The Break Message Queue N times at multiple workstation function
allows multiple users to be aware of the messages that have arrived
at a specified message queue. For example, in some environments you
may want multiple users to monitor and respond to the messages that
arrive at QSYSOPR or QSYSMSG.
Whether a message queue is in break mode or not, multiple users can
do DSPMSG and respond to messages on the same queue. This operates
on a 'first come/only served' basis. If a 2nd user attempts to
answer the same message, the system provides an error message stating
that the message queue has changed. If F10 is pressed, the reply can
be seen.
When a message queue is in break mode, only the user who has it in
break mode can delete messages.
The system does not directly support a solution to allow multiple
users to be put into *BREAK mode for the same message queue.
However, it is possible to achieve this with the technique described
with this tool.
The following shows a picture of the concept:
Message is
sent to
.
.
V
************ ************
* * * *
* QUEUE1 * . . >* QUEUE2 *
* * . * *
************ WAKEUP . ************
Break handling msg . Break handling
pgm sends msg . . . . . . . . . pgm displays QUEUE1
and then
displays QUEUE1
Shared MSGQ Attention MSGQ
The following must be done:
** The MSGQ to be shown on multiple workstations (termed the
'Shared message queue') must be set into break mode and have a
break handling program specified. Sample code is provided,
but a minor modification is needed.
** One or more message queues (termed 'Attention message queues')
must exist and be in break mode to accept a message sent by
the break handling program of the Shared message queue. You
may use a normal workstation message queue for the Attention
message queue, but a simple approach is to create unique
message queues for each user who wants to be interrupted.
These message queues must use the standard break handling
program provided.
The same Attention message queue can be used to send to by
multiple Shared message queues. For example, you might want
to have QSYSOPR and some other message queue as Shared queues
where either queue could cause a break on multiple
workstations.
The TAAMSGFC program is the break handling program for the Shared
message queue. The source must be modified as described in the
implementation instructions. When a message is received at the
Shared message queue, the break handling program will send the
special WAKEUP message to the Attention message queue(s) and then use
DSPMSG on the Shared message queue.
The TAAMSGFC2 program is the break handling program for the Attention
message queues. It is a standard program and does not need to be
modified. When a message is received at the Attention message queue,
the break handling program will check for the special message text of
'WAKEUP'. If it is not this text, the Attention message queue will
be displayed. If the WAKEUP message is read, the program removes the
message and displays the Shared message queue.
The TAAMSGFC2 program reads all of the new messages in it's queue
every time a message is received. It then causes either or both of
the Attention message queue or the Shared message queue to be
displayed.
This allows for the case where the user who is assigned to one of the
Attention message queues signs on after several messages have already
been sent. When he places the Attention message queue into break
mode, the break handling program is given control. The program would
receive all of the messages and would perform a single display
regardless of how many messages existed. All of the WAKEUP messages
are removed each time the break handling program is made active. The
non-WAKEUP messages are left in the queue under control of the user.
See the later discussion for alternatives.
Restrictions
------------
Only the user who has the shared message queue in break mode can
delete messages from the queue.
Prerequisites
-------------
The following TAA Tools must be on your system:
STACK Stack function
Implementation
--------------
The TAAMSGFC2 program already exists and does not need to be
modified.
The source for the break handling program for the Shared message
queue is in member TAAMSGFC in the file QATTCL in the TAA Archive.
Use CPYTAA to copy the source from the archive to your own member
(any name may be used). Modify the source (as described in the
source) to send the WAKEUP message to the Attention message queue(s).
Create the program with the CRTCLPGM command. Any name for the
program and any library may be used.
To set the Shared message queue into break mode, specify the
following and name the program you just created:
CHGMSGQ MSGQ(xxxx) DLVRY(*BREAK) PGM(llll/pppp)
To set the Attention message queue(s) into break mode, specify the
following:
CHGMSGQ MSGQ(yyyy) DLVRY(*BREAK) PGM(TAATOOL/TAAMSGFC2)
Objects used by the tool
------------------------
Object Type Attribute Src member Src file
------ ----- --------- ---------- -----------
CLP TAAMSGFC QATTCL
TAAMSGFC2 *PGM CLP TAAMSGFC2 QATTCL
The TAAMSGFC program is not in object form in TAATOOL. You must copy
the source, make changes, and create the program in your own library.
Alternatives
------------
It is possible to filter the messages so that not every message
causes a wakeup of the Attention message queues. For example, the
RCVMSG command is already specified to return the values for SEV,
RTNTYPE (the message type) and MSGID. These can be used to determine
if the WAKEUP message should be sent. For a description of the
RTNTYPE codes, see the help text associated with this parameter on
RCVMSG.
For example, you may only want to notify an Attention Message queue
that an inquiry type message (RTNTYPE = '05') has been received. It
would also be possible to use a status message at the Attention
message queues instead of using DSPMSG. For example, you might want
to send the status message to include the message text of the last
message that caused the WAKEUP message to be sent. This would allow
the user at the other device to continue his processing (he would not
be interrupted), but could still determine if there was a reason for
him to display the details of the Shared message queue.
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