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Chapter 8

Interactive Applicatons

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Batch Processing: Program is run without

human intervention or control.

Interactive Processing: User driven

Display files are needed for interaction.

Screen Design Aid (SDA): Graphical utility that

will generate DDS source code.

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You can have multiple record formats per

DDS member.

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Section Inquiry

Type value, then Enter.

Section number . . ____________

F3=Exit

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Section Information

Section number . . . . . 12435

Course . . . . . . . . . BIS350

Instructor . . . . . . . . Johnson

Room . . . . . . . . . . 1120

Meets on days . . . . . . MWF

Starting Time . . . . . . . 10:30

Enrollment . . . . . . . . 36

Press Enter to Continue

F3=Exit F12=Cancel

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AAN01N02N03T.Name++++++RLen++TDpBLinPosFunctions+++++++++++++++++

********** Beginning of data ************************************

A REF(SECTIONS)

A INDARA

A R SECT1

A CA03(03 'F3=EXIT')

A 1 28'SECTION INQUIRY'

A 3 2'TYPE VALUE, THEN ENTER.'

A 5 5'SECTION NUMBER . .'

A SECTION 5A I 5 24

A 23 2'F3=EXIT'

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AAN01N02N03T.Name++++++RLen++TDpBLinPosFunctions++++++++++++++++++

A R SECT2A CA03(03 'F3=EXIT')

A CA03(12 'F12=CANCEL')

A 1 10'SECTION INFORMATION'

A 3 2'SECTION NUMBER . . .'

A SECTNO R O 3 29

A 3 2'COURSE . . . . . . .'

A COURSE R O 4 29

A 5 2'INSTR . . . . . . .'

A INSTR R O 5 29

A 6 2'ROOM . . . . . . .'

A ROOM R O 6 29

A 7 2'MEETS ON DAYS . . .'

A DAYS R O 7 29

A 8 2'STARTING TIME . . .'

A BEGTIME R O 8 29A 9 2'ENROLLMENT . . . . .

A ENROLL R O 9 29

A 21 2'PRESS ENTER TO CONTINUE'

A 23 2'F3=EXIT'

A 23 11'F12=CANCEL'

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CA03(03 F3=EXIT)

CA: Command Attention, enables the

function key of F3. Returns control to RPGprogram without passing user input values.

When F3 is pressed by the user, indicator 03

is turned on.

F3=EXIT: Programmer comment.

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CF03(03 F3=EXIT)

CF: Command Function

Functions the same as CA03 except that thevalues the user has inputted are passedback to the RPG program.

CA12(12 F12=Cancel) Generally used to move the user back a

screen.

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Display files are defined in File Specs just likeany other file. Full Procedural

Externally defined

Key is not relevant (position 34 blank)

type (position 17) is C for combined file, supportsboth input and output but as independentoperations.

Optional keyword INDDS: Stores indicators passedto and from display file in data structure namedFkeys.

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Interactive programs are prone to

spaghetti code.

flow of control is not straight forward User can press F3 to Exit or F12 to Cancel

Causes programmer to back up, repeat or exit

early.

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WHILE user wants to continue (no Exit)

Display first screen

Obtain users response to the screen

IF user wants to continue (no exit)

Random read section file to get section information

IF record found

Display second screen

Obtain users response

ENDIF

ENDIF

ENDWHILE

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WHILE user wants to continue (no Exit) (*IN03 = *OFF)

Display first screen (EXFMT Sect1)

Obtain users response to the screen

IF user wants to continue (no exit) (IF *IN03 = *OFF)

Random read section file to get section information

(Section CHAIN Sections)

IF record found (IF %FOUND(Sections)

Display second screen (EXFMT Sect2)

Obtain users response

ENDIF

ENDIF

ENDWHILE

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Allowable functions for I/O

WRITE: Displays a screen and returns control to

program without waiting for user input.

READ: Sends control to currently displayed screenwaits for end of user input (usually triggered by

Enter key)

EXFMT: Combines WRITE/READ, first writes a

record to the screen and then waits for user input tothe screen, when signaled it returns control to RPG

program. USED MOST OFTEN!

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RPG IV gets away from referencingindicators

Must specify INDDS keyword in F Spec.

Indicator Data Structure in DDS (INDARA)

Define data structure in D Spec to contain

indicators.

Only have to define the ones you are using.

D FKeys DS 99

D Exit 3 3N

D Cancel 12 12N

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CL0N01Factor1+++++++Opcode&ExtExtended-factor2+++

C DOW NOT Exit

C EXFMT Sect1

C IF NOT Exit

C Section CHAIN Sections

C IF %FOUND(Sections)

C EXFMT Sect2C ENDIF

C ENDIF

C ENDDO

C EVAL *INLR = *ON

C RETURN

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File Level: Must be on first line of DDS, before Record Format

REF: reference another file for specifications

INDARA: organize indicators into 99-byte datastructure

MSGLOC: specifies message line for errormessages (default is last line, 24)

File or Record Level: CA or CF: coded at file level they will apply to all

record formats within the file PRINT: enables Print Key for user screen printing.

VLDCMDKEY: turns on indicator when userspresses any valid command key

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Record Level:

Appear on line record is named or lines

immediately following, prior to field names. BLINK: causes cursor to blink

OVERLAY: Display record without clearing

previous record display.

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Field Level:

Apply only to specific field it is associated.

EDTCDE, EDTWRD: format numeric output DSPATR: Display Attribute, determines

appearance. (BL blinking field, UL

underline)

DSPATR(BL UL)

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Field Level: Data Validation VALUES: Specify exact values allowed.

VALUES(value1 value2 . . .)

RANGE: Specify range of values allowed.

RANGE(low-value high-value) COMP: Relational comparison with inputted value

(EQ,NE,GT,NG,LT,NL,GE,LE): COMP(GT 100)

CHECK: Validity checking (ME, MF, AB)

CHECK(Validity code) ERRMSG:

TIME and DATE

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Conditioning Indicators:

Field Keyword will only apply if conditioning

indicator is turned on by the RPG program.

AAN01N02N03T.Name++++++RLen++TDpBLinPosFunctions++++++++++++++++++

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AAN01N02N03T.Name++++++RLen++TDpBLinPosFunctions++++++++++++++++++

********** Beginning of data *************************************

A REF(SECTIONS)

A PRINT

A INDARA

A R SECT1

A BLINK

A CA03(03 'F3=EXIT')

A 1 28'SECTION INQUIRY'A 3 2'TYPE VALUE, THEN ENTER.'

A 5 5'SECTION NUMBER . .'

A SECTION 5A I 5 24

A DSPATR(UL)

A DSPATR(HI)

A ERRMSG('SECTION NOT FOUND 90)

A 23 2'F3=EXIT'

A

A R SECT2A CA03(03 'F3=EXIT')

A CA03(12 'F12=CANCEL')

A 1 10'SECTION INFORMATION'

A 3 2'SECTION NUMBER . . .'

A SECTNO R O 3 29

A 3 2'COURSE . . . . . . .'

A COURSE R O 4 29

A 5 2'INSTR . . . . . . .'

A INSTR R O 5 29

A 6 2'ROOM . . . . . . .'

A ROOM R O 6 29EDTCDE(Z)

A 7 2'MEETS ON DAYS . . .'

A DAYS R O 7 29

A 8 2'STARTING TIME . . .'

A BEGTIME R O 8 29EDTWRD(' 0: ')

A 9 2'ENROLLMENT . . . . .'

A ENROLL R O 9 29EDTCDE(3)

A 21 2'PRESS ENTER TO CONTINUE'

A 23 2'F3=EXIT'

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DFKeys DS

D Exit 3 3N

D Cancel 12 12N

D SectNotFnd 90 90N

C DOW NOT ExitC EXFMT Sect1

C IF NOT Exit

C Section CHAIN Sections

C EVAL SectNotFnd = NOT %FOUND(Sections)

C IF %FOUND(Sections)

C EXFMT Sect2

C ENDIF

C ENDIF

C ENDDO

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Adding, changing or deleting records

instantly.

Must verify data validity Three methods of safeguarding

Validation Keywords in PF description

Validation Keywords in Display file description

Validating values in program