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The Semantic Sensor Network ontology (SSN) describes the arrangement of actuators and their actuations, sensors and their observations, and samplers and their samplings, along with the procedures implemented, the features of interest and samples, and the actuated and observed properties. The core classes and properties are defined using a minimal set of axioms in modules called SOSA (Sensor, Observation, Sample, and Actuator), supplemented with additional axiomatization and terms in further SSN modules. These allow SSN to support a wide range of applications and use cases, including satellite imagery, large-scale scientific monitoring, industrial and household infrastructures, social sensing, citizen science, observation-driven ontology engineering, and the Web of Things. Alignments to some existing ontologies and specifications are provided. Patterns for application of SSN are provided.

The namespace for the core terms is `http://www.w3.org/ns/sosa/`.

The suggested prefix for the SOSA namespace is `sosa:`.

The SOSA modules contain the core definitions.
The ontology IRI of SOSA is http://www.w3.org/ns/sosa/.
The version IRI of SOSA 2023 edition is http://www.w3.org/ns/sosa/2023/.

The SSN modules contain the full axiomatization of the core terms.
The ontology IRI of SSN is http://www.w3.org/ns/ssn/.
The version IRI of SSN 2023 edition is http://www.w3.org/ns/ssn/2023/.

General Information

For the OGC community, this document is a Public Draft prepared by the Spatiotemporal Data on the Web Working Group (SDW) — a joint W3C-OGC project (see charter). The document is prepared following W3C conventions. The document is released at this time to solicit public comment.

Specification

This section introduces the specifications for the Semantic Sensor Network Ontology and its RDF implementation.

SSN Extensions

This section provides the specifications for modules that extend the scope and capabilities of SSN.

Alignments

This section provides the specifications for modules that align SOSA and SSN to a variety of related ontologies and specifications.

Common Patterns

This section discusses how to handle some common modeling questions.

Wide review

TBC

Acknowledgments

The editors recognize the major contribution of the members of the original W3C Semantic Sensor Networks Incubator Group. The editors also gratefully acknowledge the contributions made by all members of the SSN subgroup of the original Spatial Data on the Web working group.

For this new edition of SSN, in addition to the contributors listed at the top of the document, the editors acknowledge the work of the editors of ISO 19156:2023 ([[iso-19156-2023]], [[OMS]]). Ted Thibodeau Jr, Openlink Software, made many small grammatical improvements to the text.

Change History

A full change-log is available on GitHub.

Changes since W3C Recommendation 19 October 2017 (https://www.w3.org/TR/2017/REC-vocab-ssn-20171019/)

  1. Updated Abstract to reflect the revised graph and axiomatization design
  2. Updated and streamlined Introduction; moved Origins section to an Annex.
  3. Add conformance clause Chapter 3
  4. Updated Chapter 4 and Chapter 5.1 to explain modularization and RDF implementation
  5. OGC ModSpec explanation in Chapter 3. Conformance, and tabulations in Chapter 4 - Modularization
  6. Refactored SOSA and SSN into modules - sosa-common sosa-actuation sosa-observation sosa-sampling sosa (all), and matching ssn-* files (also ssn-deprecated). Refactored HTML sources to match.
  7. Moved basic rdfs:sub*Of axioms to the SOSA modules, reference RDFS-Plus
  8. re-drafted all figures as SVG; added a clause on notation
  9. Mark `ssn:Input`, `ssn:Output`, `sosa:Result` deprecated
  10. Add 'abstract' superclasses `Execution` (superclass of Actuation, Observation and Sampling), `Asset` (superclass of Platform and System)
  11. Add `ExecutionCollection`, `ActuationCollection`, `ObservationCollection`, `SamplingCollection`, `SampleCollection`, `hasMember`, `isMemberOf`
  12. remove `rdfs:range` on `resultTime`
  13. Clarify meaning of `hasResult`, `resultTime`, `phenomenonTime` in the context of `Actuations`
  14. Add `startTime` property
  15. Add `forProperty` links from `Procedure`, and inverse `hasProcedure`
  16. add inverses for all object-properties, add tabulation of all properties
  17. Add `madeBySystem`, `madeExecution`
  18. Remove `Sample is subclass of FeatureOfInterest` axiom
  19. Add Sample subclasses - `MaterialSample`, `SpatialSample`, `StatisticalSample`
  20. Add `madeSamplingHasResult` and `usedForExecutionHasResult` properties
  21. Add `hasOriginalSample`, `isSampleOfUltimateFOI` (from SSN-ext)
  22. Deprecate `ActuatableProperty`, `ObservableProperty` in favour of generic `Property`
  23. Add `ActuatingProcedure`, `ObservingProcedure`, `SamplingProcedure` specializations of `Procedure` for each execution type
  24. Add `hasFeatureOfInterest` support to `Deployment`
  25. Remove Functional and InverseFunctional axioms except on `hasResult`
  26. Simplify the System Capabilities Module
  27. Move System Capabilities module to Appendix
  28. Add SAREF alignment
  29. Update OBOE alignment - using `ObservationCollection`, `SampleCollection`, `hasMember`
  30. Add detailed OMS Extension module
  31. Retire O&Mv2 alignment - superseded by OMS extension
  32. Retire SSNX alignment - incubator version is now two generations back
  33. Added IDO alignment.
  34. Add BFO alignment
  35. Relaxed and simplified DUL alignment
  36. Add DOLCE alignment
  37. Fully revise Common Modeling patterns, also with diagrams
  38. Make patterns for Location, UoM more prescriptive
  39. Move extended examples out of the document into an online repository
  40. Remove Warnings for terms that have 2 evidences of implementation