REG_TASKER(3PVM)					     REG_TASKER(3PVM)

NAME
  pvm_reg_tasker - Register task as PVM	task starter.

SYNOPSIS
  C	  #include <pvmsdpro.h>

	  int cc = pvm_reg_tasker()

  Fortran Not Available

DISCUSSION

  Registers the	calling	task as	a PVM task starter.  When a tasker is
  registered with a pvmd, and the pvmd receives	a DM_EXEC message, instead of
  fork()ing and	exec()ing the task itself, it passes a message to the tasker,
  which	does the dirty work and	sends a	message	back to	the pvmd.

  Note:	 If this doesn't make sense, don't worry about it.  This function is
  for folks who	are writing stuff like debugger	servers	and so on.  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 only a
  man page.  That said...

  When the pvmd	receives a DM_EXEC message (request to exec new	tasks),	it
  searches epath (the PVM executable search path) for the file name.  If it
  finds	the file, it then either attempts to start the processes (using
  fork() and exec()) or, if a tasker has registered, sends it a	SM_STTASK
  message.

  The format of	the SM_STTASK message is:
      int tid		    // of task
      int flags		    // as passed to spawn()
      string path	    // absolute	path of	the executable
      int argc		    // number of args to process
      string argv[argc]	    // args
      int nenv		    // number of envars	to pass	to task
      string env[nenv]	    // environment strings

  The tasker must attempt to start the process when it gets one	of these mes-
  sages.  The tasker doesn't reply to the pvmd if the task is successfully
  started; the task will reconnect to the pvmd on its own (using the identif-
  ier in envar PVMEPID).

  The tasker must send a SM_TASKX message to the pvmd when any task that it
  owns (has started) exits, or if it can't start a particular task.  The for-
  mat of the SM_TASKX message is:

      int tid		    // of task
      int status	    // the Unix	exit status (from wait())
      int u_sec		    // user time used by the task, seconds
      int u_usec	    // microseconds
      int s_sec		    // system time used	by the task, seconds
      int s_usec	    // microseconds

  The tasker task must use pvm_setopt(PvmResvTids, 1) to allow sending
  reserved messages.  Messages must be packed using data format	PvmDataFoo.

  pvm_reg_tasker() returns PvmOk when successful.

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