SDLC: System Development Life Cycle

1. SDLC: System Development Life Cycle Dr. Dania Bilal IS 582 Spring 2008

2. Systems Analysis & Design • Method used to create and maintain systems that perform specific functions. • Examples: processing orders, employee payroll, acquisitions, cataloging, etc. • Use of application software designed to help employees to complete these functions

3. Application Software • Developed internally: in businesses & other organizations • Developed externally: by specific companies • Off-the-shelf application software may not fit the needs of all organizations

4. Components of IS Application • System software • Application software • Hardware • Documentation & training manuals • People who use the system • Technical personnel • People who keep system operating; trouble shooters • Controls/security • Prevent fraud and theft

5. Software Engineering Process • Components • Methodologies • Techniques • Tools

6. Methodologies • Approaches taken by system developers to develop the information system • Qualitative (e.g., interviewing users) • Quantitative (e.g., collect data via direct observations of users)

7. Techniques • Based on methodology chosen • Qualitative vs. quantitative or both • Processes or procedures followed to gather data about current and/or potential users • Design interviews, observations, focus groups

8. IS Tools • Computer-aided software engineering (CASE) • Used to develop the software • Draw diagrams, models, relationships among tasks, etc.

9. System Concepts • Decomposition • Modularity • Coupling • Cohesion

10. Decomposition • Process of breaking down a system into subsystems or smaller components • Smaller components may be broken down into small parts

11. Modularity • A result of decomposition • Divides system into modules • Makes system easier to understand, design/redesign, build/rebuild

12. Coupling • The degree subsystems or modules are dependent on each other in terms of operation (physically separate) • Subsystems should be as independent as possible • If one module fails, the other modules remain in operation

13. Cohesion • “The extent to which a system or subsystem performs a single function.” • Examples: • Check-in • Check-out

14. Important Concepts • Data • Information • Database • Data flow • Processing logic • Process-oriented approach to SD • Data-oriented approach to SD

15. Systems Development Life Cycle (Valacich, George, & Hoffer, 2006)

16. Phase 1: Planning & Selection • Product identification and selection • Product initiation and planning • Identify potential development projects • Classify and rank projects • Select projects for development

17. Phase 2: Systems Analysis • Determine system requirements • Select appropriate methods to elicit system requirements from users of system • Interviews, focus groups, surveys, discussions, or other techniques

18. Phase 3: Systems Design • Structure system requirements • Modeling processes • Develop data flow diagrams (DFDs) based on specific rules and guidelines that lead to accurate and well-structured process models. • Use DFDs to support analysis of IS

19. Phase 3: Systems Design • Use modeling and/or other techniques to represent data • Process modeling – based on specifications • Conceptual data modeling – user oriented • Select best alternative design strategy using both qualitative and quantitative methods

20. Phase 3: Systems Design • Design the human interface • Design the interaction (dialogue) • Build a prototype • Perform usability testing • Design the database

21. Phase 4: System Implementation & Operation • Implement system: • Design specifications are turned into working computer code • Test code for errors and other problems • Use a sample data set

22. Phase 4: System Implementation & Operation • Install system • Prepare documentation • Train users of the system • Provide support • Maintain system on a regular basis

23. Class Activity • Work in groups • Examine the SDLC • Assess how the SDLC may apply to purchasing a product of your choice. This can be a house, car, computer, etc.