Valid Value Definition¶

A valid value definition stores a single authoritative value that data - or metadata - is allowed to take. It is the building block of Egeria's reference data management.

Most systems store coded values: a country is held as GB, an order status as 03, a department as a four-digit number. Each system tends to invent its own codes, and the meaning of those codes lives in a code table somewhere - or in someone's head. A valid value definition brings that code table into open metadata, where it can be governed, shared and used to drive the systems that depend on it.

Properties¶

In addition to the properties it inherits as a referenceable, a valid value definition records:

• preferredValue - the actual value to use.
• dataType - the type of value this valid value represents.
• usage - the intended use of the value.
• scope - the scope within which the value is valid.
• ordinal - an integer used to sequence the values within a set.
• isCaseSensitive - whether the value is case sensitive.
• namespacePath - the root of the properties path name, where one applies.

Organizing valid values¶

Valid value definitions are gathered into sets using the ValidValueMember relationship. Because a set can be nested inside another set, valid values form a hierarchy - which is how taxonomies and multi-level code tables are represented.

Several specializations cover the different jobs valid values do:

• ReferenceDataValue - a single code value from a business code table, with its associated properties. ReferenceDataSet represents the top of such a hierarchy.
• SpecificationPropertyValue - the specification of a configurable property, such as the properties a connector or catalog template expects.
• ValidMetadataValue - a valid value for an open metadata property, allowing open metadata itself to be governed by reference data.
• TechnologyType - a specialized ValidMetadataValue holding the valid values of deployedImplementationType. These are the technology types that drive Egeria's automated cataloguing.

Using valid values¶

• ValidValuesAssignment links a set of valid values to the element representing a data field - a data field, glossary term or schema element. Its strictRequirement property says whether the listed values are the only ones permitted, or merely the preferred ones.
• ValidValuesImplementation maps a valid value to the value actually used in a particular code table, which is what makes it possible to keep the code tables across an information supply chain consistent - or to generate the mapping tables that translate between them.
• ValidValuesMapping records that values from different sets - different standards, regulations or industry definitions - are equivalent.
• ConsistentValidValues supports cross-field validation, showing which values in one set are consistent with values in another.
• ReferenceValueAssignment uses a valid value as a tag on another metadata element, marking that the element has a particular property or belongs to a particular group.

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