Felix Leif Keppmann

Integrating highly dynamic RESTful linked data APIs in a virtual reality environment.

We demonstrate a Virtual Reality information system that shows the applicability of REST in highly dynamic environments as well as the advantages of Linked Data for on-the-fly data integration. We integrate a motion detection sensor application to remote control an avatar in the Virtual Reality. In the Virtual Reality, information about the user is integrated and visualised. Moreover, the user can interact with the visualised information.

Semantic Technologies for Realising Decentralised Applications for the Web of Things

The vision of the Internet of Things (IoT) promises the capability of connecting billions of devices, resources and things together. In the realisation of this vision, we are currently neglecting the interoperability between devices that is caused by a heterogeneous landscape of things and which leads to the proliferation of isolated islands of custom IoT solutions. A first step towards enabling some interoperability is to connect things to the Web and to use the Web stack, thereby conceiving the socalled Web of Things (WoT). However, even when a homogeneous access is reached through Web protocols, a common understanding is still missing. In addition, decentralised applications, advocated by the IoT vision, and a-priori unknown requirements of specific integration scenarios demand new concepts for the adaptation of things at runtime. Our work focuses on two main aspects: overcoming not only data but also device and interface heterogeneity, and enabling adaptable and scalable decentralised WoT applications. To this end we present an approach for realising decentralised WoT applications based on three main building blocks: 1) semantics of the devices’ capabilities and interfaces, 2) rules to enable embedding controller logic within device’s interfaces for supporting a decentralised applications, and 3) support for reconfiguring the controller logic at runtime for customising and adapting the application. We show how our approach can be applied by introducing a reference architecture, provide a thorough evaluation in terms of a proof-of-concept implementation of an example use case, and performance tests.

DLUBM : A Benchmark for Distributed Linked Data Knowledge Base Systems

Linked Data is becoming a stable technology alternative and is no longer only an innovation trend. More and more companies are looking into adapting Linked Data as part of the new data economy. Driven by the growing availability of data sources, solutions are constantly being newly developed or improved in order to support the necessity for data exchange both in web and enterprise settings. Unfortunately, currently the choice whether to use Linked Data is more an educated guess than a fact-based decision. Therefore, the provisioning of open benchmarking tools and reports, which allow developers to assess the fitness of existing solutions, is key for pushing the development of better Linked Data-based approaches and solutions. To this end we introduce a novel Linked Data benchmark – Distributed LUBM, which enables the reproducible creation and deployment of distributed interlinked LUBM datasets. We provide a system architecture for distributed Linked Data benchmark environments, accompanied by guiding design requirements. We instantiate the architecture with the actual DLUBM implementation and evaluate a Linked Data query engine via DLUBM.

Virtuelle Techniken und Semantic-Web

Virtuelle Techniken (VT) haben schon seit vielen Jahren in der Industrie in vielfaltiger Weise Eingang gefunden. Ebenso gibt es durchaus umfangreiche, interoperable Anwendungen in anderen Fachdomanen, die auf etablierten, standardisierten Web-Technologien beruhen. Daher liegt es nahe, die unbestreitbaren Vorteile von semantischen Web-Technologien fur den Aufbau interoperabler VT-Anwendungen zu nutzen. In diesem Kapitel werden daher grundlegende Elemente und der aktuelle Entwicklungsstand virtueller Techniken sowie auch die Grundkonzepte semantischer Web-Technologien beschrieben. Im Uberblick wird deutlich, dass zahlreiche Einzelkomponenten fur komplexere VT-Anwendungen zusammenarbeiten mussen und dass neben der Interoperabilitat die erreichte Gesamtperformanz einer Anwendung eine essentielle Anforderung fur die ARVIDA-Referenzarchitektur ist. Die gewunschte Kapselung der hier beschriebenen Einzelelemente in Web-Dienste ist bisher noch im Forschungsstadium. Eine detaillierte Beschreibung, wie semantische Web-Technologien aus dem ARVIDA-Projekt heraus fur VT-Anwendungen angewendet werden, ist in den Folgekapiteln zu finden.

Towards Optimising the Data Flow in Distributed Applications

Networked applications continuously move towards service-based and modular solutions. At the same time, web technologies, proven to be modular and distributed, are applied to these application areas. However, web technologies have to be adapted to the new characteristics of the involved systems -- no explicit client and server roles, use of heterogeneous devices, or high frequency and low latency data communication. To this end, we present an approach for describing distributed applications in terms of graphs of communicating nodes. In particular, we develop a formal model for capturing the communication between nodes, by including dynamic and static data producing devices, data consuming client applications, as well as devices that can serve as data produces and consumers at the same time. In our model, we characterise nodes by their frequencies of data exchange. We complement our model with a decision algorithm for determining the pull/push communication direction to optimise the amount of redundantly transferred data (i.e., data that is pushed but cannot be processed or data that is pulled but is not yet updated). The presented work lays the foundation for creating distributed applications which can automatically optimise data exchange.