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Integrating wireless sensor networks in heterogeneous networks is a complex task. A reason is the absence of a standardized data exchange format that is supported in all participating sub networks. XML has evolved to the de facto standard data exchange format between heterogeneous networks and systems. However, XML usage within sensor networks has not been introduced because of the limited hardware resources. In this paper, we introduce XML template objects making XML usage applicable within sensor networks. This new XML data binding technique provides significant high compression results while still allowing dynamic XML processing and XML navigation. This is a step towards more complex but exchangeable data management in sensor networks and the extension of the service-oriented paradigm to sensor network application engineering.

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Using XML as a standardized data exchange format in wireless sensor networks is a means to support more complex data management and heterogeneous networks. Moreover, XML is a key feature towards service-oriented sensor networks. Recent work has shown that XML can be compressed to meet the general hardware restrictions of sensor nodes while still supporting updates. In this work we outline the vision and benefits of XML usage in wireless sensor networks. We further present first evaluation results of an implemented XPath query engine, that is able to evaluate a large set of XPath queries dynamically on XML using sensor nodes.

Despite much research in the area of wireless sensor networks in recent years, the programming of sensor nodes is still time-consuming and tedious. A new paradigm which seems to be qualified to simplify the programming of sensor networks is the Service Oriented Architecture. The composition of simple services to more complex ones can be a convenient way to design applications. To enable the sophisticated techniques known from service oriented architectures like replication and migration of services, a transaction model for sensor networks is required. In this paper, we study the applicability of the standard commit protocols Two Phase Commit (2PC) and Transaction Commit On Timeout and show in experiments with real sensor nodes that 2PC can enable consistent service migration in wireless sensor networks.

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The Semantic Web and its technologies become increasingly important. As more and more Semantic Web applications are being used, developing more stable Semantic Web applications becomes a key issue. The state-of-the-art in programming Semantic Web applications is using complex application programming interfaces of Semantic Web frameworks, where extensive tests are necessary for the detection of errors, although many types of errors could be detected already at compile time. In this paper, we propose an embedding of Semantic Web languages into the java programming language, such that Semantic Web data and queries can be transparently used, type safety is guaranteed, and already at compile time, syntax errors of Semantic Web data and queries are reported, unsatisfiable queries are detected and the types of query results are determined. A demonstration of our system is available online.

Using structured data formats like XML in wireless sensor networks to support exchangeability and heterogeneity on application level has become an important research topic in the area of large scale networked sensing systems. Besides, the usage of XML encourages the adaptation of service oriented programming techniques to simplify sensor network application engineering. While the sensor nodes still have significant resource limitations in terms of energy and memory capacity and computational power, recent data management approaches show positive results to bridge this resource gap. Nevertheless, further optimizations are needed to enhance the application range to support larger sets of data within the networks. In this work we present an optimization for a template object compression scheme that is based on a stream-oriented XML compression and supports dynamic data management and query evaluation on the compressed data. We hereby present a complete solution for XML compression, data processing and query evaluation that can be further embedded in the engineering process to support developers. The presented solutions are evaluated and result into significant improvements in comparison to previous approaches, when processing complex large scale XML documents.