Auflistung nach Autor:in "Schuldt, Heiko"
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- ZeitschriftenartikelADAMpro: Database Support for Big Multimedia Retrieval(Datenbank-Spektrum: Vol. 16, No. 1, 2016) Giangreco, Ivan; Schuldt, HeikoFor supporting retrieval tasks within large multimedia collections, not only the sheer size of data but also the complexity of data and their associated metadata pose a challenge. Applications that have to deal with big multimedia collections need to manage the volume of data and to effectively and efficiently search within these data. When providing similarity search, a multimedia retrieval system has to consider the actual multimedia content, the corresponding structured metadata (e.g., content author, creation date, etc.) and—for providing similarity queries—the extracted low-level features stored as densely populated high-dimensional feature vectors. In this paper, we present ADAMpro, a combined database and information retrieval system that is particularly tailored to big multimedia collections. ADAMpro follows a modular architecture for storing structured metadata, as well as the extracted feature vectors and it provides various index structures, i.e., Locality-Sensitive Hashing, Spectral Hashing, and the VA-File, for a fast retrieval in the context of a similarity search. Since similarity queries are often long-running, ADAMpro supports progressive queries that provide the user with streaming result lists by returning (possibly imprecise) results as soon as they become available. We provide the results of an evaluation of ADAMpro on the basis of several collection sizes up to 50 million entries and feature vectors with different numbers of dimensions.
- KonferenzbeitragContext-aware service coordination for mobile e-Health applications(European Conference on eHealth 2006, 2006) Bergenti, Federico; Caceres, Cesar; Fernandez, Alberto; Fröhlich, Nadine; Helin, Heikki; Keller, Oliver; Kinnunen, Ari; Klusch, Matthias; Laamanen, Heimo; Lopes, António; Ossowski, Sascha; Schuldt, Heiko; Schumacher, MichaelIn this paper, we present a general architecture for service delivery and coordination in intelligent peer-to-peer (IP2P) environments that has been developed within the CASCOM research project. Our essential approach is an innovative combination of agent technology, Semantic Web Services, peer-to-peer, context-awareness, and mobile computing for intelligent peer-to-peer mobile service environments. Services are provided by software agents exploiting the coordination infrastructure to efficiently operate in highly dynamic environments. Our infrastructure includes efficient communication means, support for contextaware adaptation techniques, as well as dynamic service discovery and composition planning. For end users, the architecture provides seamless access to Semantic Web Services anytime, anywhere, and using any device. Our architecture is being evaluated using a sample ad-hoc emergency healthcare assistance application scenario. We deployed a prototype of an open IP2P service environment and expect results on methods for service provision, discovery, composition, and monitoring in mobile environments.
- KonferenzbeitragFlexible Fehlerbehandlung für mobile Ad-hoc-Prozesse(Persistence, scalability, transactions – Database mechanisms for mobile applications, workshop by the GI-Arbeitskreis 'Mobile Datenbanken', 2003) Haller, Klaus; Schuldt, Heiko; Türker, CanDurch die inhärente Mobilität und Dynamik moderner Dienstanbieter und -nutzer werden Informationssysteme zunehmend dezentral, auf dem Peer-to-Peer-Paradigma basierend, organisiert. Gleichzeitig werden die Benutzeranforderungen immer individueller. Daher verwenden wir Ad-hoc-Prozesse, die Dienste verschiedener Anbieter bündeln, um damit individuelle Benutzerbedürfnisse zu erfüllen. Solche Ad-hoc-Prozesse zeichnen sich dadurch aus, dass sie – im Gegensatz zu Geschäftsprozessen mit hoher Wiederholfrequenz – jeweils vom Benutzer individuell zusammengestellt beziehungsweise konfiguriert werden und daher nur einmal oder wenige Male zur Ausführung kommen. Mobile Agenten werden dabei zur Prozessausführung eingesetzt, um auch ein temporäres Entkoppeln der Benutzer während der Ausführung ihrer Prozesse zu unterstützen. In diesem Beitrag bieten wir einen Überblick über unsere Ausführungsinfrastruktur und zeigen mögliche Fehlerfälle auf, die bei der Ausführung von Prozessen durch mobile Agenten zu beachten sind. Ferner diskutieren wir, wie Recovery bzw. flexible Fehlerbehandlung und Mobilität von Anwendungen zusammengeführt werden können.
- ZeitschriftenartikelOptimized P2P Data Management for ReliableWorkflow Execution in Mobile Environments(Datenbank-Spektrum: Vol. 15, No. 2, 2015) Stojnić, Nenad; Schuldt, HeikoWorkflows allow to build complex applications out of existing services. Hence, workflows are inherently distributed. At the same time, workflows are mostly executed by centralized workflow engines that invoke the services of a workflow in a request/reply style. These engines may become a performance bottleneck and limit the scalability of the entire system. As a consequence, approaches to distributed workflow execution have been proposed. While these approaches have better scalability characteristics, they require additional efforts to deal with (partial) failures of the system. To cope with such failures, workflow instance data must be stored redundantly at different sites. This is even more important in mobile environments or mixed mobile/stationary environments where the nodes hosting services for workflows may be mobile and are thus more likely to fail permanently or become temporarily unavailable. This is the case, for instance, for sensor net applications where mobile devices capture data, or when smartphone apps share and jointly process data.In this paper, we present the combination of OSIRIS-SR, an extension to the distributed and decentralized workflow engine OSIRIS that focuses on reliable workflow execution by means of instance data replication, and Compass, an extension to Chord that is particularly tailored for efficient P2P data management on mobile devices.
- KonferenzbeitragTowards reliable data stream processing with OSIRIS-SE(Datenbanksysteme in Business, Technologie und Web, 11. Fachtagung des GIFachbereichs “Datenbanken und Informationssysteme” (DBIS), 2005) Brettlecker, Gert; Schuldt, Heiko; Schek, Hans-JörgRecent advances in sensor technologies, wireless communication, powerful mobile devices, and wearable computers strongly support novel types of applications. Especially in healthcare, telemonitoring applications will make use of this new technology to improve the quality of treatment and care for patients and the elderly. These telemonitoring applications require an infrastructure that is able to efficiently combine, process, and manage continuous streams of data coming from the different sensors. In healthcare where applications can be life saving, a particularly important requirement is that this infrastructure is highly reliable. In this paper, we introduce OSIRIS-SE, a novel information management infrastructure for data stream processing based on the hyperdatabase OSIRIS that features a high degree of reliability.