System Messages; Application Conversion; Error Return Conventions - HP Guardian Errors Manual

20 System Messages

A system message is an interprocess message that is sent from the operating system to an application
process. System messages are received by an application process through its $RECEIVE file.
There are two procedures you can use to open $RECEIVE: FILE_OPEN_ and OPEN. The OPEN
procedure, which is superseded by the FILE_OPEN_ procedure, is supported for compatibility with
previous software and should not be used for new development.
When $RECEIVE is opened with FILE_OPEN_, you can choose to receive D-series-format system
messages (the default action) or C-series-format system messages. When $RECEIVE is opened with
OPEN, you receive C-series-format messages. Some D-series messages supersede one or more
C-series messages, while other D-series messages support newer features. If a process requests
C-series messages and uses a feature for which there is no C-series message, then the process
receives a D-series message.
Table 14 (page 247)
provides the equivalent D-series-format system message. D-series-format system messages that do
not have an equivalent C-series-format system message are listed at the end of this table.

Application Conversion

D-series-format system messages are available for converted applications to read from $RECEIVE
when using the D-series and later system procedures. See the Guardian Application Conversion
Guide and the Guardian Programmer's Guidefor more detailed information.

Error Return Conventions

The completion of a read associated with a C-series-format system message returns a condition
code of "greater than" (CCG) and file-system error 6 from FILE_GETINFO_.
D-series-format system messages do not use condition codes to indicate an error. Instead, each
procedure returns an integer error value. If an error condition contains more information than the
procedure can return in an integer parameter, the procedure returns additional information in an
integer error-detail parameter.
For more information about system messages, refer to the Guardian Programmer's Guide.
NOTE: When you read system messages by calling the READUPDATE procedure, you must reply
in a corresponding call to REPLY, even if you have no message to return. If your application process
is performing message queuing, call FILE_GETRECIEVEINFO, LASTRECEIVE, or RECEIVEINFO
immediately following completion of the READUPDATE and pass the message tag back to the
REPLY procedure.
The message lengths discussed in this section are subject to change. Do not test the received length
for equality to an expected length.
The following table lists the D-series-format system messages in numerical order.
Table 13 D-Series-Format System Messages
-2
-3
- 1 0
- 1 1
- 1 2
- 1 3
-21
246 System Messages
Table 13 lists D-series-format system messages in numerical order;
lists C-series-format system messages in numerical order and, for each message,
Processor Down
Processor Up
SETTIME
Power On
NEWPROCESSNOWAIT Completion
System Message Buffer Overrun
3270 Device Status Received