ILE RPG Programmer's Guide


Using Externally Described WORKSTN Files

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:

A display-device-record format contains three types of fields:

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.

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