NAME

       zephyr - Zephyr Notification Service

DESCRIPTION

       Zephyr is a notice transport and delivery system developed at MIT which runs under 4.3BSD Unix.

       A  Notice  Transport  and  Delivery  system  is  a  method  of getting small quantities of time sensitive
       information efficiently from one client (or server) on a network to another.  The object is to accomplish
       this with the highest possible fan-out (i.e., client to server ratio) while maintaining both network  and
       server  performance.   Zephyr  is  a  multi-cast  notice  transport  and  delivery  system  based upon an
       authenticated datagram protocol.  Localized Zephyr servers  provide  routing,  queueing  and  dispatching
       services  to  clients  which  communicate  with  them via the Zephyr Client Library.  Two special purpose
       Zephyr clients,  the  WindowGram  client  and  the  HostManager  client  provide  user  and  client  host
       communication support.

       Zephyrd(8) servers run on designated server machines.  These servers maintain a database of subscriptions
       and  locations  for every user using Zephyr.  The servers stay in contact with one another, and provide a
       reliable backup system (via duplication) in the event of network failures.

       Each client machine on the network runs a zhm(8) HostManager client program which is the link between the
       Zephyr servers and the users.  User programs  send  notices  to  the  HostManager,  and  the  HostManager
       forwards  these  notices  to  the nearest server for action.  The HostManager is responsible for ensuring
       that the notices reach a server, and for finding a new one if its server fails to respond.

       Each user on the network usually runs a WindowGram client  program  automatically  upon  login.   Zwgc(1)
       displays  notices to the user, and handles user responses.  Only notices to which the user has subscribed
       will be sent to the WindowGram client.

       Subscriptions are handled through the zctl(1) program.  This program allows the user  to  add  or  delete
       subscriptions  from  Zephyr,  to  add  the  subscriptions  to  a file, and to perform other miscellaneous
       functions.

SEE ALSO

       kerberosintro(1)
       zaway(1), zctl(1), zleave(1), zlocate(1), znol(1), zwgc(1), zwrite(1), zmailnotify(1)
       zhm(8), zephyrd(8), zinit(8), zstat(8),  zpopnotify(8), zshutdown_notify(8), syslogd(8)
       Project Athena Technical Plan Section E.4.1, `Zephyr Notification Service'

AUTHORS

       Tony Della Fera (MIT-Project Athena, DEC), Mark W. Eichin (MIT-Project Athena), Robert  S.  French  (MIT-
       Project Athena), David C. Jedlinsky (MIT-Project Athena), John T. Kohl (MIT-Project Athena, DEC), William
       E. Sommerfeld (MIT-Project Athena).

RESTRICTIONS

       Copyright (c) 1987,1988,1989 by the Massachusetts Institute of Technology.  All Rights Reserved.
       Permission  to  use, copy, modify, and distribute this software and its documentation for any purpose and
       without fee is hereby granted, provided that the above copyright notice appear in  all  copies  and  that
       both  that  copyright  notice and this permission notice appear in supporting documentation, and that the
       name of the Massachusetts Institute of Technology not be used in advertising or publicity  pertaining  to
       distribution of the software without specific, written prior permission.
       M.I.T.  DISCLAIMS  ALL  WARRANTIES  WITH  REGARD  TO  THIS  SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
       MERCHANTABILITY AND  FITNESS,  IN  NO  EVENT  SHALL  M.I.T.  BE  LIABLE  FOR  ANY  SPECIAL,  INDIRECT  OR
       CONSEQUENTIAL  DAMAGES  OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
       AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE  USE
       OR PERFORMANCE OF THIS SOFTWARE.

MIT Project Athena                                July 1, 1988                                         ZEPHYR(1)