ORR API Documentation

The API documentation is described in detail for each ORR instance according to the version of the ORR Ont software being used. Besides containing the documentation itself, the API Documentation pages referenced below also allow users to directly exercise the API against the corresponding ORR REST endpoint.

ORR Instance API Documentation Portal Page
MMI ORR https://mmisw.org/ontapi/ https://mmisw.org/ont
XDOMES ORR https://xdomes.org/ontapi/ https://xdomes.org/ont
ESIP COR http://cor.esipfed.org/ontapi/ http://cor.esipfed.org/ont
SensorML ORR http://sensorml.com/ontapi/ http://sensorml.com/ont

In each case you can use the "Authorize" button at the top of the API Documentation page to login with your corresponding credentials. Once authorized, you will be able to not only perform the basic GET operations, but also see expanded responses according to your access privileges as well as perform other operations.

In each API operation description, you are able to set the variables in the descriptions of the API interface, so that you can execute the API call, as well as see it appropriately formatted for an invocation with the curl command line tool.

Format Parameter

Various API operations accept a format parameter to indicate the relevant serialization format: either the desired one for GET requests, or that of the submitted ontology payload in POST requests.

The recognized values for the format parameter are:

format Name Reference
jsonld JSON-LD https://www.w3.org/TR/json-ld/
rdf RDF/XML https://www.w3.org/TR/REC-rdf-syntax/
n3 Notation3 https://www.w3.org/TeamSubmission/n3/
nt N-TRIPLE https://www.w3.org/TR/n-triples/
ttl TURTLE https://www.w3.org/TeamSubmission/turtle/
owx OWL/XML https://www.w3.org/TR/owl-xml-serialization/

Special format for metadata

Only for GET ontology requests, the special format parameter value !md can be used to retrieve metadata about the ontology. The metadata is given in terms of the list of predicates associated with the IRI as a subject in corresponding triples in the registered ontology.

For example, for


the returned JSON looks like so:

  "uri": "http://www.w3.org/ns/ssn/",
  "metadata": {
    "http://purl.org/dc/terms/title": [
      "Semantic Sensor Network Ontology"
    "http://purl.org/dc/terms/description": [
      "This ontology describes sensors, actuators and observations, and related concepts..."
    "http://purl.org/vocab/vann/preferredNamespaceUri": [
    "http://www.w3.org/2000/01/rdf-schema#seeAlso": [
    "http://purl.org/dc/terms/rights": [
      "Copyright 2017 W3C/OGC."
    "http://purl.org/dc/terms/created": [
    "http://purl.org/dc/terms/license": [
    "http://www.w3.org/2000/01/rdf-schema#comment": [
      "Please report any errors to the W3C Spatial Data on the Web Working Group via the SDW WG Public List public-sdw-wg@w3.org"
    "http://www.w3.org/2002/07/owl#versionInfo": [
      "New modular version of the SSN ontology. \n\nThis ontology was originally developed in 2009-2011 by ..."
    "http://www.w3.org/2002/07/owl#imports": [
    "http://purl.org/vocab/vann/preferredNamespacePrefix": [
    "http://www.w3.org/1999/02/22-rdf-syntax-ns#type": [
  "name": "Semantic Sensor Network Ontology",
  "author": "OGC Spatial Data on the Web Working Group",
  "format": "ttl",
  "status": "draft",
  "version": "20200414T164723",
  "versions": [
      "version": "20200414T164723",
      "visibility": "public",
      "status": "draft"
      "version": "20170529T160905",
      "visibility": "public",
      "status": "unstable"

Note that besides the metadata entry, the main returned object will also include some pieces of metadata at the ORR system level related with the ontology (including, file format of the submitted ontology, current version designation and summary of all versions, and others). These extra metadata pieces are mainly intended for processing by client applications and tools (like the ORR portal itself).