DFD ExamplesCreating 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 DFD Naming Guidelines • External Entity Noun • Data Flow Names of data • Process verb phrase – a system name – a subsystem name • Data Store Noun . Creating Data Flow Diagrams Lemonade Stand Example . Create a list of activities • • Old way: no Use-Case Diagram New way: use Use-Case Diagram 2.n DFD (identifies actual data flows and data stores ) .Creating Data Flow Diagrams Example The operations of a simple lemonade stand will be used to demonstrate the creation of dataflow diagrams. Steps: 1. Construct Level 1. Construct Level 0 DFD (identifies manageable sub processes ) 4. Construct Context Level DFD (identifies sources and sink) 3. Create a list of activities .Creating Data Flow Diagrams Example Think through the activities that take place at a lemonade stand. Customer Order Serve Product Collect Payment Produce Product Store Product 1. Create a list of activities . Customer Order Serve Product Collect Payment Produce Product Store Product Order Raw Materials Pay for Raw Materials Pay for Labor 1.Creating Data Flow Diagrams Example Also think of the additional activities needed to support the basic activities. 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 . Construct Context Level DFD (identifies sources and sink) Context Level DFD Order Sales Forecast 0. Customer Order Serve Product Collect Payment Produce Product Store Product CUSTOMER 2.Creating Data Flow Diagrams Example Create a context level diagram identifying the sources and sinks (users).0 Lemonade Production Schedule EMPLOYEE Pay System Product Served Payment Received Goods Payment Time Worked Purchase Order VENDOR Order Raw Materials Pay for Raw Materials Pay for Labor . 0 Procurement Order Raw Materials Pay for Raw Materials Pay for Labor Order Decisions Pay Time Worked 4.Creating Data Flow Diagrams Example Create a level 0 diagram identifying the logical subsystems that may exist.0 Production Production Schedule EMPLOYEE Inventory 3.0 Sale Customer Order Product Ordered Payment CUSTOMER Sales Forecast Product Served Received Goods Purchase Order Payment 2. Customer Order Serve Product Collect Payment Produce Product Store Product VENDOR 3.0 Payroll . Construct Level 0 DFD (identifies manageable sub processes ) Level 0 DFD 1. n DFD (identifies actual data flows and data stores ) Level 1 DFD CUSTOMER Customer Order ORDER 1.3 Produce Sales Forecast Sales Forecast Order Raw Materials Pay for Raw Materials Pay for Labor .2 Receive Payment PAYMENT 4. Construct Level 1. Customer Order Serve Product Collect Payment Produce Product Store Product Payment 1.1 Record Order Request for Forecast 1.Creating Data Flow Diagrams Example Create a level 1 decomposing the processes in level 0 and identifying data stores. Construct Level 1 (continued) Level 1 DFD Product Order ORDER 2. Customer Order Serve Product Collect Payment Produce Product Store Product 4.3 Store Product Quantity Produced & Location Stored .2 Produce Product Quantity Used INVENTORTY Order Raw Materials Pay for Raw Materials Pay for Labor Production Data 2.Creating Data Flow Diagrams Example Create a level 1 decomposing the processes in level 0 and identifying data stores.1 Serve Product Quantity Severed RAW MATERIALS Production Schedule 2. 3 Pay Vendor VENDOR .1 Produce Purchase Order PURCHASE ORDER Quantity On-Hand Quantity Received RAW MATERIALS Received Goods 3. Customer Order Serve Product Collect Payment Produce Product Store Product 4.2 Receive Items Payment Approval RECEIVED ITEMS Order Raw Materials Pay for Raw Materials Pay for Labor Payment 3. Construct Level 1 (continued) Level 1 DFD Order Decision 3.Creating Data Flow Diagrams Example Create a level 1 decomposing the processes in level 0 and identifying data stores. 1 Record Time Worked Level 1 DFD TIME CARDS Employee ID EMPLOYEE Payroll Request 4.3 Pay Employe e PAYMENTS .Creating Data Flow Diagrams Example Create a level 1 decomposing the processes in level 0 and identifying data stores.2 Calculate Payroll Unpaid time cards PAYROLL Payment Approval Order Raw Materials Pay for Raw Materials Pay for Labor Payment 4. Construct Level 1 (continued) Time Worked 4. Customer Order Serve Product Collect Payment Produce Product Store Product 4. 0 Sale 1.3 Pay Vendor 4.1 Record Time Worked 4.1 Produce Purchase Order 3.3 Store Product 0.2 Produce Product 2.2 Calculate Payroll 4.3 Pay Employe e Context Level Level 0 Level 1 .2 Receive Payment 2.0 Payroll 4.1 Serve Product 2.0 Procurement 3.0 Production 2.1 Record Order 1.2 Receive Items 3.0 Lemonade System 3.Process Decomposition 1. DFD Example: Bus Garage Repairs • Buses come to a garage for repairs. parts monitoring by the inventory management computer system and a performance review by the supervisor. parts and repair outcome is used for billing by the Accounting Department. record the reason for the repair and record the total cost of all parts used on a Shop Repair Order. • A mechanic and helper perform the repair. • Information on labor. . Inventory Management System. cost . Accounting Department. etc. Helper. Supervisor. • Key process (“the system”): performing repairs and storing information related to repairs • Processes: – – – – – Record Bus ID and reason for repair Determine parts needed Perform repair Calculate parts extended and total cost Record labor hours. Mechanic.DFD Example: Bus Garage Repairs (cont’d) • External Entities: Bus. DFD Example: Bus Garage Repairs (cont’d) • Data stores: – – – – – – – – – Personnel file Repairs file Bus master list Parts list Repair order Bus record Parts record Employee timecard Invoices • Data flows: . Bus Garage Context Diagram Bus Mechanical problem to be repaired Fixed mechanical problems Helper Labor Bus Repair Process System Labor. parts cost details Repair summary List of parts used Supervisor Labor Inventory Management System Mechanic Accounting . CSUB Burger’s Order Processing System • Draw the CSUB Burger’s context diagram – System • Order processing system – External entities • Kitchen • Restaurant • Customer – Processes • • • • Customer order Receipt Food order Management report .