Path: utzoo!attcan!uunet!mcvax!enea!erix!bengtb
From: bengtb@erix.UUCP (Bengt Baeverman)
Newsgroups: comp.os.vms
Subject: Re: VMS Mailboxes
Message-ID: <1616@erix.UUCP>
Date: 18 May 88 19:02:24 GMT
Reply-To: bengtb@erix.UUCP (Bengt Baverman)
Organization: Ericsson Telecom, Stockholm, Sweden
Lines: 87


Sending and receiving things through mailboxes are not that complicated.
Below are two programs that can be run by two processes in the same group.

This receiver side has to create the mailbox and wait for a message
before the sender can see the mailbox and send the message.

[inherit('sys$library:starlet')]
program receiver (input, output);
const
    mailboxname	= 'demo_box';

type
    word	= [word] 0..65535;
    iosbtype	= record
    		      status	: word;
		      count	: word;
		      pid	: unsigned;
    		  end;

var
    string	: varying [255] of char;
    channel	: word;
    status	: unsigned;
    iosb	: iosbtype;

    procedure lib$signal(%immed signal: unsigned); external;

begin
    status := $crembx(chan := channel, lognam := mailboxname);
    if not odd(status) then lib$signal(status);

    status := $qiow(chan := channel, func := io$_readvblk, iosb := iosb,
    		    p1 := string.body, p2 := size(string.body));
    if not odd(status) then lib$signal(status);
    if not odd(iosb.status) then lib$signal(iosb.status);

    string.length := iosb.count;

    writeln('I just recieved <', string, '>');

    status := $dassgn(channel);
    if not odd(status) then lib$signal(status);
end.

[inherit('sys$library:starlet')]
program sender (input, output);
const
    mailboxname	= 'demo_box';

type
    word	= [word] 0..65535;
    iosbtype	= record
    		      status	: word;
		      count	: word;
		      pid	: unsigned;
    		  end;

var
    string	: varying [255] of char;
    channel	: word;
    status	: unsigned;
    iosb	: iosbtype;

    procedure lib$signal(%immed signal: unsigned); external;

begin
    status := $crembx(chan := channel, lognam := mailboxname);
    if not odd(status) then lib$signal(status);

    status := $qiow(chan := channel, func := io$_readvblk, iosb := iosb,
    		    p1 := string.body, p2 := size(string.body));
    if not odd(status) then lib$signal(status);
    if not odd(iosb.status) then lib$signal(iosb.status);

    string.length := iosb.count;

    writeln('I just recieved <', string, '>');

    status := $dassgn(channel);
    if not odd(status) then lib$signal(status);
end.

Good luck!

	bengt baverman, bengtb@erix.se
	OPIAB Digitech, Stockholm, Sweden.