A RESTful proxy and data model for linked sensor data

Abstract

The vision of a Digital Earth calls for more dynamic information systems, new sources of information, and stronger capabilities for their integration. Sensor networks have been identified as a major information source for the Digital Earth, while Semantic Web technologies have been proposed to facilitate integration.. So far, sensor data is stored and published using the Observations & Measurements standard of the Open Geospatial Consortium (OGC) as data model. With the advent of Volunteered Geographic Information and the Semantic Sensor Web, work on an ontological model gained importance within Sensor Web Enablement (SWE). In contrast to data models, an ontological approach abstracts from implementation details by focusing on modeling the physical world from the perspective of a particular domain. Ontologies restrict the interpretation of vocabularies towards their intended meaning. The ongoing paradigm shift to Linked Sensor Data complements this attempt. Two questions have to be addressed: (i) how to refer to changing and frequently updated data sets using Uniform Resource Identifiers, and (ii) how to establish meaningful links between those data sets, i.e., observations, sensors, features of interest, and observed properties? In this paper, we present a Linked Data model and a RESTful proxy for OGC's Sensor Observation Service to improve integration and inter-linkage of observation data for the Digital Earth.Keywords: Digital Earth, Geospatial data integration, Spatial Data Infrastructure, Earth Observation, Data exchange models, Linked Data, Semantic Enablement * Corresponding author: Krzysztof Janowicz; email: jano@geog.ucsb.edu 1 MotivationThe initial vision of a Digital Earth was first formulated by former US Vice President Al Gore as a multi-resolution, three-dimensional representation of the planet, into which we can embed vast quantities of geo-referenced data (Gore, 1998). Ten years after this speech, Craglia et al. published a position paper to argue that this vision has not yet been achieved (Craglia et al., 2008). In parallel to the growing availability of information, the need to better understand the interplay of environmental and social phenomena has also increased, thus requiring more dynamic systems, new sources of information, and stronger capacities for their integration. The Sensor Web has been identified as a central building block to address these challenges (De Longueville et al., 2010). A digital nervous system for the globe has been suggested as a vibrant approach for the Digital Earth. An implementation based on Spatial Data Infrastructures (SDI), especially on the Sensor Web Enablement (SWE) standards of the Open Geospatial Consortium (OGC), has been proposed. These infrastructures do not only deliver data but also offer geospatial processing capabilities and the final rendering on a virtual globe. Grounded in spatial and temporal reference systems, the outcomes of a variety of services can be combined into a multi-layered representation of the Earth's surface and help to an...

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