|Title||Semantic Sensor Network XG Final Report|
|Year of Publication||2011|
|Authors||Payam Barnaghi, Michael Compton, Oscar Corcho, Raul Garcia Castro, John Graybeal, Arthur Herzog, Krzysztof Janowicz, Holger Neuhaus, Andriy Nikolov, Kevin Page|
|Series Editor||Laurent Lefort, Cory Henson, Kerry Taylor|
|Keywords||Ontology, Semantic Sensor Network, Sensor|
This document is the final report of the W3C Semantic Sensor Network Incubator Group. The group had two main objectives. The first was to develop an ontology to describe sensors and sensor networks for use in sensor network and sensor web applications. The second was to study and recommend methods for using the ontology to semantically enable applications developed according to available standards such as the Open Geospatial Consortium's (OGC ) Sensor Web Enablement (SWE) standards. The Sensor and Sensor Network ontology presented here, known as the SSN ontology, answers the need for a domain-independent and end-to-end model for sensing applications by merging sensor-focused (e.g. SensorML), observation-focused (e.g. Observation & Measurement) and system-focused views. It covers the sub-domains which are sensor-specific such as the sensing principles and capabilities and can be used to define how a sensor will perform in a particular context to help characterise the quality of sensed data or to better task sensors in unpredictable environments. Although the ontology leaves the observed domain unspecified, domain semantics, units of measurement, time and time series, and location and mobility ontologies can be easily attached when instantiating the ontology for any particular sensors in a domain. The alignment between the SSN ontology and the DOLCE Ultra Lite upper ontology has helped to normalise the structure of the ontology to assist its use in conjunction with ontologies or linked data resources developed elsewhere. While the OGC SWE standards provide description and access to data and metadata for sensors, they do not provide facilities for abstraction, categorization, and reasoning offered by semantic technologies. This report presents a semantic annotation method defined by the XG. This method should help the users of OGC standards to retrofit XML-based web services to better support semantic mashups and to ease the integration with linked open data applications relying on semantic web technologies like RDF and SPARQL. Finally, this report identifies where ongoing research and standardisation efforts are likely to benefit from the work done by this Incubator Activity and also where further work is required. Three directions for future work have been identified: (1) standardise the SSN ontology to use it in a Linked Sensor Data context, (2) standardise the SSN ontology to bridge the Internet of Things and the Internet of Services, (3) foster the adoption of the SSN ontology in the OGC community More than 25 papers discussing applications of the SSN XG work have been published by the XG participants and by early adopters which were not directly involved in the ontology development but were closely following it via the mailing list and the wiki. This is a clear signal that there is an good prospect for the creation of W3C community group focused on the maintenance and extension of the SSN Ontology. This is the first recommendation issued by the group. The group's decision to align the SSN Ontology with DOLCE Ultra Lite has raised specific challenges for the publication, packaging and maintenance of the SSN Ontology which are not frequently addressed by other W3C groups publishing recommendations focusing on ontologies. The second recommendation is to encourage further work on these issues at W3C. The third recommendation made by the group is to encourage its participants and followers to join the Provenance working group to work on sensor-specific issues. The fourth recommendation requests the W3C to promote uptake of the SSN ontology in the W3C community and beyond. The final recommendation of this report is to encourage W3C and OGC to coordinate their activities in this area and especially to build a larger pool of experts to tackle the challenges linked to differences between the modelling approach used by the group, based on OWL, and the modelling principles currently applied within the OGC community.