Sebastian Käbisch

Enabling IoT Ecosystems through Platform Interoperability

Today, the Internet of Things (IoT) comprises vertically oriented platforms for things. Developers who want to use them need to negotiate access individually and adapt to the platform-specific API and information models. Having to perform these actions for each platform often outweighs the possible gains from adapting applications to multiple platforms. This fragmentation of the IoT and the missing interoperability result in high entry barriers for developers and prevent the emergence of broadly accepted IoT ecosystems. The BIG IoT (Bridging the Interoperability Gap of the IoT) project aims to ignite an IoT ecosystem as part of the European Platforms Initiative. As part of the project, researchers have devised an IoT ecosystem architecture. It employs five interoperability patterns that enable cross-platform interoperability and can help establish successful IoT ecosystems.

Efficient and Flexible XML-Based Data-Exchange in Microcontroller-Based Sensor Actor Networks

One of the critical challenges in embedded sensor actor networks is the communication between the diversity of widespread nodes. XML-based message formats are already widely adopted in other IT domains such as the Web and would be perfectly suited for data exchange in heterogeneous environments. Despite all its strengths, the common markup language cannot be adopted on small embedded devices with limited resources due to its verbosity and associated processing overhead. The paper describes an innovative source code generation technique by means of W3Cs Efficient XML Interchange (EXI) format that enables the efficient usage of XML-based messages on small devices with limited resources. The outcome is an EXI Processor that allows an end-to-end XML-based communication between systems ranging from powerful workstations to microcontroller-based systems. Particularly, the paper emphasizes the flexibility with regard to alter an exchange format and its minimal adaption efforts due to the generated EXI Processor. An example application proves the applicability of the proposed approach and demonstrates a real life show-case for XML-based Web service communication on microcontroller-based devices.

An ontology design pattern for IoT device tagging systems

Modeling devices has become a crucial task in the Internet of Things (IoT) and Semantic Web technologies are seen as a promising tool for this purpose. However, as it may be arduous to manipulate semantic models, industrial solutions often re-define non-standard, simplified semantics. This is the case with Project Haystack, a framework to tag devices with labels from a predefined vocabulary in the field of Building Automation. In order to make Project Haystack standard and fully semantic, we wrapped its vocabulary in an ontology. In this paper, we present the general structure of this ontology, along with a method to turn tag sets into a Semantic Web model and back. The whole results in a reusable ontology design pattern. We aligned our Haystack tagging ontology with the wide-spreaded Semantic Sensor Network upper ontology and we designed a configuration environment for Building Automation systems based on semantic data to illustrate, so as to discuss the added-value of semantics in automation.

Optimized XML-based Web service generation for service communication in restricted embedded environments

Embedded network programming remains a highly complex task for developers since unique characteristics of such networks have to be faced: one of them is the communication between a diversity of resource constraint nodes. Another one is the infrastructure dynamics. The widely-used standardized Web service technologies would perfectly meet such unique characteristics and ease the development of applications. Such technologies that enable, e.g., requesting or subscribing service data, however, process usually plain XML documents which are not suitable for small embedded devices with very limited resources. This is due to XMLs verbosity, its bandwidth usage, and its associated processing overhead. The paper addresses these issues and describes an innovative and optimized source code generation technique by means of W3Cs Efficient XML Interchange (EXI) format for developing XML-based Web services for the embedded domain. This offers developers a seamless use of the wide-spread service protocols in the embedded domain as well. Evaluation results based on the dataset from the ISO/IEC standardization of the vehicle to grid communication interface (V2G CI) prove the applicability of the generated XML-based Web services of restricted devices in terms of message size, performance, and code footprint.

Standardized and Efficient RDF Encoding for Constrained Embedded Networks

In the context of Web of Things WoT, embedded networks have to face the challenge of getting ever more complex. The complexity arises as the number of interchanging heterogeneous devices and different hardware resource classes always increase. When it comes to the development and the use of embedded networks in the WoT domain, Semantic Web technologies are seen as one way to tackle this complexity. For example, properties and capabilities of embedded devices may be semantically described in order to enable an effective search over different classes of devices, semantic data integration may be deployed to integrate data produced by these devices, or embedded devices may be empowered to reason about semantic data in the context of WoT applications. Despite these possibilities, a wide adoption of Semantic Web or Linked Data technologies in the domain of embedded networks has not been established yet. One reason for this is an inefficient representation of semantic data. Serialisation formats of RDF data, such as for instance a plain-text XML, are not suitable for embedded devices. In this paper, we present an approach that enables constrained devices, such as microcontrollers with very limited hardware resources, to store and process semantic data. Our approach is based on the W3C Efficient XML Interchange EXI format. To show the applicability of the approach, we provide an EXI-based

An Architecture for Interoperable IoT Ecosystems

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Towards a Binary Object Notation for RDF

RDF Store and show associated evaluation results.

Semantic data integration on the web of things

The development of applications for embedded sensor actor networks involves two major challenges: one of them is the communication between a diversity of widespread resource constraint nodes. The other one is the infrastructure dynamics. Web service based Service Oriented Architecture (SOA) would perfectly meet such unique characteristics of embedded networks and ease the development of applications. Standardized Web services, however, process usually plain XML messages which are not suitable for small embedded devices with very limited resources due to XMLs verbosity, its bandwidth usage, and its associated processing overhead. The paper addresses these issues and describes an innovative source code generation technique by means of W3Cs Efficient XML Interchange (EXI) format for developing XML-based Web services for microcontrollers. This offers developers a seamless use of the wide-spreadWeb service protocols in the embedded domain. First evaluation results prove the applicability of the generated XML-basedWeb services on microcontroller-based devices.