/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.ejb.access;
import java.lang.reflect.InvocationTargetException;
import java.rmi.RemoteException;
import javax.ejb.CreateException;
import javax.ejb.EJBObject;
import javax.naming.NamingException;
import org.aopalliance.intercept.MethodInvocation;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.lang.Nullable;
import org.springframework.remoting.RemoteLookupFailureException;
Basic invoker for a remote Stateless Session Bean.
Designed for EJB 2.x, but works for EJB 3 Session Beans as well.
"Creates" a new EJB instance for each invocation, or caches the session bean instance for all invocations (see setCacheSessionBean). See JndiObjectLocator for info on how to specify the JNDI location of the target EJB.
In a bean container, this class is normally best used as a singleton. However,
if that bean container pre-instantiates singletons (as do the XML ApplicationContext
variants) you may have a problem if the bean container is loaded before the EJB
container loads the target EJB. That is because by default the JNDI lookup will be
performed in the init method of this class and cached, but the EJB will not have been
bound at the target location yet. The best solution is to set the "lookupHomeOnStartup"
property to "false", in which case the home will be fetched on first access to the EJB.
(This flag is only true by default for backwards compatibility reasons).
This invoker is typically used with an RMI business interface, which serves
as super-interface of the EJB component interface. Alternatively, this invoker
can also proxy a remote SLSB with a matching non-RMI business interface, i.e. an
interface that mirrors the EJB business methods but does not declare RemoteExceptions.
In the latter case, RemoteExceptions thrown by the EJB stub will automatically get
converted to Spring's unchecked RemoteAccessException.
Author: Rod Johnson, Juergen Hoeller See Also: Since: 09.05.2003
/**
* Basic invoker for a remote Stateless Session Bean.
* Designed for EJB 2.x, but works for EJB 3 Session Beans as well.
*
* <p>"Creates" a new EJB instance for each invocation, or caches the session
* bean instance for all invocations (see {@link #setCacheSessionBean}).
* See {@link org.springframework.jndi.JndiObjectLocator} for info on
* how to specify the JNDI location of the target EJB.
*
* <p>In a bean container, this class is normally best used as a singleton. However,
* if that bean container pre-instantiates singletons (as do the XML ApplicationContext
* variants) you may have a problem if the bean container is loaded before the EJB
* container loads the target EJB. That is because by default the JNDI lookup will be
* performed in the init method of this class and cached, but the EJB will not have been
* bound at the target location yet. The best solution is to set the "lookupHomeOnStartup"
* property to "false", in which case the home will be fetched on first access to the EJB.
* (This flag is only true by default for backwards compatibility reasons).
*
* <p>This invoker is typically used with an RMI business interface, which serves
* as super-interface of the EJB component interface. Alternatively, this invoker
* can also proxy a remote SLSB with a matching non-RMI business interface, i.e. an
* interface that mirrors the EJB business methods but does not declare RemoteExceptions.
* In the latter case, RemoteExceptions thrown by the EJB stub will automatically get
* converted to Spring's unchecked RemoteAccessException.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @since 09.05.2003
* @see org.springframework.remoting.RemoteAccessException
* @see AbstractSlsbInvokerInterceptor#setLookupHomeOnStartup
* @see AbstractSlsbInvokerInterceptor#setCacheHome
* @see AbstractRemoteSlsbInvokerInterceptor#setRefreshHomeOnConnectFailure
*/
public class SimpleRemoteSlsbInvokerInterceptor extends AbstractRemoteSlsbInvokerInterceptor
implements DisposableBean {
private boolean cacheSessionBean = false;
@Nullable
private Object beanInstance;
private final Object beanInstanceMonitor = new Object();
Set whether to cache the actual session bean object.
Off by default for standard EJB compliance. Turn this flag
on to optimize session bean access for servers that are
known to allow for caching the actual session bean object.
See Also: - setCacheHome
/**
* Set whether to cache the actual session bean object.
* <p>Off by default for standard EJB compliance. Turn this flag
* on to optimize session bean access for servers that are
* known to allow for caching the actual session bean object.
* @see #setCacheHome
*/
public void setCacheSessionBean(boolean cacheSessionBean) {
this.cacheSessionBean = cacheSessionBean;
}
This implementation "creates" a new EJB instance for each invocation.
Can be overridden for custom invocation strategies.
Alternatively, override getSessionBeanInstance and releaseSessionBeanInstance to change EJB instance creation, for example to hold a single shared EJB component instance.
/**
* This implementation "creates" a new EJB instance for each invocation.
* Can be overridden for custom invocation strategies.
* <p>Alternatively, override {@link #getSessionBeanInstance} and
* {@link #releaseSessionBeanInstance} to change EJB instance creation,
* for example to hold a single shared EJB component instance.
*/
@Override
@Nullable
@SuppressWarnings("deprecation")
protected Object doInvoke(MethodInvocation invocation) throws Throwable {
Object ejb = null;
try {
ejb = getSessionBeanInstance();
return org.springframework.remoting.rmi.RmiClientInterceptorUtils.invokeRemoteMethod(invocation, ejb);
}
catch (NamingException ex) {
throw new RemoteLookupFailureException("Failed to locate remote EJB [" + getJndiName() + "]", ex);
}
catch (InvocationTargetException ex) {
Throwable targetEx = ex.getTargetException();
if (targetEx instanceof RemoteException) {
RemoteException rex = (RemoteException) targetEx;
throw org.springframework.remoting.rmi.RmiClientInterceptorUtils.convertRmiAccessException(
invocation.getMethod(), rex, isConnectFailure(rex), getJndiName());
}
else if (targetEx instanceof CreateException) {
throw org.springframework.remoting.rmi.RmiClientInterceptorUtils.convertRmiAccessException(
invocation.getMethod(), targetEx, "Could not create remote EJB [" + getJndiName() + "]");
}
throw targetEx;
}
finally {
if (ejb instanceof EJBObject) {
releaseSessionBeanInstance((EJBObject) ejb);
}
}
}
Return an EJB component instance to delegate the call to.
The default implementation delegates to AbstractRemoteSlsbInvokerInterceptor.newSessionBeanInstance.
Throws: - NamingException – if thrown by JNDI
- InvocationTargetException – if thrown by the create method
See Also: Returns: the EJB component instance
/**
* Return an EJB component instance to delegate the call to.
* <p>The default implementation delegates to {@link #newSessionBeanInstance}.
* @return the EJB component instance
* @throws NamingException if thrown by JNDI
* @throws InvocationTargetException if thrown by the create method
* @see #newSessionBeanInstance
*/
protected Object getSessionBeanInstance() throws NamingException, InvocationTargetException {
if (this.cacheSessionBean) {
synchronized (this.beanInstanceMonitor) {
if (this.beanInstance == null) {
this.beanInstance = newSessionBeanInstance();
}
return this.beanInstance;
}
}
else {
return newSessionBeanInstance();
}
}
Release the given EJB instance.
The default implementation delegates to removeSessionBeanInstance.
Params: - ejb – the EJB component instance to release
See Also: - removeSessionBeanInstance
/**
* Release the given EJB instance.
* <p>The default implementation delegates to {@link #removeSessionBeanInstance}.
* @param ejb the EJB component instance to release
* @see #removeSessionBeanInstance
*/
protected void releaseSessionBeanInstance(EJBObject ejb) {
if (!this.cacheSessionBean) {
removeSessionBeanInstance(ejb);
}
}
Reset the cached session bean instance, if necessary.
/**
* Reset the cached session bean instance, if necessary.
*/
@Override
protected void refreshHome() throws NamingException {
super.refreshHome();
if (this.cacheSessionBean) {
synchronized (this.beanInstanceMonitor) {
this.beanInstance = null;
}
}
}
Remove the cached session bean instance, if necessary.
/**
* Remove the cached session bean instance, if necessary.
*/
@Override
public void destroy() {
if (this.cacheSessionBean) {
synchronized (this.beanInstanceMonitor) {
if (this.beanInstance instanceof EJBObject) {
removeSessionBeanInstance((EJBObject) this.beanInstance);
}
}
}
}
}