/*

 * Copyright 2000-2003 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.nio.channels;

import java.io.IOException;

import java.io.Closeable;

/**

 * A nexus for I/O operations.

 *

 * <p> A channel represents an open connection to an entity such as a hardware

 * device, a file, a network socket, or a program component that is capable of

 * performing one or more distinct I/O operations, for example reading or

 * writing.

 *

 * <p> A channel is either open or closed.  A channel is open upon creation,

 * and once closed it remains closed.  Once a channel is closed, any attempt to

 * invoke an I/O operation upon it will cause a {@link ClosedChannelException}

 * to be thrown.  Whether or not a channel is open may be tested by invoking

 * its {@link #isOpen isOpen} method.

 *

 * <p> Channels are, in general, intended to be safe for multithreaded access

 * as described in the specifications of the interfaces and classes that extend

 * and implement this interface.

 *

 *

 * @author Mark Reinhold

 * @author JSR-51 Expert Group

 * @since 1.4

 */

public interface Channel extends Closeable {

    /**

     * Tells whether or not this channel is open.  </p>

     *

     * @return <tt>true</tt> if, and only if, this channel is open

     */

    public boolean isOpen();

    /**

     * Closes this channel.

     *

     * <p> After a channel is closed, any further attempt to invoke I/O

     * operations upon it will cause a {@link ClosedChannelException} to be

     * thrown.

     *

     * <p> If this channel is already closed then invoking this method has no

     * effect.

     *

     * <p> This method may be invoked at any time.  If some other thread has

     * already invoked it, however, then another invocation will block until

     * the first invocation is complete, after which it will return without

     * effect. </p>

     *

     * @throws  IOException  If an I/O error occurs

     */

    public void close() throws IOException;

}