Hi abilash,
If you want to know if the application is used by another user then you can use the concept of lock objects. This will allow only one user to work in the application one at a time and other user's will not be allowed to work in it . The lock is done by enqueue and after processing Dequeue takes place.
Once the dequeue is successful then next user can work with the application.
Refer : SAP Lock Concept (SAP Library - The SAP Lock Concept (BC-CST-EQ))
Regards,
Sivaganesh