Thanks so much Craig, this has been tremendously helpful! Some
comments below...
On Wednesday, June 26, 2002, 2:38:54 PM, Craig wrote:
CRM> My suggestion is to implement this logic inside a bean that hides whether
CRM> or not you are really caching the data or not -- say a StoresBean
CRM> something like this:
CRM> public class StoresBean {
CRM> public ArrayList stores = null;
CRM> public synchronized Iterator getStores() {
CRM> if (stores == null) {
CRM> stores = new ArrayList();
CRM> ... fill in the objects in this list ...
CRM> }
CRM> return (stores.iterator());
CRM> }
CRM> }
CRM> That way, the relevant stuff will get loaded the first time and then
CRM> reused.
Ok, you've started to clear some things up for me. I always
thought thought that classes in my: myAppDir/WEB-INF/classes
directory if they had static members they were shared across the
entire application scope? This definitely is wrong though? (and
it's only session scope?).
In your above code, though, each user session would then end up
loading a new list of stores. I don't really need that. I only
need that list being loaded once and shared amongst all the
sessions.
CRM> But your calling application doesn't know that -- all it needs to
CRM> do is grab StoresBean out of the session attributes (if this is user
CRM> specific) or context attributes (if this is global), and call getStores().
How would I grab this "global" attribute from a business layer
object though? I guess that's where I'm getting confused. Say I
have my Action class call a business object:
BO.getStoresList()
Well now I want the BO to return me a List of StoreBeans, but I
only want that list populated ONE time and want all the sessions
to share it.It looks like if I want all the sessions to share the information
I have to pass servlet classes into my model layer? Am I wrong
there?
CRM> If the StoresBean bean is in application scope (i.e. a servlet context
CRM> attribute), then getStores() will go load up the list the first time *any*
CRM> user requests it, then everyone will share. This makes sense if the data
CRM> is global to all users. You would want to create this bean as part of
CRM> your application startup, by either:
CRM> * In servlet 2.2 or later, create a servlet that is configured for
CRM> load-on-startup, and set it up in the init() method.
Ok, I have set up some like this in the init() method of an
IntializationServlet I call on startup:
context.setAttribute( "storeList", storeList );
CRM> * In servlet 2.2 or later, subclass the ActionServlet class in Struts,
CRM> and override the init() method like this:
CRM> public void init() throws ServletException {
CRM> super.init();
CRM> ... initialize context attributes here ...
CRM> }
OK! Perfect this is exactly what I should do. Thank you.
(I take it there weren't be any issues doing this to my
controller which extends DispatchAction).
Thanks Craig,
Rick
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