ActiveMQ example source code file (WireFormatNegotiator.java)

This example ActiveMQ source code file (WireFormatNegotiator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

atomicboolean, command, countdownlatch, countdownlatch, exception, exception, interruptedexception, io, ioexception, ioexception, net, network, openwireformat, remote, threading, threads, wireformatinfo, wireformatinfo, wireformatnegotiator

The ActiveMQ WireFormatNegotiator.java source code

/**
 * 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.activemq.transport;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.Socket;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.activemq.command.Command;
import org.apache.activemq.command.WireFormatInfo;
import org.apache.activemq.openwire.OpenWireFormat;
import org.apache.activemq.util.IOExceptionSupport;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Negotiates the wire format with a new connection
 */
public class WireFormatNegotiator extends TransportFilter {

    private static final Logger LOG = LoggerFactory.getLogger(WireFormatNegotiator.class);

    private OpenWireFormat wireFormat;
    private final int minimumVersion;
    private long negotiateTimeout = 15000L;

    private final AtomicBoolean firstStart = new AtomicBoolean(true);
    private final CountDownLatch readyCountDownLatch = new CountDownLatch(1);
    private final CountDownLatch wireInfoSentDownLatch = new CountDownLatch(1);

    /**
     * Negotiator
     * 
     * @param next
     */
    public WireFormatNegotiator(Transport next, OpenWireFormat wireFormat, int minimumVersion) {
        super(next);
        this.wireFormat = wireFormat;
        if (minimumVersion <= 0) {
            minimumVersion = 1;
        }
        this.minimumVersion = minimumVersion;
        
        // Setup the initial negociation timeout to be the same as the inital max inactivity delay specified on the wireformat
        // Does not make sense for us to take longer.
        try {
            if( wireFormat.getPreferedWireFormatInfo() !=null ) {
                setNegotiateTimeout(wireFormat.getPreferedWireFormatInfo().getMaxInactivityDurationInitalDelay());
            }
        } catch (IOException e) {
        }
    }

    public void start() throws Exception {
        super.start();
        if (firstStart.compareAndSet(true, false)) {
            sendWireFormat();
        }
    }

    public void sendWireFormat() throws IOException {
        try {
            WireFormatInfo info = wireFormat.getPreferedWireFormatInfo();
            if (LOG.isDebugEnabled()) {
                LOG.debug("Sending: " + info);
            }
            sendWireFormat(info);
        } finally {
            wireInfoSentDownLatch.countDown();
        }
    }

    public void stop() throws Exception {
        super.stop();
        readyCountDownLatch.countDown();
    }

    public void oneway(Object command) throws IOException {
        try {
            if (!readyCountDownLatch.await(negotiateTimeout, TimeUnit.MILLISECONDS)) {
                throw new IOException("Wire format negotiation timeout: peer did not send his wire format.");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new InterruptedIOException();
        }
        super.oneway(command);
    }

    public void onCommand(Object o) {
        Command command = (Command)o;
        if (command.isWireFormatInfo()) {
            WireFormatInfo info = (WireFormatInfo)command;
            negociate(info);
        }
        getTransportListener().onCommand(command);
    }

    public void negociate(WireFormatInfo info) {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Received WireFormat: " + info);
        }

        try {
            wireInfoSentDownLatch.await();

            if (LOG.isDebugEnabled()) {
                LOG.debug(this + " before negotiation: " + wireFormat);
            }
            if (!info.isValid()) {
                onException(new IOException("Remote wire format magic is invalid"));
            } else if (info.getVersion() < minimumVersion) {
                onException(new IOException("Remote wire format (" + info.getVersion() + ") is lower the minimum version required (" + minimumVersion + ")"));
            }

            wireFormat.renegotiateWireFormat(info);
            Socket socket = next.narrow(Socket.class);
            if (socket != null) {
                socket.setTcpNoDelay(wireFormat.isTcpNoDelayEnabled());
            }

            if (LOG.isDebugEnabled()) {
                LOG.debug(this + " after negotiation: " + wireFormat);
            }

        } catch (IOException e) {
            onException(e);
        } catch (InterruptedException e) {
            onException((IOException)new InterruptedIOException().initCause(e));
        } catch (Exception e) {
            onException(IOExceptionSupport.create(e));
        }
        readyCountDownLatch.countDown();
        onWireFormatNegotiated(info);
    }

    public void onException(IOException error) {
        readyCountDownLatch.countDown();
        /*
         * try { super.oneway(new ExceptionResponse(error)); } catch
         * (IOException e) { // ignore as we are already throwing an exception }
         */
        super.onException(error);
    }

    public String toString() {
        return next.toString();
    }

    protected void sendWireFormat(WireFormatInfo info) throws IOException {
        next.oneway(info);
    }

    protected void onWireFormatNegotiated(WireFormatInfo info) {
    }

    public long getNegotiateTimeout() {
        return negotiateTimeout;
    }

    public void setNegotiateTimeout(long negotiateTimeout) {
        this.negotiateTimeout = negotiateTimeout;
    }
}