VSI OpenVMS Forum

Hi all,

We've got a complex application that makes a lot of use of mailbox interprocess communication, there are many processes and differing messages.

My question are.... is there a way of seeing what messages & contents are in the mbx without actually reading them via a $QIO(W)? Perhaps there's a tool or example program that allows access to the data in an mbx via system services etc?

Thanks!

Gary

Gary,

check out the MBMON - Mailbox Monitor - written by Ian Miller:

https://eisner.encompasserve.org/~miller/

There seem to be no hooks inside [SYS]SYSMAILBX for tracing or logging.

Volker.

Added in 3 hours 21 minutes 35 seconds:
Gary,

I did a quick test: downloaded and built MBMON010 on OpenVMS Alpha V8.3. Seems to work.

You need to build the help library and define a logical, so that MBMONCP> HELP does work:

$ LIBRARY/HELP/CREATE HELPLIB mbmon.hlp
$ DEFINE HELPLIB SYS$DISK:[]HELPLIB.HLB

Created a mailbox in one session:

CHAALP $ CREATE/MAILBOX/PERMANENT/MESSAGE_SIZE=512/LOG MY_MAILBOX
%CREATE-I-CREATED, MBA124: created
CHAALP $ open/write x mba124:
CHAALP $ write x "test"

In another session:

CHAALP $ RUN mbmoncp
MBMON> monitor mba124:
Press control-C to exit
Message from 000000d4 _RTA1:, length 4
74 65 73 74
Cancel

Exiting due to control-C
MBMON> exit

Read mailbox to allow writer to complete the write operation and exit

CHAALP $ open/read y mba124:
CHAALP $ read y line
CHAALP $ sho symb line
LINE = "test"
CHAALP $ close y

CHAALP$ delete/mailbox my_mailbox

Note that you can build and use SYS$EXAMPLES:MBX$SDA.C to find information about mailboxes in the system.

Volker.

Thanks Volker, this is very helpful.

I've had a look at this and managed to build a copy of MBU OK. The problem is, is that the VIEW command doesn't seem to work and so I can't see the messages queued up in the MBX.

I tried to build MBMON but get some compiler errors:

vp = refhdl.lid->ldrimg$l_nonpag_w_base;
.............................^
%CC-E-NEEDMEMBER, In this statement, "ldrimg$l_nonpag_w_base" is not a member of "refhdl.lid".
at line number 141 in file SYS$SYSDEVICE:[test.mbmon.src]mbmon_prv.c;1

vp = refhdl.lid->ldrimg$l_nonpag_w_base;
.....................^
%CC-E-NEEDMEMBER, In this statement, "ldrimg$l_nonpag_w_base" is not a member of "refhdl.lid".
at line number 239 in file SYS$SYSDEVICE:[test.mbmon.src]mbmon_prv.c;1

So a bit stuck here.

Thanks

Gary

Gary,

I didn't try MBU...

Which version and architecture of OpenVMS are you trying to build these tools on ?

Volker.

We have always used MBOX. It works on VAX, Alpha, and Itanium.

ISPPRB_SM30PDD2> type aaareadme.txt
MBOX V1.6 15-MAY-1995 Neill Clift (neill@macro.demon.co.uk)

It displays the mailbox messages without destroying them.

ISPPRB_SM30PDD2> mbox shael_mbx

Device: MBA23892: (SHAEL_MBX/LNM$SYSTEM_TABLE)

Channels: 0, Operations: 7, Creator: 00000000 (Nonexistent)

Total size: 50000, Remaining: 49987, Message size: 1000, Msgs: 1

Message number: 1, 13 bytes, Written by: 00000000 (Nonexistent) Waiting
33 5F325F31 5F676E69 74736574 testing_1_2_3....... 00000000


Shael Richmond

Gary,

ldrimg$l_nonpag_w_base should be declared in module LDRIMGDEF in SYS$LIBRARY:SYS$LIB_C.TLB

I need more information about your OpenVMS version to try to find out, why the compile fails on your system.

Volker.

shael_richmond wrote: ↑

Fri Sep 17, 2021 5:54 pm

We have always used MBOX. It works on VAX, Alpha, and Itanium.

ISPPRB_SM30PDD2> type aaareadme.txt
MBOX V1.6 15-MAY-1995 Neill Clift (neill@macro.demon.co.uk)

It displays the mailbox messages without destroying them.

ISPPRB_SM30PDD2> mbox shael_mbx

Device: MBA23892: (SHAEL_MBX/LNM$SYSTEM_TABLE)

Channels: 0, Operations: 7, Creator: 00000000 (Nonexistent)

Total size: 50000, Remaining: 49987, Message size: 1000, Msgs: 1

Message number: 1, 13 bytes, Written by: 00000000 (Nonexistent) Waiting
33 5F325F31 5F676E69 74736574 testing_1_2_3....... 00000000


Shael Richmond

Tried using MBOX, copied it over, built it, ran it and.... BANG, crashed our Dev server....

Back to the drawing board.

Gary

garyrevell wrote: ↑

Mon Sep 20, 2021 9:02 am

Tried using MBOX, copied it over, built it, ran it and.... BANG, crashed our Dev server....

Back to the drawing board.

Gary

; V01-007 Neill clift <neill@macro.demon.co.uk>␉␉15-MAY-1995
; Display creator of mailbox if its a temporary.
; V01-008 Neill clift <neill@macro.demon.co.uk>␉␉22-MaY-1996
; Update for 64 bit ACB fields. Truncate to 32 bits anyway!
; V01-009 Volker Halle <volker.halle@invenate.de> 14-Aug-2005
; Support new mailbox size > 64k (V7.3-1 or higher)

We also had to make a small change to deal with message size.


Shael

Gary,

the full comment of my change V01-009 is:
What kind of MBOX commands did you use on your Dev server and what kind of crash did you get ? Have a look at the CLUE$COLLECT:CLUE$node_ddmmyy.LIS file.

Please provide more information, also on the MBMON compilation problem.

Volker.

Hi Volke,

I think I sent you a private message regarding the compilation problem, not sure if you received it?

Regards

Gary