Harbor broadens the Clipper Replaceable Database Drivers (RDD) approach. It offers different RDDs, for example, DBF, DBFNTX, DBFCDX, DBFDBT and DBFFPT. In Harbor numerous RDDs can be utilized in a solitary application, and new intelligent RDDs can be characterized by joining different RDDs. The RDD design takes into consideration legacy, so a given RDD may expand the usefulness of other existing RDD(s). Outsider RDDs, as RDDSQL, RDDSIX, RMDBFCDX, Advantage Database Server, and Mediator embody a portion of the RDD design highlights. DBFNTX execution has practically same usefulness of DBFCDX and RDDSIX. NETIO and LetoDB give remote access over TCP convention.