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Information flowInformation flow
In this task you will produce a In this task you will produce a simple data flow diagramsimple data flow diagram
Your task is to produceYour task is to produce
► A diagram showing the information flow A diagram showing the information flow when sandwiches are sold, calculations are when sandwiches are sold, calculations are made, there is some sort of output.made, there is some sort of output.
► Details showing the terminators/entities, Details showing the terminators/entities, processes and data stores.processes and data stores.
Ordering a tuna rollOrdering a tuna roll
Information flowInformation flowClick to move through this show.Click to move through this show.
The customerA 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
The waitresses write this down and passes the order to the chef.
Order1 x Tuna roll
Ordering some lunch
The chef
Order1 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 rollRM 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 flowInformation flow
The next few slides demonstrate how The next few slides demonstrate how to produce the data flow diagram – to produce the data flow diagram – this example is for ordering a tuna this example is for ordering a tuna roll.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.
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.
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 SymbolsDFD 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.
CustomerCustomer ChefChef
Sandwich prices
The menu or price list keeps a record of prices – it is a data store.
CustomerCustomer ChefChef
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!
CustomerCustomer ChefChefOrder sandwich
Sandwich prices
1. order
2. order5. invoice
6. payment
7. receipt
3. query price4. price
CustomerCustomer
ChefChefOrder sandwich
8. Tuna
9. Tuna
Assignment – CDs by mail Assignment – CDs by mail orderorder
Bebop Records is a mail-order company that distributes CDs and tapes at discount prices to record club members. When anorder processing clerk receives an order formorder form, he or she verifies thatthe sender is a club member by checking the Member file. If thesender is not a member, the clerk returns the orderthe order along with amembership application formmembership application form. If the customer is a member, theclerk verifies the order itemverifies the order item data by checking the Item file. Thenthe clerk enters the order data and saves it to the Daily Order file.The clerk also prints an invoice and shipping listinvoice and shipping list for each order,which are forwarded to Order Fulfillment.
Annotating the textAnnotating the textProcessingProcessing
Annotating the textAnnotating the textData storesData stores
Annotating the textAnnotating the textEntitiesEntities