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.