4a: Worked Example - Bargain Books TL-DFD
4a
Bargain Books Top Level Data Flow Diagram
Bargain Books Ltd receives orders from customers by either telephone or letter. The sales
clerk registers the order in the new orders ledger. At the end of each day the orders are
checked against the stock. If the order can be met in full a completed order is recorded in
the sales book. If not the order is placed in the pending orders file. Each Friday the sales
book is used to create invoices for dispatch with the goods to the customer. Price information
is contained in the price catalogue.
Specification Document
System Requirements:
The system should...
1. allow the user to enter details of an order
2. hold details of stock
3. hold details of prices
4. hold details of new orders, pending orders and completed orders
5. check orders against stock
6. create an invoice for each order
Statement of Purpose:
The system is to record the processing of all orders and create associated invoices.
Stock detail and price information is to be held.
Context Diagram:
Mansha Nawaz
Section 04 – Worked Solutions
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4a: Solution - Bargain Books TL-DFD
4a
04: Worked Solution (4a)
Bargain Books Top Level DFD - SOLUTION
Bargain Book - ASCENT FILES
3a_bargain.asc
4a_bargainfrag
4a_bargain.ASC
DFD fragments: Please note the fragments are our draft working out and help us prepare
the development for the Top-Level DFD. These fragments have been developed in Ascent.
In more detailed modeling it is preferable to record each fragment in a separate Ascent file.
Ascent only allows you to develop Context Diagram and Top-Level DFD under a single file –
see any of the model solutions. The DFD fragments are the development work undertaken in
order to produce a Top-Level DFD.
Top level DFD
Mansha Nawaz
{N.B. supporting text to explain diagram would be included}:
Section 04 – Worked Solutions
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4b: Worked Example - The Graduate TL-DFD
4b
The Graduate Top Level Data Flow Diagram
Newtown University processes applications for its postgraduate courses from internal
graduates and those from other institutions. The date of receipt of all applications is recorded
in the Applications Book.
Each day the previous day’s applications are examined. Any graduates not meeting the entry
requirements are rejected and the application is recorded as such. Internal graduates are
accepted if they meet the entry requirements (checked by reference to examination results)
and recorded as accepted. External graduates need to have a reference checked, a request
is sent to the named referee. The application is recorded as pending.
When the reference is received it is manually checked and if it is deemed satisfactory, the
graduate is accepted and the application recorded as such. The converse is also true.
At the end of the week all applications are checked, those who have been dealt with and not
yet been written to are sent a letter advising them if they have been accepted or rejected.
The date this is sent is also recorded in the Applications Book.
Specification Document
Requirements:
1. The system should allow the user to
2. enter details of all new applications
3. check applicant’s examination results
4. create a reference request letter
5. edit an application after receiving a reference
6. create applicant response letter
7. store applications over time
8. store examination results over time
Statement of Purpose:
The system is to record progress of all applications and to create appropriate letters for
communication with applicant and referees.
Context Diagram: Newtown University Application System
Event List:
1.1 Applicant sends in an application
1.2 Check application Entry Requirements (temporal)
1.3 Check applicant results (temporal)
1.4 Check reference
Mansha Nawaz
Section 04 – Worked Solutions
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4b: Solution - The Graduate TL-DFD
Graduate Book - ASCENT FILES
3b graduate
4b graduate
4b
The Graduate Top Level DFD - SOLUTION
DFD fragments:
Event List:
1.1
Applicant sends in an application
1.2
Check application Entry Requirements (temporal)
1.3
Check applicant results (temporal)
1.4
Check reference
Top Level DFD: Newtown University Admissions System
{N.B. supporting text to explain diagram would be included}:
Mansha Nawaz
Section 04 – Worked Solutions
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Solution A – provided by Mansha Nawaz
An alternative solution is provided in the online videos as follows.
two solutions.
Compare and contrast the
Solution B – provided by Gary Griffiths
Mansha Nawaz
Section 04 – Worked Solutions
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Solution C – provided by Mansha Nawaz as further refinement V3
Graduate Book - ASCENT FILES
4b graduate
fragments
DFD fragments: Solution based on 6 events
Top Level DFD: Newtown University Admissions System is based on combining the
above 6 events.
{N.B. supporting text to explain diagram would be included}:
Mansha Nawaz
Section 04 – Worked Solutions
6
4c: Worked Example - ATM TL-DFD
ASCENT FILES
Terms of Reference
ATM System
Statement of Purpose:
The system is to handle customer ticket purchasing
for a metro station.
Requirements:
1.
2.
3.
4.
5.
Display prices and ticket type information
Process payments
Issue tickets
record the transaction details
transfer weekly transactions to main computer.
Context Diagram Description
The user of the machine asks for a destination and ticket type (eg single, return or day return)
and the machine displays the price. When enough money has been put in, the machine issues
a date-stamped ticket containing the issuing station, the destination, ticket type and price. If
appropriate, the machine also gives change. The machine records the number of tickets issued
for each destination and the number of tickets of each type for each day. Once a week these
statistics are transferred to the main computer.
Context Diagram : ATM System
Events List:
1.
2.
3.
4.
User request ticket price
User pays for ticket
Record transaction (temporal)
Transfer weekly transactions to main computer (temporal)
Mansha Nawaz
Section 04 – Worked Solutions
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4c: Solution - ATM TL-DFD
Top Level DFD: ATM System
{N.B. supporting text to explain diagram would be included}:
Mansha Nawaz
Section 04 – Worked Solutions
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