Editing Federated database system (section)

== Five level schema architecture for FDBSs ==
The five level schema architecture includes the following:

* Local Schema is basically the conceptual model of a component database expressed in a native data model.<ref name=":0">{{Cite journal|url=http://majlis.fsktm.um.edu.my/document.aspx?FileName=268.pdf|title=Component and Federation Concept Models in a Federated Database System|last=Masood|first=Nayyer|last2=Eaglestone|first2=Barry|date=December 2003|journal=Malaysian Journal of Computer Science|volume=16|pages=47–57|issue=2|access-date=2016-03-03|archive-url=https://web.archive.org/web/20160307213657/http://majlis.fsktm.um.edu.my/document.aspx?FileName=268.pdf|archive-date=2016-03-07|url-status=dead}}</ref>
* Component schema is the subset of the local schema that the owner organisation is willing to share with other users of the FDBS and it is translated into a [[common data model]].<ref name=":0" /> 
* Export Schema represents a subset of a component schema that is available to a particular federation.<ref name=":0" />  It may include access control information regarding its use by a specific federation user.  The export schema helps in managing flow of control of data.
* Federated Schema is an integration of multiple export schemas. It includes information on data distribution that is generated when integrating export schemas.<ref name=":0" />
* External schema is extracted from a federated schema, and is defined for the users/applications of a particular federation.<ref name=":0" />

While accurately representing the state of the art in data integration, the Five Level Schema Architecture above does suffer from a major drawback, namely IT imposed look and feel. Modern data users demand control over how data is presented; their needs are somewhat in conflict with such bottom-up approaches to data integration.