[SOLVED] How to synchronize flow of action in java web application using struts?

How to synchronize flow of action in java web application using struts?

I am developing a web application in JSP with back-end MySQL.

I need my application to be used by more than one users simultaneously for transactions.

There i am facing the following problems.

In the application, there are time slots available to make appointments.
When multiple users are making appointments on the same slot simultaneously, system shows message like appointments has been made. In the back end , both datas are saved with different id ( for the same slot).
But in the front end- it shows only one user data.

How can make synchronization in the function.

Please help me to solve the problem

Solution

I think, currently how you codes your logic like, once the instruction to book the slot from the user , just save it.

Try like this, after when you got the instruction to book a slot, in java page( in saving logic ) first check to make sure no one else has made it. If no such result found book it, else show message that its already booked.