nested exception is java.sql.SQLException: ORA-00028: your session has been killed

  I am using two node RAC clusters 10.2.0.4. Recently we are facing some issue from application level. Like database session automatically goes killed status As i investigated with application team; there is no changes done in application level but session killed internally. Could you please tel the reason for this issue. - Babu Application log 10-02-2010,08:23:59.549, ERROR [httpSSLWorkerThread-38080-11] (com.gecf.uk.pca.dcs.biz.dao.AuditDAO$AuditStoredProcedure.execute:244) - CallableStatementCallback; SQL [{call DEBITCARD.SP_INSERT_AUDIT(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)}]; ORA-00028: your session has been killed
ORA-06512: at "PCADCS.DEBITCARD", line 410
ORA-06512: at line 1
; nested exception is java.sql.SQLException: ORA-00028: your session has been killed