Exchange/RJE Manual

Programming Considerations
Using the Exchange/RJE Programmatic Interface
104698 Tandem Computers Incorporated 4–5
The following fragment of TAL code illustrates the typical method of checking for
errors and the subsequent call to FILEINFO in the event of an error.
CALL READ (fnum, buffer, 80, count_read);
IF <> THEN
BEGIN !error or warning occurred
CALL FILEINFO (fnum, error); !identify the error
... !perform recovery
!if possible
!else exit
END;
... !successful operation
!continues here
Nowait I/O and Errors
The procedure call that initiates a nowait I/O operation does not set the condition
code according to how the I/O operation completed. Rather, the procedure call sets
the condition code according to whether or not the message that initiates the operation
was sent successfully. Thus, the condition code does not give any indication of how
the the operation completed. You still should check the condition code after the initial
procedure call to check that the operation started successfully.
The call to AWAITIO that completes a nowait I/O operation sets the condition code
according to how the I/O operation completed. You must check the condition code
after a call to AWAITIO to determine whether or not a nowait I/O operation
completed successfully.
Error Numbers
In the event of an error or warning, the call to FILEINFO returns the error number.
For a complete list of all Tandem defined error numbers and their meanings, see the
Operator Messages Manual.
Table 4-2 lists the most common errors that pertain to the Exchange/RJE line server or
the underlying communication subsystem.