Database for RMO

hi friends, i found following very appropriate database type
Federated database server:
Some information system are best served by a federated database server which is mainly used to access data stored in database with incompatible storage models or DBMSs. A single unifies database schema is created on a combined database server. That server acts as an intermediary between application programmes and the database residing on other server. Database request are first sent to the combined database server, which in turns makes appropriate request of the underlying database server. Results from multiple servers are combined and reformatted to fit the unified schema before the system returns a response to the client.
This can be extremely complex. This also tends to demand considerable computer hardware and network capacity, but there expense and management complexity are generally less than would be required to implement and maintain application programme that interact directly with all of the underlying databases. This is used to implement a data warehouse. The fig 5 is the federated database server architecture.