For a Tomcat installation I needed to connect to a Oracle RAC database backend. I figured out the correct connection string, shown below:

jdbcUrl="jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=rac01)(PORT=1521))(ADDRESS=(PROTOCOL=TCP)(HOST=rac02)(PORT=1521))(LOAD_BALANCE=on)(FAILOVER=on)(CONNECT_DATA=(SERVICE_NAME=orcl)))"