Lab/Sessional -CSE-374

SYSTEM DEVELOPMENT LIFE CYCLE

Phase 2: Define New Systems Requirements:- In phase 2 of the SDLC, systems analyst defines the requirement of the new system in detail and evaluates alternative solutions to problems. In phase 2 the analyst focus attention on what they –and the user –want the new system to do. But before designing the new system, the analysts have to define the requirements that it must satisfy. And the requirements must be defined very carefully; otherwise the new system might not end up doing what the users hope it will do.

Purpose of Phase 2 In the second phase of the SDLC, the analyst defines the requirements for the new system in enough detail so both computer professionals and users know exactly what the new system is going to do and how the system is going to do it. Needless to say, these requirements should solve the problems identified in the first phase. Requirements That Affect Software Requirements That Affect Hardware Evaluating Alternative Solutions Systems Requirements Report

Phase 3: Design the new system In phase 3 of the SDLC, systems analyst and designers do the actual design work, often using computer-aided systems engineering tools to speed up the design process. Purpose of phase 3 Phase 3 involves two main objectives: (1) to design the new system and (2) to establish a sound framework of controls within the new system should operate. Tools used are, among others, data flow diagrams, systems flowcharts, program flowcharts (used by programmers writing software programs), structured design and programming, and prototyping.

-Computer –added systems engineering (CASE) tools -Project dictionary organization. -Among other outputs, CASE tools can generate: -Designing New Systems Controls and Security Functions Concluding the Design phase At the end of pahse3, the analyst / design complete, organize, and assemble the new systems design documentation by using a combination of the tools and techniques discussed earlier in the chapter. The documentation should include: A complete overview of the new system as a whole

Phase 4: Develop the new System and Have Users Test it:- In the fourth phase of the SDLC, hardware and software are obtained, and the new system is tested. Purpose of phase 4 During Phase 4, four major activities occur: Acquire software Acquire hardware Train the users Test the new system

Phase 5: Implement the New system:- In the fifth phase of the SDLC, final operating documentation and procedures are created, files are converted, and the new system is used. Conversion to the new system may proceed in four ways: direct, parallel, phased, or pilot. Purpose of Phase 5 The implementation phase, which gets the new system up and running, involves creating the final operating documentation and procedures, converting files, and using the new system.

New system Old system New system Old system New system 1. Direct-implementation : All- at-once change 2.Parallel implementation: run at the same time. 3.Phased implementation: step-by-step change. 4. Pilot implementation: tried first in only one part of the company

Phase 6: Post implementation Evaluation and Maintenance (Support):- The last phase of the SDLC consists of keeping the system running through system audits and periodic evaluations. When the time and money spent on maintaining and updating a system reach a critical point, its time to start planning a new systems development life cycle. Purpose of Phase 6 After a new system has been in operation for several months and any necessary systems maintenance has been done, a formal evaluation –called a post implementation evaluation –of the new system takes place. This evaluation determines either that the new system is meeting its objectives or that certain things need to be done so that it will meet these objectives.

What Skills does the User Need? Why do Some Systems Development Projects Fail? The chances are great that a system development project will fail if a clearly define SDLC isn’t followed. Sometimes, however, even when companies go to the trouble to establish a formal and comprehensive SDLC, projects still fail to achieve their objectives. Why? Most failures can be traced to a breakdown in communications between the users and the data processing group and information-specialists. The reasons for failure often include: --Inadequate user involvement: --Continuation of a project that should have been canceled: --The failure of two more portions of the new system to fit together properly (called system integration):