0011 Managing Referenceables¶

Referenceable entities can have chains of related feedback and additional knowledge attached to them. The following types help a metadata manager to process these collections of elements more efficiently.

LatestChange classification¶

The LatestChange classification is a convenience mechanism to indicate where the last change occurred. Components that are monitoring Referenceable entities can use the open metadata events related to classifications to monitor changes to the entity.

Template classification¶

Templates are used when creating new elements that are similar. For example, consider the case when multiple resources need to be catalogued as assets with the same classifications. One of the assets can be set up to act as a template. The other resources can be catalogued using the first asset as a template.

The Template classification indicates that a Referenceable entity is a good element be used as a template when creating a new element of the same type. There is no restriction on using Referenceable entities without this classification as templates. The Template classification is simply a useful marker to indicate that the referenceable does not represent a real resource, since it is only a template.

The properties for the Template classification are:

• name - name of the template, designed to help the selection of the correct template.
• description - further information on the purpose of the template.
• versionIdentifier - allows different versions of a template to be kept in the metadata repository.
• additionalProperties - allows additional information about the template to be supplied

Templates can include relationships. If the relationship links to an entity that has the same anchor as the starting entity, the entity and the relationship is replicated. If the linked entity is part of a different anchor, only the relationship is created. In the example above, the glossary term has a different anchor to the asset. Therefore any assets created with tAsset as a template will be linked to the same glossary term.

TemplateSubstitute classification¶

If a query requests all assets linked to the glossary term, GlossaryTerm, the tAsset entity will be returned with the other assets. This could be confusing. Therefore it is possible to create a copy of the glossary term that is linked to tAsset. This copy has the TemplateSubstitute classification to show that the real glossary term to link a new asset to is identified by the SourcedFrom relationship.

With this set up, when Asset2 is created with the template tAsset, it is linked to the same glossary term as Asset.

SourcedFrom relationship¶

When one Referenceable entity is created by using another Referencable entity as a template, the qualifiedName must be changed in the new entity to give it a unique name - often the displayName value changes, too. This makes it hard to identify the source of a Referenceable entity's values.

The SourcedFrom relationship is used to show the provenance of the information from the template. This is useful to help trace where information has come from and to help understand any potential impact cause by a change to the template if this change also needs to be made to the elements that were copied from it.

The sourceVersionNumber identifies the version number of the template used when the new entity was created.

CatalogTemplate relationship¶

The CatalogTemplate relationship links an OpenMetadataRoot entity that describes a class of technology with a template for creating a catalog entry for a resource of this class.

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