The SMB$SEND_TO_JOBCTL routine is used by your symbiont to send
messages to the job controller. Three types of messages can be
sent: request-completion messages, task-completion messages, and
task-status messages.
Format
SMB$SEND_TO_JOBCTL stream [,request] [,accounting]
[,checkpoint] [,device_status] [,error]
1 – Returns
OpenVMS usage:cond_value
type: longword (unsigned)
access: write only
mechanism: by value
Longword condition value. Most utility routines return a
condition value in R0. Condition values that this routine can
return are listed under Condition Values Returned.
2 – Arguments
stream
OpenVMS usage:longword_unsigned
type: longword (unsigned)
access: read only
mechanism: by reference
Stream number specifying the stream to which the message refers.
The stream argument is the address of a longword containing the
number of the stream to which the message refers.
request
OpenVMS usage:identifier
type: longword (unsigned)
access: read only
mechanism: by reference
Request code identifying the request being completed. The request
argument is the address of a longword containing the code that
identifies the request that has been completed.
The code usually corresponds to the code the job controller
passed to the symbiont by means of a call to SMB$READ_MESSAGE.
But the symbiont can also initiate task-completion and task-
status messages that are not in response to a request. (See the
Description help topic.)
accounting
OpenVMS usage:char_string
type: character string
access: read only
mechanism: by descriptor
Accounting information about a task. The accounting argument
is the address of a descriptor pointing to the accounting
information about a task. Note that this structure is passed
by descriptor and not by reference.
The job controller accumulates task statistics into a job-
accounting record, which it writes to the accounting file when
the job is completed.
The following diagram depicts the contents of the 16-byte
structure:
31 0
-----------------------------------------------------
Number of pages printed for the job
-----------------------------------------------------
Number of reads from disk or tape
-----------------------------------------------------
Number of writes to the printing device
-----------------------------------------------------
Unused
-----------------------------------------------------
checkpoint
OpenVMS usage:char_string
type: character string
access: read only
mechanism: by descriptor
Checkpoint data about the currently executing task. The
checkpoint argument is the address of the descriptor that points
to checkpointing information that relates to the status of
a task. When the symbiont sends this information to the job
controller, the job controller saves it in the queue database.
When a restart-from-checkpoint request is executed for the queue,
the job controller retrieves the checkpointing information from
the queue database and sends it to the symbiont in the SMBMSG$K_
CHECKPOINT_DATA item that accompanies a SMBMSG$K_START_TASK
request.
Print symbionts can use the checkpointing information to
reposition the input file to the point corresponding to the page
being output when the last checkpoint was taken. Other symbionts
might use checkpoint information to specify restart information
for partially completed tasks.
NOTE
Because each checkpoint causes information to be written
into the job controller's queue database, taking a
checkpoint incurs significant overhead. Use caution in
regard to the size and frequency of checkpoints. When
determining how often to checkpoint, weigh processor and
file-system overhead against the convenience of restarting.
device_status
OpenVMS usage:longword_unsigned
type: longword (unsigned)
access: read only
mechanism: by reference
Status of the device served by the symbiont. The device_
status argument is the address of a longword passed to the job
controller, which contains the status of the device to which the
symbiont is connected.
This longword contains a longword bit vector, each bit of which
specifies device-status information. Each programming language
provides an appropriate mechanism for defining these device-
status bits. The following table describes each bit:
Device Status Bit Description
SMBMSG$V_LOWERCASE The device to which the symbiont is
connected supports lowercase characters.
SMBMSG$V_PAUSE_ The symbiont sends this message to inform
TASK the job controller that the symbiont has
paused on its own initiative.
SMBMSG$V_REMOTE The device is connected to the symbiont by
means of a modem.
SMBMSG$V_SERVER The symbiont is not connected to a device.
SMBMSG$V_STALLED Symbiont processing is temporarily stalled.
SMBMSG$V_STOP_ The symbiont requests that the job
STREAM controller stop the queue.
SMBMSG$V_TERMINAL The symbiont is connected to a terminal.
SMBMSG$V_ The device to which the symbiont is
UNAVAILABLE connected is not available.
error
OpenVMS usage:vector_longword_unsigned
type: longword (unsigned)
access: read only
mechanism: by reference
Condition codes returned by the requested task. The error
argument is the address of a vector of longword condition codes.
The first longword contains the number of longwords following it.
If the low bit of the first condition code is clear, the job
controller aborts further processing of the job. Output of
any remaining files, copies of files, or copies of the job is
canceled. In addition, the job controller saves up to three
condition values in the queue database. The first condition value
is included in the job-accounting record that is written to the
system's accounting file (SYS$MANAGER:ACCOUNTNG.DAT).
3 – Description
The symbiont uses the SMB$SEND_TO_JOBCTL routine to send messages
to the job controller.
Most messages the symbiont sends to the job controller are
responses to requests made by the job controller. These responses
inform the job controller that the request has been completed,
either successfully or with an error. When the symbiont sends
the message, it usually indicates that the request has been
completed.
In such messages, the request argument corresponds to the
function code of the request that has been completed. Thus, if
the job controller sends a request using the SMBMSG$K_START_
TASK code, the symbiont responds by sending a SMB$SEND_TO_JOBCTL
message using SMBMSG$K_START_TASK as the request argument.
The responses to some requests use additional arguments to send
more information in addition to the request code. The following
table shows which additional arguments are allowed in response to
each different request:
Request Arguments
SMBMSG$K_START_STREAM request
device_status
error
SMBMSG$K_STOP_STREAM request
SMBMSG$K_RESET_STREAM request
SMBMSG$K_START_TASK request
SMBMSG$K_PAUSE_TASK request
SMBMSG$K_RESUME_TASK request
SMBMSG$K_STOP_TASK request
error (See footnote.)
Footnote: This is usually the value specified in the SMBMSG$K_
STOP_CONDITION item that was sent by the job controller with the
SMBMSG$K_STOP_TASK request.)
In addition to responding to requests from the job controller,
the symbiont can send other messages to the job controller. If
the symbiont sends a message that is not a response to a request,
it uses either the SMBMSG$K_TASK_COMPLETE or SMBMSG$K_TASK_STATUS
code. Following are the additional arguments that you can use
with the messages identified by these codes:
Code Arguments
SMBMSG$K_TASK_ request
COMPLETE
accounting
error
SMBMSG$K_TASK_STATUS request
checkpoint
device_status
The symbiont uses the SMBMSG$K_TASK_STATUS message to update the
job controller on the status of a task during the processing
of that task. The checkpoint information passed to the job
controller with this message permits the job controller to
restart an interrupted task from an appropriate point. The
device-status information permits the symbiont to report changes
in device's status (device stalled, for example).
The symbiont can use the SMBMSG$K_TASK_STATUS message to request
that the job controller send a stop-stream request. It does this
by setting the stop-stream bit in the device-status argument.
The symbiont can also use the SMBMSG$K_TASK_STATUS message
to notify the job controller that the symbiont has paused in
processing a task. It does so by setting the pause-task bit in
the device-status argument.
The symbiont uses the SMBMSG$K_TASK_COMPLETE message to signal
the completion of a task. Note that, when the symbiont receives a
START_TASK request, it responds by sending a SMB$SEND_TO_JOBCTL
message with SMBSMG$K_START_TASK as the request argument. This
response means that the symbiont has started the task; it does
not mean the task has been completed. When the symbiont has
completed a task, it sends a SMB$SEND_TO_JOBCTL message with
SMBMSG$K_TASK_COMPLETE as the request argument.
Optionally, the symbiont can specify accounting information when
sending a task-completion message. The accounting statistics
accumulate to give a total for the job when the job is completed.
Also, if the symbiont is aborting the task because of a symbiont-
detected error, you can specify up to three condition values in
the error argument. Aborting a task causes the remainder of the
job to be aborted.
4 – Condition Values Returned
SS$_NORMAL Normal successful completion.
This routine also returns any condition value returned by the
$QIO system service and the LIB$GET_VM routine.