The BDC is essentially a catalog of business applications that are of interest to SharePoint Server 2007 users, and it bridges the gap between the portal and business applications by bringing in key data from various applications to SharePoint sites, lists, search, and user profiles. The BDC is the key infrastructural component around which most of the other business data features of SharePoint Server 2007 are built. Administrators can register business applications in the BDC, after which the data in the application is immediately available to SharePoint through the business data features described below. A key requirement for each registered business application is an XML-based metadata model that describes the application programming interfaces (API) of the application or the schema of the database that maps to business objects (e.g. customer) and properties (e.g. name) that a SharePoint user can understand. These metadata models can be easily created by DBAs or database developers.
Business Data Catalog