Today I am getting below error in J2EE application:

    java.sql.SQLException: ORA-01033: ORACLE initialization or shutdown in progress
at java.lang.Throwable.<init>(Throwable.java)
at java.lang.Throwable.<init>(Throwable.java)
at java.sql.SQLException.<init>(SQLException.java:53)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
at oracle.jdbc.ttc7.O3log.receive1st(O3log.java:408)
at oracle.jdbc.ttc7.TTC7Protocol.logon(TTC7Protocol.java:260)
at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:365)
at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:547)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:347)
at oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:169)
at oracle.jdbc.pool.OracleConnectionPoolDataSource.getPhysicalConnection(OracleConnectionPoolDataSource.java:149)
at oracle.jdbc.pool.OracleConnectionPoolDataSource.getPooledConnection(OracleConnectionPoolDataSource.java:95)

Can someone please let me know what does that error mean?