Protocols for the
Efficient Dissemination of
Context-Aware Messages
Von der Fakultät für Informatik, Elektrotechnik und Informationstechnik
der Universität Stuttgart zur Erlangung der Würde eines Doktors der
Naturwissenschaften (Dr. rer. nat.) genehmig te Abhandlung
Vorgelegt von
Lars Christian Geiger
aus Nürtingen
Hauptberichter: Prof. Dr. rer. nat. Dr. h.c. Kurt Rothermel
Mitberichter: Prof. Dr. rer. nat. Jörg Hähner
Tag der mündlichen Prüfung: 19. Juli 2016
Institut für Parallele und Verteilte Systeme (IPVS)
der Universität Stuttgart
2016
Acknowledgments
First of all, I would like to thank my doctoral advisor, Prof. Kurt Rothermel, for the
opportunity to work on this challenging topic in his research group. Without his
guidance, support, and many interesting discussions over the years, this dissertation
would not have been possible. Furthermore, my thanks go to the co-reviewer of
my thesis, Prof. Jörg Hähner, for taking the time to read this document and for his
feedback.
I also want to mention some of the people that I had the privilege to meet and
work with during my time at the Distributed Systems group and the Nexus project.
Especially Frank Dürr always took the time to discuss my research, sometimes to the
detriment of his own full schedule. I would also like to thank (in alphabetical order)
Andreas Brodt, Nazario Cipriani, Dominique Dudkowski, Andreas Grau, Ralph
Lange, Faraz Memon, Stamatia Rizou, and Harald Weinschrott for the inspiring
discussions and the fun I had during my time as a doctoral researcher. Also, I
am grateful to Annemarie Rösler, Martina Guttroff, Sabine Thielmann, and Martin
Brodbeck for supporting me with administrative duties and thus allowing me to
focus on my research. Additionally, during my time at the Distributed Systems
group I had the chance to work with a number of talented and enthusiastic students.
I greatly enjoyed the opportunity and I am thankful to all of you for that.
I would also like to mention and thank the Ger man Research Foundation, whose
funding for the SFB 627 Nexus allowed me to work on my research in the first place.
And last but certainly not least, I would like to thank my parents Werner and
Monika, my sister Ramona, and all my closest friends for their support and patience
both during my undergrad studies and my doctoral work. They put up with my
lack of time and my irritability but hardly ever complained. I am deeply grateful
for having all of you in my life.
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Contents
Acknowledgments 3
Abstract 9
Zusammenfassung 11
1 Introduction 13
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.2 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2.1 Technological Trends . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2.2 Paradigmatic Trend: Context-aware Computing . . . . . . . . . 16
1.2.3 SFB 627: Nexus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.2.4 Context-aware Communication . . . . . . . . . . . . . . . . . . . 18
1.3 Focus and Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.3.1 Focus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.3.2 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.4 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2 Foundations 27
2.1 Context-based Communication: Contextcast . . . . . . . . . . . . . . . 27
2.2 Requirements for Contextcast . . . . . . . . . . . . . . . . . . . . . . . . 28
2.3 Classification of Related Work . . . . . . . . . . . . . . . . . . . . . . . . 29
2.3.1 Classification Criteria . . . . . . . . . . . . . . . . . . . . . . . . 29
2.3.2 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.4 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.4.1 ContextHost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.4.2 ContextNode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
2.4.3 ContextRouter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.4.4 Overlay Network . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3 Contextcast Semantics 53
3.1 Contexts & Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.1.1 Client Contexts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.1.2 Contextual Messages . . . . . . . . . . . . . . . . . . . . . . . . . 55
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