ILE RPG Programmer's Guide
An RPG WORKSTN file can use an externally described
display-device file or ICF-device file, which contains file information
and a description of the fields in the records to be written. The
most commonly used externally described WORKSTN file is a display
file. (For information about describing and creating display files,
refer to the DB2 Universal Database™ for iSeries® section of the Database
and File Systems category in the i5/OS® Information Center at
this Web site - http://www.ibm.com/systems/i/infocenter/.)
In addition to the field descriptions (such as field names and
attributes), the DDS for a display-device file are used to:
- Format the placement of the record on the screen by specifying
the line-number and position-number entries for each field and constant.
- Specify attention functions such as underlining and highlighting
fields, reverse image, or a blinking cursor.
- Specify validity checking for data entered at the display work
station. Validity-checking functions include detecting fields where
data is required, detecting mandatory fill fields, detecting incorrect
data types, detecting data for a specific range, checking data for
a valid entry, and processing modules 10 or 11 check-digit verification.
- Control screen management functions, such as determining if fields
are to be erased, overlaid, or kept when new data is displayed.
- Associate indicators 01 through 99 with command attention keys
or command function keys. If a function key is described as a command
function key (CF), both the response indicator and the data record
(with any modifications entered on the screen) are returned to the
program. If a function key is described as a command attention key
(CA), the response indicator is returned to the program but the data
record remains unmodified. Therefore, input-only character fields
are blank and input-only numeric field are filled with zeros, unless
these fields have been initialized otherwise.
- Assign an edit code (EDTCDE) or edit word (EDTWRD) keyword to
a field to specify how the field’s values are to be displayed.
- Specify subfiles.
A display-device-record format contains three types of fields:
- Input fields. Input fields are passed
from the device to the program when the program reads a record. Input
fields can be initialized with a default value. If the default value
is not changed, the default value is passed to the program. Input
fields that are not initialized are displayed as blanks into which
the work-station user can enter data.
- Output fields. Output fields are passed
from the program to the device when the program writes a record to
a display. Output fields can be provided by the program or by the
record format in the device file.
- Output/input (both) fields. An output/input
field is an output field that can be changed. It becomes an input
field if it is changed. Output/input fields are passed from the program
when the program writes a record to a display and passed to the program
when the program reads a record from the display. Output/input fields
are used when the user is to change or update the data that is written
to the display from the program.
If you specify the keyword INDARA in the DDS for a WORKSTN file,
the RPG program passes indicators to the WORKSTN file in a separate
indicator area, and not in the input/output buffer.
For a detailed description of an externally-described
display-device file and for a list of valid DDS keywords, refer to
the DB2
Universal Database for iSeries section
of the Database and File Systems category
in the i5/OS Information
Center at this Web site - http://www.ibm.com/systems/i/infocenter/.
Figure 192 shows an example of the DDS for a display-device
file.
Figure 192. Example of the Data Description Specifications for a Display Device File
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ..*
AAN01N02N03T.Name++++++RLen++TDpBLinPosFunctions++++++++++++++++++++*
A** ITEM MASTER INQUIRY
A REF(DSTREF) 1
A R PROMPT TEXT('Item Prompt Format')
A 73N61 OVERLAY 2
A CA03(98 'End of Program') 3
A 1 2'Item Inquiry'
A 3 2'Item Number'
A ITEM R I 3 15PUTRETAIN 4
A 61 ERRMSG('Invalid Item Number' 61) 5
A R RESPONSE TEXT('Response Format')
A OVERLAY 2
A LOCK 6
A 5 2'Description'
A DESCRP R 5 15
A 5 37'Price'
A PRICE R 5 44
A 7 2'Warehouse Location' 7
A WHSLOC R 7 22
A 9 2'On Hand'
A ONHAND R 9 10
A 9 19'Allocated' 8
A ALLOC R 9 30
A 9 40'Available'
A AVAIL R 9 51
A*
This display device file contains two record formats: PROMPT and
RESPONSE.
- 1
- The attributes for the fields in this file are defined in the
DSTREF field reference file.
- 2
- The OVERLAY keyword is used so that both record formats can
be used on the same display.
- 3
- Function key 3 is associated with indicator 98, which is used
by the programmer to end the program.
- 4
- The PUTRETAIN keyword allows the value that is entered in the
ITEM field to be kept in the display. In addition, the ITEM field
is defined as an input field by the I in position 38. ITEM is the
only input field in these record formats. All of the other fields
in the record are output fields since position 38 is blank for each
of them.
- 5
- The ERRMSG keyword identifies the error message that is displayed
if indicator 61 is set on in the program that uses this record format.
- 6
- The LOCK keyword prevents the work-station user from using the
keyboard when the RESPONSE record format is initially-displayed.
- 7
- The constants such as ‘Description’, ‘Price’,
and ‘Warehouse Location’ describe the fields that are written
out by the program.
- 8
- The line and position entries identify where the fields or constants
are written on the display.
[ Top of Page | Previous Page | Next Page | Contents |
Index ]