The FEDERATED Storage Engine is a legacy storage engine no longer being supported. A fork, FederatedX is being actively maintained. Since MariaDB 10.0, the CONNECT storage engine also allows to access a remote database via MySQL or ODBC connection (table types: MYSQL, ODBC). Though, in the current implementation there are several limitations.
The FEDERATED Storage Engine was originally designed to let one access data remotely without using clustering or replication, and perform local queries that automatically access the remote data.