Re: POST

This is from the online manual:

The POST operation puts information in an INFDS (file information data
structure). This information contains the following:

1) File Feedback Information specific to RPG I/O for the file


2) Open Feedback Information for the file


3) Input/Output Feedback Information and Device Dependent Feedback Information
for the file OR Get Attribute Information


In factor 1, you can specify a program device name to get information about that
specific program device. If you specify a program device in factor 1, the file
must be defined as a WORKSTN file. If factor 1 does contain a program device,
then the INFDS will contain Get Attribute Information following the Open
Feedback Information. Use either a character field of length 10 or less, a
character literal, or a character named constant. If you leave factor 1 blank,
then the INFDS will contain Input/Output Feedback Information and Device
Dependent Feedback Information following the Open Feedback Information.


In factor 2, specify the name of a file. Information for this file is posted in
the INFDS associated with this file.


If you specify a file in factor 2, you can leave the result field blank. The
INFDS associated with this file using the INFDS keyword in the file
specification will be used. You can specify a file in factor 2 and its
associated INFDS in the result field. If you leave factor 2 blank, you must
specify the data structure name that has been used in the INFDS keyword for the
file specification in the result field; information from the associated file in
the file specification will be posted.


To handle POST exceptions (file status codes greater than 1000), either the
operation code extender 'E' or an error indicator ER can be specified, but not
both. For more information on error handling, see "File Exception/Errors" in
topic 1.5.1.


Even when a POST operation code is not processed, its existence in your program
can affect the way the RPG IV language operates. Usually, the INFDS is updated
at each input and output operation or block of operations. However, if anywhere
in your program, you have specified a POST operation with factor 1 blank, then
RPG IV updates the I/O Feedback Information area and the Device Dependent
Feedback Information area in the INFDS of any file only when you process a POST
operation for that file. The File Dependent Information in the INFDS is updated
on all Input/Output operations. If you have opened a file for multiple-member
processing, the Open Feedback Information in the INFDS will be updated when an
input operation (READ, READP, READE READPE) causes a new member to be opened.


Note that DUMP retrieves its information directly from the Open Data Path and
not from the INFDS, so the file information sections of the DUMP do not depend
on POST.


If a program has no POST operation code, or if it has only POST operation codes
with factor 1 specified, the Input/Output Feedback and Device Dependent Feedback
section is updated with each input/output operation or block of operations. If
RPG is blocking records, most of the information in the INFDS will be valid only
for the last complete block of records processed. When doing blocked input, from
a data base file, RPG will update the relative record number and key information
in the INFDS for each read, not just the last block of records processed. If you
require more accurate information, do not use record blocking. See "File
Information Data Structure" in topic 1.5.1.1 for more information on record
blocking. If you do not require feedback information after every input/output
operation, you may be able to improve performance by using the POST operation
only when you require the feedback information.


When a POST operation is processed, the associated file must be open. If you
specify a program device on the POST operation, it does not have to be acquired
by the file.



Regards,
Peter Vidal
Pall Aeropower Corp. / SR Programmer Analyst
www.pall.com /  Peter_Vidal@Pall.com
727-539-8448, x2414