ActiveMQ example source code file (NIOTransport.java)

This example ActiveMQ source code file (NIOTransport.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

bytebuffer, bytebuffer, dataoutputstream, exception, io, ioexception, ioexception, net, network, nio, nioinputstream, niooutputstream, niotransport, niotransport, selectorselection, throwable, throwable, uri

The ActiveMQ NIOTransport.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.nio;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.net.Socket;
import java.net.URI;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;

import javax.net.SocketFactory;

import org.apache.activemq.command.Command;
import org.apache.activemq.transport.Transport;
import org.apache.activemq.transport.tcp.TcpTransport;
import org.apache.activemq.util.IOExceptionSupport;
import org.apache.activemq.util.ServiceStopper;
import org.apache.activemq.wireformat.WireFormat;

/**
 * An implementation of the {@link Transport} interface using raw tcp/ip
 * 
 * 
 */
public class NIOTransport extends TcpTransport {

    // private static final Logger log = LoggerFactory.getLogger(NIOTransport.class);
    private SocketChannel channel;
    private SelectorSelection selection;
    private ByteBuffer inputBuffer;
    private ByteBuffer currentBuffer;
    private int nextFrameSize;

    public NIOTransport(WireFormat wireFormat, SocketFactory socketFactory, URI remoteLocation, URI localLocation) throws UnknownHostException, IOException {
        super(wireFormat, socketFactory, remoteLocation, localLocation);
    }

    public NIOTransport(WireFormat wireFormat, Socket socket) throws IOException {
        super(wireFormat, socket);
    }

    protected void initializeStreams() throws IOException {
        channel = socket.getChannel();
        channel.configureBlocking(false);

        // listen for events telling us when the socket is readable.
        selection = SelectorManager.getInstance().register(channel, new SelectorManager.Listener() {
            public void onSelect(SelectorSelection selection) {
                serviceRead();
            }

            public void onError(SelectorSelection selection, Throwable error) {
                if (error instanceof IOException) {
                    onException((IOException)error);
                } else {
                    onException(IOExceptionSupport.create(error));
                }
            }
        });

        // Send the data via the channel
        // inputBuffer = ByteBuffer.allocateDirect(8*1024);
        inputBuffer = ByteBuffer.allocate(8 * 1024);
        currentBuffer = inputBuffer;
        nextFrameSize = -1;
        currentBuffer.limit(4);
        NIOOutputStream outPutStream = new NIOOutputStream(channel, 16 * 1024);
        this.dataOut = new DataOutputStream(outPutStream);
        this.buffOut = outPutStream;
    }

    private void serviceRead() {
        try {
            while (true) {

                int readSize = channel.read(currentBuffer);
                if (readSize == -1) {
                    onException(new EOFException());
                    selection.close();
                    break;
                }
                if (readSize == 0) {
                    break;
                }

                if (currentBuffer.hasRemaining()) {
                    continue;
                }

                // Are we trying to figure out the size of the next frame?
                if (nextFrameSize == -1) {
                    assert inputBuffer == currentBuffer;

                    // If the frame is too big to fit in our direct byte buffer,
                    // Then allocate a non direct byte buffer of the right size
                    // for it.
                    inputBuffer.flip();
                    nextFrameSize = inputBuffer.getInt() + 4;
                    if (nextFrameSize > inputBuffer.capacity()) {
                        currentBuffer = ByteBuffer.allocate(nextFrameSize);
                        currentBuffer.putInt(nextFrameSize);
                    } else {
                        inputBuffer.limit(nextFrameSize);
                    }

                } else {
                    currentBuffer.flip();

                    Object command = wireFormat.unmarshal(new DataInputStream(new NIOInputStream(currentBuffer)));
                    doConsume((Command)command);

                    nextFrameSize = -1;
                    inputBuffer.clear();
                    inputBuffer.limit(4);
                    currentBuffer = inputBuffer;
                }

            }

        } catch (IOException e) {
            onException(e);
        } catch (Throwable e) {
            onException(IOExceptionSupport.create(e));
        }
    }

    protected void doStart() throws Exception {
        connect();
        selection.setInterestOps(SelectionKey.OP_READ);
        selection.enable();
    }

    protected void doStop(ServiceStopper stopper) throws Exception {
        if (selection != null) {
            selection.close();
        }
        super.doStop(stopper);
    }
}