When the Java client is running on the same machine as the Data Access Server (DAS), and DBMS authentication is not enabled, the JDBC Driver does not require a user ID and password to establish a DBMS connection. The Java client process user ID is used to establish the connection when a user ID and password are not provided.

If DBMS authentication is enabled and the user password is required, then the user ID and password must be provided even if the connection is to the same machine.

If the target database specification includes a VNODE (see Tools for Defining Vnodes), the VNODE login information is used to access the DBMS machine. Optionally, a userID/password can be provided and is handled as described next.

When the Java client and DAS are on different machines, a user ID and password are required to establish a connection to the DBMS. If the DAS and DBMS Server are running in the same Ingres instance (no VNODE in target database specification), the userID/password is used to validate access to the DAS/DBMS machine.

When the DAS and DBMS servers are on different machines, a VNODE is required in the target database specification. The VNODE provides the connection and (optionally) login information needed to establish the DBMS connection.

The driver property vnode_usage determines how the VNODE is used to access the DBMS. The vnode_usage property also determines the context (DAS or DBMS) in which the application userID/password is used. VNODE usage without a userID/password is described above. If the target database specification does not contain a VNODE, the vnode_usage property is ignored.

When vnode_usage is set to 'connect', only global VNODE connection information is used to establish the DBMS connection. The application-provided user ID and password are used in the DBMS context to access the DBMS machine.

When vnode_usage is set to 'login', both connection and login VNODE information is used to access the DBMS machine. The application-provided user ID and password are used in the DAS context, allowing access to private and global VNODEs.