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DFD_Examples.ppt
- 1. DFD Example
- 2. Creating Data Flow Diagrams Steps: 1. Create a list of activities 2. Construct Context Level DFD (identifies external entities and processes) 3. Construct Level 0 DFD (identifies manageable sub process ) 4. Construct Level 1- n DFD (identifies actual data flows and data stores ) 5. Check against rules of DFD
- 3. DFD Naming Guidelines • External Entity Noun • Data Flow Names of data • Process verb phrase – a system name – a subsystem name • Data Store Noun
- 4. Creating Data Flow Diagrams Lemonade Stand Example
- 5. Creating Data Flow Diagrams Steps: 1. Create a list of activities • Old way: no Use-Case Diagram • New way: use Use-Case Diagram 2. Construct Context Level DFD (identifies sources and sink) 3. Construct Level 0 DFD (identifies manageable sub processes ) 4. Construct Level 1- n DFD (identifies actual data flows and data stores ) Example The operations of a simple lemonade stand will be used to demonstrate the creation of dataflow diagrams.
- 6. Creating Data Flow Diagrams 1. Create a list of activities Example Think through the activities that take place at a lemonade stand. Customer Order Serve Product Collect Payment Produce Product Store Product
- 7. Creating Data Flow Diagrams Example Also think of the additional activities needed to support the basic activities. Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 1. Create a list of activities
- 8. Creating Data Flow Diagrams Example Group these activities in some logical fashion, possibly functional areas. Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 1. Create a list of activities
- 9. Creating Data Flow Diagrams 0.0 Lemonade System EMPLOYEE CUSTOMER Pay Payment Order Context Level DFD Example Create a context level diagram identifying the sources and sinks (users). Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor VENDOR Payment Purchase Order Production Schedule Received Goods Time Worked Sales Forecast 2. Construct Context Level DFD (identifies sources and sink) Product Served
- 10. Creating Data Flow Diagrams Level 0 DFD Example Create a level 0 diagram identifying the logical subsystems that may exist. Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 3. Construct Level 0 DFD (identifies manageable sub processes ) 2.0 Production EMPLOYEE Production Schedule 1.0 Sale 3.0 Procure- ment Sales Forecast Product Ordered CUSTOMER Pay Payment Customer Order VENDOR Payment Purchase Order Order Decisions Received Goods Time Worked Inventory Product Served 4.0 Payroll
- 11. Creating Data Flow Diagrams Level 1 DFD Example Create a level 1 decomposing the processes in level 0 and identifying data stores. 4. Construct Level 1- n DFD (identifies actual data flows and data stores ) 1.3 Produce Sales Forecast Sales Forecast Payment Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 1.1 Record Order Customer Order ORDER 1.2 Receive Payment PAYMENT Severed Order Request for Forecast CUSTOMER
- 12. Creating Data Flow Diagrams Level 1 DFD Example Create a level 1 decomposing the processes in level 0 and identifying data stores. 4. Construct Level 1 (continued) Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 2.1 Serve Product Product Order ORDER 2.2 Produce Product INVENTORTY Quantity Severed Production Schedule RAW MATERIALS 2.3 Store Product Quantity Produced & Location Stored Quantity Used Production Data
- 13. Creating Data Flow Diagrams Level 1 DFD Example Create a level 1 decomposing the processes in level 0 and identifying data stores. 4. Construct Level 1 (continued) Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 3.1 Produce Purchase Order Order Decision PURCHASE ORDER 3.2 Receive Items Received Goods RAW MATERIALS 3.3 Pay Vendor Quantity Received Quantity On-Hand RECEIVED ITEMS VENDOR Payment Approval Payment
- 14. Creating Data Flow Diagrams Level 1 DFD Example Create a level 1 decomposing the processes in level 0 and identifying data stores. 4. Construct Level 1 (continued) Time Worked Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 4.1 Record Time Worked TIME CARDS 4.2 Calculate Payroll Payroll Request EMPLOYEE 4.3 Pay Employe e Employee ID PAYROLL PAYMENTS Payment Approval Payment Unpaid time cards