The talk will cover the use of decision tables in a variety of programming languages and software products and follow the development from simple Condition/Action tables to those with Initial Action and Multi-condition sections. This will include a brief history of the use of decision tables in IT from the 1970’s to present day. Table structures and rule formats used will be shown. The speaker will cover the topics of rule redundancy, rule reduction and optimisation as well as bit masking techniques for runtime evaluation, and demonstrate the importance of relevance testing. Examples of code will be used to show shortcut compact coding techniques and comparison with simple truth logic. There will be an explanation of the benefits and downsides of tools which use interpretive execution of decision table logic and those which use tokenised or fully compiled execution. Examples of program code and complex logic coding will be given and comparison made with “conventional” programming languages, which will demonstrate that Decision Tables can be used not just as visual representations of complex logical processing but also as a practical and efficient programming tool. A summary of current programming and application development tools which use decision tables will be given, and the speaker will discuss future developments and techniques that will allow decision table structured and expressed logic to be incorporated in other programming languages.

1. rapidgen.com
Howard Rogers
Director Technical Support
howard.rogers@rapidgen.com
Decision Tables as a Programming tool

2. rapidgen.com
Agenda
•A brief history
•Decision table structures
•Rule formats
•Rule redundancy, reduction and optimisation
•Relevance testing
•Some practical examples
•Current examples of use
•Future developments
•Questions and Answers
2

3. rapidgen.com
Speaker
•Statistics & Operation Research
•UK National Health Service
•35 years IT
•Decision table based languages and compilers
•Query & reporting tools
•Generic file & database access
•Brief interlude with RTPI
•Technical support
3

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History
•NASA
•Morgan Crucible – LITA – List &Tabulate
•TABN for ICL 1900 series mainframes
•(DE)TAB-360 for IBM System/360
•UNITAB for UNIVAC
•HTAB for Honeywell
•TAB-11 for RSTS/E on PDP-11
•FTL6/DTPL for ICT 1900 series
•RPL-11 for RT-11, RSTS/E, RSX-11 on PDP-11
•RPL-3 for IBM System/3
•Filetab-D for x86 and PDP-11, OpenVMS VAX
•FPL - IBM PCs and compatibles.
•RPL, Rapid-Expert and expertGenius extended syntax for Microsoft Windows, Unix, Linux and OpenVMS,VAX, Alpha & Itanium
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History
•Excel – query tables
•COPE – Translate DTs to COBOL
•LogicGEM – Translate to BASIC,C, C++, FORTRAN, Pascal etc etc
•CCIDE – Pre-processor for BASIC, JAVA, CC, C++, BASH, QB, VB, and EX(euphoria)
•Silk (Simple In-line Logic Kompiler) converting decision tables to Cobol code and vice versa.
•PASPREP – Pascal preprocessor
•Many many others
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Decision table structure
•Conditions
•Actions
•Condition rules
•Action rules
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Single Condition Decision Table
Condition Stubs
Rules
Action Stubs
Actions
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Quantity > 100
Y N
Apply 20% Discount
X -

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Decision Tables Horizontal vs Vertical
Condition Stubs
Action Stubs
Rules
Actions
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Quantity > 100
Apply 20% Discount
Y
N
X
-

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Multiple Single Decision Table
Condition Stubs
Rules
Action Stubs
Actions
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Quantity > 100
Y Y N N
Cash payment
Y N Y N
Apply 20% Discount
X - - -
Apply 10% Discount
- X - -
Apply 5% Discount
- - X -
No discount
- - - -

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Multiple Condition DTs
10
•Complete True/False Y N require 2^Conditions rules
•3 Conditions – 8 rules
•4 Conditions – 16 rules
•etc
•Use of “-” to reduce completeness
•Practical limit 32

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Five Conditions – One rule
11
Initially no discount
Quantity > 100
Y -
Cash payment
Y -
Credit_check
Y -
Product type is laptop
Y -
Employee
N -
Apply 5% Discount
X -

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Multiple Section Decision Table
12
Quantity > 100
Y Y N N
Cash payment
Y N Y N
Apply 20% Discount
X - - -
Apply 10% Discount
- X - -
Apply 5% Discount
- - X -
No discount
- - - -
Discount_amount < $1
Y -
No discount
X -
Discount amount > $1000
Y -
Set discount $1000
X -

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Simplifying Decision Tables 1
13
1 2 3 4 5 6 7 8
Credit limit exceeded
Y Y Y Y N N N N
Cash payment
Y Y N N Y Y N N
Special clearance
Y N Y N Y N Y N
Accept order
X X X - X X X X
Reject Order
- - - X - - - -

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Simplifying Decision Tables 2
14
1&2 3 4 5 6 7 8
Credit limit exceeded
Y Y Y N N N N
Cash payment
Y N N Y Y N N
Special clearance
- Y N Y N Y N
Accept order
X X - X X X X
Reject Order
- - X - - - -

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Simplifying Decision Tables 3
15
1&2 3 4 5&6 7&8
Credit limit exceeded
Y Y Y N N
Cash payment
Y N N Y N
Special clearance
- Y N - -
Accept order
X X - X X
Reject Order
- - X - -

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Simplifying Decision Tables 4
16
1&2 3 4 567&8
Credit limit exceeded
Y Y Y N
Cash payment
Y N N -
Special clearance
- Y N -
Accept order
X X - X
Reject Order
- - X -

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Simplifying Decision Tables 5
17
4 123567&8
Credit limit exceeded
Y ELSE
Cash payment
N -
Special clearance
N -
Accept order
- X
Reject Order
X -

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Optimising Decision Tables
18
1 2 3 4 5 6 7 8
Credit limit exceeded
Y Y Y Y N N N N
Cash payment
Y Y N N Y Y N N
Special clearance
Y N Y N Y N Y N
Accept order
X - X - X X X X
Reject Order
- X - X - - - -
2&4 123567&8
Credit limit exceeded
Y ELSE
Special clearance
N -
Accept order
- X
Reject Order
X -

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ELSE Rule
19
4 123567&8
Credit limit exceeded
Y ELSE
Cash payment
N -
Special clearance
N -
Accept order
- X
Reject Order
X -

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Simplifying Decision Tables – Extended entry
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TRANSKEY GT MASTKEY
Y - - - ELSE
TRANSKEY EQ MASTKEY
- Y Y - -
TRANSKEY LT MASTKEY
- - - Y -
TRANSTYPE = “I”
- - - Y -
TRANSTYPE = “D”
- - Y - -
TRANSTYPE = “A”
- Y - - -
CALL PROCESS_MATCH
- X - - -
CALL PROCESS_MISS
- - X - -
CALL PROCESS_ADD
- - - X -
CALL NEXT_TRANS
- X X X -
CALL NEXT_MAST
X X X - -
REPEAT
X X X X -

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Simplifying Decision Tables – Extended entry
21
TRANSKEY ? MASTKEY
> = = < ELSE
TRANSTYPE = “?”
- A D I -
CALL PROCESS_?
- MATCH MISS ADD -
CALL NEXT_TRANS
- X X X -
CALL NEXT_MAST
X X X - -
REPEAT
X X X X -

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Ambiguity or Multi-ruling?
22
Set discount
Initialise DISCOUNT_PERC
Cash payment
Y - - -
Special offer
- Y - -
Good credit history
- - Y -
DISCOUNT_PERC + ?
5 10 2 -

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Code generation 1
23
|--------------------------------------------------|
|--------------------------------------------------|
|# |STATEMENT 1 2 3 4 5 6 7 8 |
|--------------------------------------------------|
|C1 |Cash payment |y |y |y |y |n |n |n |n |
|C2 |Special offer |y |y |n |n |y |y |n |n |
|C3 |Good credit history |y |n |y |n |y |n |y |n |
|==================================================|
|A1 |Discount initialise | | | | | | | | |
|A2 |Discount + 5 |X |X |X |X | | | | |
|A3 |Discount + 10 |X |X | | |X |X | | |
|A4 |Discount + 2 |X | |X | |X | |X | |
|--------------------------------------------------|

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Generation – Nested If/else 1
24
{
if ((Cash payment)) {
if ((Special offer)) {
if ((Good credit history)) {
/* rule 1 */
Discount + 5;
Discount + 10;
Discount + 2; }
else {
/* rule 2 */
Discount + 5;
Discount + 10; }
}
else {
if ((Good credit history)) {
/* rule 3 */
Discount + 5;
Discount + 2; }
else {
/* rule 4 */
Discount + 5;
}
}
}
else {

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Generation – Nested If/else 2
25
if ((Special offer)) {
if ((Good credit history)) {
/* rule 5 */
Discount + 10;
Discount + 2;
}
else {
/* rule 6 */
Discount + 10;
}
}
else {
if ((Good credit history)) {
/* rule 7 */
Discount + 2;
}
else {
/* rule 8 */
}
}
}
}

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Generation – Case Switch 1
26
{
if ((Cash payment)) {
if ((Special offer)) {
if ((Good credit history)) {
rule_number = 1;
}
else {
rule_number = 2;
}
}
else {
if ((Good credit history)) {
rule_number = 3;
}
else {
rule_number = 4;
}
}
}

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Generation – Case Switch 2
27
else {
if ((Special offer)) {
if ((Good credit history)) {
rule_number = 5;
}
else {
rule_number = 6;
}
}
else {
if ((Good credit history)) {
rule_number = 7;
}
else {
rule_number = 8;
}
}
}

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Generation – Case Switch 3
28
switch (rule_number) {
case 1:
Discount + 5;
Discount + 10 ;
Discount + 2;
break;
case 2:
Discount + 5;
Discount + 10;
break;
case 3:
Discount + 5;
Discount + 2;
break;
case 4:
Discount + 5;
break;

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Generation – Case Switch 4
29
case 5:
Discount + 10;
Discount + 2;
break;
case 6:
Discount + 10;
break;
case 7:
Discount + 2;
break;
case 8:
break; }

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Generation – Rule List 1
30
{
if ( ((Cash payment)) &&
((Special offer)) &&
((Good credit history)) ) {
Discount + 5; Discount + 10; Discount + 2;
}
if ( ((Cash payment)) &&
((Special offer)) &&
(!(Good credit history)) ) {
Discount + 5; Discount + 10;
}
if ( ((Cash payment)) &&
(!(Special offer)) &&
((Good credit history)) ) {
Discount + 5; Discount + 2;
}
if ( ((Cash payment)) &&
(!(Special offer)) &&
(!(Good credit history)) ) {
Discount + 5;
}

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Generation – Rule List 2
31
if ( (!(Cash payment)) &&
((Special offer)) &&
((Good credit history)) ) {
Discount + 10; Discount + 2;
}
if ( (!(Cash payment)) &&
((Special offer)) &&
(!(Good credit history)) ) {
Discount + 10;
}
if ( (!(Cash payment)) &&
(!(Special offer)) &&
((Good credit history)) ) {
Discount + 2;
}
if ( (!(Cash payment)) &&
(!(Special offer)) &&
(!(Good credit history)) ) {
}
}

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Generation – Rule Mask
32
{Mask = 11111111
{if ( Cash payment)
Mask AND 11110000;
}
{if ( Special Offer)
Mask AND 11001100;
}
{if (Good credit history)
Mask AND 10101010;
}
{if (Mask AND 11110000)
Discount + 5 ;
}
if (Mask AND 11001100)
Discount + 10;
}
if (Mask AND 10101010)
Discount + 2;
}

33. rapidgen.com
Rule masking
33
•Succinct code
•Reduces repetition of condition testing
•Reduced repetition of action code
•Fast execution
•No frequency/cost weighting of rules needed
• All conditions are evaluated

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Relevance Testing
34
AGE > 50
Y - -
CALL ADJUST_COVER
Y - -
TRANSKEY LT MASTKEY
- Y -
LOOKUP MASTER TRANSKEY
- Y -
Some operations require dynamic masking where actions may be performed or I/O occurs

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Relevance Testing
35
AGE > 50
Y - -
COVER + 20
R - -
TRANSKEY LT MASTKEY
- Y -
DISPLAY “Message”
- R -
Dynamic masking again needed when Actions are inserted into condition section of Decision Table using “R”

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Decision table linkage
36
CALLs to other DTs or object library routines
CALL Credit_limit_exceeded
Y ELSE
CALL Cash_payment
N -
CALL Special_clearance
N -
CALL ACCEPT_ORDER
- X
CALL REJECT_ORDER
X -
GOTO link to DT or indirect CALL
CALL Credit_limit_exceeded
Y ELSE
CALL Cash_payment
N -
CALL Special_clearance
N -
GOTO ACCEPT_ORDER
- X
CALL_I Variable_name
X -

37. rapidgen.com
Requirements of a DT language
•Feature rich language
•Support for multiple data types
•Unmatched data type comparison
•Good string handling/text manipulation
•Access external routines/library functions
•File, database, object and data dictionary
•Callable access from other products
•Source code maintenance, version control
•Compiled and portable execution
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Decision Tables in other products
•Uses GUI in SAP HANA Studio
•SAP Parameter/Database DTs
•Alternate use via Excel spreadsheets
•SMARTS
•OpenRules Engine
•Decision First Modeler
•Drools
•Many more …
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39. rapidgen.com
Usage of RPL - expertGenius
•Self compiling
•Cross compiling
•Source of Genius Suite
•Code writing and compiling 4GL and RAD toolset
•Complete layered application suites
•Reporting – fixed logic
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Genius deployment
•Aerospace factory tracking systems
•Mobile phone billing systems
•Payroll data mining
•HR system ad-hoc querying
•Newspaper distribution system
•Stock control
•Sales order dashboard & EIS
•Web based on-line parts ordering
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CDT Callable Decision Tables
•Simple calculator
•Calculator code
•Tax formula (UK)
•Tax calculator
•Tax code
•CDT Callable access from other languages and applications
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Future developments
•Extend range of generic database access
•Ports to new architectures
•Macro expansions for FEEL or S-FEEL
•GUI extensions
•CDT Callable access from other languages and applications
•Cloud based compiler
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43. rapidgen.com
Questions
?
43

44. rapidgen.com
Howard Rogers
Director Technical Support
howard.rogers@rapidgen.com
howard.rogers@rapidgen.co.uk
Decision Tables as a Programming tool

45. rapidgen.com
Filetab
•DEcision TABle-based computer programming language.
•Long history originating in late 1960s
•Developed by the UK National Computing Centre (NCC)
•Originally used on ICL OS such as GEORGE 2/3 and VME,
•Ported to a large number of others.
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Filetab
•Original architect - Tom Barnard, who developed the program (LITA - LIst and TAbulate) for Morgan Crucible on an ICL 1902 from 1965–1968. Original purpose was to produce simple ad hoc reports with a plugboard on a punched card tabulator, replaced PLAN assembly language.
•80 column card based parameters
•Reporting tool specifying input and output formats, headings, sequencing and totalling.
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RapidGen Solutions
RapidGen solves tough integration problems for OpenVMS customers
• A variety of flexible options available
–Analyse and provide ‘Customised Solutions’
–Future Proofing options with RapidGen
• In-depth Legacy expertise
• Services + Software
–OpenVMS to Linux Migration Routines
•Databases and Porting
•Data Structures migration
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What Customers Tell Us
Want to preserve, modernize or replace
• Total cost of ownership
• Risk, flexibility
…but difficult
• Bespoke or end-of-life applications
• Custom interfaces issues
• Skills shortage becoming more evident
• Application Changes not permitted
–E.g. Aerospace, Defence, Nuclear, Utilities
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Customers Want Flexibility They Need Options
Choices
1.Update OpenVMS
–Until end of 2015
2.Modernise
–Translate data
–Translate logic
–Redefine logic in 4GL
–Redevelop
–Seamless Transition
3.Emulation Options
–Reduce Operating Costs
–Suitable for some
Want
•Proceed in stages
–Reduces risk
•Integration
–Legacy ↔ Modern
•Portability
–Future-proof
•Cost-effective Solutions
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HP Forward-looking statements
Published Jan 2014
This is a rolling (up to three year) roadmap and is subject to change without notice.
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HP Forward-looking statements
51

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Example of HANA parameter DT
QUANTITY
ORDER_AMOUNT
DISCOUNT
<=2000
>10000
10
<=10000
5
>2000
>10000
15
<=10000
10
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Example of HANA Database DT
MANUFACTURER
MODEL_CLASS
QUANTITY
DISCOUNT
Sprongal
Handset
>5
25
<=5
10
Notebook
>5
15
<=5
10
Pruckman
Tablet
>5
15
<=5
8
Range Extender
>5
10
<=5
5
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HP Forward-looking statements
54

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Genius Supported Platforms
55
Operating System
Platforms
Min. Version
OpenVMS
VAX
5.6
OpenVMS
Alpha
6.1
OpenVMS
Integrity / Itanium
*
Tru64
Alpha
4.0
HP-UX
HP PA
9.x
Windows
Intel/AMD 32/64
2000
Linux
•Red Hat, Debian, SUSE, Ubuntu, Fedora, Knoppix, Gentoo etc
Intel/AMD 32/64
2.6.18 kernel

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Genius Supported File Types & Databases
56
OpenVMS
Tru64
Windows
Linux
RMS Indexed
✔
via TCP/IP
via TCP/IP
ISAM
✔
✔
✔
✔
Oracle RDB
•via DSRI
✔
Oracle
•via OCI
✔
✔
✔
✔
DBMS-32
•Codasyl
✔
Generic ODBC
•SQL Server
•MySQL
•PostgreSQL
•…others on request
✔
✔
Ingres
•Low-level API
✔
✔
✔

57. rapidgen.com
• Howard Rogers
• Jolyon Cox
QUESTIONS

58. rapidgen.com
Howard Rogers
howard.rogers@rapidgen.com
Tel: +44 (0) 1732 850081
Mob: +44 (0) 7734 962855
Providing Solutions and Options For OpenVMS Customers
RapidGen Offices
Info@RapidGen.com
Tel: +44 (0) 207 630 9291

59. rapidgen.com
About RapidGen
•Integrating and modernizing legacy IT systems for over 30 years
•Specialise in OpenVMS and Tru64
•Software is Powered by the ‘Genius’ Suite
•Our USP Unique Selling Point – Decision Tables =
–Rapid Development Turnaround
–Providing Cost Effective Solutions
–Applications Future Proofing
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60. rapidgen.com
Customers in EMEA include