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

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

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

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

Software Engineering Process Components Methodologies Techniques Tools

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)

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

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

System Concepts Decomposition Modularity Coupling Cohesion

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

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

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

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

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

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

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

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

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

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

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

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

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

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.