Presentation on theme: "DFD Examples Create a data flow diagram. Which way does the window face."— Presentation transcript:
DFD Examples Create a data flow diagram
Which way does the window face
How many legs do you see
Information flow In this task you will produce a simple data flow diagram Your task is to produce ► A diagram showing the information flow when sandwiches are sold, calculations are made, there is some sort of output. ► Details showing the terminators/entities, processes and data stores.
Ordering a tuna roll Information flow Click to move through this show.
The customer A customer wants to order some lunch. They walk to the counter and ask for the menu. They make their choice and ask the waitress for a tuna roll. Tuna roll please! Ordering some lunch
The waitresses Order 1 x Tuna roll The waitresses write this down and passes the order to the chef. Order 1 x Tuna roll Ordering some lunch
The chef Order 1 x Tuna roll The chef gets the order and makes the roll. The roll is then passed back to the waitress. Ordering some lunch
The waitresses The customer Whilst the chef makes the roll, the waitress gives the customer a paper bill produced from the cash till. This shows how much the customer owes. The customer pays their bill. Coffee Control 1 tuna roll RM 2.99 Thank you Ordering some lunch
The waitresses The customer When the food arrives from the chef, the waitress gives it to the customer. Ordering some lunch
Information flow The next few slides demonstrate how to produce the data flow diagram – this example is for ordering a tuna roll.
1.Put a square around any inputs or outputs involved - these are entities. 2.Circle any data stores. 3.Underline any processing that takes place 4.Sketch out the information flow, joining up the people (entities, the processing and the data stores Analyse the problem
A customer wants to order some lunch. They walk to the counter and ask for the menu. They make their choice and ask the waitress for a tuna roll. The waitresses write this down and passes the order to the chef. The chef gets the order and makes the roll. The roll is then passed back to the waitress. Whilst the chef makes the roll, the waitress gives the customer a paper bill produced from the till. This shows how much the customer owes. The customer pays their bill. When the food arrives from the chef, the waitress gives it to the customer.
DFD Symbols External Entity Flow of Data Process Data Store Customer Bill Preparing a bill Menu Chef
The customer is a source of information – the person who start the whole process off. The chef is a destination of the information. Customer Chef
Sandwich prices The menu or price list keeps a record of prices – it is a data store. Customer Chef
Sandwich prices The waitress processes the order The waitress is not shown as an entity because she does not produce or receive information (ultimately – the order goes to the chef!!). She is not a data SOURCE or SINK! Customer Chef Order sandwich
Sandwich prices 1. order 2. order 5. invoice 6. payment 7. receipt 3. query price4. price Customer Chef Order sandwich 8. Tuna 9. Tuna
Before you start! A few rules to follow!!
Order sandwich Customer Sandwich prices Chef
Assignment – CDs by mail order Bebop Records is a mail-order company that distributes CDs and tapes at discount prices to record club members. When an order form order processing clerk receives an order form, he or she verifies that the sender is a club member by checking the Member file. If the the order sender is not a member, the clerk returns the order along with a membership application form membership application form. If the customer is a member, the verifies the order item clerk verifies the order item data by checking the Item file. Then the clerk enters the order data and saves it to the Daily Order file. invoice and shipping list The clerk also prints an invoice and shipping list for each order, which are forwarded to Order Fulfillment.
Annotating the text Processing Annotating the text Data stores Annotating the text Entities