I am now on the duty to prepare Oracle database for three-tier application (WEB DataSnap app) in which medium and client levels are to be made by Embarcadero tools. The App takes responsibility for Authentication users and getting their logins and passwords. It connects to the database. The task is to ensure by means of Oracle that connection could be accepted if is initiated by that and only by that App. Where to go in the world of Oracle and what to do to have that task accomplished? Excuse me for ambiguity but I am new to Oracle and cannot put it in a more clear way. With best regards, Alex.