1 /*

     2  * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

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

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 /**

    26  *  Summary

    27  *  -------

    28  *

    29  *  Define a lightweight network protocol for discovering running and

    30  *  manageable Java processes within a network subnet.

    31  *

    32  *

    33  * Description

    34  * -----------

    35  *

    36  * The protocol is lightweight multicast based, and works like a beacon,

    37  * broadcasting the JMXService URL needed to connect to the external JMX

    38  * agent if an application is started with appropriate parameters.

    39  *

    40  * The payload is structured like this:

    41  *

    42  *  4 bytes JDP magic (0xC0FFEE42)

    43  *  2 bytes JDP protocol version (1)

    44  *  2 bytes size of the next entry

    45  *      x bytes next entry (UTF-8 encoded)

    46  *  2 bytes size of next entry

    47  *    ...   Rinse and repeat...

    48  *

    49  * The payload will be parsed as even entries being keys, odd entries being

    50  * values.

    51  *

    52  * The standard JDP packet contains four entries:

    53  *

    54  * - `DISCOVERABLE_SESSION_UUID` -- Unique id of the instance; this id changes every time

    55  *    the discovery protocol starts and stops

    56  *

    57  * - `MAIN_CLASS` -- The value of the `sun.java.command` property

    58  *

    59  * - `JMX_SERVICE_URL` -- The URL to connect to the JMX agent

    60  *

    61  * - `INSTANCE_NAME` -- The user-provided name of the running instance

    62  *

    63  * The protocol sends packets to 224.0.23.178:7095 by default.

    64  *

    65  * The protocol uses system properties to control it's behaviour:

    66  * - `com.sun.management.jdp.port` -- override default port

    67  *

    68  * - `com.sun.management.jdp.address` -- override default address

    69  *

    70  * - `com.sun.management.jmxremote.autodiscovery` -- whether we should start autodiscovery or

    71  * not. Autodiscovery starts if and only if following conditions are met: (autodiscovery is

    72  * true OR (autodiscovery is not set AND jdp.port is set))

    73  *

    74  * - `com.sun.management.jdp.ttl`         -- set ttl for broadcast packet, default is 1

    75  * - `com.sun.management.jdp.pause`       -- set broadcast interval in seconds default is 5

    76  * - `com.sun.management.jdp.source_addr` -- an address of interface to use for broadcast

    77  */

    78 

    79 package sun.management.jdp;