[Info-vax] Network mailbox

[VAXman- at SendSpamHere.ORG]

In article <j8dgi6$pph$1 at speranza.aioe.org>, Snowshoe <no at spam.please> writes:
>I have my network mailbox silliness working -- sort of. The problem I 
>have is that RMS doesn't deliver the messages one at a time, it sort of 
>saves them up and then unleashes them all at once. I implemented this as 
>a process that reads a (local) mailbox and writes what's there to a 
>remote mailbox over a DECnet link.  I also do the reverse (different 
>mailbox pair) and have the same problem - a $GET doesn't do anything 
>until there are a bunch of messages.  This happens even though the 
>remote FAL process reads the messages one at a time, immediately.  It is 
>the local RMS or DECnet at fault.
>
>How to tell RMS to give me the messages one at a time?  RAB$M_TMO seems 
>to be ignored.
>
>   mbx2_fab = cc$rms_fab;
>   mbx2_fab.fab$l_fop = FAB$M_SQO;
>   mbx2_fab.fab$b_fac = FAB$M_PUT;
>   mbx2_fab.fab$b_org = FAB$C_SEQ;
>   mbx2_fab.fab$b_rat = FAB$M_CR;
>   mbx2_fab.fab$b_rfm = FAB$C_RFM_DFLT;
>   mbx2_fab.fab$l_fna = "REMOTE::MBA1234:";
>   mbx2_fab.fab$b_fns = 16;
>   mbx2_fab.fab$w_mrs = 5000;
>
>   status = SYS$OPEN(&mbx2_fab);
>   if (!(status & 1)) lib$signal(status);
>
>   mbx2_rab = cc$rms_rab;
>   mbx2_rab.rab$l_rop = RAB$M_TMO;
>   mbx2_rab.rab$b_tmo = 0;
>   mbx2_rab.rab$l_rbf = rec_buffer2;
>   mbx2_rab.rab$l_fab = &mbx2_fab;
>
>   status = SYS$CONNECT (&mbx2_rab);
>   if (!(status & 1)) lib$signal(status);
>
>....
>
>void mbx2_ast(void) {
>   int status;
>   int len;
>   char zzz[5000];  //debug
>
>// status from last mbx read
>
>   status = mbx2_iosb.status;
>   if (!(status & 1)) lib$signal(status);
>
>// debug
>
>   len = mbx2_iosb.byte_cnt;
>   memcpy(zzz,rec_buffer2,len);
>   zzz[len] = '\0';
>   printf (">>> size = %d |%s|\n",len,zzz);
>
>// end debug
>
>   mbx2_rab.rab$w_rsz = mbx2_iosb.byte_cnt;
>   status = SYS$PUT(&mbx2_rab);		// write to remote mailbox
>   if (!(status & 1)) lib$signal(status);
>
>// queue next read
>
>   status = sys$qio (1, mbx_chan2, IO$_READVBLK, &mbx2_iosb, mbx2_ast, 0,
>                     rec_buffer2, sizeof(rec_buffer2), 0, 0, 0, 0 );
>   if (!(status & 1)) lib$signal(status);
>}
>

Why are you using RMS to read and write the mailbox?  The mailbox driver
has special function modifiers (ie. IO$M_NOW) that can be used with $QIO
IO$_READVBLK and IO$_WRITEVBLK when the target device is a mailbox.  The
$QIO IO$_READVBLK would normally wait and only complete when there's been
a message deposited into the mailbox.  This you apparently have correct.

I'd lose the $PUT and use IO$_WRITEVBLK|IO$M_NOW.  I think you can still
use the $OPEN but you'll probably want to specify UFO and then, there is
no need for the $CONNECT.  Just issues $QIO IO$_WRITEVBLK|IO$M_NOW to the
channel returned in the FAB's STV.

-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

All your spirit rack abuses, come to haunt you back by day.
All your Byzantine excuses, given time, given you away.