/*

 * Copyright 1995-2007 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.lang;

import java.io.*;

/**

 * The {@link ProcessBuilder#start()} and

 * {@link Runtime#exec(String[],String[],File) Runtime.exec}

 * methods create a native process and return an instance of a

 * subclass of {@code Process} that can be used to control the process

 * and obtain information about it.  The class {@code Process}

 * provides methods for performing input from the process, performing

 * output to the process, waiting for the process to complete,

 * checking the exit status of the process, and destroying (killing)

 * the process.

 *

 * <p>The methods that create processes may not work well for special

 * processes on certain native platforms, such as native windowing

 * processes, daemon processes, Win16/DOS processes on Microsoft

 * Windows, or shell scripts.  The created subprocess does not have

 * its own terminal or console.  All its standard I/O (i.e. stdin,

 * stdout, stderr) operations will be redirected to the parent process

 * through three streams

 * ({@link #getOutputStream()},

 * {@link #getInputStream()},

 * {@link #getErrorStream()}).

 * The parent process uses these streams to feed input to and get output

 * from the subprocess.  Because some native platforms only provide

 * limited buffer size for standard input and output streams, failure

 * to promptly write the input stream or read the output stream of

 * the subprocess may cause the subprocess to block, and even deadlock.

 *

 * <p>The subprocess is not killed when there are no more references to

 * the {@code Process} object, but rather the subprocess

 * continues executing asynchronously.

 *

 * <p>There is no requirement that a process represented by a {@code

 * Process} object execute asynchronously or concurrently with respect

 * to the Java process that owns the {@code Process} object.

 *

 * @author  unascribed

 * @see     ProcessBuilder

 * @since   JDK1.0

 */

public abstract class Process {

    /**

     * Returns the output stream connected to the normal input of the

     * subprocess.  Output to the stream is piped into the standard

     * input stream of the process represented by this {@code Process}

     * object.

     *

     * <p>Implementation note: It is a good idea for the returned

     * output stream to be buffered.

     *

     * @return the output stream connected to the normal input of the

     *         subprocess

     */

    abstract public OutputStream getOutputStream();

    /**

     * Returns the input stream connected to the normal output of the

     * subprocess.  The stream obtains data piped from the standard

     * output stream of the process represented by this {@code

     * Process} object.

     *

     * <p>Implementation note: It is a good idea for the returned

     * input stream to be buffered.

     *

     * @return the input stream connected to the normal output of the

     *         subprocess

     * @see ProcessBuilder#redirectErrorStream()

     */

    abstract public InputStream getInputStream();

    /**

     * Returns the input stream connected to the error output stream of

     * the subprocess.  The stream obtains data piped from the error

     * output stream of the process represented by this {@code Process}

     * object.

     *

     * <p>Implementation note: It is a good idea for the returned

     * input stream to be buffered.

     *

     * @return the input stream connected to the error output stream of

     *         the subprocess

     * @see ProcessBuilder#redirectErrorStream()

     */

    abstract public InputStream getErrorStream();

    /**

     * Causes the current thread to wait, if necessary, until the

     * process represented by this {@code Process} object has

     * terminated.  This method returns immediately if the subprocess

     * has already terminated.  If the subprocess has not yet

     * terminated, the calling thread will be blocked until the

     * subprocess exits.

     *

     * @return the exit value of the subprocess represented by this

     *         {@code Process} object.  By convention, the value

     *         {@code 0} indicates normal termination.

     * @throws InterruptedException if the current thread is

     *         {@linkplain Thread#interrupt() interrupted} by another

     *         thread while it is waiting, then the wait is ended and

     *         an {@link InterruptedException} is thrown.

     */

    abstract public int waitFor() throws InterruptedException;

    /**

     * Returns the exit value for the subprocess.

     *

     * @return the exit value of the subprocess represented by this

     *         {@code Process} object.  By convention, the value

     *         {@code 0} indicates normal termination.

     * @throws IllegalThreadStateException if the subprocess represented

     *         by this {@code Process} object has not yet terminated

     */

    abstract public int exitValue();

    /**

     * Kills the subprocess. The subprocess represented by this

     * {@code Process} object is forcibly terminated.

     */

    abstract public void destroy();

}