Yes.. Is it possible. All you need to do is use bpstart_notify and bpend_notify script to carry out any required task before and after backup.
In your case you can modify the bpstart_notify script to stop the application before the backup starts and modify the bpend_notify script to bring the application back up after the backup job is complete.
Ideally you need to append the bpstart_notify.<policy_name> with the required script or command that will bring down the application. Once the backup is triggered the bpstart script is called and executed before the job starts writting to tape. Similarly once the job is complete the bpend_notify.<policy_name> is called which in your case would be to bring up the application.
When modifying the bpstart and bpend script please ensure you append the file name with the policy name. You can use this for a particular schedule as well.
eg.
bpstart_notify.<policy_name>.<schedule>
Please let us know if you need more info.
