INFORMATION SYSTEM APPLICATIONS System Development Life Cycle

INFORMATION SYSTEM APPLICATIONS System Development Life Cycle

PRIMARY OBJECTIVES n n n 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. ) n n Describe how structured tools such as data flow diagrams and entityrelationship 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? n Organized set of activities used to guide those involved through the development of an information system

Phases in the system development life cycle (SDLC) n n n Planning Analysis Design Implementation Support

System Life Cycle System Study Project definition Design Programming Evaluate+ Maintenance Installation

Who participates in the system development life cycle? n n n Project team Users Information systems personnel Systems analyst Programmers Steering committee

Project management n n n Scope Project plan Gantt chart

Feasibility assessment n n n n 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 n n Project notebook - entire collection of documentation Project dictionary - an automated project notebook

Data and information gathering techniques n n n Reviewing current system documentation Observation Questionnaires Interviews Joint-application design (JAD) sessions Researching

Analysis Phase n n n 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 n n n 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 n Activities/Tasks: n n n 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 n n n Study the current system Identify the users’ wants, needs, and requirements Present alternative solutions

Detailed Analysis n 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 n n Covert DFDs into structure charts (Hierarchical diagram of program modules) User Interface design (Input/Output) – Forms n n n Data base design Structured walkthroughs Design Testing Procedures

Detailed Design of Software n Database design – Data store in DFD – Logical modeling (ER - diagrams) – Normalization (Data redundancy & integrity) n n Data security Program Design – Program Specification package – System Flowchart

Detailed Design of Software n n n CASE tools Computer-aided software engineering (CASE) Graphics Prototyping Quality assurance Code generators

Detailed Design n Quality review n Necessary to double-check assumptions and design n Structured walkthrough

IMPLEMENTATION PHASE – SDLC #4 Develop programs n Install and test the new system n Train and educate users n Convert to the new system

Develop programs Program development life cycle (PDLC) n – – – Analyze Design the programs Code Test the programs Maintain the programs

Implementation Phase n Install and test the new system n 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 n n n

IMPLEMENTATION PHASE – SDLC #4 n Train and educate users – – Classroom-style lectures One-on-one sessions User manuals CAI

IMPLEMENTATION PHASE – SDLC #4 n n n Convert to the new system old Direct old Parallel New Phased Pilot conversion New Old New

SUPPORT PHASE – SDLC #5 n n Conduct post-implementation system review Identify errors Identify enhancements Monitor performance

n Questions and comments?