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/*
* 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.tuscany.sca.implementation.java.invocation;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.tuscany.sca.assembly.EndpointReference;
import org.apache.tuscany.sca.context.CompositeContext;
import org.apache.tuscany.sca.context.ThreadMessageContext;
import org.apache.tuscany.sca.core.ExtensionPointRegistry;
import org.apache.tuscany.sca.core.FactoryExtensionPoint;
import org.apache.tuscany.sca.core.factory.ObjectFactory;
import org.apache.tuscany.sca.core.invocation.AsyncFaultWrapper;
import org.apache.tuscany.sca.core.invocation.AsyncResponseHandler;
import org.apache.tuscany.sca.core.invocation.AsyncResponseInvoker;
import org.apache.tuscany.sca.core.invocation.CallbackReferenceObjectFactory;
import org.apache.tuscany.sca.core.invocation.Constants;
import org.apache.tuscany.sca.core.invocation.ExtensibleProxyFactory;
import org.apache.tuscany.sca.core.invocation.ProxyFactory;
import org.apache.tuscany.sca.invocation.Message;
import org.apache.tuscany.sca.invocation.MessageFactory;
import org.apache.tuscany.sca.runtime.RuntimeEndpointReference;
import org.oasisopen.sca.ResponseDispatch;
import org.oasisopen.sca.ServiceReference;
import org.oasisopen.sca.ServiceRuntimeException;
/**
* Implementation of the ResponseDispatch interface of the OASIS SCA Java API
*
* This is used for invocations of asynchronous services, where it is passed as a parameter on async service operations
* and it provides the path by which the service implementation returns the response to the request, or a Fault
*
* Note that this class is serializable and can be serialized, stored and deserialized by the service implementation
*
* @param <T> - type of the response message
*/
public class ResponseDispatchImpl<T> implements ResponseDispatch<T>, Serializable {
/**
* Generated serialVersionUID value
*/
private static final long serialVersionUID = 300158355992568592L;
// A latch used to ensure that the sendResponse() and sendFault() operations are used at most once
// The latch is initialized with the value "false"
private AtomicBoolean latch = new AtomicBoolean();
private final Lock lock = new ReentrantLock();
private final Condition completed = lock.newCondition();
// The result
private transient volatile T response = null;
private transient volatile Throwable fault = null;
private transient ExtensionPointRegistry registry;
private MessageFactory msgFactory;
// Service Reference used for the callback
private volatile ServiceReference<AsyncResponseHandler<?>> callbackRef;
private AsyncResponseInvoker<?> respInvoker;
private String messageID;
/**
* No-arg constructor for serialization purposes
*/
public ResponseDispatchImpl() {
super();
} // end constructor
public ResponseDispatchImpl( Message msg ) {
super();
respInvoker = (AsyncResponseInvoker<?>)msg.getHeaders().get(Constants.ASYNC_RESPONSE_INVOKER);
//if( respInvoker == null ) throw new ServiceRuntimeException("Async Implementation invoked with no response invoker");
if( respInvoker == null ) {
callbackRef = getAsyncCallbackRef( msg );
} // end if
messageID = (String) msg.getHeaders().get(Constants.MESSAGE_ID);
} // end constructor
public static <T> ResponseDispatchImpl<T> newInstance( Class<T> type, Message msg ) {
return new ResponseDispatchImpl<T>( msg );
}
/**
* Provide Context data for this ResponseDispatch that the service implementation can use
*/
public Map<String, Object> getContext() {
return null;
}
/**
* Send a Fault. Must only be invoked once for this ResponseDispatch object
* @param e - the Fault to send
* @throws IllegalStateException if either the sendResponse method or the sendFault method have been called previously
*/
public void sendFault(Throwable e) {
if( sendOK() ) {
lock.lock();
try {
fault = e;
completed.signalAll();
} finally {
lock.unlock();
} // end try
} else {
throw new IllegalStateException("sendResponse() or sendFault() has been called previously");
} // end if
// Use response invoker if present
if( respInvoker != null ) {
//respInvoker.invokeAsyncResponse(new AsyncFaultWrapper(e));
respInvoker.invokeAsyncResponse(e, null);
return;
} // end if
// Now dispatch the response to the callback...
AsyncResponseHandler<T> handler = (AsyncResponseHandler<T>) callbackRef.getService();
setResponseHeaders();
handler.setWrappedFault(new AsyncFaultWrapper(e));
} // end method sendFault
/**
* Send the response message. Must only be invoked once for this ResponseDispatch object
* @throws IllegalStateException if either the sendResponse method or the sendFault method have been called previously
* @param res - the response message, which is of type T
*/
@SuppressWarnings("unchecked")
public void sendResponse(T res) {
if( sendOK() ) {
lock.lock();
try {
response = res;
completed.signalAll();
} finally {
lock.unlock();
} // end try
} else {
throw new IllegalStateException("sendResponse() or sendFault() has been called previously");
} // end if
// Now dispatch the response to the callback, if present...
if( callbackRef != null ) {
AsyncResponseHandler<T> handler = (AsyncResponseHandler<T>) callbackRef.getService();
setResponseHeaders();
handler.setResponse(res);
} // end if
// Use response invoker if present
if( respInvoker != null ) {
respInvoker.invokeAsyncResponse(res, null);
return;
} // end if
} // end method sendResponse
public T get(long timeout, TimeUnit unit) throws Throwable {
lock.lock();
try {
// wait for result to be available
if( response == null && fault == null ) completed.await( timeout, unit);
if( response != null ) return response;
if( fault != null ) throw fault;
} finally {
lock.unlock();
} // end try
return null;
} // end method get
/**
* Indicates that sending a response is OK - this is a transactional
* query in that it also updates the state of this ResponseDispatch, so
* that it will return true once and once only
* @return - true if it is OK to send the response, false otherwise
*/
private boolean sendOK() {
return latch.compareAndSet(false, true);
}
/**
* Creates a service reference for the async callback, based on information contained in the supplied message
* @param msg - the incoming message
* @return - a CallBackServiceReference
*/
@SuppressWarnings("unchecked")
private ServiceReference<AsyncResponseHandler<?>> getAsyncCallbackRef( Message msg ) {
RuntimeEndpointReference callbackEPR = (RuntimeEndpointReference) msg.getHeaders().get(Constants.ASYNC_CALLBACK);
if( callbackEPR == null ) return null;
CompositeContext compositeContext = callbackEPR.getCompositeContext();
registry = compositeContext.getExtensionPointRegistry();
ProxyFactory proxyFactory = ExtensibleProxyFactory.getInstance(registry);
msgFactory = getMessageFactory();
List<EndpointReference> eprList = new ArrayList<EndpointReference>();
eprList.add(callbackEPR);
ObjectFactory<?> factory = new CallbackReferenceObjectFactory(AsyncResponseHandler.class, proxyFactory, eprList);
return (ServiceReference<AsyncResponseHandler<?>>) factory.getInstance();
} // end method getAsyncCallbackEPR
/**
* Sets the values of various headers in the response message
*/
private void setResponseHeaders() {
// Is there an existing message context?
Message msgContext = ThreadMessageContext.getMessageContext();
if( msgContext == null ) {
// Create a message context
msgContext = msgFactory.createMessage();
} // end if
// Add in the header for the RelatesTo Message ID
msgContext.getHeaders().put(Constants.RELATES_TO, messageID);
ThreadMessageContext.setMessageContext(msgContext);
} // end method setResponseHeaders
private MessageFactory getMessageFactory() {
FactoryExtensionPoint modelFactories = registry.getExtensionPoint(FactoryExtensionPoint.class);
return modelFactories.getFactory(MessageFactory.class);
} // end method getMessageFactory
}
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