Metadata model

摘要

A metadata model defines model objects to represent one or more data sources. The metadata model comprises a data access layer, a business layer and a package layer. The data access layer contains data access model objects. The data access model objects include a data access model object that describes how to retrieve data from the data sources. The business layer contains business model objects. The business model objects include a business model object that describes a business view of data in the data sources. The package layer contains package model objects which reference subsets of business model objects.