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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
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
role of system users or customers narrowly defined
focus on deadlines
Agile Methodologies (3 principles)
a focus on adaptive rather than predictive methodologies
a focus on people rather than roles
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
Note
Flashcard