Multiple inheritance in remote interfaces for EJB 3.0 session beans on Webl

Question

Hi All,
We started migration from EJB 2.1(WLS 8.1) to EJB 3.0(WLS 10.3.2) and identified few serious problems. One of them is related with multiple business interfaces inheritance. I wrote simple example that presents point of the problem.
we have session bean AImpl:
+@Stateless(name="A")+
+@Remote({A.class})+
+@TransactionAttribute(TransactionAttributeType.REQUIRED)+
+public class AImpl implements A {+
+@Override+
+public void writeA() {+
System.out.println("A");
+}+
+@Override+
+public void writeB() {+
System.out.println("B");
+}+
+@Override+
+public void writeC() {+
System.out.println("C");
+}+
+}+
with remote interface A:
+@Remote+
+@JNDIName(A.JNDI_NAME)+
+public interface A extends B, C {+
public static String JNDI_NAME = "A_JNDI_NAME";
void writeA();
+}+
As you can see A extends B, and C. Definition of both interfaces is very simple:
+public interface B {+
void writeB();
+}+
+public interface C {+
void writeC();
+}+
Everything looks nice until we want to invoke some method on AImpl bean. For above implementation code:
A a = ctx.lookup(A. JNDI_NAME);
a.writeA();
a.writeB();
a.writeC();
writes down ”A \n B” and throws exception:
caused by: java.lang.NoSuchMethodException: pl.gov.arimr.zszik.bazowe.slowniki.ejb.A_vt0zts_AImpl_1032_WLStub.*writeC()*
at java.lang.Class.getMethod(Class.java:1605)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.getTargetMethod(RemoteBusinessIntfProxy.java:165)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.invoke(RemoteBusinessIntfProxy.java:57)
so.. in stub generated by WLS there is no method from interface C ! What more interesting after small change in interface A rely on change in interface implementation order from B, C to C, B (+public interface A extends C, B {+) server writes down only A and I have stack like below:
Caused by: java.lang.NoSuchMethodException: pl.gov.arimr.zszik.bazowe.slowniki.ejb.A_vt0zts_AImpl_1032_WLStub.*writeB()*
at java.lang.Class.getMethod(Class.java:1605)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.getTargetMethod(RemoteBusinessIntfProxy.java:165)
at weblogic.ejb.container.internal.RemoteBusinessIntfProxy.invoke(RemoteBusinessIntfProxy.java:57)
After this experience I came up with suspicion that Weblogic 10.3 does not support inheritance from multiple interfaces in one “generation”. Instead of that it takes only the first interface from the list.
Does anybody have some experience with such a situation? maybe someone have an idea how to work around this problem?

Answer 1

This is Not Supported in WebLogic that the Remote Interface extends other Interfaces. Because Annotation Processor just looks up inside the implemented interface methods. The actual interface which is Implemented by the Bean Class. So the Methods declared inside the Interface B and Interface C will be ignored and will not be available as part of the generated Stubs. Thats why u are getting NoSuchMethodError.
You can even contact Oracle Support on this...there are 3-4 Cases on it. And the Solution is Work As Designed.
Workaround is : edit your interface A as following
Declare all the Business Methods only in the Remote Interface and not inside it's Super Interfaces.
Example:
@Stateless(name="A")
@Remote({A.class})
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public class AImpl implements A {
@Override
public void writeA() {
System.out.println("A");
@Override
public void writeB() {
System.out.println("B");
@Override
public void writeC() {
System.out.println("C");
@Remote
@JNDIName(A.JNDI_NAME)
public interface A extends B, C {
public static String JNDI_NAME = "A_JNDI_NAME";
void writeA();
void writeB();
void writeC();
Thanks
Jay SenSharma
http://jaysensharma.wordpress.com (WebLogic Wonders Are Here)