0505 Schema Attributes¶

Schemas typically have a hierarchical structure. Model 0505 provides for a structure of complex schema types that have their own internal structure. This structure is defined through one or more nested schema attributes each with their own type.

TypeEmbeddedAttribute classification¶

The TypeEmbeddedAttribute classification is applied directly to the SchemaAttribute to provide its type information. For example, if a ComplexSchemaType has a simple string attribute this can be captured as a SchemaAttribute (giving the name of the attribute) with a TypeEmbeddedAttribute classification (whose dataType property indicates string).

TypeEmbeddedAttribute can represent any of the standard schema types. Where a schema type is described using multiple schema type objects,(such as MapSchemaType, SchemaOptionChoice and ExternalSchemaType) the schema relationships for that type begin with SchemaElement and then map to more detailed SchemaTypes. This is so they can be connected to a SchemaAttribute or a SchemaType.

• encodingStandard - Format of the schema.
• dataType - The name of a primitive data type.
• schemaTypeName - Open metadata type name for the associated schema type.
• qualifiedName - Unique name for the element.
• displayName - Display name of the element used for summary tables and titles.
• description - Description of the element or associated resource in free-text.
• defaultValue - Value that is used when an instance of the data field is created.
• fixedValue - The value of a literal data type.
• usage - Guidance on how the element should be used.

• additionalProperties - Additional properties for the element.

• category - Descriptive name of the concept that this element applies to.

• namespacePath - Prefix for element names to ensure uniqueness.
• versionIdentifier - Version identifier to allow different versions of the same resource to appear in the catalog as separate assets.

NestedSchemaAttribute relationship¶

A SchemaAttribute can be nested within another SchemaAttribute using the NestedSchemaAttribute relationship. See 0534 Relational Schemas for an example of this between RelationalTables and RelationalColumns. The properties are:

• position - The position of the attribute in the parent schema attribute. Zero (0) means no position and a positive number identifies the position of the nested schema attribute.
• minCardinality - The minimum number of occurrences of the nested schema attribute in the parent schema.

• maxCardinality - The maximum number of occurrences of the nested schema attribute in the parent schema. A negative number means "many".

• coverageCategory - Used to describe how a collection of data values for an attribute covers the domain of the possible values to the linked attribute.

DataItemSortOrder enum¶

DataItemSortOrder provides the valid values for the sortOrder property of SchemaAttribute. It indicates whether the rows/instances of the data stored in this schema appear in any particular order or not.

ComplexSchemaType entity¶

A schema type that has a complex structure of nested attributes and types.

SchemaAttribute entity¶

A schema element that nests another schema type in its parent.

• allowsDuplicateValues - When multiple occurrences are allowed, indicates whether duplicates of the same value are allowed or not.
• orderedValues - When multiple occurrences are allowed, indicates whether the values are ordered or not.
• nativeClass - Native class used by the client to represent this element.
• aliases - List of alternative names.
• sortOrder - Defines the suggested order that data values in this data item should be sorted by.
• minimumLength - Minimum length of the data value (zero means unlimited).
• length - Length of the data field (zero means unlimited).
• isNullable - Accepts null values or not.
• precision - Number of digits after the decimal point.
• namespacePath - Prefix for element names to ensure uniqueness.

AttributeForSchema relationship¶

Link between a complex schema type and its attributes.

• position - Position of the element in a collection of relationships. Zero means no position set. A positive value identified the position starting from 1 for the first position.
• minCardinality - Minimum number of allowed instances.
• maxCardinality - Maximum number of allowed instances.
• coverageCategory - Used to describe how a collection of data values for an attribute covers the domain of the possible values to the linked attribute.

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