Frank Lauterwald

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In this paper, we present DSAM, a data stream application manager. DSAM supports the deployment of global queries to distributed and heterogeneous sensor nodes and Stream Processing Systems (SPSs). We provide a graph-based global query language DSAM-AQL. The Abstract Query Language (AQL) is a declarative streamoriented query language that abstracts from(More)
Operator placement for distributed stream-processing systems is still a challenging problem that can be modeled as a <i>Task Assignment Problem</i> (TAP). Multiple objectives are relevant for the optimization in heterogeneous stream-processing systems as there are different capabilities of the underlying networks and stream-processing nodes. We present an(More)
REQUIRED) In recent years, several process models for data quality management have been proposed. As data quality problems are highly application-specific, these models have to remain abstract. This leaves the question of what to do exactly in a given situation unanswered. The task of implementing a data quality process is usually delegated to data quality(More)
Database Management Systems (DBMSs) that can be tailored to specific requirements offer the potential to improve reliability and maintainability and simultaneously the ability to reduce the footprint of the code base. If the requirements of an application change during runtime the DBMS should be adapted without a shutdown. Runtime-adaptation is a new and(More)
Data Stream Systems (DSSs) use cost models to determine if a DSS can cope with a given workload and to optimize query graphs. However, certain relevant input parameters of these models are often unknown or highly imprecise. Especially selectivities are stream-dependent and application-specific parameters. In this paper, we describe a method that supports(More)
Verteilte Datenstromverarbeitung unter Beteiligung heterogener Datenstromsysteme und Sensorknoten erfährt zunehmendes Interesse. Ein Problem dabei ist, dass die heute verfügbaren Datenstromsysteme sich hinsichtlich ihrer Verarbeitungslogik unterscheiden. Das zeigt sich darin, dass für vermeintlich gleiche Anfragen unterschiedliche Ergebnisse erzeugt werden(More)
Nowadays maintenance of database management systems (DBMSs) often requires offline operations for enhancement of functionality or security updates. This hampers the availability of the provided services and can cause undesirable implications. Therefore it is essential to minimize the downtime of DBMSs. We present the CoBRA DB (Component Based Runtime(More)
Bei verteilten Datenstromsystemen ist es ebenso wie bei verteilten Datenbanksystemen für die Verteilung von Anfragen entscheidend, die zu erwartenden Kosten schätzen zu können. Bei der Kostenschätzung mit Kostenmodellen müssen die Parameter für jedes System und jeden Operator ausgemessen werden. In dieser Arbeit wird ein black-box-Verfahren vorgestellt, mit(More)
The ability to adapt to different computing environments or external changes is an important requirement for both stationary and mobile computing. Without this ability, all requirements have to be foreseen, which is often not possible in practice. Classical software engineering approaches often lead to redeployment or even software migration. Therefore(More)