 System Development Life Cycle System Development Life Cycle  SDLC Phases SDLC Phases Phase 1: Preliminary Investigation Phase 2: Feasibility Study Phase 3: System Analysis Phase 4: System Design Phase 5: System Development Phase 6: System Testing Phase 7: System Implementation and Evaluation Phase 8: Operations & Maintenance  Deliverables of the SDLC Deliverables of the SDLC

 System Development Life Cycle(SDLC) is a well defined process by which a System is conceived, developed and implemented. BACK

Preliminary Investigation System Operation & Maintenance System Analysis System Implementation and Evaluation System Design System Development System Testing Feasibility Study BACK

 Determine if a new system is needed  Three primary tasks: ◦ Define the problem  By observation and interview, determine what information is needed by whom, when, where and why ◦ Suggest alternative solutions ◦ Prepare a short report BACK

 Evaluate alternatives based upon: ◦ Economic feasibility – Cost benefit analysis is performed to determine the benefits and servings that are expected. ◦ Technical feasibility – It decides whether the technical resources are sufficient for the proposed system or not. ◦ Operational feasibility – It is determined whether the system will operate in the way that users want or not. BACK

 This Phase includes studying of existing system in details and collecting data in order to find out the requirements of the user. ◦ The system analyst must consult a variety of persons to understand the whole details,processes involved in it and problems faced by staff and should identify the reasons for the problems that have occurred and the preventive measures to avoid them  In addition to observation and interviews, examine: ◦ Formal lines of authority (org chart) ◦ Standard operating procedures ◦ How information flows ◦ Reasons for any inefficiencies

 Checklists - list of questions  Top-down analysis - start with top level components, break down into smaller parts through each successive level  Grid charts - to show relationship between inputs and outputs  System flowcharts - charts flow of input data, processing, and output which show system elements and interactions

 Complete description of current system and its problems  Requirements for for new system including: ◦ Subject ◦ Scope ◦ Objectives ◦ Benefits  Possible development schedule BACK

 In System Design phase,the primary objective is to identify user requirements and to build a system that satisfies these requirements, system specialists often refer to this stage as logical design and the process of developing program software,which is referred to as Physical Design.  Uses specifications from the systems analysis to design alternative systems BACK

 Build the system to the design specifications. ◦ Develop the software  Purchase off-the-shelf software OR  Write custom software ◦ Acquire the hardware BACK

◦ The main purpose of this phase is to test the new system and find the errors and correct them.  Module (unit) test - tests each part of system  Integration testing - tests system as one unit ◦ The main objective of system testing is to make sure that the system during operation will perform as per the specification laid down initially at the time of system analysis. ◦ To ensure that during the operation, incorrect inputted data and processing will be detected. ◦ The system is tested with special test data and the results are examined for the validity so that the analyst can ascertain that the system can work in the specified environment. BACK

 Convert from old system to new system  Train users  Compile final documentation  Once the system is implemented,then evaluate the new system

 Direct/plunge/crash approach – entire new system completely replaces entire old system, in one step  Parallel approach - both systems are operated side by side until the new system proves itself  Pilot approach - launched new system for only one group within the business -- once new system is operating smoothly, implementation goes company-wide  Phased/incremental approach - individual parts of new system are gradually phased-in over time, using either crash or parallel for each piece.

 Evaluation of the system is performed to identify its strength and weakness.the actual evaluation can occur alomg any of the following dimensions: a) Operational Evaluation : Assesment of the manner in which the sytsem functions including response time,overall reliability and the level of utilization b) Organisational impact:Identification and measurement of benefits to the organisation in such areas as financial concerns,operational efficiency and competitive impact c) User Manager Assesment : Judge the Attitudes of senior and user manager within the organisation as well as end users. d) Development Performance : Evaluation of cost,time and effort taken for the overall project.

 User Training ◦ Ease into system, make them comfortable, and gain their support ◦ Most commonly overlooked ◦ Can be commenced before equipment delivery ◦ Outside trainers sometimes used BACK

 Maintenance is actually improvement and updation of software in response to the changes in the organisation.  Types of changes: ◦ Physical repair of the system ◦ Correction of new bugs found (corrective) ◦ System adjustments to environmental changes ◦ Adjustments for users’ changing needs (adaptive) ◦ Changes to user better techniques when they become available (perfective)

 Evaluation Methods ◦ Systems audit - performance compared to original specifications ◦ Periodic evaluation - “checkups” from time to time, modifications if necessary BACK

Begin building new system System converted Users trained Coded and Tested System Design Specifications Preliminary Investigation System Analysis System Design System Implementation System Development System Maintenance Approved Feasibility Study Operational System Documentation completed Abort Project Goto next phase Goto Previous phase Problem Specifications BACK