The Metadata hub is used for handling the interchange and distributing of technical Metadata between decision processing products. It is designed for use primarily by technical staff during the growth and maintenance of data warehouses. There are four requirements of this hub are −
A Metadata hub should provide the interchange of Metadata among systems and products in a shared Meta data environment. The hub must have a record and open programmatic object interface (employing COM or CORBA, for example) that allows third-party tools to control the services of the hub. A file transfer structure supporting industry-identified file formats (comma delimited file, Meta Data Coalition MDIS, Microsoft XML Interchange Format, for example) should also be supported for Metadata interchange.
A Metadata hub must provide constant stores for the administration and sharing of Metadata. Metadata in a store should be maintainable by the object API and file transfer methods defined above and via supplied GUI and Web user interactive interfaces.
An interactive and batch Metadata impact analysis and documenting feature is also needed. The hub must provide an agent interface that can scan and capture, at user-defined intervals, local products, and systems for new or modified Metadata for adding to the Metadata Store.
The Metadata manager used to maintain Metadata in the store should support version and library control features that can create a historical record of Metadata changes and support group development. In large distributed environments, the administrator should be able to physically partition the Metadata environment across multiple hub servers and Metadata stores.
The Metadata hub should, at a minimum, be able to manage data warehouse information store definitions. Formats supported should include relational tables and columns, and multidimensional measures and dimensions.
There is a different type of Meta data that can be handled is data about the data sources used to create data warehouse records and about the transforms used to this source data before it is loaded in a warehouse.
It is recognized, however, that current ETL tools use their proprietary transformation methods, making it complex to make a generalized facility for managing this type of Metadata. The product should minimum provide the ability to document data source and transformation Metadata in free-form text format.
Perfectly, the hub must also document details about the business Metadata related to the common business model and the business views employed by business intelligence tools and analytic software to access warehouse data.