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NOTIFY(3PVM)			 PVM Version 3.4		    NOTIFY(3PVM)

NAME
     pvm_notify - Request notification of PVM event such as host failure.

SYNOPSIS
     C	  int info = pvm_notify( int what, int msgtag, int cnt, int *tids )

     Fortran   call pvmfnotify( what, msgtag, cnt, tids, info )

PARAMETERS
     what    Type of event to trigger the notification.  Presently one of:
		  Value 	      Meaning
		  PvmTaskExit	      Task exits or is killed
		  PvmHostDelete       Host is deleted or crashes
		  PvmHostAdd	      New host is added

     msgtag  Message tag to be used in notification.

     cnt     For PvmTaskExit and PvmHostDelete, specifies the length of the tids
	     array.  For PvmHostAdd, specifies the number of times to notify.

     tids    For  PvmTaskExit  and PvmHostDelete, an array of length cnt of task
	     or pvmd TIDs to be notified about.  The array is not used with  the
	     PvmHostAdd option.

     info    Integer status code returned by the routine.  Values less than zero
	     indicate an error.

DESCRIPTION
     The  routine pvm_notify requests PVM to notify the caller on detecting cer-
     tain events.  One or more notify messages (see below) are sent by PVM  back
     to the calling task.  The messages have tag msgtag supplied to notify.

     The notification messages have the following format:

     PvmTaskExit
	    One  notify  message  for each TID requested.  The message body con-
	    tains a single TID of exited task.

     PvmHostDelete
	    One notify message for each TID requested.	The  message  body  con-
	    tains a single pvmd-TID of exited pvmd.

     PvmHostAdd
	    cnt  notify  messages  are sent, one each time the local pvmd's host
	    table is updated.  The message body contains an integer length  fol-
	    lowed  by  a  list	of  pvmd-TIDs  of  new	pvmds.	 The  counter of
	    PvmHostAdd messages yet to be sent is replaced by  successive  calls
	    to	pvm_notify.  Specifying a cnt of -1 turns on PvmHostAdd messages
	    until a future notify; a count of zero disables them.

     TIDs in the notify messages are packed as integers.

     The calling task is responsible for receiving messages with  the  specified
     tag and taking appropriate action.

     Future  versions  of  PVM	may  expand  the  list of available notification
     events.

EXAMPLES
     C:
	  info = pvm_notify( PvmTaskExit, 9999, ntask, tids );

     Fortran:
	  CALL PVMFNOTIFY( PVMHOSTDELETE, 1111, NUMHOSTS, DTIDS, INFO )

     To "cancel" a notify request in PVM, the pvm_notify routine can  be  re-in-
     voked  with  an  additional PvmNotifyCancel flag in the what argument.  The
     remaining arguments to this cancelling invocation must match  the	original
     invocation  exactly, aside from the additional PvmNotifyCancel which can be
     added(+) or OR-ed(|) to the what argument:

	  pvm_notify( PvmTaskExit, 9999, ntask, tids );

	  . . .

	  pvm_notify( PvmTaskExit | PvmNotifyCancel, 9999, ntask, tids );

     Note that when a notify is cancelled, the notify message is  delivered,  as
     if the given event (i.e. task exit, host add or delete) had occurred.

ERRORS
     PvmSysErr
	    pvmd not responding.

     PvmBadParam
	    giving an invalid argument value.

SEE ALSO
     pvm_tasks(3PVM), pvm_config(3PVM)

				31 January, 1994		    NOTIFY(3PVM)

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