MessageLossSimulator.java

/**
 * 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.camel.component.cxf.wsrm;

import java.io.IOException;
import java.io.OutputStream;
import java.util.ListIterator;

import org.apache.cxf.interceptor.Fault;
import org.apache.cxf.interceptor.Interceptor;
import org.apache.cxf.interceptor.InterceptorChain;
import org.apache.cxf.interceptor.MessageSenderInterceptor;
import org.apache.cxf.io.AbstractWrappedOutputStream;
import org.apache.cxf.message.Message;
import org.apache.cxf.phase.AbstractPhaseInterceptor;
import org.apache.cxf.phase.Phase;
import org.apache.cxf.phase.PhaseInterceptor;
import org.apache.cxf.ws.rm.RMContextUtils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MessageLossSimulator extends AbstractPhaseInterceptor<Message> {

    private static final Logger LOG = LoggerFactory.getLogger(MessageLossSimulator.class.getName());
    private int appMessageCount; 
    
    public MessageLossSimulator() {
        super(Phase.PREPARE_SEND);
        addBefore(MessageSenderInterceptor.class.getName());
    }

    private static String getAction(Object map) {
        if (map == null) {
            return null;
        }
        try {
            Object o = map.getClass().getMethod("getAction").invoke(map);
            return (String)o.getClass().getMethod("getValue").invoke(o);
        } catch (Throwable t) {
            throw new Fault(t);
        }
    }

    public void handleMessage(Message message) throws Fault {
        Object maps =
            RMContextUtils.retrieveMAPs(message, false, true);
        // RMContextUtils.ensureExposedVersion(maps);
        String action = getAction(maps);

        if (RMContextUtils.isRMProtocolMessage(action)) { 
            return;
        }
        appMessageCount++;
        // do not discard odd-numbered messages
        if (0 != (appMessageCount % 2)) {
            return;
        }
        
        // discard even-numbered message
        InterceptorChain chain = message.getInterceptorChain();
        ListIterator<Interceptor<? extends Message>> it = chain.getIterator();
        while (it.hasNext()) {
            PhaseInterceptor<?> pi = (PhaseInterceptor<?>)it.next();
            if (MessageSenderInterceptor.class.getName().equals(pi.getId())) {
                chain.remove(pi);
                LOG.debug("Removed MessageSenderInterceptor from interceptor chain.");
                break;
            }
        }
        
        message.setContent(OutputStream.class, new WrappedOutputStream(message));  

        message.getInterceptorChain().add(new AbstractPhaseInterceptor<Message>(Phase.PREPARE_SEND_ENDING) {

            public void handleMessage(Message message) throws Fault {
                try {
                    message.getContent(OutputStream.class).close();
                } catch (IOException e) {
                    throw new Fault(e);
                }
            }
            
        });   
    }
    
    private class WrappedOutputStream extends AbstractWrappedOutputStream {

        private Message outMessage;

        WrappedOutputStream(Message m) {
            this.outMessage = m;
        }

        @Override
        protected void onFirstWrite() throws IOException {
            if (LOG.isDebugEnabled()) {
                Long nr = RMContextUtils.retrieveRMProperties(outMessage, true).getSequence().getMessageNumber();
                LOG.debug("Losing message {}", nr);
            }
            wrappedStream = new DummyOutputStream();
        }
    }    

    private class DummyOutputStream extends OutputStream {

        @Override
        public void write(int b) throws IOException {
            // noop
        }
    }
}