information system applications

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

Programming

InstallationEvaluate+Maintenance

Project definition

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

oldNew

Newold

OldNew

SUPPORT PHASE – SDLC #5

Conduct post-implementation system review

Identify errors Identify enhancements Monitor performance

Questions and comments?