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Structured Analysis Structured Design

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					Structured Analysis/
 Structured Design
      CS2335
      Fall 2001
Agenda
 Administration
 Review
 Structured Analysis
 Structured Design
Structured Analysis
 Context Diagram
 Data Flow Diagram (DFD)
 Data Dictionary (DD)
 Procedure Specification (PSPEC)
 Context Diagrams
What is in system? (System Boundary)
What do we have to interface with? (External Actors)

      User                    Display
                              Info      Payroll System

             Keypress Info     0.
                             System
                                        Employee Salary Info



                       Budget System
Lab 3 Context Diagram
Data Flow Diagrams
What are processes?
What is information being processed?
How does information flow between processes?


               1.
            Process


           Data Store

        Information Flow
          Example DFD
                                                         Config File
                                                     Configuration
           User                                      Information
                                                      2.
             Keypress Info                          Update
Display                          1.                 Config
Info                           Input    Selection
             4.               Handler   Info
           Display
           Results

                     Expenditure               3.
                        Data                Process                Employee Salary Info
                                          Salary Data


               Budget Information                              Payroll System
Lab 3 Data Flow Diagram
 Data Dictionary
 What is the definition and makeup of the data in
 the data flows?

Name: Employee Number
Alias: SSN
Where/How Used: Process Salary, indexes employees
Description: string length 9
Lab 3 Data Dictionary

    Name:
    Alias:
    Where/How Used:
    Description:
Procedure Specification
Pseudo-code spec of decomposed process

Use for comments in actual code.
Structured Design
 Refine DFD as necessary
 Determine type of information flow
 Establish flow boundaries
 Map DFD onto program structure
 Factor control hierarchy
 Refine program structure
          Flow Determination
                                                         Config File
                                                     Configuration
           User                                      Information
                                                      2.
             Keypress Info                          Update
Display                          1.                 Config
Info                           Input    Selection
             4.               Handler   Info
           Display
           Results

                     Expenditure               3.                  Employee Salary Info
                        Data                Process
                                          Salary Data


               Budget Information                              Payroll System
First Level Factoring
               Main
             Controller



    Input       Data      Output
   Handler   Transform    Handler
               Engine
Second Level Factoring
                              Main
                            Controller




               Input           Data         User Display
              Handler       Transform        Manager
                              Engine


 User Input      Payroll         Salary     Configuration
  Handler       Interface      Processor      Manager



              Then refine structure based on principles
Lab 3 Structured Design
Next Time

    Back to teams
     Team Communications
       Farmer Exercise

				
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