INFORMATION SYSTEM APPLICATIONS. System Development Life Cycle. PRIMARY OBJECTIVES. Explain the phases in the system development life cycle Identify the guidelines for system development
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INFORMATION SYSTEM APPLICATIONS System Development Life Cycle
PRIMARY OBJECTIVES • Explain the phases in the system development life cycle • Identify the guidelines for system development • Discuss the importance of project management, feasibility assessment, information gathering techniques and documentation
PRIMARY OBJECTIVES (cont.) • Describe how structured tools such as data flow diagrams and entity-relationship diagrams are used in analysis and design • Identify program development as part of the system development life cycle
WHAT IS THE SYSTEM DEVELOPMENT LIFE CYCLE? • Organized set of activities used to guide those involved through the development of an information system
Phases in the system development life cycle (SDLC) • Planning • Analysis • Design • Implementation • Support
System Life Cycle System Study Design Project definition Programming Installation Evaluate+ Maintenance
Who participates in the system development life cycle? • Project team • Users • Information systems personnel • Systems analyst • Programmers • Steering committee
Project management • Scope • Project plan • Gantt chart
Feasibility assessment • Operational feasibility • Will the system work in their environment? • Schedule feasibility • Are project deadlines reasonable? • Technical feasibility • Do they have the resources to support the system – people, hardware, software? • Economic feasibility • Does it make economic sense?
Documentation • Project notebook - entire collection of documentation • Project dictionary - an automated project notebook
Data and information gathering techniques • Reviewing current system documentation • Observation • Questionnaires • Interviews • Joint-application design (JAD) sessions • Researching
Analysis Phase • Activities/Tasks: • Fact Gathering • Data Flow Diagrams (DFD) : Used to document the flow of information through an information system and identify problem areas.
Analysis Phase • Activities/Tasks: • Process Description: Used to define the internal workings of a process on the DFD. • Data Dictionary : Used to document the data definitions and formats.
Analysis Phase • Activities/Tasks: • Data Modeling: Designing the necessary databases and specifying how they may be accessed. • System Modeling: Using requirements to create actual plans for the new information system. • Project Management: The process of controlling the project to ensure schedules are met, estimates are updated, and costs are contained.
Detailed Analysis • Study the current system • Identify the users’ wants, needs, and requirements • Present alternative solutions
Detailed Analysis • Structured Analysis and Design Tools • Data Flow Diagrams • Structured Analysis (HIPO charts) • Work Break Down Structure • Entity Relationship Diagrams • Decision Tables • Decision Trees • Data Dictionary
Design phase activities • Covert DFDs into structure charts (Hierarchical diagram of program modules) • User Interface design (Input/Output) • Forms • Data base design • Structured walkthroughs • Design Testing Procedures
Detailed Design of Software • Database design • Data store in DFD • Logical modeling (ER - diagrams) • Normalization (Data redundancy & integrity) • Data security • Program Design • Program Specification package • System Flowchart
Detailed Design of Software • CASE tools Computer-aided software engineering (CASE) • Graphics • Prototyping • Quality assurance • Code generators
Detailed Design • Quality review • Necessary to double-check assumptions and design • Structured walkthrough
IMPLEMENTATION PHASE – SDLC #4 Develop programs • Install and test the new system • Train and educate users • Convert to the new system
Develop programs • Program development life cycle (PDLC) • Analyze • Design the programs • Code • Test the programs • Maintain the programs
Implementation Phase • Install and test the new system • System test - verify that all programs work and work together • Integration test - verify that an application works with other application in the system • Acceptance test - performed by users with real data • Types of testing varies
IMPLEMENTATION PHASE – SDLC #4 • Train and educate users • Classroom-style lectures • One-on-one sessions • User manuals • CAI
IMPLEMENTATION PHASE – SDLC #4 • Convert to the new system • Direct • Parallel • Phased • Pilot conversion old New old New Old New
SUPPORT PHASE – SDLC #5 • Conduct post-implementation system review • Identify errors • Identify enhancements • Monitor performance