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 certain 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 contains a single TID of exited task.

       PvmHostDelete
	      One notify message for each TID requested.  The message body contains 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
	      followed	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-invoked 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)