Type 1: JDBC-ODBC Drawback: client code must be loaded and configured on each client machine.  

Type 2: A Native-API partly-Java driver JDBC call -> client API

• drawback: require native code on the client
• sample: Oracle OCI through SQL*net

Type 3: A Net-Protocol All-Java driver JDBC call -> DBMS-independent net protocol -> DBMS protocol(by middleware server)  

Type 4: A Native-Protoco All-Java driver JDBC call -> DBMS server

• Sample: Oracle JDBC THIN driver