1 Introduction......................................................................................................... 2
1.1 Motivation.................................................................................................. 3
1.1.1 Study: Behavioral Intention to Use........................................................... 4
1.1.1.1 Study design................................................................................... 4
1.1.1.2 Study results................................................................................... 5
1.1.2 Example Message Types........................................................................ 8
1.2 Objectives of CAIPS.................................................................................. 9
1.3 Contribution.............................................................................................. 10
1.4 Thesis Outline........................................................................................... 11
2 Background and Theoretical Foundations............................................................. 13
2.1 Knowledge Representation and Expert Systems.......................................... 13
2.1.1 Knowledge Representation.................................................................... 14
2.1.2 Knowledge Representation Technologies................................................ 19
2.1.2.1 Object-Oriented Representation Technology................................... 19
2.1.2.2 Rules........................................................................................... 20
2.1.2.3 Ontologies.................................................................................... 22
2.1.3 Expert Systems..................................................................................... 23
2.1.3.1 Demarcation of Expert Systems..................................................... 26
2.1.4 Utilization within CAIPS & Discussion................................................... 28
2.2 Context-Aware Systems........................................................................... 29
2.2.1 Basics.................................................................................................. 30
2.2.2 Architecture......................................................................................... 34
2.2.3 Utilization within CAIPS & Discussion................................................... 36
2.3 Publish/Subscribe Systems......................................................................... 37
2.3.1 Terminology of Publish/Subscribe Systems............................................. 37
2.3.2 Structure.............................................................................................. 38
2.3.2.1 Events and Notifications................................................................ 39
2.3.2.2 Producers and Consumers............................................................. 40
2.3.2.3 Subscriptions................................................................................ 40
2.3.2.4 Event Notification Service............................................................. 43
2.3.3 Models of Interaction & Abstraction Levels........................................... 43
2.3.4 Subscription Language & Event Algebra................................................ 47
2.3.5 Utilization within CAIPS & Discussion................................................... 48
2.4 Recommender Systems............................................................................. 50
2.4.1 Utilization within CAIPS & Discussion................................................... 54
3 Designing CAIPS.............................................................................................. 56
3.1 Overview of CAIPS................................................................................. 57
3.2 Stakeholders............................................................................................. 59
3.3 Requirements Elicitation............................................................................ 60
3.4 Definitions................................................................................................ 61
3.4.1 Message Type...................................................................................... 62
3.4.2 Information Value Chain Concept.......................................................... 62
3.4.3 Information Value Chain Instance.......................................................... 63
3.4.4 Message Instance................................................................................. 63
3.4.5 Final Message...................................................................................... 64
3.4.6 Message Triggering Situation................................................................. 65
3.4.7 Duplicate Message............................................................................... 65
3.5 Conceptual Framework............................................................................. 66
3.5.1 Reference Model.................................................................................. 66
3.5.1.1 Knowledge-Base.......................................................................... 69
3.5.1.2 Rule Interpreter............................................................................ 70
3.5.1.3 IVCI Retrieval.............................................................................. 71
3.5.1.4 Explanation Provider..................................................................... 72
3.5.1.5 Publisher...................................................................................... 72
3.5.1.6 Event Service............................................................................... 73
3.5.1.7 Context Provider........................................................................... 73
3.5.1.8 Sensor.......................................................................................... 73
3.5.1.9 Message Renderer........................................................................ 74
3.5.1.10 Message Gateway........................................................................ 74
3.5.1.11 IVCI Provider.............................................................................. 74
3.5.1.12 Add-On Services.......................................................................... 74
3.5.1.13 User Interfaces............................................................................ 74
3.5.2 Context-Aware Information Triggering Language (CAITL)..................... 75
3.5.2.1 Combining Knowledge Representations.......................................... 75
3.5.2.2 CAITL: Modular Framework......................................................... 77
3.5.2.3 CAITL: Global Semantics.............................................................. 78
3.5.2.4 CAITL: Syntax............................................................................. 81
3.5.2.5 CAITL: Communication and Built-In Variables............................... 85
3.5.2.6 CAITL: Rule Execution Example................................................... 92
4 Case Study: innsbruck.mobile.............................................................................. 99
4.1 CAIPS-IM: Context Representation......................................................... 100
4.2 CAIPS-IM: CAITL-IM........................................................................... 104
4.2.1 CAITL-IM: Applied Message Types & Corresponding Rules................ 107
4.3 CAIPS-IM: Architecture......................................................................... 110
4.3.1 innsbruck.mobile – System Overview................................................... 110
4.3.1.1 CWA Subsystem........................................................................ 111
4.3.2 CAIPS-IM – Conceptual View............................................................ 113
4.3.2.1 PushServer................................................................................. 114
4.3.2.2 MessagingServiceClient............................................................... 119
4.3.3 Innsbruck.mobile – Deployment View.................................................. 120
4.4 Qualitative Evaluation.............................................................................. 123
4.4.1 Service Provider Requirements............................................................ 123
4.4.1.1 Automatic Message Delivery....................................................... 123
4.4.1.2 Situation Dependent Message Content Definition.......................... 124
4.4.1.3 Automatic Personalization............................................................ 124
4.4.1.4 Extensibility................................................................................ 124
4.4.1.5 Ease-of-Use............................................................................... 125
4.4.1.6 Multiple Communication Channels................................................ 129
4.4.2 User Requirements............................................................................. 129
4.4.2.1 Expressive Subscription Specification........................................... 129
4.4.2.2 Practical Subscription Interfaces.................................................. 130
4.4.2.3 Avoid Similar Message Content................................................... 130
5 Related Work.................................................................................................. 132
5.1 SOCAM................................................................................................. 132
5.1.1 Overview........................................................................................... 132
5.1.2 Discussion.......................................................................................... 133
5.2 SE Framework for Context-Aware Pervasive Computing.......................... 134
5.2.1 Overview........................................................................................... 134
5.2.2 Discussion.......................................................................................... 135
5.3 CybreMinder.......................................................................................... 136
5.3.1 Overview........................................................................................... 136
5.3.2 Discussion.......................................................................................... 137
5.4 COMPASS............................................................................................ 138
5.4.1 Overview........................................................................................... 138
5.4.2 Discussion.......................................................................................... 138
5.5 Summary................................................................................................ 139
6 Conclusion....................................................................................................... 142
6.1 Summary................................................................................................ 142
6.2 Future Work 144