Australian Government Linked Data Working Group

How To

The AGLDWG can assist Australian governments with some Linked Data-related tasks. At the moment, the task that is most requested is helping organisations publish ontologies.

How to publish an ontology

Suitability

The AGLDWG is keen to assist government organisations publish Semantic Web/Linked Data ontologies for any purposes they see fit within the realm of government business.

Examples

To date we have published some big, and some small, ontologies, such as:

• The AGRIF Ontology
  • an ontology published by the Department of Finance for whole-of-government record keeping
• The Dataset Ontology
  • an ontology published by the AGLDWG itself for describing datasets in catalogues such as data.gov.au using Semantic Web terms
• The Energy Use Dataset Model (EUDM) ontology
  • an draft ontology published by CSIRO for describing specialised energy-related Datasets. A specialised version of the Dataset Ontology

Process

We suggest this general process if you wish to publish an ontology to be used for Australian Government data, which means practically publishing it using some part of the data.gov.au domain:

1. Arrange suitable URI namespaces for your ontology
   • Ontologies will likely need several URIs.
     • A /def/ URI (like http://reference.data.gov.au/def/ont/agrif) which is the "home" of the ontology; this will usually also be the base URI for the new classes and properties on the ontology
     • one or more URIs denoting lists or vocabularies of things required when the ontology is used, but which are maintained on a different schedule
       • note that these URIs are different again from the addresses where datasets are published
   • For example:
     • The EUDM ontology is defined at http://infrastructure.data.gov.au/def/ont/edum
     • The EUDM things - datasets - will be listed at http://infrastructure.data.gov.au/dataset/eudm/ (not yet working), http://transport.data.gov.au/dataset/eudm/ (not yet working) and potentially elsewhere too.
   • The AGLDWG will help find appropriate URIs for your ontology and then implement the technical arrangements for them
2. Design your ontology
   • You will have to design this yourself! We can assist with recommending textbooks, people and tools, just ask
   • We recommend using a desktop ontology builder tool to perform your modelling, such as Protégé. It will produce an ontology document in an RDF document
   • You will need to use the URI assigned to the ontology (above) in the ontology builder
3. Present your ontology
   • An ontology must, at least, be delivered in an RDF file (in rdf/xml, text/turtle or another RDF format). However it is good practice and a requirement of the AGLDWG to also provide a human-readable version of the ontology to document it (HTML).
   • The latter can be generated from ontology files using a range of tools such as LODE.
   • The HTML page for the ontology will be provided to a web-browser requesting the ontology's persistent address: e.g. http://reference.data.gov.au/def/ont/dataset
   • We suggest including a diagram of the ontology's main classes and relationships.These have to be prepared separately as most tools won't do it automatically. You can use CMap or PowerPoint (which is used for the EUDM ontology).
   • See the "make_html.txt" file in the AGRIF ontology's code repository for a full explanation of a process you can emulate
4. Deliver your ontology
   • The AGLDWG can host simple ontologies easily for you on our web server, as we host the three examples above
   • You may choose to host your ontology elsewhere, in which case you will just need to arrange where the AGLDWG points the assigned URIs too
   • The AGLDWG will retain a copy of the ontology, even if you host it elsewhere as a fall-back to ensure all URIs minted can always point somewhere