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	/*
	* Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package com.sun.nio.sctp;

	import java.net.SocketAddress;
	import java.net.InetAddress;
	import java.io.IOException;
	import java.util.Set;
	import java.nio.ByteBuffer;
	import java.nio.channels.spi.AbstractSelectableChannel;
	import java.nio.channels.spi.SelectorProvider;
	import java.nio.channels.ClosedChannelException;
	import java.nio.channels.SelectionKey;

	/**
	* A selectable channel for message-oriented connected SCTP sockets.
	*
	* <P> An SCTP channel can only control one SCTP association.
	* An {@code SCTPChannel} is created by invoking one of the
	* {@link #open open} methods of this class. A newly-created channel is open but
	* not yet connected, that is, there is no association setup with a remote peer.
	* An attempt to invoke an I/O operation upon an unconnected
	* channel will cause a {@link java.nio.channels.NotYetConnectedException} to be
	* thrown. An association can be setup by connecting the channel using one of
	* its {@link #connect connect} methods. Once connected, the channel remains
	* connected until it is closed. Whether or not a channel is connected may be
	* determined by invoking {@link #getRemoteAddresses getRemoteAddresses}.
	*
	* <p> SCTP channels support <i>non-blocking connection:</i> A
	* channel may be created and the process of establishing the link to
	* the remote socket may be initiated via the {@link #connect connect} method
	* for later completion by the {@link #finishConnect finishConnect} method.
	* Whether or not a connection operation is in progress may be determined by
	* invoking the {@link #isConnectionPending isConnectionPending} method.
	*
	* <p> Socket options are configured using the
	* {@link #setOption(SctpSocketOption,Object) setOption} method. An SCTP
	* channel support the following options:
	* <blockquote>
	* <table border summary="Socket options">
	* <tr>
	* <th>Option Name</th>
	* <th>Description</th>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SCTP_DISABLE_FRAGMENTS
	* SCTP_DISABLE_FRAGMENTS} </td>
	* <td> Enables or disables message fragmentation </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SCTP_EXPLICIT_COMPLETE
	* SCTP_EXPLICIT_COMPLETE} </td>
	* <td> Enables or disables explicit message completion </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SCTP_FRAGMENT_INTERLEAVE
	* SCTP_FRAGMENT_INTERLEAVE} </td>
	* <td> Controls how the presentation of messages occur for the message
	* receiver </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SCTP_INIT_MAXSTREAMS
	* SCTP_INIT_MAXSTREAMS} </td>
	* <td> The maximum number of streams requested by the local endpoint during
	* association initialization </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SCTP_NODELAY SCTP_NODELAY} </td>
	* <td> Enables or disable a Nagle-like algorithm </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SCTP_PRIMARY_ADDR
	* SCTP_PRIMARY_ADDR} </td>
	* <td> Requests that the local SCTP stack use the given peer address as the
	* association primary </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SCTP_SET_PEER_PRIMARY_ADDR
	* SCTP_SET_PEER_PRIMARY_ADDR} </td>
	* <td> Requests that the peer mark the enclosed address as the association
	* primary </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SO_SNDBUF
	* SO_SNDBUF} </td>
	* <td> The size of the socket send buffer </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SO_RCVBUF
	* SO_RCVBUF} </td>
	* <td> The size of the socket receive buffer </td>
	* </tr>
	* <tr>
	* <td> {@link SctpStandardSocketOptions#SO_LINGER
	* SO_LINGER} </td>
	* <td> Linger on close if data is present (when configured in blocking mode
	* only) </td>
	* </tr>
	* </table>
	* </blockquote>
	* Additional (implementation specific) options may also be supported. The list
	* of options supported is obtained by invoking the {@link #supportedOptions()
	* supportedOptions} method.
	*
	* <p> SCTP channels are safe for use by multiple concurrent threads.
	* They support concurrent reading and writing, though at most one thread may be
	* reading and at most one thread may be writing at any given time. The
	* {@link #connect connect} and {@link #finishConnect
	* finishConnect} methods are mutually synchronized against each other, and
	* an attempt to initiate a send or receive operation while an invocation of one
	* of these methods is in progress will block until that invocation is complete.
	*
	* @since 1.7
	*/
	@jdk.Exported
	public abstract class SctpChannel
	extends AbstractSelectableChannel
	{
	/**
	* Initializes a new instance of this class.
	*
	* @param provider
	* The selector provider for this channel
	*/
	protected SctpChannel(SelectorProvider provider) {
	super(provider);
	}

	/**
	* Opens an SCTP channel.
	*
	* <P> The new channel is unbound and unconnected.
	*
	* @return A new SCTP channel
	*
	* @throws UnsupportedOperationException
	* If the SCTP protocol is not supported
	*
	* @throws IOException
	* If an I/O error occurs
	*/
	public static SctpChannel open() throws
	IOException {
	return new sun.nio.ch.sctp.SctpChannelImpl((SelectorProvider)null);
	}

	/**
	* Opens an SCTP channel and connects it to a remote address.
	*
	* <P> This is a convenience method and is equivalent to evaluating the
	* following expression:
	* <blockquote><pre>
	* open().connect(remote, maxOutStreams, maxInStreams);
	* </pre></blockquote>
	*
	* @param remote
	* The remote address to which the new channel is to be connected
	*
	* @param maxOutStreams
	* The number of streams that the application wishes to be able
	* to send to. Must be non negative and no larger than {@code 65536}.
	* {@code 0} to use the endpoints default value.
	*
	* @param maxInStreams
	* The maximum number of inbound streams the application is prepared
	* to support. Must be non negative and no larger than {@code 65536}.
	* {@code 0} to use the endpoints default value.
	*
	* @return A new SCTP channel connected to the given address
	*
	* @throws java.nio.channels.AsynchronousCloseException
	* If another thread closes this channel
	* while the connect operation is in progress
	*
	* @throws java.nio.channels.ClosedByInterruptException
	* If another thread interrupts the current thread
	* while the connect operation is in progress, thereby
	* closing the channel and setting the current thread's
	* interrupt status
	*
	* @throws java.nio.channels.UnresolvedAddressException
	* If the given remote address is not fully resolved
	*
	* @throws java.nio.channels.UnsupportedAddressTypeException
	* If the type of the given remote address is not supported
	*
	* @throws SecurityException
	* If a security manager has been installed
	* and it does not permit access to the given remote peer
	*
	* @throws UnsupportedOperationException
	* If the SCTP protocol is not supported
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public static SctpChannel open(SocketAddress remote, int maxOutStreams,
	int maxInStreams) throws IOException {
	SctpChannel ssc = SctpChannel.open();
	ssc.connect(remote, maxOutStreams, maxInStreams);
	return ssc;
	}

	/**
	* Returns the association on this channel's socket.
	*
	* @return the association, or {@code null} if the channel's socket is not
	* connected.
	*
	* @throws ClosedChannelException
	* If the channel is closed
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract Association association() throws IOException;

	/**
	* Binds the channel's socket to a local address.
	*
	* <P> This method is used to establish a relationship between the socket
	* and the local addresses. Once a relationship is established then
	* the socket remains bound until the channel is closed. This relationship
	* may not necesssarily be with the address {@code local} as it may be removed
	* by {@link #unbindAddress unbindAddress}, but there will always be at least
	* one local address bound to the channel's socket once an invocation of
	* this method successfully completes.
	*
	* <P> Once the channel's socket has been successfully bound to a specific
	* address, that is not automatically assigned, more addresses
	* may be bound to it using {@link #bindAddress bindAddress}, or removed
	* using {@link #unbindAddress unbindAddress}.
	*
	* @param local
	* The local address to bind the socket, or {@code null} to
	* bind the socket to an automatically assigned socket address
	*
	* @return This channel
	*
	* @throws java.nio.channels.AlreadyConnectedException
	* If this channel is already connected
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.ConnectionPendingException
	* If a non-blocking connection operation is already in progress on this channel
	*
	* @throws java.nio.channels.AlreadyBoundException
	* If this channel is already bound
	*
	* @throws java.nio.channels.UnsupportedAddressTypeException
	* If the type of the given address is not supported
	*
	* @throws IOException
	* If some other I/O error occurs
	*
	* @throws SecurityException
	* If a security manager has been installed and its
	* {@link SecurityManager#checkListen checkListen} method denies
	* the operation
	*/
	public abstract SctpChannel bind(SocketAddress local)
	throws IOException;

	/**
	* Adds the given address to the bound addresses for the channel's
	* socket.
	*
	* <P> The given address must not be the {@link
	* java.net.InetAddress#isAnyLocalAddress wildcard} address.
	* The channel must be first bound using {@link #bind bind} before
	* invoking this method, otherwise {@link
	* java.nio.channels.NotYetBoundException} is thrown. The {@link #bind bind}
	* method takes a {@code SocketAddress} as its argument which typically
	* contains a port number as well as an address. Addresses subquently bound
	* using this method are simply addresses as the SCTP port number remains
	* the same for the lifetime of the channel.
	*
	* <P> Adding addresses to a connected association is optional functionality.
	* If the endpoint supports dynamic address reconfiguration then it may
	* send the appropriate message to the peer to change the peers address
	* lists.
	*
	* @param address
	* The address to add to the bound addresses for the socket
	*
	* @return This channel
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.ConnectionPendingException
	* If a non-blocking connection operation is already in progress on
	* this channel
	*
	* @throws java.nio.channels.NotYetBoundException
	* If this channel is not yet bound
	*
	* @throws java.nio.channels.AlreadyBoundException
	* If this channel is already bound to the given address
	*
	* @throws IllegalArgumentException
	* If address is {@code null} or the {@link
	* java.net.InetAddress#isAnyLocalAddress wildcard} address
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract SctpChannel bindAddress(InetAddress address)
	throws IOException;

	/**
	* Removes the given address from the bound addresses for the channel's
	* socket.
	*
	* <P> The given address must not be the {@link
	* java.net.InetAddress#isAnyLocalAddress wildcard} address.
	* The channel must be first bound using {@link #bind bind} before
	* invoking this method, otherwise {@link java.nio.channels.NotYetBoundException}
	* is thrown. If this method is invoked on a channel that does not have
	* {@code address} as one of its bound addresses or that has only one
	* local address bound to it, then this method throws
	* {@link IllegalUnbindException}.
	* The initial address that the channel's socket is bound to using {@link
	* #bind bind} may be removed from the bound addresses for the channel's socket.
	*
	* <P> Removing addresses from a connected association is optional
	* functionality. If the endpoint supports dynamic address reconfiguration
	* then it may send the appropriate message to the peer to change the peers
	* address lists.
	*
	* @param address
	* The address to remove from the bound addresses for the socket
	*
	* @return This channel
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.ConnectionPendingException
	* If a non-blocking connection operation is already in progress on
	* this channel
	*
	* @throws java.nio.channels.NotYetBoundException
	* If this channel is not yet bound
	*
	* @throws IllegalArgumentException
	* If address is {@code null} or the {@link
	* java.net.InetAddress#isAnyLocalAddress wildcard} address
	*
	* @throws IllegalUnbindException
	* If {@code address} is not bound to the channel's socket. or
	* the channel has only one address bound to it
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract SctpChannel unbindAddress(InetAddress address)
	throws IOException;

	/**
	* Connects this channel's socket.
	*
	* <P> If this channel is in non-blocking mode then an invocation of this
	* method initiates a non-blocking connection operation. If the connection
	* is established immediately, as can happen with a local connection, then
	* this method returns {@code true}. Otherwise this method returns
	* {@code false} and the connection operation must later be completed by
	* invoking the {@link #finishConnect finishConnect} method.
	*
	* <P> If this channel is in blocking mode then an invocation of this
	* method will block until the connection is established or an I/O error
	* occurs.
	*
	* <P> If a security manager has been installed then this method verifies
	* that its {@link java.lang.SecurityManager#checkConnect checkConnect}
	* method permits connecting to the address and port number of the given
	* remote peer.
	*
	* <p> This method may be invoked at any time. If a {@link #send send} or
	* {@link #receive receive} operation upon this channel is invoked while an
	* invocation of this method is in progress then that operation will first
	* block until this invocation is complete. If a connection attempt is
	* initiated but fails, that is, if an invocation of this method throws a
	* checked exception, then the channel will be closed.
	*
	* @param remote
	* The remote peer to which this channel is to be connected
	*
	* @return {@code true} if a connection was established, {@code false} if
	* this channel is in non-blocking mode and the connection
	* operation is in progress
	*
	* @throws java.nio.channels.AlreadyConnectedException
	* If this channel is already connected
	*
	* @throws java.nio.channels.ConnectionPendingException
	* If a non-blocking connection operation is already in progress on
	* this channel
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.AsynchronousCloseException
	* If another thread closes this channel
	* while the connect operation is in progress
	*
	* @throws java.nio.channels.ClosedByInterruptException
	* If another thread interrupts the current thread
	* while the connect operation is in progress, thereby
	* closing the channel and setting the current thread's
	* interrupt status
	*
	* @throws java.nio.channels.UnresolvedAddressException
	* If the given remote address is not fully resolved
	*
	* @throws java.nio.channels.UnsupportedAddressTypeException
	* If the type of the given remote address is not supported
	*
	* @throws SecurityException
	* If a security manager has been installed
	* and it does not permit access to the given remote peer
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract boolean connect(SocketAddress remote) throws IOException;

	/**
	* Connects this channel's socket.
	*
	* <P> This is a convience method and is equivalent to evaluating the
	* following expression:
	* <blockquote><pre>
	* setOption(SctpStandardSocketOptions.SCTP_INIT_MAXSTREAMS, SctpStandardSocketOption.InitMaxStreams.create(maxInStreams, maxOutStreams))
	* .connect(remote);
	* </pre></blockquote>
	*
	* <P> The {@code maxOutStreams} and {@code maxInStreams} parameters
	* represent the maximum number of streams that the application wishes to be
	* able to send to and receive from. They are negotiated with the remote
	* peer and may be limited by the operating system.
	*
	* @param remote
	* The remote peer to which this channel is to be connected
	*
	* @param maxOutStreams
	* Must be non negative and no larger than {@code 65536}.
	* {@code 0} to use the endpoints default value.
	*
	* @param maxInStreams
	* Must be non negative and no larger than {@code 65536}.
	* {@code 0} to use the endpoints default value.
	*
	* @return {@code true} if a connection was established, {@code false} if
	* this channel is in non-blocking mode and the connection operation
	* is in progress
	*
	* @throws java.nio.channels.AlreadyConnectedException
	* If this channel is already connected
	*
	* @throws java.nio.channels.ConnectionPendingException
	* If a non-blocking connection operation is already in progress on
	* this channel
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.AsynchronousCloseException
	* If another thread closes this channel
	* while the connect operation is in progress
	*
	* @throws java.nio.channels.ClosedByInterruptException
	* If another thread interrupts the current thread
	* while the connect operation is in progress, thereby
	* closing the channel and setting the current thread's
	* interrupt status
	*
	* @throws java.nio.channels.UnresolvedAddressException
	* If the given remote address is not fully resolved
	*
	* @throws java.nio.channels.UnsupportedAddressTypeException
	* If the type of the given remote address is not supported
	*
	* @throws SecurityException
	* If a security manager has been installed
	* and it does not permit access to the given remote peer
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract boolean connect(SocketAddress remote,
	int maxOutStreams,
	int maxInStreams)
	throws IOException;

	/**
	* Tells whether or not a connection operation is in progress on this channel.
	*
	* @return {@code true} if, and only if, a connection operation has been initiated
	* on this channel but not yet completed by invoking the
	* {@link #finishConnect} method
	*/
	public abstract boolean isConnectionPending();

	/**
	* Finishes the process of connecting an SCTP channel.
	*
	* <P> A non-blocking connection operation is initiated by placing a socket
	* channel in non-blocking mode and then invoking one of its {@link #connect
	* connect} methods. Once the connection is established, or the attempt has
	* failed, the channel will become connectable and this method may
	* be invoked to complete the connection sequence. If the connection
	* operation failed then invoking this method will cause an appropriate
	* {@link java.io.IOException} to be thrown.
	*
	* <P> If this channel is already connected then this method will not block
	* and will immediately return <tt>true</tt>. If this channel is in
	* non-blocking mode then this method will return <tt>false</tt> if the
	* connection process is not yet complete. If this channel is in blocking
	* mode then this method will block until the connection either completes
	* or fails, and will always either return <tt>true</tt> or throw a checked
	* exception describing the failure.
	*
	* <P> This method may be invoked at any time. If a {@link #send send} or {@link #receive receive}
	* operation upon this channel is invoked while an invocation of this
	* method is in progress then that operation will first block until this
	* invocation is complete. If a connection attempt fails, that is, if an
	* invocation of this method throws a checked exception, then the channel
	* will be closed.
	*
	* @return {@code true} if, and only if, this channel's socket is now
	* connected
	*
	* @throws java.nio.channels.NoConnectionPendingException
	* If this channel is not connected and a connection operation
	* has not been initiated
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.AsynchronousCloseException
	* If another thread closes this channel
	* while the connect operation is in progress
	*
	* @throws java.nio.channels.ClosedByInterruptException
	* If another thread interrupts the current thread
	* while the connect operation is in progress, thereby
	* closing the channel and setting the current thread's
	* interrupt status
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract boolean finishConnect() throws IOException;

	/**
	* Returns all of the socket addresses to which this channel's socket is
	* bound.
	*
	* @return All the socket addresses that this channel's socket is
	* bound to, or an empty {@code Set} if the channel's socket is not
	* bound
	*
	* @throws ClosedChannelException
	* If the channel is closed
	*
	* @throws IOException
	* If an I/O error occurs
	*/
	public abstract Set<SocketAddress> getAllLocalAddresses()
	throws IOException;

	/**
	* Returns all of the remote addresses to which this channel's socket
	* is connected.
	*
	* <P> If the channel is connected to a remote peer that is bound to
	* multiple addresses then it is these addresses that the channel's socket
	* is connected.
	*
	* @return All of the remote addresses to which this channel's socket
	* is connected, or an empty {@code Set} if the channel's socket is
	* not connected
	*
	* @throws ClosedChannelException
	* If the channel is closed
	*
	* @throws IOException
	* If an I/O error occurs
	*/
	public abstract Set<SocketAddress> getRemoteAddresses()
	throws IOException;

	/**
	* Shutdown a connection without closing the channel.
	*
	* <P> Sends a shutdown command to the remote peer, effectively preventing
	* any new data from being written to the socket by either peer. Further
	* sends will throw {@link java.nio.channels.ClosedChannelException}. The
	* channel remains open to allow the for any data (and notifications) to be
	* received that may have been sent by the peer before it received the
	* shutdown command. If the channel is already shutdown then invoking this
	* method has no effect.
	*
	* @return This channel
	*
	* @throws java.nio.channels.NotYetConnectedException
	* If this channel is not yet connected
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract SctpChannel shutdown() throws IOException;

	/**
	* Returns the value of a socket option.
	*
	* @param <T>
	* The type of the socket option value
	*
	* @param name
	* The socket option
	*
	* @return The value of the socket option. A value of {@code null} may be
	* a valid value for some socket options.
	*
	* @throws UnsupportedOperationException
	* If the socket option is not supported by this channel
	*
	* @throws ClosedChannelException
	* If this channel is closed
	*
	* @throws IOException
	* If an I/O error occurs
	*
	* @see SctpStandardSocketOptions
	*/
	public abstract <T> T getOption(SctpSocketOption<T> name)
	throws IOException;

	/**
	* Sets the value of a socket option.
	*
	* @param <T>
	* The type of the socket option value
	*
	* @param name
	* The socket option
	*
	* @param value
	* The value of the socket option. A value of {@code null} may be
	* a valid value for some socket options.
	*
	* @return This channel
	*
	* @throws UnsupportedOperationException
	* If the socket option is not supported by this channel
	*
	* @throws IllegalArgumentException
	* If the value is not a valid value for this socket option
	*
	* @throws ClosedChannelException
	* If this channel is closed
	*
	* @throws IOException
	* If an I/O error occurs
	*
	* @see SctpStandardSocketOptions
	*/
	public abstract <T> SctpChannel setOption(SctpSocketOption<T> name, T value)
	throws IOException;

	/**
	* Returns a set of the socket options supported by this channel.
	*
	* <P> This method will continue to return the set of options even after the
	* channel has been closed.
	*
	* @return A set of the socket options supported by this channel
	*/
	public abstract Set<SctpSocketOption<?>> supportedOptions();

	/**
	* Returns an operation set identifying this channel's supported operations.
	*
	* <P> SCTP channels support connecting, reading, and writing, so this
	* method returns <tt>(</tt>{@link SelectionKey#OP_CONNECT}
	* <tt>\|</tt> {@link SelectionKey#OP_READ} <tt>\|</tt> {@link
	* SelectionKey#OP_WRITE}<tt>)</tt>. </p>
	*
	* @return The valid-operation set
	*/
	@Override
	public final int validOps() {
	return (SelectionKey.OP_READ \|
	SelectionKey.OP_WRITE \|
	SelectionKey.OP_CONNECT);
	}

	/**
	* Receives a message into the given buffer and/or handles a notification.
	*
	* <P> If a message or notification is immediately available, or if this
	* channel is in blocking mode and one eventually becomes available, then
	* the message or notification is returned or handled, respectively. If this
	* channel is in non-blocking mode and a message or notification is not
	* immediately available then this method immediately returns {@code null}.
	*
	* <P> If this method receives a message it is copied into the given byte
	* buffer. The message is transferred into the given byte buffer starting at
	* its current position and the buffers position is incremented by the
	* number of bytes read. If there are fewer bytes remaining in the buffer
	* than are required to hold the message, or the underlying input buffer
	* does not contain the complete message, then an invocation of {@link
	* MessageInfo#isComplete isComplete} on the returned {@code
	* MessageInfo} will return {@code false}, and more invocations of this
	* method will be necessary to completely consume the messgae. Only
	* one message at a time will be partially delivered in any stream. The
	* socket option {@link SctpStandardSocketOptions#SCTP_FRAGMENT_INTERLEAVE
	* SCTP_FRAGMENT_INTERLEAVE} controls various aspects of what interlacing of
	* messages occurs.
	*
	* <P> If this method receives a notification then the appropriate method of
	* the given handler, if there is one, is invoked. If the handler returns
	* {@link HandlerResult#CONTINUE CONTINUE} then this method will try to
	* receive another message/notification, otherwise, if {@link
	* HandlerResult#RETURN RETURN} is returned this method will return {@code
	* null}. If an uncaught exception is thrown by the handler it will be
	* propagated up the stack through this method.
	*
	* <P> This method may be invoked at any time. If another thread has
	* already initiated a receive operation upon this channel, then an
	* invocation of this method will block until the first operation is
	* complete. The given handler is invoked without holding any locks used
	* to enforce the above synchronization policy, that way handlers
	* will not stall other threads from receiving. A handler should not invoke
	* the {@code receive} method of this channel, if it does an
	* {@link IllegalReceiveException} will be thrown.
	*
	* @param <T>
	* The type of the attachment
	*
	* @param dst
	* The buffer into which message bytes are to be transferred
	*
	* @param attachment
	* The object to attach to the receive operation; can be
	* {@code null}
	*
	* @param handler
	* A handler to handle notifications from the SCTP stack, or {@code
	* null} to ignore any notifications.
	*
	* @return The {@code MessageInfo}, {@code null} if this channel is in
	* non-blocking mode and no messages are immediately available or
	* the notification handler returns {@link HandlerResult#RETURN
	* RETURN} after handling a notification
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.AsynchronousCloseException
	* If another thread closes this channel
	* while the read operation is in progress
	*
	* @throws java.nio.channels.ClosedByInterruptException
	* If another thread interrupts the current thread
	* while the read operation is in progress, thereby
	* closing the channel and setting the current thread's
	* interrupt status
	*
	* @throws java.nio.channels.NotYetConnectedException
	* If this channel is not yet connected
	*
	* @throws IllegalReceiveException
	* If the given handler invokes the {@code receive} method of this
	* channel
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract <T> MessageInfo receive(ByteBuffer dst,
	T attachment,
	NotificationHandler<T> handler)
	throws IOException;

	/**
	* Sends a message via this channel.
	*
	* <P> If this channel is in non-blocking mode and there is sufficient room
	* in the underlying output buffer, or if this channel is in blocking mode
	* and sufficient room becomes available, then the remaining bytes in the
	* given byte buffer are transmitted as a single message. Sending a message
	* is atomic unless explicit message completion {@link
	* SctpStandardSocketOptions#SCTP_EXPLICIT_COMPLETE SCTP_EXPLICIT_COMPLETE}
	* socket option is enabled on this channel's socket.
	*
	* <P> The message is transferred from the byte buffer as if by a regular
	* {@link java.nio.channels.WritableByteChannel#write(java.nio.ByteBuffer)
	* write} operation.
	*
	* <P> The bytes will be written to the stream number that is specified by
	* {@link MessageInfo#streamNumber streamNumber} in the given {@code
	* messageInfo}.
	*
	* <P> This method may be invoked at any time. If another thread has already
	* initiated a send operation upon this channel, then an invocation of
	* this method will block until the first operation is complete.
	*
	* @param src
	* The buffer containing the message to be sent
	*
	* @param messageInfo
	* Ancillary data about the message to be sent
	*
	* @return The number of bytes sent, which will be either the number of
	* bytes that were remaining in the messages buffer when this method
	* was invoked or, if this channel is non-blocking, may be zero if
	* there was insufficient room for the message in the underlying
	* output buffer
	*
	* @throws InvalidStreamException
	* If {@code streamNumner} is negative or greater than or equal to
	* the maximum number of outgoing streams
	*
	* @throws java.nio.channels.ClosedChannelException
	* If this channel is closed
	*
	* @throws java.nio.channels.AsynchronousCloseException
	* If another thread closes this channel
	* while the read operation is in progress
	*
	* @throws java.nio.channels.ClosedByInterruptException
	* If another thread interrupts the current thread
	* while the read operation is in progress, thereby
	* closing the channel and setting the current thread's
	* interrupt status
	*
	* @throws java.nio.channels.NotYetConnectedException
	* If this channel is not yet connected
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract int send(ByteBuffer src, MessageInfo messageInfo)
	throws IOException;
	}

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