ELFIE

JSON-LD Context Files

Summary

This document summarizes normative JSON-LD Context Files to be referenced by JSON-LD encoded representations of resources provided by ELFIE participants. These contexts and the example files linked below are general in nature and do not make reference to any ELFIE use cases or specific demos. This is due to the fact that they were developed in support of all use cases and slightly preceding primary implementation of the demos.

They have been designed using the ‘Testbed-12 JSON and GeoJSON User Guide’ OGC 16-122r1 as a guideline. The ELFIE team relied on that guide as a cumulative summary of earlier discussions (e.g. those out of Testbed 11). The contexts and linking recommendations were later reviewed against the Architecture DWG’s draft JSON Best Practice.

To ensure confidence that normative contexts are being used the context of a JSON-LD document should not be provided inline but by reference to the normative context document. This practice should ensure consistency of encoding (e.g. use of the same key values) as an in-line context object could be modified by the provider.

These contexts assume they are building blocks for a larger graph-of-graphs. As such, they will define self-contained representations that make consistent use of links to reference other features. The rationale is that larger documents, pulling together a set of linked features, are use case specific and therefore should not be limited by a core set of contexts. Obviously, being JSON-LD, an appropriate context should be referenced with a vigorous expectation that the semantics of ELFIE contexts be preserved.

File structure

ELFIE JSON-LD Best Practices

Contexts

CONTEXT FILE EXAMPLE COMMENT
elf.jsonld   Core properties of each feature that support discovery, indexing and basic linking. Each domain specific JSON file should include these.
elf-network.jsonld   A simple set of spatial and temporal topological relations from GeoSPARQL and OWL Time.
floodcast.jsonld TX_Harvey2017_1.json FloodCast classes.
gsml.jsonld BSS001REWW.json GeoSciML 4.0 classes.
gw.jsonld 507AC00.json GroundWaterML 2.0 classes.
hyf.jsonld 010300032404.json HY Features classes and relations.
skos.jsonld skos-concept-nzsc-uym.json SKOS classes and relations.
soilie.jsonld soilie-soil-2108.json Soil Data IE application schema classes and relations.
sosa.jsonld sosa-sample-2108.json Based on the O&M ttl examples introduced in Annex C.10 of SOSA specification. Restricted to O&M sampling and observation features for simplicity’s sake (no sensor descriptions etc).
tsml.jsonld   Context for time-series Observations. See notes below.
  xample-elf-tsml-observation-byref.json Example where the observation result (“hasResult”) is presented as a reference to another file. In this case a pair of TSML GML files (xample-elf-tsml-result-dr.xml; xample-elf-tsml-result-tvp.xml).
  xample-elf-tsml-observation-inline.json Example where the observation result (“hasResult”) is presented as an inline JSON object.
  xample-elf-tsml-result-dr.xml Target of the reference in xample-elf-tsml-observation-byref.json. Domain-Range encoding.
  xample-elf-tsml-result-tvp.xml Target of the reference in xample-elf-tsml-observation-byref.json. Time-Value-Pair encoding.

Deprecated Contexts

A number of contexts were deprecated or renamed as the experiment progressed. These can be found here.

TimeseriesML Experiment

A simple experiment to test the provision of time-series data using the Timeseries profile of Observations and Measurements (OGC 15-043r3).