Systems Planning MODULE 3 System Development Life Cycle

Systems Planning MODULE 3

System Development Life Cycle (SDLC) Ø A framework that describes the activities performed at each stage of a software development project.

System Development Life Cycle (SDLC)

System Development Life Cycle (SDLC) Phase 1 : Preliminary Investigation Ø Determine if a new system is needed Three primary tasks: o Define the problem § By observation and interview, determine what information is needed by whom, when, where and why o Suggest alternative solutions o Prepare a short report

System Development Life Cycle (SDLC) Phase 2 : System Analysis Ø In depth study of the existing system to determine what the new system should do. o Expand on data gathered in Phase 1 Ø In addition to observation and interviews, examine: o Formal lines of authority (org chart) o Standard operating procedures o How information flows o Reasons for any inefficiencies

System Development Life Cycle (SDLC) Phase 2 : System Analysis Tools Used Ø Checklists - list of questions Ø Top-down analysis - start with top level components, break down into smaller parts through each successive level Ø Grid charts - to show relationship between inputs and outputs Ø System flowcharts - charts flow of input data, processing, and output which show system elements and interactions

System Development Life Cycle (SDLC) Phase 2 : System Analysis Documentation Produced Ø Complete description of current system and its problems Ø Requirements for new system including: o Subject o Scope o Objectives o Benefits Ø Possible development schedule

System Development Life Cycle (SDLC) Phase 3 : System Design Ø Uses specifications from the systems analysis to design alternative systems Ø Evaluate alternatives based upon: o Economic feasibility - Do benefits justify costs? o Technical feasibility - Is reliable technology and training available? o Operational feasibility - Will the managers and users support it?

System Development Life Cycle (SDLC) Phase 3 : System Design Tools Used Ø Computer-Aided Software Engineering (CASE) tools are software-based products designed to help automate the production of information systems. Ø Examples: o o o Diagramming Tools Data Repositories Prototyping Tools Test Data Generators Documentation Tools Project Management Tools

System Development Life Cycle (SDLC) Phase 3 : System Design Documentation Produced Ø System Design Report o Describe Alternatives including: § Inputs/Outputs § Processing § Storage and Backup o Recommend Top Alternative based upon: § System Fit into the Organization § Flexibility for the future § Costs vs. benefits

System Development Life Cycle (SDLC) Phase 4 : System Development Ø Build the system to the design specifications o Develop the software § Purchase off-the-shelf software OR § Write custom software o Acquire the hardware o Test the new system § Module (unit) test - tests each part of system § Integration testing - tests system as one unit o Create manuals for users and operators

System Development Life Cycle (SDLC) Phase 5 : System Implementation Ø Convert from old system to new system Ø Train users Ø Compile final documentation Ø Evaluate the new system

System Development Life Cycle (SDLC) Phase 5 : System Implementation Ø Types of Conversion o Direct/plunge/crash approach – entire new system completely replaces entire old system, in one step o Parallel approach - both systems are operated side by side until the new system proves itself

System Development Life Cycle (SDLC) Phase 5 : System Implementation Ø Types of Conversion o Pilot approach - launched new system for only one group within the business -- once new system is operating smoothly, implementation goes company-wide o Phased/incremental approach individual parts of new system are gradually phased-in over time, using either crash or parallel for each piece.

System Development Life Cycle (SDLC) Phase 5 : System Implementation Ø User Training o Ease into system, make them comfortable, and gain their support o Most commonly overlooked o Can be commenced before equipment delivery o Outside trainers sometimes used

System Development Life Cycle (SDLC) Phase 6 : Operations and Maintenance Ø Types of changes: o Physical repair of the system o Correction of new bugs found (corrective) o System adjustments to environmental changes o Adjustments for users’ changing needs (adaptive) o Changes to user better techniques when they become available (perfective)

System Development Life Cycle (SDLC) Phase 6 : Operations and Maintenance Ø Evaluation Methods o Systems audit - performance compared to original specifications o Periodic evaluation - “checkups” from time to time, modifications if necessary

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