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Systems Analysis and Design approaches

Systems Analysis and Design approaches. Structured analysis Looks at processes -> then Data Event list – event table Context diagram – DFD – ERD (define the data to satisfy the required information flows) Information Engineering Looks at Data -> then process

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Systems Analysis and Design approaches

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  1. Systems Analysis and Design approaches • Structured analysis • Looks at processes -> then Data • Event list – event table • Context diagram – DFD – ERD (define the data to satisfy the required information flows) • Information Engineering • Looks at Data -> then process • ERD – Data Dictionary – DFD (how data is captured,stored, used, and maintained) • Object Oriented • Looks at Objects(data and processes[methods])

  2. Relative Cost to Fix Error • (P)roblem 1 • (A)nalsis 1-3 • (D)esign 2-4 • (I)mplementation 5-25 • (T)esting/Operations 25-100

  3. Event List • Customer makes payment • Customer picks up order • Employee makes pizza • Customer makes an order • Owner orders inventory • Customer requests delivery • Time to order supplies • Time to pay Employees • Time to pay State and Fed taxes • Time to fix car • Employee sends pay time card

  4. Event Table from event list Event System Source System Receiver Data Input of Input Output of Output Store Customer order Customer clerk Order places order Receipt sent Receipt Customer Order to customer Time to pay Paycheck Employee Employee employee Employee timecard Employee Owner Employee sends timecard

  5. Decomposition Numbering of events in the Event Table and using a spread sheet will aid in the repetitive process. 1.2.1 Customer makes payment 1.2.2 Customer picks up order 1.4.1 Employee makes pizza 1. Customer makes an order 2.1. Owner orders inventory 1.2.3 Customer requests delivery 2.1 Time to order supplies 3. Time to pay Employees 3.3. Time to pay State and Fed employee taxes X Time to fix car 3.1 Employee sends pay time card

  6. Make a Context diagram of the System Def: a model that defines the scope and boundary for the system and project – subject to constant change Contains a system domain Contains entities that are generators or receivers of events These entities come from “Source of Input” and “Receiver of Output” from the Event Table

  7. Context Diagram from Event Table Employee --order food Customer timesheet- --W2 Food and Receipt- --paycheck Bambino Pizza Product Suppliers Purchase order shipment invoice Add Other entities- BANK, Owners

  8. Create a Data Flow Diagram (DFD) • DFD-0 • Contains Data Flows ( “System Inputs” and “System Outputs” from the Event Table) [Processes the Event] • Contains the major (general) event functions (transitions) that are in the System domain as illustrated in the context diagram. • Contains the Data stores from the Event Table • May contain Entities from the Context Diagram

  9. Data Flow Diagram 0 - level 0 from Event Table order Customer -order inventory Receipt- Process Order Manage inventory 1. 2 Goods and shipping list- P.O. Pay employees -purchase order 3. Vendor Note: could say Process inventory 2. , Process employees 3. Need to add 4., 5., 6., …

  10. Data Flow Diagram 3 - level 1 from DFD 0 and event table employee -W2 Employee -timeCard Tax tables Pay check- Process timeCard Process state and Fed Qtr taxes 3.1 3.3 -tax laws 941-A -- Produce pay check Do payroll Reports 3.4 3.2 IRS Need to add 3.4, 3.5, … Note: 3.1 is probably a primitive, but 3.3 will most likely be decomposed into 3.3.1, 3.3.2, …

  11. Decomposition Diagram from DFD Pay Employees 3. Time Cards Write Checks Pay reports IRS Tax State Fed

  12. Data dictionary From the data stores, data flow inputs, and data flow outputs as shown on the DFD’s we can build the data dictionary. 1.Order = {order-item-code+order-quantity+…. 2. Receipt = {order-item-code+… 3. Purchase_Order = (PO_number+item_code + quanity + … 4. Shipping_List = {PO_number + item_code + … 5. Pay_check = [Employee_ID =Employee_name+rate + hours .., 6. Time_card = 7. W2_form = 8. 941A_form = Input requirements are 1, 3, 4, 6 Output requirements are 2, 5, 7, 8 You need to also define the data stores

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