INFO 3234 Ch1

Information Systems Analysis and Design

the complex, challenging, and simulating organizational process that a team of business and systems professionals uses to develop and maintain information systems

Application Software

software designed to support organizational function or process

Systems Analyst

organizational role most responsible for analysis and design of information systems

Present

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Continued focus on developing systems for the Internet and for firm’s intranets and extranets

– Implementation involving three-tier design

▪ Database on one server

▪ Application on second server

▪ Client logic located on user machines

– Move to wireless system components (access from anywhere)

– Continuing trend toward assembling systems from programs and components purchased off the shelf

Systems development methodology

a standard process followed in an organization to conduct all the steps necessary to analyze, design, implement, and maintain information systems

Systems development life cycle (SDLC)

the traditional methodology used to develop, maintain and replace information systems

* features several phases that mark the progress of the systems analysis and design efforts
* Circular= never ending
* iterative= back up if needed

5 phases of SDLC

* Planning
* Analysis
* Design
* Implementation
* Maintenance

Planning

– Need for a new or enhanced system is identified

– Needs are identified, analyzed, prioritized, and arranged

– Determine the scope of the proposed system

– Baseline project plan is developed

Analysis

– System requirements are studied from user input and structured

– Requires careful study of current systems, manual and computerized, that might be replaced or be enhanced

\-Two sub phases:

\-==Requirement determination==

==-Study the req and structure them according to their interrelationships and eliminate any redundancies==

– Output is description of the alternate (new) solution recommend by the analysis team

Design

– Analyst converts the alternate solution into logical and physical specifications

– Logical Design

▪ The design process part that is independent of any specific hardware or software platform

▪ Concentrates on business aspect- high level

– Physical Design

▪ The logical specifications of the system from logical design are transformed into technology-specific details from which all programing/system construction can be accomplished

Implementation

– Occurs when the information system is coded, tested, installed, and supported in the organization

– New systems become part of the daily activities of the organization

Maintenance

– The phase in which an information system is systematically repaired and improved

– Organization’s needs may change over time requiring changes to the system based on user’s needs

When to replace systems (SDLC)

* when the info system is no longer performing as desired
* when maintenance costs become prohibitive
* when the org needs have substantially changed
* not just when the system has reached an arbitrary time limit

Analysis Design Code Test Loop

an example of traditional practice

HOSD

encompasses analysis, design, and partially implementation phase to indicate combination of their respective activities into a single process

Heart of Systems Development

current practice combines analysis, design, and implementation into a single process

Why is waterfall good?

Timing, scope determined, limit scope creep

Why is waterfall bad?

not as easy to go back phases or back up, users-assume requirements established in advance, focused on deadlines

SDLC Traditional Waterfall problems

* once one phase ends another begins, going downhill until complete
* makes it diff to go back
* results in great expense to make changes
* ==r**ole of system users or customers narrowly defined**==
* focus on deadlines

Agile Methodologies (3 principles)

1. a focus on adaptive rather than predictive methodologies
2. a focus on people rather than roles
3. a focus on self-adaptive processes

eXtreme Programming

* short, incremental development cycles
* focus on automated tests written by programmers
* emphasis on two-person programming teams
* customers to monitor the development process

Scrum

* primary unit is the sprint (runs two weeks to a month)

Criticisms of SDLC include

* forced timed phases on intangible and dynamic processes were doomed to fail
* life-cycle reliance has resulted in massive amounts of process and documentation
* cycles are not necessarily waterfalls

Evolutionary Model

a spiral process in which one is constantly cycling through phases at different levels

\-start small: min risk

\-early feedback from users

downside: complex to manage