CHAPTER 9: Structuring System Requirements: Logic Modeling Logic Modeling 1.1 MSIS 5653 Advanced...

CHAPTER 9:CHAPTER 9:Structuring System Requirements:Structuring System Requirements:

Logic ModelingLogic Modeling

1.11.1

MSIS 5653MSIS 5653Advanced Systems DevelopmentAdvanced Systems Development

Dursun Delen, Ph.D.Dursun Delen, Ph.D.Department of ManagementDepartment of ManagementOklahoma State UniversityOklahoma State University

D. Delen MSIS 5653 – Advanced Systems Development

Learning ObjectivesLearning Objectives Use Structured English as a tool for

representing steps in logical processes in data flow diagrams

Use decision tables and decision trees to represent the logic of choice in conditional statements

Select among Structured English, decision tables, and decision trees for representing processing logic

9.29.2


Structuring System Requirements Structuring System Requirements in SDLCin SDLC


Logic ModelingLogic ModelingWhat is the purpose of Logic Modeling?

Data flow diagrams do not show the logic inside the processes

Logic modeling involves representing internal structure and functionality of processes depicted on a DFD

Logic modeling can also be used to show when processes on a DFD occur

9.49.4

What is the purpose of Logic Modeling?


Logic ModelingLogic ModelingDeliverables and Outcomes

Structured English Decision Tables Decision Trees State-transition diagrams Sequence diagrams Activity diagrams

9.59.5


Modeling Logic with Modeling Logic with Structured EnglishStructured English

Modified form of English used to specify the logic of information processesNo specific standardsUses a subset of English

Action verbs Noun phrases No adjectives or adverbs

It can be used to represent all three process types of structured programming

Sequence, Conditional Statement and Repetition

9.69.6


Modeling Logic with Modeling Logic with Structured EnglishStructured English

Similar to programming language If conditions Case statements Do-Until, While-do loops

Example:BEGIN IF

IF Quantity-In-Stock is LESS THAN Minimum-Order-QuantityTHEN GENERATE New-OrderELSE DO nothing

END IF

Structured English vs. Pseudo Code 9.79.7


Example: Example: Hoosier Burger’s Inventory SystemHoosier Burger’s Inventory System

Process 1.0: Update Inventory AddedDO

READ next Invoice-item-recordFIND matching Inventory-recordADD Quantity-added

UNTIL End-of-file

Process 2.0: Update Inventory UsedDO

READ next Stock-item-recordFIND matching Inventory-recordSUBTRACT Quantity-used

UNTIL End-of-file

Process 3.0: Generate OrdersDO

READ next Invoice-item-recordBEGIN IF

If Qty-in-stock LESS THAN Min-order-qty THEN GENERATE

END IFUNTIL End-of-file

Process 4.0: Generate PaymentsREAD Today’s-dateDO

SORT Invoice-records by DateREAD next Invoice-recordBEGIN IF

IF Date is 30 days or greater THEN GENERATE Payment

END IFUNTIL End-of-file


Modeling Logic withModeling Logic with Decision Tables Decision Tables

A matrix representation of the logic of a decision

Specifies the possible conditions and the resulting actions

Best used for complicated decision logic

Consists of three parts Condition stubs

Lists condition relevant to decision Action stubs

Actions that result from a given set of conditions Rules

Specify which actions are to be followed for a given set of conditions

9.99.9


Modeling Logic withModeling Logic withDecision TablesDecision Tables

9.109.10

Example: Payroll System


Modeling Logic withModeling Logic with Decision Tables Decision Tables

Indifferent Condition Condition whose value does not affect which

action is taken for two or more rules

Standard procedure for creating decision tables

Step 1: Name the condition and all values each condition can assume

Step 2: Name all possible actions that can occurStep 3: List all rulesStep 4: Define the actions for each ruleStep 5: Simplify the table

9.119.11


Example: Example: Hoosier Burger’s Inventory SystemHoosier Burger’s Inventory System


Modeling Logic with Modeling Logic with Decision TreesDecision Trees

A graphical representation of a decision situation

Consists of nodes, arcs and ovals

Each node corresponds to a choice

All possible actions are listed on the far right with ovals

Nodes and Ovals are connected with arcs

Should be read from left to right9.149.14


Example: Example: A Generic Decision TreeA Generic Decision Tree

D. Delen MSIS 5653 – Advanced Systems Development9.169.16

Example: Payroll SystemExample: Payroll System


Deciding Among Structured English, Deciding Among Structured English, Decision Tables and Decision TreesDecision Tables and Decision Trees

CriteriaStructured

EnglishDecision Tables

Decision Trees

Determining Conditions and Actions

Second Best Third Best Best

Transforming Conditions and Actions into Sequence

Best Third Best Best

Checking Consistency and Completeness

Third Best Best Best

9.179.17


Deciding Among Decision Tables Deciding Among Decision Tables and Decision Treesand Decision Trees

9.189.18


SummarySummarySeveral methods of logic modeling

Structured English Primarily communication technique for analysts and users

Decision Tables Conditions are listed in condition stubs Possible actions are listed in action stubs Rules link conditions with actions Lists all possible rules

Decision Trees Conditions are portrayed by decision points Values are represented by paths between decision points and

ovals that contain actions

Comparison of Structured English, Decision Tables and Decision Trees

9.199.19


Problem 9.1 – 8Problem 9.1 – Page 198

Figure 9.5 – Page 298


Problem 9.5Problem 9.5Represent the logic of the given scenario by using:

Structured English Decision Table Decision Tree


Problem 9.5 – Structured EnglishProblem 9.5 – Structured EnglishBEGIN IF

IF Purchase-amount is greater than $15,000.00THEN Purchasing–Department APPROVES RFP

DO Bid ProcessELSEPurchasing-Department APPROVES Purchase

PURCHASE equipmentEND IFRETURN

(Bid Process)SEND RFPBEGIN IF

IF three Proposals receivedAND Winning-Vendor is APPROVEDAND no Violations

THEN AWARD contractPURCHASE equipment

ELSE DO Rebid ProcessEND IFRETURN

(Rebid Process)SEND RFPBEGIN IF

IF Winning-Vendor is APPROVED by PurchasingAND no Violations

THEN AWARD contract PURCHASE equipment

END IFISSUE Purchase OrderRETURN


Problem 9.5 – Decision TableProblem 9.5 – Decision Table


Problem 9.5 – Decision TreeProblem 9.5 – Decision Tree

1

1. Is purchase greater than $15,000?2. Is the vendor approved by Purchasing Department?

Y

N2

Find another approved vendor

Y

N

Issue purchase order, purchase equipment

Award contract to other approved vendor

Y

N

Award contract to winning vendor, issue purchase order, purchase equipment

2


Homework Assignment #4Homework Assignment #4Solve the following problems: Problem 13 in Chapter 8

HINT: You may combine the “review of prescription orders by stations” in a single process (as opposed to three separate processes).

Problem 9 in Chapter 9 HINT

In Structured English section you are to calculate commission and bonus for sales reps

In Decision Table and Decision Tree sections you can limit your answer to calculating sales commission only

Assignments Assignments should be typedshould be typed, , professionally organizedprofessionally organized, , and and should have a cover pageshould have a cover page..

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