1. Context
&
Dataflow
Diagrams

2. CONTEXT
DIAGRAM

3. A context diagram is a graphical method of
representing using a single process together
with inputs and outputs (external entities)
Three symbols only exist
The process;
The data flow;
The external entity.
Process
Entity

4. Entity
Data flow
Process
Data flow
Entity
A context diagram

5. A context diagram URL Student Keyword Use Search Student engine
Student searches the internet
A context diagram

6. Create a context diagram for:
Searching an online telephone database.
Use of an ATM.
Use self server check out.

7. DFD
DFD
DFD
DFD
DFD
DFD
DFD
DFD

8. A DFD is a graphical method of
Representing a system using a number of
processes together with
inputs;
outputs;
storage.

9. The 4 main symbols used to show : the process;
the data flow;
the data store;
the external entity.
Process
Database
Data
store
External
Entity

10. A data flow diagram Call details Customer Search Customer details
Call number
details
Database
A data flow diagram

11. A data flow diagram invoice Customer Order is processed Customer order
Customer & order details
Invoice & book
Database
invoice is generated
and sent
A data flow diagram

12. A data flow diagram search for image
Load website
Use search
engine
URL
student
keyword
graphic
URL
keyword
Database
Of website
Project
A data flow diagram search for image

13. A video store is considering installing a ‘self-checkout’ system where customers
can borrow videos by scanning their membership cards and videos and pay by
EFTPOS.
A ‘self-checkout’ transaction has three steps:
• membership validation;
• borrowing limit check;
• payment processing.
For membership validation the barcode on the membership card is used to
access the member database to find a match. The customer proceeds to the
scanning of videos if the membership is valid, otherwise a message is displayed.
Using the video barcode data and details from the member database, the system checks that no more than six videos are borrowed. A message is displayed if the limit is exceeded.
Payment processing involves the calculation of borrowing charges, the scanning
of the customer’s EFTPOS card, the entry of a personal identification number
and the electronic communication of these details to the financial institution.
Video charges are obtained from the video database via the video barcodes.
Transaction details are written to the transaction file for each video borrowed.

14. (i) Draw a dataflow diagram with the three processes that represents this proposed ‘self-checkout’ system, ensuring that you show external entities and data stores. (Refer standards package section 2 Q.25)

15. Create a data flow diagram for the borrowing of a book.
STEPS I TAKE WHEN CREATING SUCH A TOOL.
Decide upon the:
processes ,
entities,
dataflow
storage.
2. Draw rough diagram adding the:
3. Label as you go.

16. Search d/b of borrowers for borrowing eligibility
Create a data flow diagram for the borrowing of a book:
Entity
Processes
Data flow
borrower
Search d/b of borrowers for borrowing eligibility
Borrowers details & book request
Search d/b for details of requested book
Information about borrower
Locate book, scan book & user bar code
Information about books
Update borrower & book records
Information about library transactions
Result of d/b search
Storage
D/b of borrowers, books & library transactions

17. Process borrower Database 6 Process 10 1 7 2 9 Process 5 3 8 Process 64

18. Create a data flow diagram for:
1.Searching an online telephone database.
2.Use of an ATM.
3.Use self server check out.

19. A video store is considering installing a ‘self-checkout’ system where customers
can borrow videos by scanning their membership cards and videos and pay by
EFTPOS.
A ‘self-checkout’ transaction has three steps:
• membership validation;
• borrowing limit check;
• payment processing.
For membership validation the barcode on the membership card is used to
access the member database to find a match. The customer proceeds to the
scanning of videos if the membership is valid, otherwise a message is displayed.
Using the video barcode data and details from the member database, the system checks that no more than six videos are borrowed. A message is displayed if the limit is exceeded.
Payment processing involves the calculation of borrowing charges, the scanning
of the customer’s EFTPOS card, the entry of a personal identification number
and the electronic communication of these details to the financial institution.
Video charges are obtained from the video database via the video barcodes.
Transaction details are written to the transaction file for each video borrowed.

20. (i) Draw a dataflow diagram with the three processes that represents this proposed ‘self-checkout’ system, ensuring that you show external entities and data stores. (Refer standards package section 2 Q.25)

22. Link to dfd tutorials http://www.getahead-direct.com/gwbadfd.htm

23. Systems
Flow
Chart

24. Systems flow chart is a graphical method of representing both the flow of data and the logic of the system.
It documents the essential details of the system such as sequence, processes and precise rules for selecting particular actions.
The flow chart will also show the hardware used to process data, such as the peripheral devices, storage media and processing units.

25. Symbol Meaning Input/output Manual operation Paper document
Magnetic tape
Online display
Direct access storage device
Online input
Flowline
Punched cards
Telecommunication link
Process
Predefined process
Terminal
Decision

26. A system flow chart for finding a book in the library.
begin
Enter book
details
Library software
Library database
Search results
False
Need printout
True
Search report
False
Are you finished
True
End

27. Processing Output Input A system flow chart for hardware Colour inkjet
printer
Keyboard
Laptop
CD-Rom
drive
Scanner
Floppy
drive
Internet
Zip drive
modem
Network
connection
Mouse
File server
Processing
Output
Input