented approaches GOMS Norman's cycle Task analysis methods Task analysis Groupware Task Analysis UAN Petri Nets UML Formal Methods for HCI Exercises 30 3 ANALYSIS OF INTERACTIVE APPLICATIONS Scenarios Use Cases Task analysis Support for task identification in informal scenarios Task and errors Exercises 38 4 THE CONCURTASKTREES NOTATION Introduction to ConcurTaskTrees Motivations for ConcurTaskTrees 39 ix

9 x Model-Based Design and Evaluation of Interactive Applications Main features ofconcurtasktrees Task allocation Temporal relationships Task types Additional information associated with tasks Objects Further task-related information Structuring the task model The ambiguity problem Inheritance of temporal relationships Relationships between parent task and its subtasks Recursion Optional tasks Example of ConcurTaskTrees specification The first levels of the example Refinement of the example Tool support Task models for cooperative applications Possible approaches to design cooperative task models Describing multi-user cooperation in ConcurTaskTrees Exercises 66 5 TASK-BASED DESIGN Approaches to task-based design Main aspects in task-based design Approaches to designing presentations Aspects to consider when designing user interfaces Criteria for grouping tasks to be supported by the same presentation Identifying presentations Identifying enabled task sets Task-driven design of user interfaces Designing layout of presentations Considering task types for selecting user interface techniques Gathering information from temporal relations among tasks Relationships among enabled task sets Structuring the information An example Tasks for accessing databases Task-oriented help Adaptability Example of user classification How to support adaptation Adaptivity When to provide adaptive support? What information should adaptive support provide? Example of adaptive presentation techniques 95

10 Contents xi 5.10 Concluding remarks Exercises 97 6 ARCHITECTURAL MODELS OF INTERACTIVE APPLICATIONS Architectures for user interfaces Models for interactive systems Conceptual models Architectural models for logical input devices Architectural models for user-interaction objects The interactor model Composition operators for interactors External composition Internal composition Internal-External Composition Operators Control Composition Operators Activation and deactivation composition operators From the task model to the user interface architecture model The transformation algorithm Connecting interactors to support the information flow An example of application of the transformation Exercises PATTERNS IN INTERACTIVE APPLICATIONS Introduction Patterns How to represent a task pattern An example of a task pattern Architectural patterns An example of an architectural pattern Relationships between tasks and architectural patterns Tool support for patterns Comments on patterns Exercises USABILITY EVALUATION Criteria for user interface evaluation Introduction to approaches to usability evaluation Model-based evaluation GOMS-based evaluation Empirical evaluation The MUSiC method Inspection-based evaluation Cognitive walkthrough Metrics-based evaluation Comparing methods for usability evaluation Remote usability evaluation 151

11 xii Model-Based Design and Evaluation of Interactive Applications 8.5 The RemUSINE method The preparation part The elaboration of the tool An example ofan analysis of a small log Results obtained by a RemUSINE analysis of a single session How to interpret the results Results provided to analyse groups of sessions An example of an appiication Evaluation of RemUSINE Exercises CONCLUSIONS Summarising the results described Suggestions for open areas of interests 178 REFERENCES SUBJECT INDEX