Define Prefixes / Namespaces

Introduction

A namespace declaration consists of a prefix name and a namespace IRI. Namespace declarations allow for the abbreviation of IRIs by using a prefixed resource name instead of a full IRI.

For example, after defining a namespace with the values

• prefix name = cohw, and the
• namespace IRI = https://data.company.org/hardware/

you can use the term cohw:test as an abbreviation for the full IRI https://data.company.org/hardware/test.

This is particularly useful when you have to write source code in Turtle and SPARQL.

Managing Namespace Declarations

Using the Vocabulary Catalog

After installing a vocabulary from the Vocabulary Catalog, the vocabulary namespace declaration is automatically added to all integration projects.

In order to get the prefix name and the namespace IRI from the vocabulary graph, the following terms from the VANN vocabulary need to be used on the Ontology resource.

• vann:preferredNamespacePrefix - to specify the prefix name
• vann:preferredNamespaceUri - to specify the namespace IRI

In the Explore area, an Ontology with a correct namespace declaration looks like this:

Using cmemc

The vocabulary command group of cmemc has an import command that you can use to install arbitrary vocabulary documents and register them as vocabularies in Corporate Memory.

Beginning with v22.2, this command has an additional option --namespace which you can use to set a vocabulary namespace even if the vocabulary does not include the data needed for autodiscovery:

$ cmemc vocabulary import my-ont.ttl --namespace myo https//example.org/my/`

Using the Project Configuration

In addition to the used vocabulary namespace declarations, you may want to add well-known namespaces for organizing the Knowledge Graphs.

Such organization use cases include:

• Namespaces per class / resource type:
  • prefix name = persons, namespace IRI = https://example.org/data/persons/
• Namespaces per data owner or origin:
  • prefix name = sales, namespace IRI = https://example.org/data/sales/

Prefixes in Data Integration are defined on a project basis. When creating a new project, a list of well-know prefixes is already declared.

After selecting a project from the search results the prefix management is available in the project configuration in the lower right area:

By using the Edit Prefix Settings button in this Configuration area, you will see the Manage Prefixes dialog:

In this dialog, you are able to

• Delete a namespace declaration → Delete Prefix
• Add a new namespace declaration → Add

Validating Namespace Declarations

After adding namespace declarations to a project you are able to use the abbreviated IRIs in the user interface, for instance, in the mapping editor, the Turtle editor or the Query editor:

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