Hi:
In "Mastering Enterprise Java Beans" Roman states that, and I quote: "When
you call a method on a session bean instance, your EJB container guarantees
that no other clients are using that instance[...]Thus, if multiple clients
simultaneusly invoke methods on a session bean, they invocations are
serialized, or performed in lock-step..." but then, in the Java Blueprints
you can see things like this:
"Code Example 10.14 contains an excerpt from ShoppingClientController-
WebImpl. Notice that all the methods of ShoppingClientController are
synchronized
so that concurrent requests to ShoppingClientController are serialized.
This is done because an EJB container will throw an exception if a request
is made
to a session bean while it is servicing another request.
public class ShoppingClientControllerWebImpl
{
private com....ejb.ShoppingClientController sccEjb;
private HttpSession session;
public ShoppingClientControllerWebImpl(HttpSession session) {
this.session = session;
ModelManager mm =
(ModelManager)session.getAttribute("modelManager");
sccEjb = mm.getSCCEJB();
}
public synchronized AccountModel getAccount() {
CHAPTER 10 THE SAMPLE APPLICATION 288
return sccEjb.getAccount().getDetails();
}
...
public synchronized Collection handleEvent(EStoreEvent ese) {
return sccEjb.handleEvent(ese);
}
public synchronized void remove() {
sccEjb.remove();
}
}
Code Example 10.14 ShoppingClientControllerWebImpl"
I'm I missing something? According to Roman the EJB container *guarantees*
thread safe access to the bean instances...
Sorry if this a silly question, but I do see a contradiction here.
Sincerelly
J.
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