http://netty.io/netty-all/: Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers and clients. (The Netty Project) 
/*
 * Copyright 2011 The Netty Project
 *
 * The Netty Project 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 io.netty.channel.sctp.nio;

import com.sun.nio.sctp.Association;
import com.sun.nio.sctp.MessageInfo;
import com.sun.nio.sctp.NotificationHandler;
import com.sun.nio.sctp.SctpChannel;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.Channel;
import io.netty.channel.ChannelException;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelMetadata;
import io.netty.channel.ChannelOutboundBuffer;
import io.netty.channel.ChannelPromise;
import io.netty.channel.RecvByteBufAllocator;
import io.netty.channel.nio.AbstractNioMessageChannel;
import io.netty.channel.sctp.DefaultSctpChannelConfig;
import io.netty.channel.sctp.SctpChannelConfig;
import io.netty.channel.sctp.SctpMessage;
import io.netty.channel.sctp.SctpNotificationHandler;
import io.netty.channel.sctp.SctpServerChannel;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.StringUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;


SctpChannel implementation which use non-blocking mode and allows to read / write SctpMessages to the underlying SctpChannel. Be aware that not all operations systems support SCTP. Please refer to the documentation of your operation system, to understand what you need to do to use it. Also this feature is only supported on Java 7+. 
/**
 * {@link io.netty.channel.sctp.SctpChannel} implementation which use non-blocking mode and allows to read /
 * write {@link SctpMessage}s to the underlying {@link SctpChannel}.
 *
 * Be aware that not all operations systems support SCTP. Please refer to the documentation of your operation system,
 * to understand what you need to do to use it. Also this feature is only supported on Java 7+.
 */
public class NioSctpChannel extends AbstractNioMessageChannel implements io.netty.channel.sctp.SctpChannel {
    private static final ChannelMetadata METADATA = new ChannelMetadata(false);

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(NioSctpChannel.class);

    private final SctpChannelConfig config;

    private final NotificationHandler<?> notificationHandler;

    private static SctpChannel newSctpChannel() {
        try {
            return SctpChannel.open();
        } catch (IOException e) {
            throw new ChannelException("Failed to open a sctp channel.", e);
        }
    }

    
Create a new instance

/**
     * Create a new instance
     */
    public NioSctpChannel() {
        this(newSctpChannel());
    }

    
Create a new instance using SctpChannel 
/**
     * Create a new instance using {@link SctpChannel}
     */
    public NioSctpChannel(SctpChannel sctpChannel) {
        this(null, sctpChannel);
    }

    
Create a new instance

Params:
/**
     * Create a new instance
     *
     * @param parent        the {@link Channel} which is the parent of this {@link NioSctpChannel}
     *                      or {@code null}.
     * @param sctpChannel   the underlying {@link SctpChannel}
     */
    public NioSctpChannel(Channel parent, SctpChannel sctpChannel) {
        super(parent, sctpChannel, SelectionKey.OP_READ);
        try {
            sctpChannel.configureBlocking(false);
            config = new NioSctpChannelConfig(this, sctpChannel);
            notificationHandler = new SctpNotificationHandler(this);
        } catch (IOException e) {
            try {
                sctpChannel.close();
            } catch (IOException e2) {
                if (logger.isWarnEnabled()) {
                    logger.warn(
                            "Failed to close a partially initialized sctp channel.", e2);
                }
            }

            throw new ChannelException("Failed to enter non-blocking mode.", e);
        }
    }

    @Override
    public InetSocketAddress localAddress() {
        return (InetSocketAddress) super.localAddress();
    }

    @Override
    public InetSocketAddress remoteAddress() {
        return (InetSocketAddress) super.remoteAddress();
    }

    @Override
    public SctpServerChannel parent() {
        return (SctpServerChannel) super.parent();
    }

    @Override
    public ChannelMetadata metadata() {
        return METADATA;
    }

    @Override
    public Association association() {
        try {
            return javaChannel().association();
        } catch (IOException ignored) {
            return null;
        }
    }

    @Override
    public Set<InetSocketAddress> allLocalAddresses() {
        try {
            final Set<SocketAddress> allLocalAddresses = javaChannel().getAllLocalAddresses();
            final Set<InetSocketAddress> addresses = new LinkedHashSet<InetSocketAddress>(allLocalAddresses.size());
            for (SocketAddress socketAddress : allLocalAddresses) {
                addresses.add((InetSocketAddress) socketAddress);
            }
            return addresses;
        } catch (Throwable ignored) {
            return Collections.emptySet();
        }
    }

    @Override
    public SctpChannelConfig config() {
        return config;
    }

    @Override
    public Set<InetSocketAddress> allRemoteAddresses() {
        try {
            final Set<SocketAddress> allLocalAddresses = javaChannel().getRemoteAddresses();
            final Set<InetSocketAddress> addresses = new HashSet<InetSocketAddress>(allLocalAddresses.size());
            for (SocketAddress socketAddress : allLocalAddresses) {
                addresses.add((InetSocketAddress) socketAddress);
            }
            return addresses;
        } catch (Throwable ignored) {
            return Collections.emptySet();
        }
    }

    @Override
    protected SctpChannel javaChannel() {
        return (SctpChannel) super.javaChannel();
    }

    @Override
    public boolean isActive() {
        SctpChannel ch = javaChannel();
        return ch.isOpen() && association() != null;
    }

    @Override
    protected SocketAddress localAddress0() {
        try {
            Iterator<SocketAddress> i = javaChannel().getAllLocalAddresses().iterator();
            if (i.hasNext()) {
                return i.next();
            }
        } catch (IOException e) {
            // ignore
        }
        return null;
    }

    @Override
    protected SocketAddress remoteAddress0() {
        try {
            Iterator<SocketAddress> i = javaChannel().getRemoteAddresses().iterator();
            if (i.hasNext()) {
                return i.next();
            }
        } catch (IOException e) {
            // ignore
        }
        return null;
    }

    @Override
    protected void doBind(SocketAddress localAddress) throws Exception {
        javaChannel().bind(localAddress);
    }

    @Override
    protected boolean doConnect(SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
        if (localAddress != null) {
            javaChannel().bind(localAddress);
        }

        boolean success = false;
        try {
            boolean connected = javaChannel().connect(remoteAddress);
            if (!connected) {
                selectionKey().interestOps(SelectionKey.OP_CONNECT);
            }
            success = true;
            return connected;
        } finally {
            if (!success) {
                doClose();
            }
        }
    }

    @Override
    protected void doFinishConnect() throws Exception {
        if (!javaChannel().finishConnect()) {
            throw new Error();
        }
    }

    @Override
    protected void doDisconnect() throws Exception {
        doClose();
    }

    @Override
    protected void doClose() throws Exception {
        javaChannel().close();
    }

    @Override
    protected int doReadMessages(List<Object> buf) throws Exception {
        SctpChannel ch = javaChannel();

        RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
        ByteBuf buffer = allocHandle.allocate(config().getAllocator());
        boolean free = true;
        try {
            ByteBuffer data = buffer.internalNioBuffer(buffer.writerIndex(), buffer.writableBytes());
            int pos = data.position();

            MessageInfo messageInfo = ch.receive(data, null, notificationHandler);
            if (messageInfo == null) {
                return 0;
            }

            allocHandle.lastBytesRead(data.position() - pos);
            buf.add(new SctpMessage(messageInfo,
                    buffer.writerIndex(buffer.writerIndex() + allocHandle.lastBytesRead())));
            free = false;
            return 1;
        } catch (Throwable cause) {
            PlatformDependent.throwException(cause);
            return -1;
        }  finally {
            if (free) {
                buffer.release();
            }
        }
    }

    @Override
    protected boolean doWriteMessage(Object msg, ChannelOutboundBuffer in) throws Exception {
        SctpMessage packet = (SctpMessage) msg;
        ByteBuf data = packet.content();
        int dataLen = data.readableBytes();
        if (dataLen == 0) {
            return true;
        }

        ByteBufAllocator alloc = alloc();
        boolean needsCopy = data.nioBufferCount() != 1;
        if (!needsCopy) {
            if (!data.isDirect() && alloc.isDirectBufferPooled()) {
                needsCopy = true;
            }
        }
        ByteBuffer nioData;
        if (needsCopy) {
            data = alloc.directBuffer(dataLen).writeBytes(data);
        }
        nioData = data.nioBuffer();
        final MessageInfo mi = MessageInfo.createOutgoing(association(), null, packet.streamIdentifier());
        mi.payloadProtocolID(packet.protocolIdentifier());
        mi.streamNumber(packet.streamIdentifier());
        mi.unordered(packet.isUnordered());

        final int writtenBytes = javaChannel().send(nioData, mi);
        return writtenBytes > 0;
    }

    @Override
    protected final Object filterOutboundMessage(Object msg) throws Exception {
        if (msg instanceof SctpMessage) {
            SctpMessage m = (SctpMessage) msg;
            ByteBuf buf = m.content();
            if (buf.isDirect() && buf.nioBufferCount() == 1) {
                return m;
            }

            return new SctpMessage(m.protocolIdentifier(), m.streamIdentifier(), m.isUnordered(),
                                   newDirectBuffer(m, buf));
        }

        throw new UnsupportedOperationException(
                "unsupported message type: " + StringUtil.simpleClassName(msg) +
                " (expected: " + StringUtil.simpleClassName(SctpMessage.class));
    }

    @Override
    public ChannelFuture bindAddress(InetAddress localAddress) {
        return bindAddress(localAddress, newPromise());
    }

    @Override
    public ChannelFuture bindAddress(final InetAddress localAddress, final ChannelPromise promise) {
        if (eventLoop().inEventLoop()) {
            try {
                javaChannel().bindAddress(localAddress);
                promise.setSuccess();
            } catch (Throwable t) {
                promise.setFailure(t);
            }
        } else {
            eventLoop().execute(new Runnable() {
                @Override
                public void run() {
                    bindAddress(localAddress, promise);
                }
            });
        }
        return promise;
    }

    @Override
    public ChannelFuture unbindAddress(InetAddress localAddress) {
        return unbindAddress(localAddress, newPromise());
    }

    @Override
    public ChannelFuture unbindAddress(final InetAddress localAddress, final ChannelPromise promise) {
        if (eventLoop().inEventLoop()) {
            try {
                javaChannel().unbindAddress(localAddress);
                promise.setSuccess();
            } catch (Throwable t) {
                promise.setFailure(t);
            }
        } else {
            eventLoop().execute(new Runnable() {
                @Override
                public void run() {
                    unbindAddress(localAddress, promise);
                }
            });
        }
        return promise;
    }

    private final class NioSctpChannelConfig extends DefaultSctpChannelConfig {
        private NioSctpChannelConfig(NioSctpChannel channel, SctpChannel javaChannel) {
            super(channel, javaChannel);
        }

        @Override
        protected void autoReadCleared() {
            clearReadPending();
        }
    }
}