A matter of memory 2003-10-28 - By Kalra, Ashwani
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>conversition states. There is a statemachine in the
>EJBController,
from your code , it looks otherway ?
/Ashwani
>-- --Original Message-- --
>From: peng wang [mailto:wp0@(protected)]
>Sent: Monday, October 27, 2003 8:04 PM
>To: J2EEPATTERNS-INTEREST@(protected)
>Subject: A matter of memory
>
>
>Hi All,
>
>I'v adopted the Petstore EJBController pattern for our
>application.
>I make a little modification that I change
>EJBController from
>stateful session bean to stateless due to no need for
>us to maintain
>the statemachine has a hashmap used to cache Actions
>which are
>event handlers. Because EJBController is now
>stateless, it instances
>will be pooled and in primary memory. Since each
>statemachine caches
>a different set of Actions, I'm concerning if the
>Actions objects will
>cause the memory problem.(We have about 40 Actions.
>And the user number
>of EJBController online will be very large.)
>
>public class StateMachine implements
>java.io.Serializable  {
>
> private EJBControllerLocalEJB ccejb;
> private HashMap attributeMap;
> private HashMap actionMap;
> private SessionContext sc;
>
> public StateMachine(EJBControllerLocalEJB ccejb,
>SessionContext sc) {
> this.ccejb = ccejb;
> this.sc = sc;
> attributeMap = new HashMap();
> actionMap = new HashMap();
> }
>
> public EventResponse processEvent(Event ev) throws
>EventException {
> String actionName =
>ev.getEJBActionClassName();
> EventResponse response = null;
> if (actionName != null) {
> EJBAction action = null;
> try {
> if (actionMap.get(actionName) !=
>null) {
> action =
>(EJBAction)actionMap.get(actionName);
> } else {
> action =
>(EJBAction)Class.forName(actionName).newInstance();
> // ********** caching here
>************
> actionMap.put(actionName,
>action);
> }
> } catch (Exception ex) {
> System.err.println("StateMachine:
>error loading " + actionName + " :" + ex);
> }
> if (action != null) {
> action.init(this);
> // do the magic
> action.doStart();
> response = action.perform(ev);
> action.doEnd();
> }
> }
> return response;
> }
>...
>}
>
>I have thought of making the Actions class as light as
>possible that the Actions call other
>stateless EJBs to do services. Does an alternative
>strategy needed here, such as implementing
>all Actions as Singleton?
>
>Thanks a lot,
>
>wp
>
>
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