Question

Programmer A, wrote an application using JDBC 3 (db2jcc.jar) and deployed on WebSphere App Server.

Is it ok to change JDBC connection to use JDBC 4 (db2jcc4.jar), instead of JDBC 3 ?

Is JDBC 4 fully compliant with JDBC 3?

Answer 1

JDBC 4 shall be backward compatible with JDBC 3 and you shall have no problems replacing the driver.

Quoting from JDBC 4.0 specification 2.2 Overview of goal section, one of the goals of JDBC 4.0 is to

8) Maintain backward compatibility with existing applications and drivers Existing JDBC technology-enabled drivers ( JDBC drivers) and
the applications that use them must continue to work in an
implementation of the Java virtual machine that supports the JDBC 4.0
API. Applications that use only features defined in earlier releases
of the JDBC API will not require changes to continue running. It
should be straightforward for existing applications to migrate to JDBC
4.0 technology.