Check the "Using SPECIAL Files" section in the ILE RPG PRogrammers Guide:
Using SPECIAL Files<
http://publib.boulder.ibm.com/infocenter/iseries/v5r3/topic/books_web/c092507502.htm#ToC_410>
The RPG device name SPECIAL (positions 36 - 42 of the file description
specifications) allows you to specify an input and/or output device that is
not directly supported by the ILE RPG operations. The input and output
operations for the file are controlled by a user-written routine. The name
of the user-written routine, must be identified in the file description
specifications using the keyword PGMNAME('*program name*').
ILE RPG calls this user-written routine to open the file, read and write the
records, and close the file. ILE RPG also creates a parameter list for use
by the user-written routine. The parameter list contains:
- option code parameter (option)
- return status parameter (status)
- error-found parameter (error)
- record area parameter (area).
This parameter list is accessed by the ILE RPG compiler and by the
user-written routine; it cannot be accessed by the program that contains the
SPECIAL file.
The following describes the parameters in this RPG-created parameter list:
*Option *The option parameter is a one-position character field that
indicates the action the user-written routine is to process. Depending on
the operation being processed on the SPECIAL file (OPEN, CLOSE, FEOD, READ,
WRITE, DELETE, UPDATE), one of the following values is passed to the
user-written routine from ILE RPG: *Value Passed **Description* *O *Open the
file. *C *Close the file. *F *Force the end of file. *R *Read a record and
place it in the area defined by the area parameter. *W *The ILE RPG program
has placed a record in the area defined by the area parameter; the record is
to be written out. *D *Delete the record. *U *The record is an update of the
last record read. *Status *The status parameter is a one-position character
field that indicates the status of the user-written routine when control is
returned to the ILE RPG program. Status must contain one of the following
return values when the user-written routine returns control to the ILE RPG
program:
*Return Value **Description* *0 *Normal return. The requested action was
processed. *1 *The input file is at end of file, and no record has been
returned. If the file is an output file, this return value is an error. *2 *The
requested action was not processed; error condition exists. *Error *The
error parameter is a five-digit zoned numeric field with zero decimal
positions. If the user-written routine detects an error, the error parameter
contains an indication or value representing the type of error. The value is
placed in the first five positions of location *RECORD in the INFDS when the
status parameter contains 2. *Area *The area parameter is a character field
whose length is equal to the record length associated with the SPECIAL file.
This field is used to pass the record to or receive the record from the ILE
RPG program.
You can add additional parameters to the RPG-created parameter list. Specify
the keyword PLIST(*parameter list name*) on the file description
specifications for the SPECIAL file. See Figure
181<
http://publib.boulder.ibm.com/infocenter/iseries/v5r3/topic/books_web/c0925075318.htm#FIGSPECDVC>.
Then use the PLIST operation in the calculation specifications to define the
additional parameters.
The user-written routine, specified by the keyword PGMNAME of the
filedescription specifications for the
SPECIAL file, must contain an entry parameter list that includes both the
RPG-created parameters and the user-specified parameters.
If the SPECIAL file is specified as a primary file, the user-specified
parameters must be initialized before the first primary read. You can
initialize these parameters with a factor 2 entry on the PARM statements or
by the specification of a compile-time array or an array element as a
parameter.
Table 42<
http://publib.boulder.ibm.com/infocenter/iseries/v5r3/topic/books_web/c0925075317.htm?resultof=%22%53%50%45%43%49%41%4c%22%20%22%73%70%65%63%69%61%6c%22%20%22%66%69%6c%65%22%20#TBLSPECIAL>shows
the
file operation codes that are valid for a SPECIAL file.
*Table 42. Valid File Operations for a SPECIAL File*
File Description Specifications Positions Calculation Specifications
Positions *17* *18* *26-35* I P/S CLOSE, FEOD C P/S WRITE, CLOSE, FEOD U P/S
UPDATE, DELETE, CLOSE, FEOD O
WRITE, OPEN, CLOSE, FEOD I F READ, OPEN, CLOSE, FEOD C F READ, WRITE, OPEN,
CLOSE, FEOD U F READ, UPDATE, DELETE, OPEN, CLOSE, FEOD
On Fri, Dec 4, 2009 at 10:36 AM, <JDHorn@xxxxxxxxxxxxxx> wrote:
When you declare an input or update primary file as a special file
FFILE UP E SPECIAL PGMNAME('FILESQL')
the Chain, Update, Read, Write rpg opcodes the record format passes
correctly between the special program and the calling program.
Does anyone know the rules for -
What does the calling program pass to the special program if you use the
Delete opcode?
What does the calling program pass to the special program if you use the
Update opcode with the %fields option?
Jim
midrange.com
