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Context and Data Flow Diagrams

Context and Data Flow Diagrams. Activity presented by Coral Shand March 2012. Scenario

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Context and Data Flow Diagrams

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  1. Context and Data Flow Diagrams Activity presented by Coral Shand March 2012

  2. Scenario The Car Club has many enthusiastic members. Prospective members can join the club by sending in a membership form along with $10. A planning committee decides on new activities for the coming month and these are passed on to members in a monthly newsletter. Information about all activities past and present are stored for future use. Members also receive reminder letters when their membership is due for renewal.

  3. CONTEXT DIAGRAM Prospective Member The Car Club Planning Committee Member

  4. CONTEXT DIAGRAM Prospective Member Planning Committee New member details The Car Club Planned activities Newsletter Renewal Reminder Member

  5. DATA FLOW DIAGRAM Prospective Member Create newsletter Add new member Create renewal reminder Add planned activities Planning Committee Member

  6. Members Activities

  7. Prospective Member DATA FLOW DIAGRAM Create newsletter Add new member Create renewal reminder Members Activities Add planned activities Planning Committee Member

  8. Prospective Member DATA FLOW DIAGRAM Create newsletter Add new member New member details Member details Create renewal reminder Members Activities Add planned activities Member details Renewal reminder Planning Committee Member

  9. DATA FLOW DIAGRAM Prospective Member Create newsletter Member details Updated activities Add new member New member details Updated activities Member details Add planned activities Create renewal reminder Members Activities Member details Planned activities Renewal reminder Newsletter Planning Committee Member

  10. TEN RULES • An external entity must be an intelligence. • Data flows are labelled with adjective-noun. • Processes are named with a verb-noun. • A data flow arrow coming from a process cannot have the same name as a data flow arrow going into that process. • Processes and data stores must have at least one data flow arrow in and one out.

  11. A data store cannot link directly to another data store. An external entity cannot link directly to another external entity. • Data flows from external entity may keep the same name. Data flowing to and from a data store must have the same name. • Events at same time are one event. • Data flow arrows should not cross each other. • Do not use words ‘data’ or ‘process’ in label names.

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