warning pop up issue

Hello All,
i want to send a warning message(YES/No) to client side from server side based on some calculated values.
After the warinig message user will click YES/No.then it will come to server side. At that time i want the calculted values which i had before sending the warning message.how can i handle this.
EG:
using Front End JSP
For Bussiness we are using MVC architecture
from the business java class (BO) i calculted some values Eg:calculated my age as 25 before sending the warning msg
if (myage > 25 ) send warning msg anduser clicked yes/No and come back to BO.Now i need my calcuted age 25 in BO class i dont want to calculte again .

Either store it in the session (not a scalable solution in general) or pass the calculated values back and forth.
You could persist them, though that's not a common one to use.