Doctoral Dissertation Academic Year 2018 A State-Transfer-based Open Framework for Internet of Things Service Composition Keio University Graduate School of Media Design Ruowei Xiao A Doctoral Dissertation submitted to Keio University Graduate School of Media Design in partial fulfillment of the requirements for the degree of Ph.D of Media Design Ruowei Xiao Thesis Advisor: Associate Professor Kazunori Sugiura (Principal Advisor) Professor Akira Kato (Co-advisor) Professor Keiko Okawa (Co-advisor) Thesis Committee: Professor Akira Kato (Principal Advisor) Professor Keiko Okawa (Member) Professor Kai Kunze (Member) Senior Assistant Professor Takeshi Sakurada (Member) Abstract of Doctoral Dissertation of Academic Year 2018 A State-Transfer-based Open Framework for Internet of Things Service Composition Category: Science / Engineering Summary Current Internet-of-Things (IoT) applications are built upon multiple architec- tures, standards and platforms, whose heterogeneity leads to domain specific tech- nology solutions that cannot interoperate with each other. It generates a growing need to develop and experiment with technology solutions that break and bridge the barriers. This research introduces an open IoT development framework that offers gen- eral, platform-agnostic development interfaces, and process. It allows IoT re- searchers and developers to (re-)use and integrate a wider range of IoT and Web services. A Finite State Machine (FSM) model was adopted to provide a uniform service representation as well as an entry point for swift and flexible service com- position under Distributed Service Architecture (DSA). Leveraging this open IoT service composition framework, value-added, cross-domain IoT applications and business logic can be developed, deployed, and managed in an on-the-fly manner. As a typical implementation, a set of web development toolkit named Hyper Sensor Markup Language (HSML) has been developed. Several target domain applications, e.g. multi-source environmental monitoring, open automation sys- tems and etc., have been built. Based on the HSML, the proposed framework has been evaluated by means of user experiment, expert interview and architectural comparison. Results have indicated a better overall performance on expertise requirement, customization cost, reusability and cross-domain interoperability, when compared with other mainstream open IoT service composition frameworks. The proposed framework has demonstrated its capability to greatly lower down the technical threshold of IoT application development and facilitate fast- prototyping and test over a variety of application domains, including but not limited to smart cities, public environment automation, and precision agriculture. i ABSTRACT And going hand in hand with other complementary technologies like semantic web, machine learning and block chain etc., it will hopefully become the primary step towards the equity of future IoT services. Keywords: Service Composition, Service Oriented Architecture, IoT Application Keio University Graduate School of Media Design Ruowei Xiao ii Acknowledgements The past three and half years have been the most grinding period of my whole life, when I was struggling through endless self-doubt and challenges from both physical and mental aspects. Here, I want to express my gratitude to those people who have generously offered their help during my Ph.D study. Firstly, I appreciate all the supports from my supervisor Professor Kazurori Sugiura, without him there would be no my research at all. Also I want to thank Professor Akira Kato. As my dissertation committee chair, he always spent the most time and patience to provide concrete academic instructions. Sincere grat- itude also for my committee members, Professor Keiko Okawa, Professor Kai Kunze as well as Senior Assistant Professor Takeshi Sakurada from Tokyo Uni- versity of Agriculture and Technology. Even when extremely occupied, they were always willing to offer inspiring advice and second opinions. Thanks to these kind people, I became more informed about the nature of scientific research: It is all about how to establish a self-consistent theory, how to position and verify it, and most importantly, figure out where your limitation is at. Secondly, I feel more than grateful to my friends, Wang Dongyu and Yu Xiejing. The three of us first met at the graduate school opening ceremony in September 2012, then became the only three Chinese students in our batch. They were the witnesses to all my trial-and-error within the past six years. Specifically Mr. Wang, he has always been a supportive colleague. And we cooperated in the Omron project, in which I collected a lot of important basic data for this very research. Both of us pursued similar academic goal and also being devotional believers. The only difference may be that he is a Christian, while I am not. At last, there is another person I have to express specific thanks to. I want to thank Dr. Zhanwei Wu, for being not only my tutor, my colleague, my family, my comrade who fights side by side with me, but also my guide who has led me through those dimmest moments in my life. iii Table of Contents Acknowledgements iii 1 Introduction 1 1.1Background.............................. 1 1.2 Research Issues ............................ 4 1.3 Research Goal ............................. 5 1.4 Research Constraint ......................... 7 1.5ContentOverview........................... 7 2 Research Background 11 2.1 Internet of Things Technology Stack ................ 11 2.1.1 GeneralOverview....................... 11 2.1.2 NetworkInterfaceLayer................... 13 2.1.3 InternetLayer......................... 13 2.1.4 TransportandResourceLayer................ 15 2.1.5 Resource Representation Layer ............... 16 2.2OpenIoTDevelopmentFramework................. 18 2.2.1 Process Virtual Machine Frameworks ............ 19 2.2.2 DomesticServiceHubFrameworks............. 20 2.3MainstreamWebServiceArchitecture................ 21 2.3.1 WS-*Architecture...................... 22 2.3.2 REpresentational State Transfer ............... 25 2.3.3 Operation-based Paradigm and State-based Paradigm . 27 2.4WebServiceComposition...................... 29 2.4.1 ServiceComposition..................... 30 2.4.2 WebServiceCompositionCategory............. 31 2.4.3 WebServiceCompositionApproach............. 32 2.5 IoT Service Composition: Parallel Research ............ 34 2.5.1 Programming/Process-based Composition ......... 35 2.5.2 Rule-basedComposition................... 36 iv TABLE OF CONTENTS 2.5.3 Flow-basedComposition................... 37 2.6 Summary ............................... 39 3 Approach 41 3.1 Research History ........................... 41 3.2State-basedComposableServiceInterface.............. 43 3.3PhysicalandVirtualStateSynchronization............. 46 3.4 State-Transfer-based IoT Service Composition ........... 50 3.5 StateML: A Unified Resource Representation ............ 53 3.5.1 Hybrid State-based Service Interface Description ...... 53 3.5.2 State-Transfer-based Messaging ............... 58 3.6 Summary ............................... 60 4 IoT Service Composition Framework: HSML 61 4.1Servitization.............................. 61 4.2GeneralSystemArchitecture..................... 64 4.3WebDevelopmentToolkit...................... 68 4.3.1 HSMLSyntaxParadigm................... 68 4.3.2 HSML Usage Sample ..................... 74 4.4CentralServiceOrchestration.................... 78 4.5TypicalDeploymentCases...................... 82 4.5.1 TwoDeploymentPatterns.................. 82 4.5.2 DeploymentCaseI:EnvironmentMonitoring........ 85 4.5.3 DeploymentCaseII:OpenAutomation........... 89 4.6 Summary ............................... 91 5 Evaluation 93 5.1UserTest............................... 94 5.1.1 Learnability .......................... 94 5.1.2 Sociability ........................... 95 5.1.3 Retrievability ......................... 96 5.1.4 TaskLoadComparison.................... 99 5.2ExpertInterview........................... 105 5.3 Architectural Assessment ....................... 107 5.3.1 CustomizationCost...................... 108 5.3.2 Reusability .......................... 110 5.3.3 Cross-Domain Interoperability ................ 113 v TABLE OF CONTENTS 5.3.4 Scalability ........................... 115 5.4 Discussions and Limitations ..................... 120 5.5 Summary ............................... 122 6 Conclusion 124 6.1Contribution.............................. 124 6.2 Limitation ............................... 126 6.3 Future Issues ............................. 128 6.4 Summary ............................... 129 References 130 Appendix 143 A Sensor StateML Description Sample ................. 143 B Actuator StateML Description Sample ............... 147 C Servitization Example in Node.JS .................. 151 D User Experiment Guidance . ..................... 153 D.1 ExperimentTasks....................... 153 D.2 ExperimentEnvironment................... 153 D.3 ComparisonSystems..................... 154 D.4 ExperimentProcedure.................... 154 vi List of Figures 1.1 From Closed, Monolithic to Open, Modular IoT Application Ar- chitecture............................... 2 1.2 Research Contents Overview .................... 8 2.1 MainstreamWebTechnologyStack................ 12 2.2 WS-*WorkflowandProtocolStack................ 23 2.3 Statefulv.s.Stateless........................ 28 2.4 ServiceOrchestrationv.s.ServiceChoreography......... 31 2.5 an example of editing PubNub process ............... 35 2.6 an example of