اطلاعات تکميلي

• نام نویسندگان: Frank Matthias Kovatsch
• چکیده شامل:

  The Internet of Things (IoT) can be considered as a modern manifestation of MarkWeiser’s

  classic vision of ubiquitous computing where tiny networked computers become part of

  everyday objects interweaving the virtual world and the physical world. The concept of the

  IoT originated some 15 years ago from linking real-world artifacts to virtual counterparts

  through radio-frequency identification (RFID) tags. More recently, environments have

  become ‘smart’ by augmenting physical objects with sensing or actuation capabilities and

  networking them with digital services. The ongoing standardization of Internet protocols

  for such IoT devices enables the seamless integration of smart things into the Internet.

  This trend is expected to eventually result in hundreds of billions of connected devices

  that need to be programmed, managed, and maintained. It has been shown that Web

  technology can significantly ease this process by providing well-known patterns and tools

  for developers and users. The existing solutions are, however, often too heavyweight for

  highly resource-constrained IoT devices. Indeed, most connected devices are expected

  to remain resource-constrained, as progress in technology witnessed by Moore’s Law is

  primarily leveraged to minimize dimensions, power consumption, and unit costs.

  This dissertation presents a comprehensive solution for the seamless integration of

  highly resource-constrained IoT systems into the World Wide Web. Our thesis is that

  existing protocols and programming models do not effectually meet the needs of the IoT.

  We identify two key challenges for the vision to succeed: application-layer interoperability

  and improved usability for both developers and users. Both requirements can be met by

  an approach that amalgamates results from the field of Wireless Sensor Networks and the

  WorldWideWeb. This leads to the research questions (i) how to scaleWeb technology down

  to resource-constrained devices, (ii) how to scale it up to hundreds of billions of devices,

  and (iii) how to use it to improve the usability of the tiny networked computers. Our

  work addresses the resulting challenges with the following contributions: Being actively

  involved in the design and standardization of the Constrained Application Protocol (CoAP)

  within the Internet Engineering Task Force (IETF), we (i) evaluate the new Web protocol

  iii

  Abstract

  in the different components of IoT systems, namely resource-constrained devices, Cloudbased

  services, and user interaction. Based on this, we (ii) propose system architectures

  and guidelines for an optimal implementation and utilization of CoAP. Furthermore, we

  (iii) present concepts and tools for Web-like software development for the IoT. To support

  our thesis, we also (iv) provide working open source implementations of our concepts,

  which build the basis for several IoT projects in academia and industry.

  More concretely, we show in this dissertation that the CoAP protocol suite closes

  the technological gap between low-power IoT devices and the well-known patterns of

  the Web. We first consider resource-constrained environments, where efficient Web

  technology can relieve application developers from the burdens of embedded programming

  while maintaining the performance of classic approaches. In addition to a proof of

  concept and system evaluation, we give guidelines that allow for significantly smaller

  memory footprints of CoAP implementations. Next, we show that the low overhead

  of the new protocol also improves performance in unconstrained environments, such as

  IoT cloud services that have to manage the myriad of IoT devices. We present a system

  architecture for scalable back-end services that outperforms classic high-performance

  Hypertext Transfer Protocol (HTTP) Web servers as well as other state-of-the-art CoAP

  implementations. Finally, our work evaluates usability aspects of the Web programming

  model for IoT applications. We show that Web mashups, that is, the linking of different

  services through lightweight scripting, are also directly applicable to our concepts for

  highly resource-constrained systems. Complementary, we study Web browser support for

  CoAP to fully close the gap between IoT devices and the Web. Based on these findings,

  we motivate the design decisions behind CoAP, in particular for our contributions, and

  explain how developers can improve their protocol implementations accordingly.

  Along with this dissertation, we deliver open source implementations of our approach

  that go beyond prototypes. Our Erbium (Er) REST Engine is an optimized CoAP implementation

  for constrained environments. It provides application developers with resource

  handler abstractions like regular Web frameworks while maintaining a small memory

  footprint. Erbium became the default CoAP implementation for Contiki, a popular embedded

  operating system for the IoT that is used in many industry products. Our Java-based

  Californium (Cf) CoAP framework enables high-performance CoAP services. The project

  also contains a DTLS 1.2 implementation called Scandium (Sc) and the Actinium (Ac)

  application server, a RESTful runtime system for Web-like IoT mashups. Representing

  the state of the art for RESTful IoT services, the Californium project was adopted by the

  Eclipse Foundation within its IoT Industry Working Group.

• محل نشر: Universität Erlangen-Nürnberg
• سال انتشار: دوشنبه, 28 فروردين 1396
• دانشگاه: Erlangen-Nürnberg
• مقطع: دکتزا