Java tutorial
/* * 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.java.security.AccessController; import org.apache.axis2.jaxws.ExceptionFactory; import org.apache.axis2.jaxws.core.MessageContext; import org.apache.axis2.jaxws.description.EndpointDescription; import org.apache.axis2.jaxws.handler.AttachmentsAdapter; import org.apache.axis2.jaxws.handler.HandlerChainProcessor; import org.apache.axis2.jaxws.handler.HandlerInvokerUtils; import org.apache.axis2.jaxws.handler.SOAPHeadersAdapter; import org.apache.axis2.jaxws.handler.TransportHeadersAdapter; import org.apache.axis2.jaxws.i18n.Messages; import org.apache.axis2.jaxws.message.attachments.AttachmentUtils; import org.apache.axis2.jaxws.spi.Constants; import org.apache.axis2.jaxws.spi.migrator.ApplicationContextMigratorUtil; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import javax.xml.ws.Response; import java.security.PrivilegedAction; import java.util.HashMap; import java.util.Map; import java.util.concurrent.CancellationException; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutionException; import java.util.concurrent.TimeUnit; import java.util.concurrent.TimeoutException; /** * The AsyncResponse class is used to collect the response information from Axis2 and deliver it to * a JAX-WS client. AsyncResponse implements the <link>javax.xml.ws.Response</link> API that is * defined in the JAX-WS 2.0 specification. The <code>Response</code> object will contain both the * object that is returned as the response along with a <link>java.util.Map</link> with the context * information of the response. */ public abstract class AsyncResponse implements Response { private static final Log log = LogFactory.getLog(AsyncResponse.class); private boolean cancelled; private Throwable fault; private MessageContext faultMessageContext; private MessageContext response; private EndpointDescription endpointDescription; private Map<String, Object> responseContext; // CountDownLatch is used to track whether we've received and // processed the async response. For example, the client app // could be polling on 30 second intervals, and we don't receive // the async response until the 1:15 mark. In that case, the // first few polls calling the .get() would hit the latch.await() // which blocks the thread if the latch count > 0 private CountDownLatch latch; private boolean cacheValid = false; private Object cachedObject = null; // The response business object to be returned private Object responseObject = null; // The exception to be returned in the event of a fault or failure in // processing the response content. private ExecutionException savedException = null; protected AsyncResponse(EndpointDescription ed) { endpointDescription = ed; latch = new CountDownLatch(1); } protected void onError(Throwable flt, MessageContext mc, ClassLoader cl) { ClassLoader contextCL = (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() { public Object run() { return Thread.currentThread().getContextClassLoader(); } }); onError(flt, mc); checkClassLoader(cl, contextCL); } /** * @param flt Throwable fault that occurred * @param faultCtx MessageContext if fault is a SOAP Fault */ protected void onError(Throwable flt, MessageContext faultCtx) { // Note: // This code is hardened to prevent a secondary exception from being // thrown back to the caller of onError. It is likely that a // thrown exception will cause other errors leading to // system fragility. if (log.isDebugEnabled()) { log.debug("AsyncResponse received a fault."); } Throwable t = null; try { fault = flt; faultMessageContext = faultCtx; if (faultMessageContext != null) { faultMessageContext.setEndpointDescription(endpointDescription); } else { if (log.isDebugEnabled()) { log.debug("The faultMessageContext is not available because the error likely occurred on" + " the client and is not the result of a SOAP Fault"); } } // Probably a good idea to invalidate the cache cacheValid = false; cachedObject = null; t = processFaultResponse(); } catch (Throwable unexpected) { // An unexpected error occurred while processing the fault. // The Response's throwable is set to this unexpected exception. if (log.isDebugEnabled()) { log.debug("A secondary exception occurred during onError processing: " + unexpected); } t = unexpected; } // JAXWS 4.3.3 conformance bullet says to throw an ExecutionException from here savedException = new ExecutionException(t); try { // Countdown so that the Future object will know that procesing is complete. latch.countDown(); if (log.isDebugEnabled()) { log.debug("New latch count = [" + latch.getCount() + "]"); } } catch (Throwable unexpected) { // An unexpected error occurred after processing the fault response // The Response's throwable has already been set to the savedException if (log.isDebugEnabled()) { log.debug("A secondary exception occurred during onError processing " + "after the fault is processed: " + unexpected); } } } /** * Check for a valid relationship between unmarshalling classloader and * Application's current context classloader * @param cl * @param contextCL */ private void checkClassLoader(final ClassLoader cl, final ClassLoader contextCL) { // Ensure that the classloader (cl) used for unmarshalling is the same // or a parent of the current context classloader. Otherwise // ClassCastExceptions can occur if (log.isDebugEnabled()) { log.debug("AsyncResponse ClassLoader is:"); log.debug(cl.toString()); } if (cl.equals(contextCL)) { if (log.isDebugEnabled()) { log.debug("AsyncResponse ClassLoader matches Context ClassLoader"); } return; } else { if (log.isDebugEnabled()) { log.debug("Context ClassLoader is:"); log.debug(contextCL.toString()); } ClassLoader parent = getParentClassLoader(contextCL); while (parent != null) { if (parent.equals(cl)) { return; } if (log.isDebugEnabled()) { log.debug("AsyncResponse ClassLoader is an ancestor of the Context ClassLoader"); } parent = getParentClassLoader(parent); } } throw ExceptionFactory.makeWebServiceException(Messages.getMessage("threadClsLoaderErr", contextCL.getClass().toString(), cl.getClass().toString())); } ClassLoader getParentClassLoader(final ClassLoader cl) { return (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() { public Object run() { return cl.getParent(); } }); } protected void onComplete(MessageContext mc, ClassLoader cl) { ClassLoader contextCL = (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() { public Object run() { return Thread.currentThread().getContextClassLoader(); } }); onComplete(mc); checkClassLoader(cl, contextCL); } protected void onComplete(MessageContext mc) { if (log.isDebugEnabled()) { log.debug("AsyncResponse received a MessageContext."); } // A new message context invalidates the cached object retrieved // during the last get() if (response != mc) { cachedObject = null; cacheValid = false; } response = mc; response.setEndpointDescription(endpointDescription); // Check for cached attachment file(s) if attachments exist. if (response.getAxisMessageContext().getAttachmentMap() != null) { AttachmentUtils.findCachedAttachment(response.getAxisMessageContext().getAttachmentMap()); } // Process the response as soon as it is available. This means making sure that // no content is left unread in the response stream. Leaving content there could // result in an error if the runtime is greedy about cleaning up. try { responseObject = processResponse(); } catch (ExecutionException e) { savedException = e; if (log.isDebugEnabled()) { log.debug("An error occurred while processing the response: " + e.getCause()); } latch.countDown(); } // Countdown so that the Future object will know that procesing is complete. latch.countDown(); if (log.isDebugEnabled()) { log.debug("New latch count = [" + latch.getCount() + "]"); } } //------------------------------------- // javax.xml.ws.Response APIs //------------------------------------- public boolean cancel(boolean mayInterruptIfRunning) { // The task cannot be cancelled if it has already been cancelled // before or if it has already completed. if (cancelled || latch.getCount() == 0) { if (log.isDebugEnabled()) { log.debug("Cancellation attempt failed."); } return false; } cancelled = true; return cancelled; } public Object get() throws InterruptedException, ExecutionException { if (cancelled) { throw new CancellationException(Messages.getMessage("getErr")); } // Wait for the response to come back if (log.isDebugEnabled()) { log.debug("Waiting for async response delivery."); } // If latch count > 0, it means we have not yet received // and processed the async response, and must block the // thread. latch.await(); if (savedException != null) { throw savedException; } return responseObject; } public Object get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { if (cancelled) { throw new CancellationException(Messages.getMessage("getErr")); } // Wait for the response to come back if (log.isDebugEnabled()) { log.debug("Waiting for async response delivery with time out."); log.debug("timeout = " + timeout); log.debug("units = " + unit); } // latch.await will only block if its count is > 0 latch.await(timeout, unit); if (savedException != null) { throw savedException; } // If the response still hasn't been returned, then we've timed out // and must throw a TimeoutException if (latch.getCount() > 0) { throw new TimeoutException(Messages.getMessage("getErr1")); } return responseObject; } public boolean isCancelled() { return cancelled; } public boolean isDone() { return (latch.getCount() == 0); } public Map getContext() { return responseContext; } private Object processResponse() throws ExecutionException { // If we don't have a fault, then we have to have a MessageContext for the response. if (response == null) { latch.countDown(); throw new ExecutionException( ExceptionFactory.makeWebServiceException(Messages.getMessage("processRespErr"))); } // Avoid a reparse of the message. If we already retrived the object, return // it now. if (cacheValid) { if (log.isDebugEnabled()) { log.debug("Return object cached from last get()"); } return cachedObject; } Object obj = null; try { // Install the adapters and invoke inbound handlers. TransportHeadersAdapter.install(response); AttachmentsAdapter.install(response); SOAPHeadersAdapter.install(response); HandlerInvokerUtils.invokeInboundHandlers(response.getMEPContext(), response.getInvocationContext().getHandlers(), HandlerChainProcessor.MEP.RESPONSE, false); // TODO: IMPORTANT: this is the right call here, but beware that the // messagecontext may be turned into a fault context with a fault message. // We need to check for this and, if necessary, make an exception and throw it. if (log.isDebugEnabled()) { log.debug("Unmarshalling the async response message."); } // Do the real work to unmarshall the response. obj = getResponseValueObject(response); if (log.isDebugEnabled() && obj != null) { log.debug("Unmarshalled response object of type: " + obj.getClass()); } // Cache the object in case it is required again cacheValid = true; cachedObject = obj; responseContext = new HashMap<String, Object>(); // Migrate the properties from the response MessageContext back // to the client response context bag. ApplicationContextMigratorUtil.performMigrationFromMessageContext( Constants.APPLICATION_CONTEXT_MIGRATOR_LIST_ID, responseContext, response); } catch (Throwable t) { throw new ExecutionException(ExceptionFactory.makeWebServiceException(t)); } return obj; } private Throwable processFaultResponse() { // A faultMessageContext means that there could possibly be a SOAPFault // on the MessageContext that we need to unmarshall. if (faultMessageContext != null) { Throwable throwable = null; // it is possible the message could be null. For example, if we gave the proxy a bad endpoint address. // If it is the case that the message is null, there's no sense running through the handlers. if (faultMessageContext.getMessage() != null) { // The adapters are intentionally NOT installed here. They cause unit test failures // TransportHeadersAdapter.install(faultMessageContext); // AttachmentsAdapter.install(faultMessageContext); try { // Invoke inbound handlers. if (log.isDebugEnabled()) { log.debug("Invoking the JAX-WS handler chain for the fault response."); } HandlerInvokerUtils.invokeInboundHandlers(faultMessageContext.getMEPContext(), faultMessageContext.getInvocationContext().getHandlers(), HandlerChainProcessor.MEP.RESPONSE, false); } catch (Throwable t) { if (log.isDebugEnabled()) { log.debug("An error occurred (" + t.getClass() + " while processing " + "the fault response handler chain."); } throwable = t; } } if (throwable == null) { // Do the real work to unmarshal the fault response. throwable = getFaultResponse(faultMessageContext); } if (throwable != null) { return throwable; } else { return ExceptionFactory.makeWebServiceException(fault); } } else { return ExceptionFactory.makeWebServiceException(fault); } } public abstract Object getResponseValueObject(MessageContext mc); public abstract Throwable getFaultResponse(MessageContext mc); }