Systems analysis and development CIS210 ch 08

CIS 210
Systems Analysis
and Development
Week 4 Part II
Structuring System
Logic Requirements


Objectives
• Upon completion of part II you will be able to:
– Understand and be able to explain the concepts
related to using Structured English as a tool for
representing steps in logical processes in data flow
diagrams
– Understand and be able to explain the concepts
related to decision tables and decision trees
– Understand and be able to explain the concepts
related to logical modeling


Overview
• Modeling Process Decision Logic
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–
–
–

Structured English
Decision Tables
Decision Trees
Criteria for choosing logic modeling techniques

Logic Modeling
• Overview
– Internal structure
– Functionality of processes
– Analysis phase

• Modeling a System’s Logic
– Requirements structuring

• Deliverables and Outcomes
– Structured descriptions
– Diagrams outlining logic
– New entries


Structured English
• Conditional Statements
BEGIN IF
IF Quantity-in-stock is less than Minimum-order-quantity
THEN GENERATE new order
ELSE DO nothing

END IF

• Repetition Statement
DO
READ Inventory records
BEGIN IF

IF Quantity-in-stock is less than Minimum-order-quantity
THEN GENERATE new order
ELSE DO nothing

END IF

UNTIL End-of-file


Decision Tables
• Overview
– Better for complicated logic
– Tabular form

• Components
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–
–
–

Condition stubs
Action stubs
Rules
Procedures to follow


Decision Trees
• Overview
– Depicts a decision or choice situations
– Nodes and branches

• Components
– Decision points
– Actions
– Rules


Making a Decision


Summary
•
•
•
•
•
•

Modeling process decision logic
Deliverables and outcomes of logic modeling
Structured English
Decision tables
Decision trees
Choosing amount decision logic methods