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	/*
	* Copyright (c) 2007, 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 java.nio.channels;

	import java.nio.ByteBuffer;
	import java.util.concurrent.Future;

	/**
	* An asynchronous channel that can read and write bytes.
	*
	* <p> Some channels may not allow more than one read or write to be outstanding
	* at any given time. If a thread invokes a read method before a previous read
	* operation has completed then a {@link ReadPendingException} will be thrown.
	* Similarly, if a write method is invoked before a previous write has completed
	* then {@link WritePendingException} is thrown. Whether or not other kinds of
	* I/O operations may proceed concurrently with a read operation depends upon
	* the type of the channel.
	*
	* <p> Note that {@link java.nio.ByteBuffer ByteBuffers} are not safe for use by
	* multiple concurrent threads. When a read or write operation is initiated then
	* care must be taken to ensure that the buffer is not accessed until the
	* operation completes.
	*
	* @see Channels#newInputStream(AsynchronousByteChannel)
	* @see Channels#newOutputStream(AsynchronousByteChannel)
	*
	* @since 1.7
	*/

	public interface AsynchronousByteChannel
	extends AsynchronousChannel
	{
	/**
	* Reads a sequence of bytes from this channel into the given buffer.
	*
	* <p> This method initiates an asynchronous read operation to read a
	* sequence of bytes from this channel into the given buffer. The {@code
	* handler} parameter is a completion handler that is invoked when the read
	* operation completes (or fails). The result passed to the completion
	* handler is the number of bytes read or {@code -1} if no bytes could be
	* read because the channel has reached end-of-stream.
	*
	* <p> The read operation may read up to <i>r</i> bytes from the channel,
	* where <i>r</i> is the number of bytes remaining in the buffer, that is,
	* {@code dst.remaining()} at the time that the read is attempted. Where
	* <i>r</i> is 0, the read operation completes immediately with a result of
	* {@code 0} without initiating an I/O operation.
	*
	* <p> Suppose that a byte sequence of length <i>n</i> is read, where
	* <tt>0</tt> <tt><</tt> <i>n</i> <tt><=</tt> <i>r</i>.
	* This byte sequence will be transferred into the buffer so that the first
	* byte in the sequence is at index <i>p</i> and the last byte is at index
	* <i>p</i> <tt>+</tt> <i>n</i> <tt>-</tt> <tt>1</tt>,
	* where <i>p</i> is the buffer's position at the moment the read is
	* performed. Upon completion the buffer's position will be equal to
	* <i>p</i> <tt>+</tt> <i>n</i>; its limit will not have changed.
	*
	* <p> Buffers are not safe for use by multiple concurrent threads so care
	* should be taken to not access the buffer until the operation has
	* completed.
	*
	* <p> This method may be invoked at any time. Some channel types may not
	* allow more than one read to be outstanding at any given time. If a thread
	* initiates a read operation before a previous read operation has
	* completed then a {@link ReadPendingException} will be thrown.
	*
	* @param <A>
	* The type of the attachment
	* @param dst
	* The buffer into which bytes are to be transferred
	* @param attachment
	* The object to attach to the I/O operation; can be {@code null}
	* @param handler
	* The completion handler
	*
	* @throws IllegalArgumentException
	* If the buffer is read-only
	* @throws ReadPendingException
	* If the channel does not allow more than one read to be outstanding
	* and a previous read has not completed
	* @throws ShutdownChannelGroupException
	* If the channel is associated with a {@link AsynchronousChannelGroup
	* group} that has terminated
	*/
	<A> void read(ByteBuffer dst,
	A attachment,
	CompletionHandler<Integer,? super A> handler);

	/**
	* Reads a sequence of bytes from this channel into the given buffer.
	*
	* <p> This method initiates an asynchronous read operation to read a
	* sequence of bytes from this channel into the given buffer. The method
	* behaves in exactly the same manner as the {@link
	* #read(ByteBuffer,Object,CompletionHandler)
	* read(ByteBuffer,Object,CompletionHandler)} method except that instead
	* of specifying a completion handler, this method returns a {@code Future}
	* representing the pending result. The {@code Future}'s {@link Future#get()
	* get} method returns the number of bytes read or {@code -1} if no bytes
	* could be read because the channel has reached end-of-stream.
	*
	* @param dst
	* The buffer into which bytes are to be transferred
	*
	* @return A Future representing the result of the operation
	*
	* @throws IllegalArgumentException
	* If the buffer is read-only
	* @throws ReadPendingException
	* If the channel does not allow more than one read to be outstanding
	* and a previous read has not completed
	*/
	Future<Integer> read(ByteBuffer dst);

	/**
	* Writes a sequence of bytes to this channel from the given buffer.
	*
	* <p> This method initiates an asynchronous write operation to write a
	* sequence of bytes to this channel from the given buffer. The {@code
	* handler} parameter is a completion handler that is invoked when the write
	* operation completes (or fails). The result passed to the completion
	* handler is the number of bytes written.
	*
	* <p> The write operation may write up to <i>r</i> bytes to the channel,
	* where <i>r</i> is the number of bytes remaining in the buffer, that is,
	* {@code src.remaining()} at the time that the write is attempted. Where
	* <i>r</i> is 0, the write operation completes immediately with a result of
	* {@code 0} without initiating an I/O operation.
	*
	* <p> Suppose that a byte sequence of length <i>n</i> is written, where
	* <tt>0</tt> <tt><</tt> <i>n</i> <tt><=</tt> <i>r</i>.
	* This byte sequence will be transferred from the buffer starting at index
	* <i>p</i>, where <i>p</i> is the buffer's position at the moment the
	* write is performed; the index of the last byte written will be
	* <i>p</i> <tt>+</tt> <i>n</i> <tt>-</tt> <tt>1</tt>.
	* Upon completion the buffer's position will be equal to
	* <i>p</i> <tt>+</tt> <i>n</i>; its limit will not have changed.
	*
	* <p> Buffers are not safe for use by multiple concurrent threads so care
	* should be taken to not access the buffer until the operation has
	* completed.
	*
	* <p> This method may be invoked at any time. Some channel types may not
	* allow more than one write to be outstanding at any given time. If a thread
	* initiates a write operation before a previous write operation has
	* completed then a {@link WritePendingException} will be thrown.
	*
	* @param <A>
	* The type of the attachment
	* @param src
	* The buffer from which bytes are to be retrieved
	* @param attachment
	* The object to attach to the I/O operation; can be {@code null}
	* @param handler
	* The completion handler object
	*
	* @throws WritePendingException
	* If the channel does not allow more than one write to be outstanding
	* and a previous write has not completed
	* @throws ShutdownChannelGroupException
	* If the channel is associated with a {@link AsynchronousChannelGroup
	* group} that has terminated
	*/
	<A> void write(ByteBuffer src,
	A attachment,
	CompletionHandler<Integer,? super A> handler);

	/**
	* Writes a sequence of bytes to this channel from the given buffer.
	*
	* <p> This method initiates an asynchronous write operation to write a
	* sequence of bytes to this channel from the given buffer. The method
	* behaves in exactly the same manner as the {@link
	* #write(ByteBuffer,Object,CompletionHandler)
	* write(ByteBuffer,Object,CompletionHandler)} method except that instead
	* of specifying a completion handler, this method returns a {@code Future}
	* representing the pending result. The {@code Future}'s {@link Future#get()
	* get} method returns the number of bytes written.
	*
	* @param src
	* The buffer from which bytes are to be retrieved
	*
	* @return A Future representing the result of the operation
	*
	* @throws WritePendingException
	* If the channel does not allow more than one write to be outstanding
	* and a previous write has not completed
	*/
	Future<Integer> write(ByteBuffer src);
	}

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