REG_HOSTER(3PVM)						  PVM Version 3.4						  REG_HOSTER(3PVM)

NAME

       pvm_reg_hoster - Register task as PVM slave starter.

SYNOPSIS

       C    #include <pvmsdpro.h>

	    int cc = pvm_reg_hoster()

       Fortran	 Not Available

DESCRIPTION

       Registers  the calling task as a PVM slave pvmd starter.  When the master pvmd receives a DM_ADD message, instead of starting the new slave
       pvmd processes itself, it passes a message to the hoster, which does the dirty work and sends a message back to the pvmd.

       Note:  This function isn't for beginners.  If you don't grok what it does, you probably don't need it.  For a more complete explanation	of
       what's  going  on here, you should refer to the PVM source code and/or user guide section on implementation; this is just a man page.  That
       said...

       When the master pvmd receives a DM_ADD message (request to add hosts to the virtual machine), it looks up the new host IP  addresses,  gets
       parameters  from  the  host  file  if it was started with one, and sets default parameters.  It then either attempts to start the processes
       (using rsh or rexec()) or, if a hoster has registered, sends it a SM_STHOST message.

       The format of the SM_STHOST message is:
	   int nhosts		     // number of hosts
	   {
	       int tid		     // of host
	       string options	     // from hostfile so= field
	       string login	     // in form ``[username@]hostname.domain''
	       string command	     // to run on remote host
	   } [nhosts]

       The hoster should attempt to run each command on each host and record the result.  A command usually looks like:
	   $PVM_ROOT/lib/pvmd -s -d8 -nhonk 1 80a9ca95:0f5a 4096 3 80a95c43:0000

       and a reply from a slave pvmd like:
	   ddpro<2312> arch<ALPHA> ip<80a95c43:0b3f> mtu<4096>

       When finished, the hoster should send a SM_STHOSTACK message back to the address of the sender (the master pvmd).  The format of the  reply
       message is:

	   {
	       int tid		     // of host, must match request
	       string status	     // result line from slave or error code
	   } [] 		     // implied count

       The TIDs in the reply must match those in the request.  They may be in a different order, however.

       The  result  string  should  contain  the  entire reply (a single line) from each new slave pvmd, or an error code if something went wrong.
       Legal error codes are the literal names of the pvm_errno codes, for example ``PvmCantStart''.  The default PVM hoster can return PvmDSysErr
       or PvmCantStart, and the slave pvmd itself can return PvmDupHost.

       The  hoster must use pvm_setmwid() to set the wait ID in the reply message to the same value as in the request.	The wait ID in the request
       is obtained by calling pvm_getmwid().

       The hoster task must use pvm_setopt(PvmResvTids, 1) to allow sending reserved messages.	Messages should  be  packed  using  encoding  Pvm-
       DataDefault to ensure they can be unpacked anywhere in the system.

       pvm_reg_hoster() returns PvmOk when successful.

SEE ALSO

       pvm_addhosts(3PVM), pvm_config(3PVM), pvm_setmwid(3PVM)

								   4 March, 1994						  REG_HOSTER(3PVM)