10 The traditional approach to design Hisham Alkhawar

10 Systems Analysis and Design in a Changing World, 4th Edition 2 Learning Objectives u Describe the steps involved in the traditional approach to designing the application architecture u Develop a system flowchart u Develop a structure chart using transaction analysis and transform analysis u Write pseudocode for structured modules u Explain how to use three-layer design with the traditional approach

10 Systems Analysis and Design in a Changing World, 4th Edition 3 The Structured Approach to Designing the Application Architecture u Application software programs l Designed in conjunction with database and user interface l Hierarchy of modules u Design internal logic of individual modules u Top-down approach l DFDs with automation boundaries l System flowcharts, structure charts, pseudocode

10 Systems Analysis and Design in a Changing World, 4th Edition 4 Structured Design Models

10 Systems Analysis and Design in a Changing World, 4th Edition 5 The Automation System Boundary u Partitions data flow diagram processes into manual processes and automated systems u Processes can be inside or outside boundary u Data flows can be inside and outside of boundary l Data flows that cross system boundary represent inputs and outputs of system l Data flows that cross boundaries between programs represent program-to-program communication

10 Systems Analysis and Design in a Changing World, 4th Edition 6 DFD with Automation System Boundary (Figure 10-2)

10 Systems Analysis and Design in a Changing World, 4th Edition 7 The System Flowchart u Representation of various computer programs, files, databases, and associated manual processes that make up complete system u Frequently constructed during analysis activities u Graphically describes organization of subsystems into automated and manual components u Can show type of transaction processing system l Batch l Real-time

10 Systems Analysis and Design in a Changing World, 4th Edition 8 Common System Flowchart Symbols

10 Systems Analysis and Design in a Changing World, 4th Edition 9 Sample System Flowchart for Payroll System (Figure 10-4)

10 Systems Analysis and Design in a Changing World, 4th Edition 10 System Flowchart for RMO (Figure 10-5)

10 Systems Analysis and Design in a Changing World, 4th Edition 11 The Structure Chart u Describes functions and subfunctions of each part of system u Shows relationships between modules of a computer program u Simple and direct organization l Each module performs a specific function l Each layer in a program performs specific activities u Chart is tree-like with root module and branches

10 Systems Analysis and Design in a Changing World, 4th Edition 12 A Simple Structure Chart for the Calculate Pay Amounts Module

10 Systems Analysis and Design in a Changing World, 4th Edition 13 Structure Chart for Entire Payroll Program

10 Systems Analysis and Design in a Changing World, 4th Edition 14 Event-partitioned DFD for the Order-Entry Subsystem (Figure 10-9)

10 Systems Analysis and Design in a Changing World, 4th Edition 15 High-Level Structure Chart for the Order-Entry Subsystem After Transaction Analysis

10 Systems Analysis and Design in a Changing World, 4th Edition 16 First Draft of the Structure Chart for Create New Order (Figure 10-14)

10 Systems Analysis and Design in a Changing World, 4th Edition 17 Module Algorithm Design—Pseudocode u Describes internal logic of software modules u Variation of structured English that is closer to programming code u Syntax should mirror development language u Three types of control statements used in structured programming l Sequence – sequence of executable statements l Decision – if-then-else logic l Iteration – do-until or do-while

10 Systems Analysis and Design in a Changing World, 4th Edition 18 Integrating Structured Application Design with Other Design Tasks u Structure chart must be modified or enhanced to integrate design of user interface and database l Are additional modules needed? l Does pseudocode in modules need modification? l Are additional data couples needed to pass data? u Structure charts and system flowcharts must correspond to planned network architecture l Required protocols, capacity, and security