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Axis2 JAXWS Implementation
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.axis2.jaxws.client.async;
import org.apache.axis2.AxisFault;
import org.apache.axis2.client.async.AxisCallback;
import org.apache.axis2.java.security.AccessController;
import org.apache.axis2.jaxws.core.InvocationContext;
import org.apache.axis2.jaxws.core.MessageContext;
import org.apache.axis2.jaxws.registry.FactoryRegistry;
import org.apache.axis2.jaxws.server.AsyncHandlerProxyFactory;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import javax.xml.ws.AsyncHandler;
import javax.xml.ws.WebServiceException;
import java.security.PrivilegedAction;
import java.util.concurrent.Callable;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
/**
* The CallbackFuture implements the Axis2 org.apache.axis2.client.async.Callback API
* and will get registered with the Axis2 engine to receive the asynchronous callback responses.
* This object is also responsible for taking the java.util.concurrent.Executor given
* to it by the JAX-WS client and using that as the thread on which to deliver the async response
* the JAX-WS javax.xml.ws.AsynchHandler.
*/
public class CallbackFuture implements AxisCallback {
private static final Log log = LogFactory.getLog(CallbackFuture.class);
private static final boolean debug = log.isDebugEnabled();
private CallbackFutureTask cft;
private Executor executor;
private FutureTask task;
private InvocationContext invocationCtx;
public static String displayHandle(Object obj) {
return obj.getClass().getName() + '@' + Integer.toHexString(obj.hashCode());
}
/*
* There are two Async Callback Future.cancel scenario that we address
* 1) Client app creates request and call Async Operation. Now before the request is submitted
* by JAXWS to Executor for processing and any response is received client decides to cancel
* the future task.
* 2) Client app creates request and call Async Operation. Request is submitted by JAXWS
* to Executor for processing and a response is received and client decides to cancel the future
* task.
*
* We will address both these scenarios in the code. In scenario 1 we will do the following:
* 1) Check the for the future.isCancelled before submitting the task to Executor
* 2) If cancelled then do not submit the task and do not call the Async Handler of client.
* 3)The client program in this case (Since it cancelled the future) will be responsible for cleaning any resources that it engages.
*
* In Second Scenario we will call the AsyncHandler as Future.isCancelled will be false. As per java doc
* the Future cannot be cancelled once the task has been submitted. Also the response has already arrived so
* we will make the AsyncHandler and let the client code decided how it wants to treat the response.
*/
@SuppressWarnings("unchecked")
public CallbackFuture(InvocationContext ic, AsyncHandler handler) {
// We need to save off the classloader associated with the AsyncHandler instance
// since we'll need to set this same classloader on the thread where
// handleResponse() is invoked.
// This is required so that we don't encounter ClassCastExceptions.
final Object handlerObj = handler;
final ClassLoader handlerCL = (ClassLoader)AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
return handlerObj.getClass().getClassLoader();
}
});
// Allow the AsyncHandlerProxyFactory to create the proxy for the AsyncHandler
// passed in (which was provided by the client on the async invocation).
// This allows any server-specific work to be done, such as thread context management, etc.
AsyncHandler originalHandler = handler;
try {
if (debug) {
log.debug("Calling factory to create proxy for AsyncHandler instance: " + displayHandle(handler));
}
AsyncHandlerProxyFactory proxyFactory = (AsyncHandlerProxyFactory) FactoryRegistry
.getFactory(AsyncHandlerProxyFactory.class);
handler = proxyFactory.createAsyncHandlerProxy(handler);
if (debug) {
log.debug("Factory returned AsyncHandler proxy instance: " + displayHandle(handler));
}
}
catch (Exception e) {
if (debug) {
log.debug("AsyncHandlerProxyFactory threw an exception: " + e.toString());
e.printStackTrace();
}
// Just use the original handler provided by the client if we
// failed to create a proxy for it.
handler = originalHandler;
}
cft = new CallbackFutureTask(ic.getAsyncResponseListener(), handler, handlerCL);
task = new FutureTask(cft);
executor = ic.getExecutor();
/*
* TODO review. We need to save the invocation context so we can set it on the
* response (or fault) context so the FutureCallback has access to the handler list.
*/
invocationCtx = ic;
}
public Future getFutureTask() {
return (Future)task;
}
public void onComplete(org.apache.axis2.context.MessageContext mc) {
if (debug) {
log.debug("JAX-WS received the async response");
}
MessageContext response = null;
try {
response = AsyncUtils.createJAXWSMessageContext(mc);
response.setInvocationContext(invocationCtx);
// make sure request and response contexts share a single parent
response.setMEPContext(invocationCtx.getRequestMessageContext().getMEPContext());
} catch (WebServiceException e) {
cft.setError(e);
if (debug) {
log.debug(
"An error occured while processing the async response. " + e.getMessage());
}
}
if (response == null) {
// TODO: throw an exception
}
cft.setMessageContext(response);
execute();
}
public void onError(Exception e) {
// If a SOAPFault was returned by the AxisEngine, the AxisFault
// that is returned should have a MessageContext with it. Use
// this to unmarshall the fault included there.
if (e.getClass().isAssignableFrom(AxisFault.class)) {
AxisFault fault = (AxisFault)e;
MessageContext faultMessageContext = null;
try {
faultMessageContext = AsyncUtils.createJAXWSMessageContext(fault.getFaultMessageContext());
faultMessageContext.setInvocationContext(invocationCtx);
// make sure request and response contexts share a single parent
faultMessageContext.setMEPContext(invocationCtx.getRequestMessageContext().getMEPContext());
} catch (WebServiceException wse) {
cft.setError(wse);
}
cft.setError(e);
cft.setMessageContext(faultMessageContext);
} else {
cft.setError(e);
}
execute();
}
private void execute() {
if (log.isDebugEnabled()) {
log.debug("Executor task starting to process async response");
}
if (executor != null) {
if (task != null && !task.isCancelled()) {
try {
executor.execute(task);
}
catch (Exception executorExc) {
if (log.isDebugEnabled()) {
log.debug("CallbackFuture.execute(): executor exception [" +
executorExc.getClass().getName() + "]");
}
// attempt to cancel the FutureTask
task.cancel(true);
// note: if it is becomes required to return the actual exception
// to the client, then we would need to doing something
// similar to setting the CallbackFutureTask with the error
// and invoking the CallbackFutureTask.call() interface
// to process the information
//
}
if (log.isDebugEnabled()) {
log.debug("Task submitted to Executor");
}
/*
* TODO: review
* A thread switch will occur immediately after going out of scope
* on this method. This is ok, except on some platforms this will
* prompt the JVM to clean up the old thread, thus cleaning up any
* InputStreams there. If that's the case, and we have not fully
* read the InputStreams, we will likely get a NullPointerException
* coming from the parser, which has a reference to the InputStream
* that got nulled out from under it. Make sure to do the
* cft.notifyAll() in the right place. CallbackFutureTask.call()
* is the right place since at that point, the parser has fully read
* the InputStream.
*/
try {
synchronized (cft) {
if(!cft.done) {
cft.wait(180000); // 3 minutes
}
}
} catch (InterruptedException e) {
if (debug) {
log.debug("cft.wait() was interrupted");
log.debug("Exception: " + e.getMessage());
}
}
} else {
if (log.isDebugEnabled()) {
log.debug(
"Executor task was not sumbitted as Async Future task was cancelled by clients");
}
}
}
if (log.isDebugEnabled()) {
log.debug("Executor task completed");
}
}
public void onMessage(org.apache.axis2.context.MessageContext msgContext) {
onComplete(msgContext);
}
public void onComplete() {
}
public void onFault(org.apache.axis2.context.MessageContext msgContext) {
onComplete(msgContext);
}
}
class CallbackFutureTask implements Callable {
private static final Log log = LogFactory.getLog(CallbackFutureTask.class);
private static final boolean debug = log.isDebugEnabled();
AsyncResponse response;
MessageContext msgCtx;
AsyncHandler handler;
ClassLoader handlerCL;
Exception error;
boolean done = false;
CallbackFutureTask(AsyncResponse r, AsyncHandler h, ClassLoader cl) {
response = r;
handler = h;
handlerCL = cl;
}
protected AsyncHandler getHandler() {
return handler;
}
void setMessageContext(MessageContext mc) {
msgCtx = mc;
}
void setError(Exception e) {
error = e;
}
/*
* An invocation of the call() method is what drives the response processing
* for Callback clients. The end result of this should be that the AysncHandler
* (the callback instance) provided by the client is called and the response or
* an error is delivered.
*/
@SuppressWarnings("unchecked")
public Object call() throws Exception {
ClassLoader oldCL = null;
try {
if (log.isDebugEnabled()) {
log.debug("Setting up the thread's context classLoader");
log.debug(handlerCL.toString());
}
// Retrieve the existing classloader from the thread.
oldCL = (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
return Thread.currentThread().getContextClassLoader();
}
});
AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
Thread.currentThread().setContextClassLoader(handlerCL);
return null;
}
});
// Set the response or fault content on the AsyncResponse object
// so that it can be collected inside the Executor thread and processed.
if (error != null) {
response.onError(error, msgCtx, handlerCL);
} else {
response.onComplete(msgCtx, handlerCL);
}
// Now that the content is available, call the JAX-WS AsyncHandler class
// to deliver the response to the user.
if (debug) {
log.debug("Calling JAX-WS AsyncHandler.handleResponse() with response object: " + CallbackFuture.displayHandle(response));
}
handler.handleResponse(response);
if (debug) {
log.debug("Returned from handleResponse() invocation...");
}
} catch (Throwable t) {
if (debug) {
log.debug("An error occurred while invoking the callback object.");
log.debug("Error: " + t.toString());
t.printStackTrace();
}
} finally {
synchronized(this) {
// Restore the old classloader on this thread.
if (oldCL != null) {
final ClassLoader t = oldCL;
AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
Thread.currentThread().setContextClassLoader(t);
return null;
}
});
if (debug) {
log.debug("Restored thread context classloader: " + oldCL.toString());
}
}
done = true;
this.notifyAll();
}
}
return null;
}
}