Module 4
Systems and Process Design:
• Requirements Gathering
• Requirement Structuring
• Systems Design

Systems Analysis Phase
Requirements Gathering
– Understand & document existing system
• Processes, data, policies (rules)
• Data Collection techniques
Interviews, Questionnaires, Observation, Prototyping, JAD

– Analyze & determine Objectives of new system
• Performance, Information, Economics, Control, Efficiency,
Service (PIECES).

– Conduct a gap analysis (new vs. old)
– Document new System Requirements

Requirements Structuring
• Process Modeling (Process)
– Eg. Data Flow Diagrams,

• Data Modeling (Data)
– Eg. Entity Relationship Diagrams

• Logic Modeling (Policies & Rules)
– Structured English/Pseudo Code
– Decision Tables

Systems Design
• Strategy Decisions
– Level of functionality (design criteria)
– Platforms (h/w, s/w)
– Acquisition (make vs. buy)
– S/w as a Service (SaaS - Rent)

Systems Design - Activities
• File & Database Design
– Capacity, Scalability, BCP, Security, Privacy, Backup.
– Types of database design – Hierarchical, Network, Relational

• Program Design
– Centralized, Client / Server, Service Oriented Architecture

• Network
– Centralized, Distributed, Private, VPN, Intranet, Extranet

• Internal Controls
– Preventative (Data Editing), Detective (lookups), Corrective
(can’t proceed). Logging key activities, benchmarking.

• User Interface
– Work Flows, Report Utilization / Value, 80/20 rule, Standards,
Gestures, Touch Screens, Error Messages & Responses.

Process Modeling
• Data Flow Diagram
– Cellphone Activation Example Scenario :
• Customers approach a Dealer
• Choose a cellphone, a service contract, and a phone number.
• Dealer verifies customer’s credit. Updates the
Customer Information System (CIS). Make an activation request. Programs the handset. Verifies the activation.
• CIS sends a welcome text message. Updates the
Billing System.

Example
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cont…

Define the External Entities
Identify Data Stores
Identify Processes
Define Inputs / Outputs / data flows

Customer

Telco

Dealer

Credit Agency

Phones
Available

Customer

Unused Ph#

Telco

Dealer

Pending
Activation

Credit Agency

Customer

Phones
Available

Choose
Phone, #,
Contract

Unused Ph#

Notification

Dealer

Pending
Activation

Telco

Activation

Verify
Credit

Credit Agency

Accept/Reject

Customer

Phones
Available

Unused Ph#

Preferences
Choose
Phone, #,
Contract

Notification

Dealer

Pending
Activation

Telco

Activation

Verify
Credit

Credit Agency

Credit
Report

Accept/Reject

Discussion of Example
• Levels of DFDs (depict existing processes)
• Context Diagram (1 process)
• Some DFD rules
– Process (must have at least one input AND one output)
– Data Flow (must connect to at least one process; no 2 way)

• Logical (what - conceptual) vs.
Physical (How - current implementation) DFDs.

Data Modeling
• Entities
• Attributes
• Relationships
– Referential Integrity

Logic Modeling
•
•
•
•
•
•
•
•

Structured English (aka Pseudocode)
Sequential Logic
If – then – else
Nested if – then – else.
Case
Do While (test at the top)
Do Until (test at the bottom)
Decision Tables

Decision Table Example
Cell Phone Plans*
*Fictional. Only for the purposes of CGA-MS2 Course. Please do not expect to find this plan at your local dealer.

• Identify Conditions
– Number of minutes (200, 500, Unlimited)
– Evenings & Weekends (Yes, No)
– Contract Length (0, 1, 2 years)

• Identify Action Stubs
– Plan Cost
– Discount Percentage

• Identify Combinations

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Minutes
200 200 200 200 200 200 500 500 500 500 500 500 5000 5000 5000
Evenings & Weekends Y Y Y N N N Y Y Y N N N Y Y Y
Contract Length
0 1 2 0 1 2 0 1 2 0 1 2 0 1 2
$50 Per Month
$100 Per Month
$200 Per Month
$250 Per Month
Discount Percentage

X X X
X X X

X X X
X X X

X X X
0 10 20 0 10 20 0 10 20 0 10 20 0 10 20

Use Case Analysis
• Object Oriented approach (Embedded Logic)
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–
–
–

Object description & attributes
Triggers that