We Covered 2 and 4. What about 1 and 3?
Use of a JDBC Type 1 driver requires a Java application to talk to a JDBC-ODBC bridge. Conversation with the database server occurs via an ODBC driver. DB2 does not ship with a Type 1 driver; you can use the one provided by Sun Microsystems. This environment is not recommended because its performance is less than ideal.
The JDBC Type 3 driver is used to allow Java applets to access DB2 data sources. In a setup involving the Type 3 driver, client applets interact with a DB2 JDBC Applet Server. There is a Type 3 driver provided with DB2 UDB v8, but it has been deprecated and any thin driver requirements can be satisfied using the new Universal JDBC driver in type 4 mode.