Technology Systems Analysis amp Design IT 2405 Nisansala Dharmasena Bertholameuse BSc Special Hons in ITPGD in IT MSc in IT PGD in IR Dip in Journalism MPhil in Computer Science Reading ID: 783515
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Slide1
Bachelor of Information
Technology
Systems Analysis & Design
IT 2405
Nisansala
Dharmasena BertholameuseBSc Special (Hons) in IT,PGD in IT, MSc in IT,PGD in IR, Dip in Journalism, M.Phil. in Computer Science (Reading)
7. System Design
–Practical- Data Flow Diagram
Slide2Bachelor of Information Technology
Systems Analysis & Design
IT2405
Nisansala
Dharmasena
Bertholameuse
BSc Special (Hons) in IT,PGD in IT, MSc in IT,
PGD in IR, Dip in Journalism, M.Phil. in Computer Science (Reading)
7. System Design
Data
Flow Diagrams - Practical
Slide3Intended Learning Outcomes
After completing this module students should be able to
;Understand the concepts of Data Flow Diagrams
Slide4Outline
Introduction Lemonade stand example
Slide5Creating Data Flow Diagrams
Steps:
Create a list of activities
Construct Context Level DFD
(identifies external entities and processes)
Construct Level 0 DFD
(identifies manageable sub process )
Construct Level 1- n DFD
(identifies actual data flows and data stores )
Check against rules of DFD
Slide6DFD Naming Guidelines
External Entity
NounData Flow Names of dataProcess verb phrase
a system namea subsystem nameData Store Noun
Slide7Creating Data Flow
Diagrams
Lemonade
Stand Example
Slide8Creating Data Flow Diagrams
Steps:
Create a list of activities
Old way: no Use-Case Diagram
New way: use Use-Case Diagram
Construct Context Level DFD
(identifies sources and sink)
Construct Level 0 DFD
(identifies manageable sub processes )
Construct Level 1- n DFD
(identifies actual data flows and data stores )
Example
The operations of a simple lemonade stand will be used to demonstrate the creation of dataflow diagrams.
Slide9Create a list of activities
Example
Think through the activities that take place at a lemonade stand.
Customer Order
Serve Product
Collect Payment
Produce Product
Store Product
Creating Data Flow Diagrams
Slide10Example
Also think of the additional activities needed to support the basic activities.
Customer Order
Serve Product
Collect Payment
Produce Product
Store Product
Order Raw Materials
Pay for Raw Materials
Pay for Labor
Creating Data Flow Diagrams
Create a list of activities
Slide11Example
Group these activities in some logical fashion, possibly functional areas.
Customer Order
Serve Product
Collect
Payment
Produce Product
Store
Product
Order Raw Materials
Pay for Raw
Materials
Pay for
Labor
Create a list of activities
Creating Data Flow Diagrams
Slide120.0
Lemonade System
EMPLOYEE
CUSTOMER
Pay
Payment
Order
Context Level DFD
Example
Create a context level diagram identifying the sources and sinks (users).
Customer Order
Serve Product
Collect
Payment
Produce Product
Store
Product
Order Raw Materials
Pay for Raw
Materials
Pay
for
Labor
VENDOR
Payment
Purchase Order
Production Schedule
Received Goods
Time Worked
Sales Forecast
Construct Context Level DFD
(identifies sources and sink)
Product Served
Creating Data Flow Diagrams
Slide13Level 0 DFD
Example
Create a level 0 diagram identifying the logical subsystems that may exist.
Customer Order
Serve Product
Collect
Payment
Produce Product
Store
Product
Order Raw Materials
Pay for Raw
Materials
Pay for
Labor
Construct Level 0 DFD
(identifies manageable sub processes )
2.0
Production
EMPLOYEE
Production
Schedule
1.0
Sale
3.0
Procure-
ment
Sales Forecast
Product Ordered
CUSTOMER
Pay
Payment
Customer Order
VENDOR
Payment
Purchase Order
Order
Decisions
Received Goods
Time Worked
Inventory
Product Served
4.0
Payroll
Creating Data Flow Diagrams
Slide14Level 1 DFD
Example
Create a level 1 decomposing the processes in level 0 and identifying data stores.
Construct Level 1- n DFD
(identifies actual data flows and data stores )
1.3
Produce Sales Forecast
Sales Forecast
Payment
Customer Order
Serve Product
Collect Payment
Produce Product
Store Product
Order Raw Materials
Pay for Raw Materials
Pay for Labor
1.1
Record Order
Customer Order
ORDER
1.2
Receive Payment
PAYMENT
Severed Order
Request for Forecast
CUSTOMER
Creating Data Flow Diagrams
Slide15Level 1 DFD
Example
Create a level 1 decomposing the processes in level 0 and identifying data stores.
Construct Level 1 (continued)
Customer Order
Serve Product
Collect Payment
Produce
Product
Store Product
Order
Raw Materials
Pay for Raw Materials
Pay
for
Labor
2.1
Serve Product
Product Order
ORDER
2.2
Produce Product
INVENTORTY
Quantity Severed
Production
Schedule
RAW MATERIALS
2.3
Store
Product
Quantity Produced & Location Stored
Quantity Used
Production Data
Creating Data Flow Diagrams
Slide16Level 1 DFD
Example
Create a level 1 decomposing the processes in level 0 and identifying data stores.
Construct Level 1 (continued)
Customer Order
Serve Product
Collect
Payment
Produce Product
Store
Product
Order Raw Materials
Pay for Raw
Materials
Pay for Labor
3.1
Produce Purchase Order
Order Decision
PURCHASE ORDER
3.2
Receive Items
Received Goods
RAW MATERIALS
3.3
Pay Vendor
Quantity
Received
Quantity On-Hand
RECEIVED ITEMS
VENDOR
Payment Approval
Payment
Creating Data Flow Diagrams
Slide17Level 1 DFD
Example
Create a level 1 decomposing the processes in level 0 and identifying data stores.
Construct Level 1 (
continued
)
Time Worked
Customer Order
Serve Product
Collect
Payment
Produce Product
Store
Product
Order Raw Materials
Pay for Raw
Materials
Pay for
Labor
4.1
Record Time Worked
TIME CARDS
4.2
Calculate Payroll
Payroll Request
EMPLOYEE
4.3
Pay Employee
Employee ID
PAYROLL
PAYMENTS
Payment Approval
Payment
Unpaid time cards
Creating Data Flow Diagrams
Slide18Process Decomposition
4.1
Record Time Worked
4.2
Calculate Payroll
4.3
Pay Employee
3.1
Produce Purchase Order
3.2
Receive Items
3.3
Pay Vendor
2.1
Serve Product
2.2
Produce Product
2.3
Store
Product
1.1
Record Order
1.2
Receive Payment
2.0
Production
1.0
Sale
3.0
Procure-ment
4.0
Payroll
0.0
Lemonade System
Level 0
Level 1
Context Level
Slide19Screen Capture – MS Visio
Slide20Lesson Summary
Understand the concepts of Data Flow Diagrams
Slide21Bachelor of Information Technology
Systems Analysis & Design
IT2405
Nisansala
Dharmasena
Bertholameuse
BSc Special (Hons) in IT,PGD in IT, MSc in IT,
PGD in IR, Dip in Journalism, M.Phil. in Computer Science (Reading)
7. System Design
Data
Flow Diagrams - Practical
Slide22Bachelor of Information
Technology
Computer
Systems
I
IT1205Nisansala Dharmasena BertholameuseBSc Special (Hons) in IT,PGD in IT, MSc in IT,
PGD in IR, Dip in Journalism, M.Phil. in Computer Science (Reading)
7. System Design
- Practical- Data Flow Diagram