/*
* Copyright 2002-2008 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
*
* http://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.remoting.rmi;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.rmi.RemoteException;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.omg.CORBA.OBJECT_NOT_EXIST;
import org.omg.CORBA.SystemException;
import org.springframework.aop.support.AopUtils;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.jndi.JndiObjectLocator;
import org.springframework.remoting.RemoteAccessException;
import org.springframework.remoting.RemoteConnectFailureException;
import org.springframework.remoting.RemoteInvocationFailureException;
import org.springframework.remoting.RemoteLookupFailureException;
import org.springframework.remoting.support.DefaultRemoteInvocationFactory;
import org.springframework.remoting.support.RemoteInvocation;
import org.springframework.remoting.support.RemoteInvocationFactory;
import org.springframework.util.ReflectionUtils;
/**
* {@link org.aopalliance.intercept.MethodInterceptor} for accessing RMI services from JNDI.
* Typically used for RMI-IIOP (CORBA), but can also be used for EJB home objects
* (for example, a Stateful Session Bean home). In contrast to a plain JNDI lookup,
* this accessor also performs narrowing through PortableRemoteObject.
*
* <p>With conventional RMI services, this invoker is typically used with the RMI
* service interface. Alternatively, this invoker can also proxy a remote RMI service
* with a matching non-RMI business interface, i.e. an interface that mirrors the RMI
* service methods but does not declare RemoteExceptions. In the latter case,
* RemoteExceptions thrown by the RMI stub will automatically get converted to
* Spring's unchecked RemoteAccessException.
*
* <p>The JNDI environment can be specified as "jndiEnvironment" property,
* or be configured in a <code>jndi.properties</code> file or as system properties.
* For example:
*
* <pre class="code"><property name="jndiEnvironment">
* <props>
* <prop key="java.naming.factory.initial">com.sun.jndi.cosnaming.CNCtxFactory</prop>
* <prop key="java.naming.provider.url">iiop://localhost:1050</prop>
* </props>
* </property></pre>
*
* @author Juergen Hoeller
* @since 1.1
* @see #setJndiTemplate
* @see #setJndiEnvironment
* @see #setJndiName
* @see JndiRmiServiceExporter
* @see JndiRmiProxyFactoryBean
* @see org.springframework.remoting.RemoteAccessException
* @see java.rmi.RemoteException
* @see java.rmi.Remote
* @see javax.rmi.PortableRemoteObject#narrow
*/
public class JndiRmiClientInterceptor extends JndiObjectLocator implements MethodInterceptor, InitializingBean {
private Class serviceInterface;
private RemoteInvocationFactory remoteInvocationFactory = new DefaultRemoteInvocationFactory();
private boolean lookupStubOnStartup = true;
private boolean cacheStub = true;
private boolean refreshStubOnConnectFailure = false;
private Object cachedStub;
private final Object stubMonitor = new Object();
/**
* Set the interface of the service to access.
* The interface must be suitable for the particular service and remoting tool.
* <p>Typically required to be able to create a suitable service proxy,
* but can also be optional if the lookup returns a typed stub.
*/
public void setServiceInterface(Class serviceInterface) {
if (serviceInterface != null && !serviceInterface.isInterface()) {
throw new IllegalArgumentException("'serviceInterface' must be an interface");
}
this.serviceInterface = serviceInterface;
}
/**
* Return the interface of the service to access.
*/
public Class getServiceInterface() {
return this.serviceInterface;
}
/**
* Set the RemoteInvocationFactory to use for this accessor.
* Default is a {@link DefaultRemoteInvocationFactory}.
* <p>A custom invocation factory can add further context information
* to the invocation, for example user credentials.
*/
public void setRemoteInvocationFactory(RemoteInvocationFactory remoteInvocationFactory) {
this.remoteInvocationFactory = remoteInvocationFactory;
}
/**
* Return the RemoteInvocationFactory used by this accessor.
*/
public RemoteInvocationFactory getRemoteInvocationFactory() {
return this.remoteInvocationFactory;
}
/**
* Set whether to look up the RMI stub on startup. Default is "true".
* <p>Can be turned off to allow for late start of the RMI server.
* In this case, the RMI stub will be fetched on first access.
* @see #setCacheStub
*/
public void setLookupStubOnStartup(boolean lookupStubOnStartup) {
this.lookupStubOnStartup = lookupStubOnStartup;
}
/**
* Set whether to cache the RMI stub once it has been located.
* Default is "true".
* <p>Can be turned off to allow for hot restart of the RMI server.
* In this case, the RMI stub will be fetched for each invocation.
* @see #setLookupStubOnStartup
*/
public void setCacheStub(boolean cacheStub) {
this.cacheStub = cacheStub;
}
/**
* Set whether to refresh the RMI stub on connect failure.
* Default is "false".
* <p>Can be turned on to allow for hot restart of the RMI server.
* If a cached RMI stub throws an RMI exception that indicates a
* remote connect failure, a fresh proxy will be fetched and the
* invocation will be retried.
* @see java.rmi.ConnectException
* @see java.rmi.ConnectIOException
* @see java.rmi.NoSuchObjectException
*/
public void setRefreshStubOnConnectFailure(boolean refreshStubOnConnectFailure) {
this.refreshStubOnConnectFailure = refreshStubOnConnectFailure;
}
public void afterPropertiesSet() throws NamingException {
super.afterPropertiesSet();
prepare();
}
/**
* Fetches the RMI stub on startup, if necessary.
* @throws RemoteLookupFailureException if RMI stub creation failed
* @see #setLookupStubOnStartup
* @see #lookupStub
*/
public void prepare() throws RemoteLookupFailureException {
// Cache RMI stub on initialization?
if (this.lookupStubOnStartup) {
Object remoteObj = lookupStub();
if (logger.isDebugEnabled()) {
if (remoteObj instanceof RmiInvocationHandler) {
logger.debug("JNDI RMI object [" + getJndiName() + "] is an RMI invoker");
}
else if (getServiceInterface() != null) {
boolean isImpl = getServiceInterface().isInstance(remoteObj);
logger.debug("Using service interface [" + getServiceInterface().getName() +
"] for JNDI RMI object [" + getJndiName() + "] - " +
(!isImpl ? "not " : "") + "directly implemented");
}
}
if (this.cacheStub) {
this.cachedStub = remoteObj;
}
}
}
/**
* Create the RMI stub, typically by looking it up.
* <p>Called on interceptor initialization if "cacheStub" is "true";
* else called for each invocation by {@link #getStub()}.
* <p>The default implementation retrieves the service from the
* JNDI environment. This can be overridden in subclasses.
* @return the RMI stub to store in this interceptor
* @throws RemoteLookupFailureException if RMI stub creation failed
* @see #setCacheStub
* @see #lookup
*/
protected Object lookupStub() throws RemoteLookupFailureException {
try {
Object stub = lookup();
if (getServiceInterface() != null && !(stub instanceof RmiInvocationHandler)) {
try {
stub = PortableRemoteObject.narrow(stub, getServiceInterface());
}
catch (ClassCastException ex) {
throw new RemoteLookupFailureException(
"Could not narrow RMI stub to service interface [" + getServiceInterface().getName() + "]", ex);
}
}
return stub;
}
catch (NamingException ex) {
throw new RemoteLookupFailureException("JNDI lookup for RMI service [" + getJndiName() + "] failed", ex);
}
}
/**
* Return the RMI stub to use. Called for each invocation.
* <p>The default implementation returns the stub created on initialization,
* if any. Else, it invokes {@link #lookupStub} to get a new stub for
* each invocation. This can be overridden in subclasses, for example in
* order to cache a stub for a given amount of time before recreating it,
* or to test the stub whether it is still alive.
* @return the RMI stub to use for an invocation
* @throws NamingException if stub creation failed
* @throws RemoteLookupFailureException if RMI stub creation failed
*/
protected Object getStub() throws NamingException, RemoteLookupFailureException {
if (!this.cacheStub || (this.lookupStubOnStartup && !this.refreshStubOnConnectFailure)) {
return (this.cachedStub != null ? this.cachedStub : lookupStub());
}
else {
synchronized (this.stubMonitor) {
if (this.cachedStub == null) {
this.cachedStub = lookupStub();
}
return this.cachedStub;
}
}
}
/**
* Fetches an RMI stub and delegates to {@link #doInvoke}.
* If configured to refresh on connect failure, it will call
* {@link #refreshAndRetry} on corresponding RMI exceptions.
* @see #getStub
* @see #doInvoke
* @see #refreshAndRetry
* @see java.rmi.ConnectException
* @see java.rmi.ConnectIOException
* @see java.rmi.NoSuchObjectException
*/
public Object invoke(MethodInvocation invocation) throws Throwable {
Object stub = null;
try {
stub = getStub();
}
catch (NamingException ex) {
throw new RemoteLookupFailureException("JNDI lookup for RMI service [" + getJndiName() + "] failed", ex);
}
try {
return doInvoke(invocation, stub);
}
catch (RemoteConnectFailureException ex) {
return handleRemoteConnectFailure(invocation, ex);
}
catch (RemoteException ex) {
if (isConnectFailure(ex)) {
return handleRemoteConnectFailure(invocation, ex);
}
else {
throw ex;
}
}
catch (SystemException ex) {
if (isConnectFailure(ex)) {
return handleRemoteConnectFailure(invocation, ex);
}
else {
throw ex;
}
}
}
/**
* Determine whether the given RMI exception indicates a connect failure.
* <p>The default implementation delegates to
* {@link RmiClientInterceptorUtils#isConnectFailure}.
* @param ex the RMI exception to check
* @return whether the exception should be treated as connect failure
*/
protected boolean isConnectFailure(RemoteException ex) {
return RmiClientInterceptorUtils.isConnectFailure(ex);
}
/**
* Determine whether the given CORBA exception indicates a connect failure.
* <p>The default implementation checks for CORBA's
* {@link org.omg.CORBA.OBJECT_NOT_EXIST} exception.
* @param ex the RMI exception to check
* @return whether the exception should be treated as connect failure
*/
protected boolean isConnectFailure(SystemException ex) {
return (ex instanceof OBJECT_NOT_EXIST);
}
/**
* Refresh the stub and retry the remote invocation if necessary.
* <p>If not configured to refresh on connect failure, this method
* simply rethrows the original exception.
* @param invocation the invocation that failed
* @param ex the exception raised on remote invocation
* @return the result value of the new invocation, if succeeded
* @throws Throwable an exception raised by the new invocation, if failed too.
*/
private Object handleRemoteConnectFailure(MethodInvocation invocation, Exception ex) throws Throwable {
if (this.refreshStubOnConnectFailure) {
if (logger.isDebugEnabled()) {
logger.debug("Could not connect to RMI service [" + getJndiName() + "] - retrying", ex);
}
else if (logger.isWarnEnabled()) {
logger.warn("Could not connect to RMI service [" + getJndiName() + "] - retrying");
}
return refreshAndRetry(invocation);
}
else {
throw ex;
}
}
/**
* Refresh the RMI stub and retry the given invocation.
* Called by invoke on connect failure.
* @param invocation the AOP method invocation
* @return the invocation result, if any
* @throws Throwable in case of invocation failure
* @see #invoke
*/
protected Object refreshAndRetry(MethodInvocation invocation) throws Throwable {
Object freshStub = null;
synchronized (this.stubMonitor) {
this.cachedStub = null;
freshStub = lookupStub();
if (this.cacheStub) {
this.cachedStub = freshStub;
}
}
return doInvoke(invocation, freshStub);
}
/**
* Perform the given invocation on the given RMI stub.
* @param invocation the AOP method invocation
* @param stub the RMI stub to invoke
* @return the invocation result, if any
* @throws Throwable in case of invocation failure
*/
protected Object doInvoke(MethodInvocation invocation, Object stub) throws Throwable {
if (stub instanceof RmiInvocationHandler) {
// RMI invoker
try {
return doInvoke(invocation, (RmiInvocationHandler) stub);
}
catch (RemoteException ex) {
throw convertRmiAccessException(ex, invocation.getMethod());
}
catch (SystemException ex) {
throw convertCorbaAccessException(ex, invocation.getMethod());
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
catch (Throwable ex) {
throw new RemoteInvocationFailureException("Invocation of method [" + invocation.getMethod() +
"] failed in RMI service [" + getJndiName() + "]", ex);
}
}
else {
// traditional RMI stub
try {
return RmiClientInterceptorUtils.invokeRemoteMethod(invocation, stub);
}
catch (InvocationTargetException ex) {
Throwable targetEx = ex.getTargetException();
if (targetEx instanceof RemoteException) {
throw convertRmiAccessException((RemoteException) targetEx, invocation.getMethod());
}
else if (targetEx instanceof SystemException) {
throw convertCorbaAccessException((SystemException) targetEx, invocation.getMethod());
}
else {
throw targetEx;
}
}
}
}
/**
* Apply the given AOP method invocation to the given {@link RmiInvocationHandler}.
* <p>The default implementation delegates to {@link #createRemoteInvocation}.
* @param methodInvocation the current AOP method invocation
* @param invocationHandler the RmiInvocationHandler to apply the invocation to
* @return the invocation result
* @throws RemoteException in case of communication errors
* @throws NoSuchMethodException if the method name could not be resolved
* @throws IllegalAccessException if the method could not be accessed
* @throws InvocationTargetException if the method invocation resulted in an exception
* @see org.springframework.remoting.support.RemoteInvocation
*/
protected Object doInvoke(MethodInvocation methodInvocation, RmiInvocationHandler invocationHandler)
throws RemoteException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {
if (AopUtils.isToStringMethod(methodInvocation.getMethod())) {
return "RMI invoker proxy for service URL [" + getJndiName() + "]";
}
return invocationHandler.invoke(createRemoteInvocation(methodInvocation));
}
/**
* Create a new RemoteInvocation object for the given AOP method invocation.
* <p>The default implementation delegates to the configured
* {@link #setRemoteInvocationFactory RemoteInvocationFactory}.
* This can be overridden in subclasses in order to provide custom RemoteInvocation
* subclasses, containing additional invocation parameters (e.g. user credentials).
* <p>Note that it is preferable to build a custom RemoteInvocationFactory
* as a reusable strategy, instead of overriding this method.
* @param methodInvocation the current AOP method invocation
* @return the RemoteInvocation object
* @see RemoteInvocationFactory#createRemoteInvocation
*/
protected RemoteInvocation createRemoteInvocation(MethodInvocation methodInvocation) {
return getRemoteInvocationFactory().createRemoteInvocation(methodInvocation);
}
/**
* Convert the given RMI RemoteException that happened during remote access
* to Spring's RemoteAccessException if the method signature does not declare
* RemoteException. Else, return the original RemoteException.
* @param method the invoked method
* @param ex the RemoteException that happened
* @return the exception to be thrown to the caller
*/
private Exception convertRmiAccessException(RemoteException ex, Method method) {
return RmiClientInterceptorUtils.convertRmiAccessException(method, ex, isConnectFailure(ex), getJndiName());
}
/**
* Convert the given CORBA SystemException that happened during remote access
* to Spring's RemoteAccessException if the method signature does not declare
* RemoteException. Else, return the SystemException wrapped in a RemoteException.
* @param method the invoked method
* @param ex the RemoteException that happened
* @return the exception to be thrown to the caller
*/
private Exception convertCorbaAccessException(SystemException ex, Method method) {
if (ReflectionUtils.declaresException(method, RemoteException.class)) {
// A traditional RMI service: wrap CORBA exceptions in standard RemoteExceptions.
return new RemoteException("Failed to access CORBA service [" + getJndiName() + "]", ex);
}
else {
if (isConnectFailure(ex)) {
return new RemoteConnectFailureException("Could not connect to CORBA service [" + getJndiName() + "]", ex);
}
else {
return new RemoteAccessException("Could not access CORBA service [" + getJndiName() + "]", ex);
}
}
}
}