Federated information system
A federated information system (often also a federated database system ) is an information system that offers access to several autonomous information sources without their data being copied, as is the case, for example, in a data warehouse . This form of integration of several data sources, in which these themselves remain unchanged, is also known as virtual information integration or data federation. This system is called “ federated ” because it is an amalgamation of individual systems that maintain their respective independence.
definition
A short and precise definition for a federated database system is according to Bauer and Günzel (based on Conrad) as follows:
“A federated database system is a multi- database system with a (global) conceptual schema that encompasses all component systems. All component systems must retain their autonomy and their local conceptual scheme, ie they remain independent with regard to design, execution and communication. "
construction
When constructing a federated information system, the different schemas of the sources must be combined to form a global schema ( schema transformation and integration ). Local-as-View and Global-as-View are two different approaches to merging schemas. The user of a federated information system can then access the data via the global schema as if he were dealing with a single database system . The connection of data sources is usually done via so-called wrappers and a mediator, which is why most federated information systems are mediator-based information systems.
Basic properties
- The data remains on site with the individual information sources.
- The information sources are autonomous and do not have to be adapted for integration.
- Requests are made declaratively to a global schema.
- Requests can be distributed across different sources of information (for example, for load balancing).
See also
literature
- A. Bauer, H. Günzel: Data Warehouse Systems: Architecture, Development, Application , dpunkt, 2013, ISBN 3-89864-785-4
- S. Conrad: Federated Database Systems, Concepts of Data Integration , Springer, 1997, ISBN 3-540-63176-3