During a process that includes changes of the data in a database, if the process is down due to an error in the J2EE server, the consistency of the system will be maintained, because the database will return to the state prior to the occurrence of error the rollback operation. You can eliminate the error of J2EE server and restarting the Web application for recovering from the trouble.

When the host of the J2EE server hangs up or when an error occurs in the network, the operation of the database might be interrupted and the mutual exclusion (lock of the global session information) might become in an unresolved state. In this case, you must resolve the mutual exclusion of the unresolved state before the J2EE server is recovered and the Web application is re-opened.

Reference note

To release the unreleased mutual exclusion, an invalid connection to the database from the client is detected and the connected session can be terminated forcefully. For details on releasing an unreleased mutual exclusion, see the description related to the UAP processing time monitoring functionality of the manual HiRDB UAP Development Guide when using HiRDB. When using Oracle, see the Oracle manual.

When an error occurs in a database and you recover the database, the Web application using the database session failover functionality can re-open the business, because the database will return to the state prior to occurrence of the error by the rollback operation. You are not required to restart the Web application.

For details on the countermeasures to be taken when an error occurrence in other databases, see the manual of each database.