Need to persist data in JVM...

Question

Hi,
I have a requirement in my project where once the user logs in, the database is queried and some information
related to the user is retrieved and stored in JVM.So the number of hits to the database is decreased.
The requirement in detail :
This is Simple Cart-Shopping application.
There is a UI which displays various products which one can view and purchase.
*1)Once the user logs in he can view the various products.*
*2)There are restriction which decides which products that particular user can purchase,*
although a user can view all the products listed in the store.
*3)Every time a user clicks on a product, database is queried to retrieve access info for the user on that product.*
*4)If a user has proper access only then he can purchase the product.*
Presently the database is queried in all the four steps explained above.
I intend to :
Hit database once user logs in and retrive information regarding the access levels of the user for all products listed in the store.
Persist this info in JVM(serialization or by other means...).
Now for any further access info, the persisted objects will provide the data.
This reduces the database hits.
Other details :
App Server - Jboss
Database - oracle
Expected Concurrent users - 2000 - 3000
Please provide your suggestions as to what should be the ideal approach.
regards,
Abhishek.

Answer 1

Hi,
The valueHolder class is a name a suggested and it is used in axis webservice implementation to hold the value by refrence ( array ) which is an implemetaion (if I still remember ) of the wsdl array type
Even Spring is using this type of pattern to hold a constructor argument as an inner static class for another class.
Ex:
import java.util.HashMap;
import java.util.Map;
public class  ValueHolder {
     private static final Map<String, Information> valueHolder = new HashMap<String, Information>();
     public static void addValue(String userId, Information info) {
          valueHolder.put(userId, info);
     public static Information getValue(String userId) {
          return valueHolder.get(userId); // check for none existing userId to avoid null returned value
     public void cleanOnEvent(){
           * Clean on certain occation if the heap size gets into certain point etc.. or other
           *  predefined conditions etc..
          valueHolder.clear();
}Regards,
Alan Mehio
London,UK