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Introduction to Systems Development Life Cycle. The Information Systems Life Cycle. What are the four steps in the information systems life cycle (ISLC)? System development System implementation Syetem operation System obsolencence. The 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)? • System development • System implementation • Syetem operation • System obsolencence
The Systems Development Life Cycle • What are the five steps in the systems development life cycle (SDLC)? • Systems analysis • Conceptual design • Physical design • Implementation and conversion • Operations and maintenance
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
The Systems Development Life Cycle: Conceptual Design Conceptual Design Identify and evaluate design alternatives Develop design specifications Deliver conceptual design requirements Physical Design
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
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
The Systems Development Life Cycle: Operation and Maintenance Feasibility analysis and decision points: Economic Feasibility Technical Feasibility Legal Feasibility Scheduling Feasibility Operational Feasibility Operation and Maintenance Operate system Modify system Do ongoing maintenance Deliver improved system Systems Analysis
Planning Systems Development • Why is planning an important step in systems development? • consistency • efficiency • cutting edge • lower costs • adaptability
Planning Systems Development • What types of systems development plans are needed? • project development plan • master plan
Planning Techniques • Two techniques for scheduling and monitoring systems development activities are: • PERT (program evaluation and review technique) • PERT requires that all activities and the precedent and subsequent relationships among them be identified. • Gantt chart • A bar chart with project activities listed on the left-hand side and units of time across the top
Planning Techniques: Gantt Chart Project Planning Chart (Sample Gantt Chart) ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Activity Week Starting 1 2 3 4 5 6 7 8
Systems Analysis • There are five steps in the analysis phase: • Initial investigation • Systems survey • Feasibility study • Information needs and systems requirements • Systems analysis report
Systems Analysis • When a new or improved system is needed, a written request for systems developmentis 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.
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.
Feasibility Analysis • What five important aspects need to be considered during a feasibility study? • Technical feasibility • Operational feasibility • Legal feasibility • Scheduling feasibility • Economic feasibility
Feasibility Analysis • Economic feasibility is the most frequently analyzed of the five aspects. • What is the basic framework for feasibility analysis? • capital budgeting model
Feasibility Analysis • What are some capital budgeting techniques? • payback period • net present value (NPV) • internal rate of return (IRR)
Typical System Proposal Outline • Introduction • Purpose of the report • Background of the project leading to this report • Scope of the report • Structure of the report • Tools and techniques used • Solution generated • Feasibility analysis (cost-benefit) • Information systems requirements • Alternative solutions and feasibility analysis • Recommendations • Appendices
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.
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.
Computer-Aided Software Engineering (CASE) Advantages of CASE Technology Improved productivity Improved program quality Cost savings Improved control procedures Simplified documentation
Computer-Aided Software Engineering (CASE) Disadvantages of CASE Technology Incompatibility Cost Unmet expectations
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? • Evaluate design alternatives. • Prepare design specifications. • Prepare conceptual systems design report.
Conceptual Systems Design Systems analysis Evaluate design alternatives Prepare design specifications Prepare conceptual systems design report
Conceptual Systems Design • Evaluate design alternatives: • The design team should identify and evaluate design alternatives using the following criteria: • How well it meets organizational and system objectives • How well it meets users’ needs • Whether it is economically feasible • Its advantages and disadvantages
Conceptual Systems Design • Prepare design specifications: • Once a design alternative has been selected, the team develops the conceptual design specificationsfor the following elements: • Output • Data storage • Input • Processing procedures and operations
Conceptual Systems Design • Prepare conceptual systems design report: • At the end of the conceptual design a conceptual systems design reportis developed and submitted. • To guide physical systems design activities • To communicate how management and user information needs will be met • To help assess systems’ feasibility
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. Conceptual systems design Physical systems design
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: • Scheduled reports • Special-purpose analysis • Triggered exception reports • Demand reports
Physical Systems Design: File and Database Design • What are some file and database designconsiderations? • medium of storage • organization and access • processing mode • maintenance • size and activity level
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? • Forms • Computer screens
Physical Systems Design: Program Design • Program designis 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.
Physical Systems Design: Procedures Design • Procedures designshould 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
Physical Systems Design: Procedures Design What should procedures cover? (continued) • reconciliation of balances • database access • output preparation and distribution • computer operator instructions
Physical Systems Design: Control Design What are some control designconsiderations?
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.