t2 by stariya

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									DFD Examples
1 Budget Monitoring System
Departments send in their spending request to the budget monitoring system. The request
is checked against the budget allocation file to ensure that the request is valid.
If it is not valid, a special request is sent to management for approval. If this special
request is approved by management the request is then valid. If it is not approved by
management, the request is rejected and sent back to the appropriate department.

Details of all valid requests are entered into the budget monitoring department’s accounts
file. The valid requests stored in this file are then used to send out part orders to the
suppliers. This accounts file is also used to generate monthly reports for management.

1. Draw the Context Diagram for the Budget Monitoring System described above.
2. Draw the Level 1 Data Flow Diagram for this system.


2 Goods Payment System
The goods payment system in a shop buys goods from a supplier as follows:

When the shop sends the system a request for goods, an order form with the order details
is sent to the supplier. Details of the order are stored in the orders file.

When the supplier sends a delivery note this is recorded in the delivery note file. When
the supplier sends an invoice this is verified by reading the delivery note file, and then
recording the details in the invoice file.

Cheques are prepared by reading the invoice file, checking this against the orders file,
and then sending out a check to the Supplier.

1. Based on the scenario above, draw out a table with columns for processes,
   sources, sinks and data stores. Your table should also indicate the input and
   output of each process.
2. Draw the Context Diagram for the Goods Payment System described above.
3. Draw the Level 1 Data Flow Diagram for this system.
3 Order Verification System
A customer sends in an order form containing details of their order and their membership
number. A check is made to verify that they are a member. When their order is verified,
a check is made to validate that the items ordered are produced by the company. Next,
the valid order is used to update the daily order file, and then used to create a shipping list
and invoice, which are sent on to the Order Fulfilment System

1. Based on the scenario above, draw out a table with columns for processes,
   sources, sinks and data stores. Your table should also indicate the input and
   output of each process.
2. Draw the Context Diagram for the Order Verification System described above.
3. Draw the Level 1 Data Flow Diagram for this system.


4 Automatic Underground Ticket Machine
The management of the Underground train service have requested an automatic ticket
machine to function as outlined :

The user enters their destination and ticket type into the machine (e.g. single, return or
day return) and the machine calculates and 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 details of every ticket issued and records travel statistics such as 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.

1. Draw the Context Diagram for the Automatic Ticket Machine System described
   above.
2. Draw the Level 1 Data Flow Diagram for this system.


5 The Mail Order Company Plc.
The sales order processing system at the Mail Order Company Plc. works as follows:

As orders are received from customers by order clerks they are checked and validated to
ensure that all the relevant information has been completed on the order form. If the
order is incomplete then the customer is informed by post and the invalid order is not
taken any further in the process. However, if an order is valid, then the customer file
containing customer number, customer name, address, telephone number, credit limit etc.
is checked to see if the customer is an existing customer or a new customer. If the order
is from a new customer, then his/her details are added to the customer file.
Next, the stock file containing item number, item name, unit price, number in stock etc. is
then checked to ensure that the items on the order are in stock. If the items are not in
stock, then the customer is informed and the order placed on a pending order file which
contains information such as customer number, order number and expiry date.

If the items are in stock, then the valid order is sent to the accounts department where it is
priced with reference to the price file. The customer file is also checked to ensure that
the order will not take the customer over his/her credit limit. If it does, then the customer
is informed of this. Details of the amount outstanding and of the order itself are placed in
the pending orders file. Where no problems are encountered, the customer and stock files
are updated with respect to the order details. A dispatch note is prepared and sent to the
warehouse.

At the end of each week, order clerks check the pending orders file against the customer
file to see if any order should now be processed. If any orders are to be processed,
customers are notified. The stock file is also updated to take account of deliveries from
suppliers.

1. Draw the Context Diagram for the Sales Order Processing System described
   above.
2. Draw the Level 1 Data Flow Diagram for this system.

								
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