1 introduction to systems development life cycle
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Introduction to Systems Development Life Cycle
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The Information Systems Life Cycle
What are the four steps in the information systems life cycle (ISLC)?
1. System development
2. System implementation
3. Syetem Operation
4. System obsolencence
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The Systems Development Life Cycle
What are the five steps in the systems development life cycle (SDLC)?
1. Systems analysis
2. Conceptual design
3. Physical design
4. Implementation and conversion
5. Operations and maintenance
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The Systems Development Life Cycle: Systems Analysis
Systems Analysis Do initial investigation Do system survey
Do feasibility study Determine information needs
and system requirements Deliver systems requirements
Conceptual Design
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The Systems Development Life Cycle: Conceptual Design
Conceptual Design Identify and evaluate design alternatives
Develop design specifications Deliver conceptual design
requirements
Physical Design
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The Systems Development Life Cycle: Physical Design
Physical Design Design output Design database Design input Develop programs
Develop procedures Design controls
Deliver developed system
Implementation and Conversion
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The Systems Development Life Cycle: Implementation and Conversion
Implementation and Conversion Develop plan
Install hardware and software Train personnel, test the system
Complete documentation Convert from old to new system
Fine-tune and review Deliver operational system
Operation and
Maintenance
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The Systems Development Life Cycle: Operation and Maintenance
Operation and Maintenance Operate system
Modify system Do ongoing maintenance Deliver improved system
SystemsAnalysis
Feasibility analysis and decision points:
Economic Feasibility
Technical Feasibility
Legal Feasibility
Scheduling Feasibility
Operational Feasibility
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The Players
Who are the people involved in developing and implementing IS?Management Information systems steering
committeeProject development teamSystems analysts and programmersExternal players
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The Players
What are top management’s roles?– providing support and encouragement– establishing system goals and
objectives– determine information requirements
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The Players
What are the steering committee’s roles?– set policies that govern the IS– ensures top-management participation– guidance and control– facilitates coordination and integration
of IS activities
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The Players
What are the project development team’s roles?– plan each project– monitor project – make sure proper consideration is
given to the human element
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The Players
What are the system analyst’s and programmer’s roles?– study existing systems– design new systems and prepare
specifications– write computer programs
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Planning Systems Development
Why is planning an important step in systems development?– consistency– efficiency– cutting edge– lower costs– adaptability
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Planning Systems Development
What types of systems development plans are needed?– project development plan– master plan
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Planning Techniques Two techniques for scheduling and
monitoring systems development activities are:1 PERT (program evaluation and review
technique)• PERT requires that all activities and the precedent
and subsequent relationships among them be identified.
2 Gantt chart• A bar chart with project activities listed on the left-
hand side and units of time across the top
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Planning Techniques: Gantt Chart
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Activity Week Starting12345678
Project Planning Chart (Sample Gantt Chart)
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Gantt Chart
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PERT Chart
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Microsoft Project Gantt Chart
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Microsoft Project PERT Chart
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Feasibility Analysis
Systems analysis is the first step in the systems development life cycle (SDLC).
A feasibility study (also called a business case) is prepared during systems analysis and updated as necessary during the remaining steps in the SDLC.
The steering committee uses the study to decide whether to terminate a project, proceed unconditionally, or proceed conditionally.
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Feasibility Analysis
What five important aspects need to be considered during a feasibility study?
1. Technical feasibility
2. Operational feasibility
3. Legal feasibility
4. Scheduling feasibility
5. Economic feasibility
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Feasibility Analysis
Economic feasibility is the most frequently analyzed of the five aspects.
What is the basic framework for feasibility analysis?– capital budgeting model
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Feasibility Analysis
What are some capital budgeting techniques?– payback period– net present value (NPV) – internal rate of return (IRR)
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Candidate Systems Matrix
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Candidate Systems Matrix (cont.)
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Feasibility Matrix
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Typical System Proposal Outline
I. Introduction
A. Purpose of the report
B. Background of the project leading to this report
C. Scope of the report
D. Structure of the report
II. Tools and techniques used
A. Solution generated
B. Feasibility analysis (cost-benefit)
III. Information systems requirements
IV. Alternative solutions and feasibility analysis
V. Recommendations
VI. Appendices
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Behavioral Aspects of Change
Individuals involved in systems development are agents of change who are continually confronted by people’s reaction and resistance to change.
The best system will fail without the support of the people it serves.
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Behavioral Aspects of Change Why do behavioral problems occur?
– personal characteristics and background
– manner in which change is introduced– experience with prior changes– communication– disruptive nature of the change
process– fear
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Behavioral Aspects of Change
How do people resist IS changes?– aggression– projection– avoidance
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Behavioral Aspects of Change How can behavioral problems be
overcome?– meet needs of the users– keep communication lines open– maintain a safe and open atmosphere– obtain management support– allay fears– solicit user participation– make sure users understand the system
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Behavioral Aspects of Change– How can behavioral problems be
overcome? (continued)– provide honest feedback– humanize the system– describe new challenges and opportunities– reexamine performance evaluation– test the system’s integrity– avoid emotionalism– present the system in the proper context– control the users’ expectations– keep the system simple
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Systems Analysis
When a new or improved system is needed, a written request for systems development is prepared.
The request describes the current system’s problems, why the change is needed, and the proposed system’s goals and objectives.
It also describes the anticipated benefits and costs.
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Sample Request for System Services
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Sample Problem Statements
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Systems Analysis
There are five steps in the analysis phase:
1. Initial investigation
2. Systems survey
3. Feasibility study
4. Information needs and systems requirements
5. Systems analysis report
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Computer-Aided Software Engineering (CASE) CASE is an integrated package of
computer-based tools that automate important aspects of the software development process.
CASE tools are used to plan, analyze, design, program, and maintain an information system.
They are also used to enhance the efforts of managers, users, and programmers in understanding information needs.
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Computer-Aided Software Engineering (CASE) CASE tools do not replace skilled
designers; instead they provide a host of self-integrated tools that give developers effective support for all SDLC phases.
CASE software typically has tools for strategic planning, project and system management, database design, screen and report layout, and automatic code generation.
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CASE Tool Architecture
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Computer-Aided Software Engineering (CASE)
Advantages of CASE Technology
Improved productivity Improved program quality
Cost savings Improved control procedures
Simplified documentation
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Computer-Aided Software Engineering (CASE)
Disadvantages of CASE Technology Incompatibility
CostUnmet expectations
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Systems Design, Implementation, and Operation
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Conceptual Systems Design
In the conceptual systems design phase, a general framework is developed for implementing user requirements and solving problems identified in the analysis phase.
What are the three steps in conceptual design?
1. Evaluate design alternatives.2. Prepare design specifications.3. Prepare conceptual systems design report.
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Conceptual Systems Design
Systemsanalysis
Prepareconceptual
systemsdesign report
Preparedesign
specifications
Evaluatedesign
alternatives
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Conceptual Systems Design
Evaluate design alternatives: The design team should identify and
evaluate design alternatives using the following criteria:
1. How well it meets organizational and system objectives
2. How well it meets users’ needs
3. Whether it is economically feasible
4. Its advantages and disadvantages
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Conceptual Systems Design
Prepare design specifications: Once a design alternative has been
selected, the team develops the conceptual design specifications for the following elements:
1. Output
2. Data storage
3. Input
4. Processing procedures and operations
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Conceptual Systems Design
Prepare conceptual systems design report:
At the end of the conceptual design a conceptual systems design report is developed and submitted.
1. To guide physical systems design activities
2. To communicate how management and user information needs will be met
3. To help assess systems’ feasibility
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Physical Systems Design
Physical design translates the broad, user-oriented AIS requirements of conceptual design into detailed specifications that are used to code and test the computer program.
Conceptualsystems design
Physicalsystems design
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Physical Systems Design: Output Design
The objective of output design is to determine the characteristics of reports, documents, and screen displays.
Output fits into one of four categories:
1. Scheduled reports
2. Special-purpose analysis
3. Triggered exception reports
4. Demand reports
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Physical Systems Design: File and Database Design
What are some file and database design considerations?– medium of storage– organization and access– processing mode– maintenance– size and activity level
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Physical Systems Design: Input Design When evaluating input design, the
design team must identify the different types of data input and optimal input method.
What are the two principal types of data input?
1. Forms
2. Computer screens
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Physical Systems Design: Program Design Program design is one of the most time-
consuming activities in the entire SDLC. Programs should be subdivided into small,
well-defined modules to reduce complexity. What is this referred to as?
– structured programming Modules should interact with a control
module rather than with each other.
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Physical Systems Design: Procedures Design Procedures design should answer the
who, what, where, and how questions related to all AIS activities.
What should procedures cover? input preparation transaction processing error detection and corrections controls
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Physical Systems Design: Procedures Design
What should procedures cover? (continued)
reconciliation of balances database access output preparation and distribution computer operator instructions
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Physical Systems Design: Control Design
What are some control design considerations?
Validity Authorization
Accuracy Security
Numerical Control Availability
Maintainability IntegrityAudit Control
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Physical Systems Design Report
At the end of the physical design phase the team prepares a physical systems design report.
This report becomes the basis for management’s decision whether to proceed to the implementation phase.
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Systems Implementation
Systems implementation is the process of installing hardware and software and getting the AIS up and running.
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Systems ImplementationImplementation planning
Completedocumentation
Develop andtest software
programs
Conversion
Prepare site;install and
test hardware
Selectand trainpersonnel
Test system
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Systems Implementation: Implementation Planning
An implementation plan consists of implementation tasks, expected completion dates, cost estimates, and the person or persons responsible for each task.
Planning should include adjustments to the company’s organizational structure.
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Systems Implementation: Develop and test software programsSeven steps are followed when developing
and testing software programs.1. Determine user needs.
2. Develop a plan.
3. Write program instructions (code).
4. Test the program.
5. Document the program.
6. Train program users.
7. Install and use the system.
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Systems Implementation: Site Preparation
A PC requires little site preparation. A large system may require extensive
changes, such as additional electrical outlets.
Site preparation should begin well in advance of the installation date.
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Systems Implementation: Select and train personnel
Employees can be hired from outside the company or transferred internally.
Effective AIS training should include employees’ orientation to new policies and operations.
Training should occur before systems testing and conversion.
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Systems Implementation:Complete Documentation
Three types of documentation must be prepared for new systems.
1. Development documentation
2. Operations documentation
3. User documentation
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Systems Implementation: Test the System
There are three common forms of testing.
1. Walk-through
2. Processing of test transactions
3. Acceptance tests
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Systems Implementation: Conversion
There are four conversion approaches.
1. Direct conversion
2. Parallel conversion
3. Phase-in conversion
4. Pilot conversion
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Systems Implementation
Old system
New system
Direct Conversion Method
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Systems Implementation
Old system New system
Parallel Conversion Method
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Systems Implementation
Phase-in Conversion Method
Old system
New system
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Systems Implementation
Pilot Conversion Method
1 2 3 31 2
33 22 11
Old Old Old Old Old New
Old New New New New New
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Systems Implementation: Data Conversion
Data files may need to be modified in three ways:
1. Files may be moved to a different storage
2. Data content may be changed
3. File format may be changed
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Operation and Maintenance
The final step in the SDLC is to operate and maintain the new system.
A postimplementation review should be conducted on a newly installed system.
Operation andmaintenance
Implementationand conversion
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Operation and MaintenanceWhat are some factors to consider during the postimplementation review?
Goals and objectives
Satisfaction
Benefits
Costs
Reliability
Documentation
Timeliness
Controls and security
Errors
Training
Communications
Organizational changes
Accuracy
Compatibility