A Message Bus for Local Coordination
RFC 3259

Network Working Group                                             J. Ott
Request for Comments: 3259                      TZI, Universitaet Bremen
Category: Informational                                       C. Perkins
                                      USC Information Sciences Institute
                                                             D. Kutscher
                                                TZI, Universitaet Bremen
                                                              April 2002

                  A Message Bus for Local Coordination

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   The local Message Bus (Mbus) is a light-weight message-oriented
   coordination protocol for group communication between application
   components.  The Mbus provides automatic location of communication
   peers, subject based addressing, reliable message transfer and
   different types of communication schemes.  The protocol is layered on
   top of IP multicast and is specified for IPv4 and IPv6.  The IP
   multicast scope is limited to link-local multicast.  This document
   specifies the Mbus protocol, i.e., message syntax, addressing and
   transport mechanisms.

Table of Contents

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1   Mbus Overview  . . . . . . . . . . . . . . . . . . . . . . .  3
   1.2   Purpose of this Document . . . . . . . . . . . . . . . . . .  5
   1.3   Areas of Application . . . . . . . . . . . . . . . . . . . .  5
   1.4   Terminology for requirement specifications . . . . . . . . .  6
   2.    Common Formal Syntax Rules . . . . . . . . . . . . . . . . .  6
   3.    Message Format . . . . . . . . . . . . . . . . . . . . . . .  7
   4.    Addressing . . . . . . . . . . . . . . . . . . . . . . . . .  9
   4.1   Mandatory Address Elements . . . . . . . . . . . . . . . . . 10
   5.    Message Syntax . . . . . . . . . . . . . . . . . . . . . . . 11
   5.1   Message Encoding . . . . . . . . . . . . . . . . . . . . . . 11
   5.2   Message Header . . . . . . . . . . . . . . . . . . . . . . . 11
   5.3   Command Syntax . . . . . . . . . . . . . . . . . . . . . . . 12

Ott, et. al.                 Informational                      [Page 1]
RFC 3259          A Message Bus for Local Coordination        April 2002

   6.    Transport  . . . . . . . . . . . . . . . . . . . . . . . . . 13
   6.1   Local Multicast/Broadcast  . . . . . . . . . . . . . . . . . 14
   6.1.1 Mbus multicast groups for IPv4 . . . . . . . . . . . . . . . 15
   6.1.2 Mbus multicast groups for IPv6 . . . . . . . . . . . . . . . 15
   6.1.3 Use of Broadcast . . . . . . . . . . . . . . . . . . . . . . 16
   6.1.4 Mbus UDP Port Number . . . . . . . . . . . . . . . . . . . . 16
   6.2   Directed Unicast . . . . . . . . . . . . . . . . . . . . . . 16
   7.    Reliability  . . . . . . . . . . . . . . . . . . . . . . . . 18
   8.    Awareness of other Entities  . . . . . . . . . . . . . . . . 20
   8.1   Hello Message Transmission Interval  . . . . . . . . . . . . 21
   8.1.1 Calculating the Interval for Hello Messages  . . . . . . . . 22
   8.1.2 Initialization of Values . . . . . . . . . . . . . . . . . . 23
   8.1.3 Adjusting the Hello Message Interval when the Number of
         Entities increases . . . . . . . . . . . . . . . . . . . . . 23
   8.1.4 Adjusting the Hello Message Interval when the Number of
         Entities decreases . . . . . . . . . . . . . . . . . . . . . 23
   8.1.5 Expiration of hello timers . . . . . . . . . . . . . . . . . 23
   8.2   Calculating the Timeout for Mbus Entities  . . . . . . . . . 24
   9.    Messages . . . . . . . . . . . . . . . . . . . . . . . . . . 24
   9.1   mbus.hello . . . . . . . . . . . . . . . . . . . . . . . . . 24
   9.2   mbus.bye . . . . . . . . . . . . . . . . . . . . . . . . . . 25
   9.3   mbus.ping  . . . . . . . . . . . . . . . . . . . . . . . . . 25
   9.4   mbus.quit  . . . . . . . . . . . . . . . . . . . . . . . . . 26
   9.5   mbus.waiting . . . . . . . . . . . . . . . . . . . . . . . . 26
   9.6   mbus.go  . . . . . . . . . . . . . . . . . . . . . . . . . . 27
   10.   Constants  . . . . . . . . . . . . . . . . . . . . . . . . . 27
   11.   Mbus Security  . . . . . . . . . . . . . . . . . . . . . . . 28
   11.1  Security Model . . . . . . . . . . . . . . . . . . . . . . . 28
   11.2  Encryption . . . . . . . . . . . . . . . . . . . . . . . . . 28
   11.3  Message Authentication . . . . . . . . . . . . . . . . . . . 29
   11.4  Procedures for Senders and Receivers . . . . . . . . . . . . 30
   12.   Mbus Configuration . . . . . . . . . . . . . . . . . . . . . 31