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Ontologies

An ontology is a standalone model that lives in Ontology Studio in its own right. It has its own concepts, properties, and constraints, and it is published as a series of numbered releases. You don’t need a glossary to create one.
Note: Users with edit permission read and query the ontology’s working Draft by default and can switch to the Published version. Users without edit permission always read the active published release. Concepts you haven’t published don’t appear to them. For more information, see Draft and Published Views.
Existing glossaries aren’t converted into ontologies. Their terms stay in the glossary.

Choose an Ontology

The Ontology selector is the button at the top right of the Ontology Studio header. It decides what the whole Studio shows. Ontology selector listing All ontologies, each ontology with its concept count, a search field, and New ontology Hover an ontology row to show its More actions menu, which has Settings and Delete. Ontology selector with the More actions menu open on an ontology row, showing Settings and Delete If the list can’t load, the menu shows an error with a Retry button. In the All ontologies scope:
  • View shows the combined graph, with Graph and Tree surfaces.
  • Edit and Query first ask you to pick a single ontology.
  • If the catalog has too many concepts for one graph (more than 20 ontologies or 2,000 combined definitions), Studio asks you to pick one ontology instead.

First Run

If there are no ontologies yet, Studio shows No ontologies yet with three cards: Install from library, Import a file, and Create from scratch. For more information, see First Run.

Create an Ontology

  1. Open the Ontology selector and click New ontology. The item appears only if you can create ontologies. For more information, see Permissions. On the first-run screen, click Create from scratch instead. Ontology selector open with the New ontology action at the bottom of the list
  2. In the New ontology dialog, complete the fields. Create ontology stays disabled until Display name is valid and the namespace has loaded. New ontology dialog with Display name, Description, Owners, and Reviewers fields and an Advanced section
  3. Optional: Expand Advanced to review or change the generated identifiers. New ontology dialog with the Advanced section expanded, showing Name / ID, Ontology IRI, Namespace, and Layer The prefix is the first 8 letters and digits of the display name, in lowercase. It is onto when nothing is left. If another ontology already uses it, Studio appends a number. For the name Finance Core, the IRI is https://open-metadata.org/onto/financec. The base URI comes from the server’s RDF base URI setting (RDF_BASE_URI), which defaults to https://open-metadata.org/. If the base URI can’t be loaded, the dialog shows an error with a Retry button.
    Note: What is an IRI? An IRI (Internationalized Resource Identifier) is a unique, permanent name for a thing, written like a web address or a urn: string. It identifies a concept even if you rename it later. IRIs must be absolute, meaning they start with a scheme such as https: or urn:. A value like relative/path is rejected with the message Enter a valid concept IRI.
  4. Click Create ontology. The new ontology opens in Edit mode, appears in the selector, and Studio prompts you to add the first concept.
Alternatively, create an ontology by installing a pack from the Ontology Library, or by importing a file into a new ontology. Those ontologies get a generated identifier of the form urn:openmetadata:ontology:<id> instead of the onto namespace.

Edit Ontology Settings

To edit an ontology’s settings, use either of the following methods. From the Ontology selector
  1. Click the Ontology selector in the header.
  2. Hover the ontology row, click More actions, and then click Settings. The Ontology settings dialog opens. Ontology selector with the More actions menu open on the HL7 FHIR Starter row, showing Settings highlighted and Delete
From Edit mode
  1. Pick the ontology in the Ontology selector.
  2. In View mode, click Edit Ontology. Alternatively, click the Edit tab. View mode with the Edit Ontology button highlighted in the Ontology Studio header
  3. In the sub-mode bar, click Ontology. Edit mode with the Ontology view highlighted and the Overview tab showing counts, Validation, and Health
  4. Click the Settings tab. The fields appear on the page instead of in a dialog. Settings tab of the Ontology view showing Display Name, Description, Owners, Reviewers, Layer, Name, and Ontology IRI fields

Delete an Ontology

Deleting an ontology removes it together with its concepts, properties, relationships, rules, and releases. It leaves the ontology list immediately.
  1. Hover the ontology row in the selector, click More actions, and click Delete. The item is disabled if you don’t have Delete on the ontology.
  2. In the Delete ontology dialog, review the counts of concepts and releases that will be removed.
  3. Type the ontology name to confirm, then click Delete.

Work in an Ontology

With an ontology selected, the Studio modes work on it:
  • View: Read the model as a Graph, Tree, or Ontology view. For more information, see Explore.
  • Edit: Add concepts, properties, and constraints, draw relationships, and bind concepts to data assets. For more information, see Author. Each item is saved on its own, and every save is an unpublished change to the draft until you publish.
  • Publish: Publish a release, or request a review. For more information, see Releases.
  • Query: Search the ontology with SPARQL. For more information, see Query.
  • Import / Export: Bring an RDF or CSV file in as unpublished changes, or export the draft or a release. For more information, see Import & Export.
The Ontology view shows an overview of the selected ontology: counts of concepts, relationships, properties, and constraints, a Validation summary with Validate all, a Health summary of concepts without a description or without a link, and the version, namespace, owners, and reviewers. For more information, see Explore.
Note: The Edit tab appears whenever you have edit permission on ontologies. Your permissions on each item decide which changes are saved. Buttons are disabled when you don’t have them.

Permissions

Ontologies use standard OpenMetadata policies, plus two seeded roles. OntologyAuthor lets a user create ontologies and publish releases. OntologyReviewer lets a user be listed as a reviewer and decide review tasks. The DataSteward role includes both. Being listed as a reviewer doesn’t give write access.
Note: Which roles include these operations depends on your organization’s policies. Studio treats an admin as allowed to create ontologies.
If you lack the role, the dialog explains: “You do not have permission to create ontologies. An admin can grant you the OntologyAuthor role.”

Requirements

  • No RDF setup is required to create, author, publish, import, or export ontologies, or to query them. Publishing a release does queue an update to the RDF knowledge graph in the background.
  • Reviewed releases need an approval workflow. When an ontology has reviewers, a review request needs a deployed approval workflow with a user approval step. Ontologies with no reviewers publish directly and don’t need one.

REST Endpoints

Paths start with /api. For the full reference, see the Ontology API Reference.