SDLC: System Development Life Cycle Dr. Dania Bilal IS 582 Spring 2007

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  Prevent fraud and theft

Components of IS Application Documentation & training manuals People who use the system Technical personnel  People who keep system operating; trouble shooters Controls  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 modeling 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.