Faculty of Science, Technology and Communication Visual Modelling of and on Tangible User Interfaces Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of Master in Information and Computer Sciences Author: Supervisor: Eric Tobias Prof. Dr. Pierre Kelsen Reviewer: Prof. Dr. Yves Le Traon Advisors: Dr. Eric Ras Public Research Centre Henri Tudor Dr. Nuno Amalio August 2012 Abstract The purpose of this thesis is to investigate the use and benefit of visual modelling languages (VMLs) in modelling on tangible user interfaces (TUIs), and modelling TUI applications. Three main research questions are asked: • Is it possible and practical to model an application or process using a TUI? • Which General-purpose VML (GPVML) performs best in modelling a VML scenario for use on TUI? • Is it realistic to use a GPVML to model complex TUI applications? To answer the first research question, a Business Process Model and No- tation, version 2 (BPMN2), ideation scenario is used with a tangible widget toolkit prototype on a TUI table to evaluate the performance and obtain feedback from test candidates. The study showed that it is possible to model a process using a TUI and the test candidate feedback did not lead to the conclusion that the modelling was cumbersome or impractical. To find a suitable GPVML, the thesis explores and evaluates the current state of the art in VMLs for describing general problems. After gathering different VMLs, the thesis compares three languages using a simple sce- nario: the visual object constraint language (VOCL), augmented constraint diagrams (ACD), and the visual contract language (VCL). A weighted eval- uation based on multiple quality criteria led to the conclusion that VCL is best suited to model TUI applications, answering the second research ques- tion. The thesis answers the third research question by using VCL to model a more complex and complete scenario of an ideation process, which is based on using a BPMN2 on a TUI. This is done to assess VCL's suitability to more complex problems and its maturity. The study concludes that VCL is not yet mature enough to enable its general applicability in a wide variety of settings. The three research questions were dressed with a hypothesis in mind: collaborative, novice friendly modelling environments are able to reduce the gap between stakeholders and software engineers during software projects, leading to a reduction of unrealistic expectations and an increase in the availability of domain knowledge. While the hypothesis is too broad to be proven by this thesis, the research questions answered here give some insights into how to approach it. Acknowledgements I'd like to thank the KISS team for having me and actively encouraging me. Special thank to Eric Ras, Olivier Zephir, Yves Rangoni, and Val´erie Maquil. Many thanks also go to the LASSY, especially Nuno Am´aliofor helping me with VCL and ceaselessly working with Christian Glodt to add more functionality and fix problems with VCB. Thanks are also in order for Pierre Kelsen for his support and advice which led me to start my Master studies. Sarah, thank you for encouraging me, being there when I need you, and making everything worthwhile! Misha, Susi, and Hues; thank you for bright- ening my days! To Georges; may you find Ir`enewaiting for you! I will never forget! ii Contents Page 1 Introduction 1 1.1 Research questions . .3 1.2 Research objectives . .4 2 State of the Art 5 2.1 Modelling . .5 2.1.1 Definitions . .8 2.2 Visual Modelling Languages . .9 2.2.1 VML's many influences . 10 2.3 Tangible User Interfaces . 11 3 Case Study 14 3.1 Identifying suitable languages . 14 3.1.1 Collection . 16 3.2 Pre-selection . 16 3.3 VML selection . 18 3.3.1 UML & VOCL . 18 3.3.2 VCL . 19 3.3.3 Constraint Diagrams . 19 3.4 Designing a scenario . 20 3.4.1 BPMN2 introduction and model . 20 3.4.2 Preliminary TUI model . 21 3.4.3 A simple TUI instance . 22 3.5 Case study . 22 3.5.1 Measurements . 22 3.5.2 Study walkthrough . 23 3.5.3 Product . 26 3.5.3.1 UML & VOCL . 26 3.5.3.2 VCL . 27 3.5.3.3 Augmented Constraint Diagrams . 30 3.6 Evaluation . 33 3.6.1 Tool support . 33 iii 3.6.1.1 Availability . 33 3.6.1.2 Maintenance . 34 3.6.1.3 Latest version . 34 3.6.1.4 Branch . 34 3.6.2 Semantics & Transformation . 34 3.6.2.1 Formally defined . 35 3.6.2.2 Transformability . 35 3.6.3 Expressivity . 35 3.6.3.1 # X (# X) . 35 3.6.3.2 # X satisfied (# Sat X) . 35 3.6.3.3 # requirements partially satisfied (# Part Sat) 36 3.6.3.4 # unsatisfied requirements (# UnSat) . 36 3.6.3.5 Ratio . 36 3.6.4 Usability . 36 3.6.4.1 Naming conventions . 36 3.6.4.2 Naming fit . 37 3.6.4.3 Documentation . 37 3.6.4.4 Tutorial . 37 3.6.4.5 Hands-on tutorial . 37 3.6.4.6 Primitive mutability . 37 3.6.4.7 Live suggestions . 38 3.6.5 Error Checking . 38 3.6.5.1 Time . 38 3.6.5.2 Syntax highlighting . 38 3.6.5.3 Degree . 38 3.6.5.4 Error correction suggestion . 39 3.6.5.5 Debugging possible . 39 3.6.6 Verification . 39 3.6.6.1 Modularity . 40 3.6.6.2 Verification scheme . 40 3.6.7 Weighting scheme . 40 3.7 Results . 40 3.8 Study Conclusion . 43 4 The Visual Contract Language, an introduction 45 4.1 Syntax . 46 4.1.1 Primitives . 46 4.1.2 Structural diagrams . 48 4.1.3 Behavioural diagram . 49 4.1.4 Package diagram . 50 4.1.5 Assertion diagrams . 51 4.1.6 Contract diagrams . 52 4.2 Semantics . 53 4.3 Modelling in VCL, using VCB . 53 iv 5 A VCL Model of a TUI for modelling with BPMN2 55 5.1 Introduction . 55 5.2 Tangible User Interfaces . 56 5.2.1 TUI technical aspects . 56 5.2.2 A brief look at TWT . 57 5.3 BPMN2 and its usage in this document . 59 5.4 The TUI VCL metamodel . 61 5.4.1 Packages . 62 5.5 The BPMN2 VCL metamodel . 66 5.5.1 Packages . 66 5.6 The Business-to-Table concept and metamodel . 72 5.7 The Ideation model . 73 5.8 The Widget model . 74 5.9 The Interaction model . 75 5.10 Conclusion . 75 5.10.1 Separation of Concerns . 75 5.10.2 Requirements coverage . 76 5.10.3 Expressiveness . 78 5.10.4 Conclusion . 78 6 Ideation 80 6.1 Introducing the scenario . 81 6.1.1 Extending the model . 81 6.2 First test scenario . 82 6.3 Second test scenario . 84 6.4 Final test scenario . 85 6.5 Analysis & Evaluation . 86 6.6 Conclusion . 87 7 Conclusion 89 7.1 Future Work . 92 Bibliography 93 A TUI metamodel VCL packages 104 A.1 The TUIPrimitives package . 106 A.2 The Actions package . 106 A.3 The Attributes package . 110 A.4 The Effects package . 115 A.5 The EndPoints package . 119 A.6 The Functions package . 124 A.7 The Mappings package . 128 A.8 The Layers package . 132 A.9 The Widgets package . 134 v A.10 The TUI package . 138 B BPMN2 metamodel VCL packages 139 B.1 The Primitives package . 143 B.2 The Extensibilities package . 144 B.3 The BaseElements package . 146 B.4 The Foundation package . 149 B.5 The Infrastructures package . 150 B.6 The ItemDefinitions package . 152 B.7 The Messages package . 153 B.8 The Artifacts package . 154 B.9 The Resources package . 157 B.10 The ResourceAssignments package . 158 B.11 The Expressions package . 160 B.12 The Errors package . 161 B.13 The Collaborations package . 162 B.14 The GlobalTasks package . 165 B.15 The Services package . 166 B.16 The ItemAwareElements package . ..