1. SDC – SDLC integration

2. SA/SD SA/SD technique draws heavily from the following methodologies:
Constantine and Yourdon's methodology
DeMarco and Yourdon's methodology
SA/SD technique can be used to perform
high-level design.

3. Definitions Software Development Cycle System Development Life Cycle
Analyse detailed requirements
Preliminary Analysis
Design data and algorithms
Analysis
Code data structures and instructions
Design
Debug syntax and logic errors
Implementation
Test to meet specifications
Evaluation
Document internally and externally
Maintenance
Implement and test with live data
Evaluate performance of the program

4. SA/SD methodology consists of two distinct activities:
Structured Analysis (SA)
Structured Design (SD)
During structured analysis:
functional decomposition takes place.
During structured design:
module structure is formalized

5. DFD (SDLC) = STRUCTURE CHART (SDC)
DFD = Structure Chart
DFD (SDLC) = STRUCTURE CHART (SDC)

6. Consider the following DFD
Main
Validating Account
Processing Transaction

7. Structured Analysis v Structured Design
Data Flow Diagrams of Programs – Structured Analysis (SA)
Structured design requires that data flow diagrams (DFDs) first be drawn for the program.
Processes appearing on the logical, elementary DFDs may represent modules on a structure chart.
Logical DFDs need to be revised to show more detail in order to be used by programmers
The following revisions may be necessary:
Processes appearing on the DFD should do only one function.
Processes need to be added to handle data access and maintenance.
DFDs must be revised to include editing and error handling processes, and processes to implement internal controls.

8. Structured analysis
Transforms a textual problem description into a graphic model.
done using data flow diagrams (DFDs).
DFDs graphically represent the results of structured analysis.

9. Design Some tasks Module development Identify variables IPOS
Pseudocode
Flow charts
Structure diagrams (parameters/modules/functions)
Testing (desk checks/trace tables) – syntax/logic/run-time errors
Internal documentation
External documentation

10. Structured Design All the functions represented in the DFD:
mapped to a module structure (structure chart).
The module structure:
also called as the software architecture:

11. Software Development Cycle
Tasks
Analyse detailed requirements
IPOS/DFD’s
Design data and algorithms
Identify variables/ types/ structures/ pseudocode/ structure charts to show modules
Code data structures and instructions
Into preferred language
Debug syntax and logic errors
Logic errors: Desk check, trace table (logic error), Syntax Errors: use a compiler rather than interpreting program as interpreters message may not differentiate between syntax and other errors.
Runtime errors could be a logic error ie poor programming or a software install problem or a hardware issue.
Test to meet specifications
Check that any scenarios provided can be fixed in software
Document internally and externally
Comments and manuals
Implement and test with live data
Again a trace at the margins of limits.
Evaluate performance of the program
Hardware requirements, live testing/using, surveys, benchmarks