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7/31/2019 Lecture 2bw 210
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Sylnovie Merchant, Ph.D. MIS 210 Fall 2004
Lecture 2:
SDLC
Methodologies
Project Initiation and Planning
Requirements Analysis
MIS 210
Information Systems I
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Systems Development
Life Cycle(SDLC)
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Systems Development
What is a system?
A collection of related components that interact
to perform a task in order to accomplish a goal
Systems development (systems analysis and
design) is the process of creating systems,
developing them, and maintaining or enhancing
them.
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Characteristics of Software
Software is developed, not manufactured
Software does not wear outalthough it can become obsolete
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Todays Software Development
Environment
Failures
Productivity gap
Backlogs
Maintenance bound
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Alleviating the Problems in
Systems Development
Elimination of the causes of system failure lie in
1. the application of methodologies
2. modeling tools
3. techniques
4. project management techniques
to design and build IS that not only meet the needs of the
users, but also are delivered on time and within budget
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Principles of Successful Systems Development
Get the user involved
Use a problem-solving approach
Establish phases and activities
Establish standards for development and documentation Justify systems as capital investments
Don't be afraid to cancel or revise scope
Divide and conquer
Design systems for growth and change
Proper planning and project management
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Some Key Terms ...
Systems development life cycle (SDLC): the life of a project,from concept through implementation
Methodology: a comprehensive and detailed version of anentire SDLC
Technique: an approach that applies specific tools and rules tocomplete one or more phases of the methodology
Modeling tools: specific tools used to apply techniques
Project management techniques: tools used to help plan,schedule, and control a project
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Tools
Software support that helps create models
or other project components
From simple drawing programs to complexCASE tools
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Some Tools
Project management applications
Drawing/graphics applications
Word processing/text editor
Computer-aided system engineering (CASE) tools
Integrated development environment (IDF)
Database management applications
Reverse-engineering tool
Code generators
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Techniques
Collection of guidelines that help the analyst
complete a system development activity or task
Step-by-step instructions
General advice
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Some Techniques
Strategic planning
Project management
User interviewing
Data-modeling
Relational database design
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Systems Development Lifecycle (SDLC)
Three major activitiesAnalysis: understanding business needs
Design: conceptualizing computer-system
solutionImplementation: construction, testing, and
installation
Two additional phasesProject planning
Support
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The SDLC
1. Planning
a. Project identification and selection
b. Project initiation and planning
2. Analysis
a. Determine system requirements (WHAT users need)b. Modeling possible solutions (HOW to satisfy user needs)
3. Design
a. logical design
b. physical design4. Implementation
5. Maintenance / support
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SDLC Concepts
All projects use some variation of the SDLC
SDLC is more than phases
Principles of management
Planning and control
Organization and scheduling
Problem solving
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Major Attributes of the Life Cycle
The project --
Moves systematically through phases where
each phase has a standard set of outputs
Produces project deliverables
Uses deliverables in implementation
Results in actual information system
Uses gradual refinement
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Project Phases
Planning (Why build the system? How should
the team go about building it?)
Analysis (Who uses system, what will it do,
where and when will the system be used?)
Design (How will the system work?)
Implementation (System delivery)
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Identifying business value
Analyze feasibility
Develop work plan Staff the project
Control and direct project
Planning
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Design selection
Architecture design
Interface design Data storage design
Program design
Design
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Construction
Program building
Program and system testing
Installation
Conversion strategy
Training plan
Support plan
Implementation
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Support Phase
Objective: Keep system running productively
following initial installation
End-user support
Help desks
Training programs
Maintaining and enhancing computer system
Enhancements
Upgrades Maintenance
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Methodologies
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Common Development Methodologies
and Techniques
Code & fix model
Structured development
Prototyping
Rapid application development
Object-oriented development
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Code and Fix It Model
An early technique
The developer, in the following order:
codes
thinks about requirements
fixes the code
continues this process until...
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Structured Development
Based on the principles of:
modularization
top-down decomposition
process driven
Structured programming
Structured design
Structured analysis
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Systems Development Life Cycle
Waterfall Model
Project Identification
and Selection
Project Initiation
and Planning
Analysis
Logical Design
Physical Design
Implementation
Maintenance
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Waterfall Model
Problems
dependent on documents, particularly in
completing the requirements and design phases
tendency to hide poorly understood requirements
with elaborate specifications
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Advantages of Structured Development
Been used successfully for over 30 years
Provides a clear framework that defines and
divides important activities
Can be applied to both small and large projects
Division of labor is easier to facilitate
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Limitations of Structured Development
Specification problemsassumes that development is a sequential
process
Changing requirements
requirements specified at the beginningassumption that requirements will not change
Conceptualization and visualization
document led methodologyvolume of documentation can be huge
Inaccuracy
there is only downward trend
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Prototyping
Principle: a user can tell you better what they DON'T wantthan what they DO want
Expendable (throw-away) prototyping:
discarded after use
used to support the analysis and design phases
Evolutionary prototyping:
prototype evolves into the final system
is it a methodology?
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Advantages Speed
Easier for end-users to learn
System changes discovered earlier
End-user involvement (ownership) increased user satisfaction increased user acceptance
User-analyst communication
Early problem detection reduced development time
reduced maintenance
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Disadvantages
Poor documentation
Hard to control/manage
(Unrealistic) User expectations
time for final system
final system differences
reduced analysis
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Rapid Application Development
(RAD) Logistical approach to systems design
Combines
integrated CASE toolsinformation engineering methodologies
management techniques
Speeds up Systems Development by as much as20 times
Critics consider it incomplete life cycle
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Object-Oriented (OO) Development
A fundamentally new way of thinking aboutdeveloping systems
Object-oriented: means that we organizesoftware as a collection of discrete objects thatincorporate both data and behavior
Object-oriented development: an approach
to systems development that proposes the useof objects in the building of new systems andthe rebuilding of old ones
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Advantages of OO
Faster development
Higher quality
Easier maintenance
Increased scalability Better information structure
Increased adaptability
Increased modeling power Supports complexity
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Disadvantages of OO
Maturity of technology
Need for standards
Lack of database technology
Lack of reusable software Lack of metrics
Speed of execution
Availability of qualified personnel Cost of conversion
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Project Initiation and Planning
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Project Initiation and Planning
Long-term information systems strategic plan(top-down)
Department managers or process managers
(bottom-up)
Response to outside forces
Legislative changesMarket forces
Competition
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Confirming Project Feasibility
Economic
Organizational and cultural
Technological
Schedule
Resource
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Intangibles in Economic Feasibility
Costs and benefits cannot always be measured
Examples
Increased levels of service
Survival
Lost customers or sales
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Organizational and Cultural Feasibility
Each company has own culture
New system must fit into culture
Evaluate related issues for potential risks
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Technological Feasibility
Does system stretch state-of-the-art?
Does expertise exist in-house for development?
Does a third party need to be involved?
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Schedule Feasibility
Can project be completed on time?
Risk of schedule slipping
Assumptions and estimates
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Resource Feasibility
Team member availability
Team skill levels
Equipment
Support staff
Physical facilities
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Developing Project Schedule
Task: smallest piece of work
Activity: group of tasks
Phase: group of activities
Schedule processList all tasks for each SDLC activity
Estimate sizes of each task
Determine task sequenceSchedule tasks
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Project Staffing
Develop resource plan for the project
Identify and request specific technical staff
Identify and request specific user staff
Organize the project team into work groups
Conduct preliminary training and team buildingexercises
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Launching Project
Oversight committee is finalized and meets to give
go-ahead
Formal announcement made
Key question, Are we ready to start?
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Focusing the Investigation
Most system problems occur in complex
tasks that have high user impact
Application complexity
User impact
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Requirements Analysis
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Analysis
A. Determine system requirements
B. Structure requirements
1. Process modeling 2. Logic modeling
3. Data modeling
C. Select best alternative
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Requirements Analysis Goals
Fully describe the current system
Study and analyze the current system (gather
and study facts) Determine the ideal information system
Identify resource constraints
Define and prioritize requirements
Inspire user confidence/ownership
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Study & Analyze Current System
Gather information on what the system should
do from as many sources as possible
Concentrate on WHAT is needed, not HOW to
do it
Dont try to fix it unless you understand it
Major problem: analyst not understanding
user needs
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Study & Analyze Current System
-- Activities --
1. Learn about current system (gather facts)
2. Model current system
3. Analyze problems/opportunities (study facts)
4. Establish new system objectives
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Study & Analyze Current System
-- Output --
1. Complete statement of user environment
2. Models of current system
3. List of major problems/causes/effects
4. System objectives
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Learn About Current System
(gather facts)
Gather information from:
Current information system:
a current IS may exist
External sources: reviewing other IS outside the organization can
reveal practical ideas and techniques
Internal sources:
single most important source of facts is the user
existing paper work or documents is also agood source
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Tactics
Listen - dont lecture
Dont pre-solve problem
Compare stories
Look for reluctant responses
Observe your effects on system
Avoid politics (head nodding)
Expect hard, boring work
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Fact-finding Methods
Research and site visits
Existing documentation
Observation
Questionnaires
Interviews
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Observation
Not for long periods of time
will change what your measuring
Vary observation periods
Take only minimal, preplanned notes Coordinate visit beforehand
Beware of Selective Perception!!!
Q i i
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Questionnaires-- Types --
Open-ended (free format)
Closed-ended (fixed format)
multiple choice
rating
ranking
single fact
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Questionnaire Development
1. Determine what facts need to be collected
2. Determine whether free- or fixed-format is best. Usually, a
combination is used.
3. Write the questions. Examine them carefully. Make sure
the questions don't reflect your personal biases.
4. Test the questions on a small sample of respondents.
Modify those questions that respondents had problemswith.
5. Duplicate and distribute the questionnaire.
Q i i h G d d h B d
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Questionnaires - the Good and the Bad
Advantages Can be quickly answered. Cheap for gathering data from a large number of users.
Allow users to maintain anonymity.
Responses can be tabulated and analyzed quickly.
Disadvantages
Number of respondents is often low. No guarantee that the user will answer all the questions.
Inflexible - voluntary information is stifled.
Elimination of body cues.
No immediate opportunity to clarify an answer.
Good questionnaires are difficult to prepare.
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Interviews
Types of Interviews1. Unstructured
2. Structured
Types of Questions1. Open-ended
2. Closed-ended
Focus of Questions
1. Decision analysis2. Data analysis
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How to Conduct an Interview
1. Select interviewees. Learn as much as you can about
interviewee.
2. Make an appointment - never 'drop by'
3. Limit the interview to between 1/2 hour and 1 hour
4. Clear it with the interviewee's supervisor
5. Conduct the interview in a private location
6. Prepare for the interview: provide an interview agenda
7. Conduct the interview: opening, body, conclusion8. Follow-up
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Make the user feel important
Be courteous and professional
Dont take exhaustive notes
Use structured questions
Dont ask users to remember details
Avoid gang interviews
More Interviewing Tips
I i h G d d h B d
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Interviews - the Good and the Bad
Advantages
Users are actively involved SA can probe for more feedback from user
SA can reword questions for each interviewee
Body cues
Disadvantages
Very time consuming, thus very costly
Success of the interview is dependent on the SA'shuman relations skills
Interviewing may be impractical due to location ofinterviewees
O ll S f i di
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Overall Strategy for Fact Finding
1. Learn all you can from existing documents
2. If appropriate, observe the system in action
3. Conduct interviews
4. Use questionnaires to clear up things you don't
fully understand
5. Follow-up
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Some Questions That Must be Answered
What are the inputs to this system?
What are the outputs of this system?
What is the business process (i.e., how is data
processed)?
Who are the direct end-users?
How will the users feel about this system? Who developed the existing system?
Analyze Problems / Opportunities
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Analyze Problems / Opportunities(study facts)
Study and analyze the "current" system
Problem analysis is difficult. We often try to solve problems without analyzing them.
We try to state the problem in terms of a solution.
Use the PIECES framework to frame your investigation ofthe problems, opportunities, and requirements
Performance analysis Information and data analysis
Economic analysis
Control and security analysis Efficiency analysis
Service analysis
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Requirements Analysis Document
Parts
How analysis was conducted
credibility
restartsUser requirements
System constraints
Realistic System ObjectivesDocumentation
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User Requirements
User system objectives (unedited)
Reports (type/frequency)
User training needs
Effect of system on various users
Organization Chart