Understanding the spec format

One very important aspect of spec usage is the versioning of a spec, also known as the spec format.

Business requirements may change over time, and creating a new spec format allows you to make the necessary changes to a spec and to persist new attributes to the database without causing validation failure for existing attributes.

A spec can contain one or more spec formats, identified by an eight-digit spec format number, which allows for the development of specs where existing schemas require modification. Within an InfoSphere® MDM metadata project, each spec format appears as a directory within the spec. These directories have numeric names such as 00000001, which identify the spec format numbers. Spec format numbers are 8 digit decimal strings padded with leading zeros and are used to uniquely identify the spec format within the spec. When a spec is created using the InfoSphere MDM Workbench, an initial spec format 00000001 is automatically created.

All potential modifications to a spec fall into two categories, compatible and incompatible. When making incompatible modifications to a spec, the internal schema cannot be simply updated with the required changes, because this can cause existing spec values to fail validation.

If modifications to a spec cause existing spec values that are already deployed in the InfoSphere MDM runtime to become incompatible – for example, adding a mandatory XML element to the XSD – the modification will render any existing spec values incompatible because they were created without that XML element. The existing spec values will fail to validate against the XSD if these incompatible changes are introduced. See Internal schema validations for more information.

To provide continued support for existing spec values and allow for modifications to the schemas, both the old and new schemas must coexist. To allow for this, you can create a new version of an existing spec, a solution that allows you to keep existing spec values and to introduce new ones, all while avoiding validation failure. See Internal schema validations for more information on internal schema validation.

A new spec format is created by duplicating an existing spec format folder. You are responsible for allocating an appropriate spec format number and making the corresponding modifications to the new internal schema. The new spec format number must be one higher than the largest existing spec format number.

For more information on spec formats, see the InfoSphere MDM Workbench Users Guide.