Oracle JDBC Version Woes

Ran into a strange Oracle error today in a Tomcat program.

The code ran fine in two other Tomcat instances, but failed in a third one.

The error happened to be

ORA-03115: unsupported network datatype or representation

which basically means: There is a version mismatch between the database and the JDBC library.

Reason

That Tomcat instance had a copy of ojdbc14.jar in its lib/ subdirectory that was used instead of the ojdbc14.jar included in the application's *.war file.

Unfortunately it is hard to tell the version of an ojdbc14.jar from the outside.

Possible Solutions

1. Unzip the ojdbc14.jar and check its manifest file.
2. Get the version programmatically

The latter can for example be displayed on some 'internal' web page of your application:

Connection connection = ...;

DatabaseMetaData md = connection.getMetaData();

out.append(...md.getDriverName() + " " + md.getDriverVersion() ...);

That way it is possible at runtime to check which version you are actually using.

Moral

Don't put *.jar files in the Tomcat lib/ directory. Include them in the *.war file.

Yes, this way you might load multiple copies, one for each *.war, but that beats later wating time to debug an app that suddenly stops working because some Tomcat instance has the wrong *.jar in its lib/ directory.