Send and receive data with a display file

The only commands you can use with a display file to send or receive data in CL procedures and programs are the Send File (SNDF), Receive File (RCVF), and Send/Receive File (SNDRCVF) commands.

The system formats the content of the variables associated with the output or output/input fields in the record format when you run a Send File (SNDF) command. Additionally the system sends it to the display device. This is similar to when you run a Receive File (RCVF) command. The values of the fields associated with input or output/input fields in the record format on the display are placed in the corresponding CL variables.

The Send/Receive File (SNDRCVF) command sends the contents of the CL variables to the display. The command then performs the equivalent of a RCVF command to obtain the updated fields from the display. Note that CL does not support zoned decimal numbers. Consequently, fields in the display file that are defined as zoned decimal, cause *DEC fields to be defined in the CL procedure or program. *DEC fields are internally supported as packed decimal, and the CL commands convert the packed and zoned data types as required. Fields that overlap in the display file because of coincident display positions result in separately defined CL variables that do not overlap. You cannot use record formats that contain floating point data in a CL procedure or program.

Note: If a Send/Receive File (SNDRCVF) or Receive File (RCVF) command for a workstation indicates WAIT(*NO), then the system uses the WAIT command to receive data. The same is true if a Send File (SNDF) command is issued using a record format containing the INVITE DDS keyword.

Except for message subfiles, any attempt to send or receive subfile records causes run-time errors. Most other functions specified for display files in DDS are available; some functions (such as using variable starting line numbers) are not.

The following example shows the steps required to create a typical operator menu and to send and receive data using the Send/Receive File (SNDRCVF) command. The menu looks like this:

 Operator Menu
 
   1. Accounts Payable
   2. Accounts Receivable
   90. Signoff
 
 Option:

First, enter the following DDS source. The record format is MENU, and OPTION is an input-capable field. The OPTION field uses DSPATR(MDT). This causes the system to check this field for valid values even if the operator does not enter anything.

|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
     A          R MENU
     A                                  1  2'Operator Menu'
     A                                  3  4'1. Accounts Payable'
     A                                  5  4'2. Accounts Receivable'
     A                                  5  4'90. Signoff'
     A                                  7  2'Option'
     A            OPTION         2Y 01   + 2VALUES(1 2 90) DSPATR(MDT)
     A
     A

Enter the CRTDSPF command to create the display file. In CL programming, the display file name (INTMENU) can be the same as the record format name (MENU), though this is not true for some other languages, like RPG for i5/OS™.

The display file could also be created using the Screen Design Aid (SDA) utility.

Next, enter the CL source to run the menu.

The CL source for this menu is:

         PGM /* OPERATOR MENU */
         DCLF INTMENU
BEGIN:   SNDRCVF RCDFMT(MENU)
         IF COND(&OPTION *EQ 1) THEN(CALL ACTSPAYMNU)
         IF COND(&OPTION *EQ 2) THEN(CALL ACTSRCVMNU)
         IF COND(&OPTION *EQ 90) THEN(SIGNOFF)
         GOTO BEGIN
         ENDPGM

When this source is compiled, the DCLF command automatically declares the input field OPTION in the procedure as a CL variable.

The Send/Receive File (SNDRCVF) command defaults to WAIT(*YES); that is, the program waits until input is received by the program.