Data Flow Diagrams
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ActivitiesExercise 1 The following questions relate to context diagrams: a) What is it trying to show? b) How many external entities should there be? c) How can the context diagram be checked against the document flow diagram? Exercise 2 a) Represent, using the proper symbols, the following actions: i) An external entity ‘Supplier’ sending an invoice to a process ‘Deal with payment’. Assume the process takes place in the Accounts division. ii) A process called ‘Update membership’ writing customer details to a data store called ‘Customers’. Assume the process is performed by the Membership Secretary. iii) A process called ‘Order raw materials’ is performed by the Purchasing Clerk. To do this the clerk retrieves details from the ‘Supplier’ data store and sends the purchase order to the external entity ‘Supplier’. The clerk also stores the purchase order details in a data store ‘Purchase orders’. Download 259 Kb. Share with your friends:
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