Custom Search

Popular Posts

Thursday, April 10, 2014


The Systems Life Cycle is the oldest method for building information systems and is still used today for complex medium or large systems projects. This methodology assumes that an information system has a life cycle similar to that of any living organism, with a beginning, middle, and an end. The life cycle for information system has six stages: project definition, systems study, design, programming, installation, and post-implementation. Each stage consists of basic activities that must be performed before the next stage can begin. 

The life cycle methodology is a very formal approach to building systems. It partitions the systems development process into distinct stages and develops an information system sequentially, stage by stage. The life cycle methodology also has a very formal division of labor between end users and information systems specialists. Technical specialists such as systems analysts and programmers are responsible for much of the systems analysis, design, and implementation work; end users are limited to providing information requirements and reviewing the work of the technical staff. Formal sign-offs or agreements between and users and technical specialists are required as each stage is completed.  
Food Processing Line Cordless Electric Kettle Stainless Steel Electric Kettle

Product or output of each stage of the life cycle that is the basis for such sign-offs. The project definition stage results in a proposal for the development of a new system. The systems study stage provides a detailed systems proposal report outlining alternative solutions and establishing the feasibility of proposed solutions. The design stage results in a report on the design specifications for the system solution that is selected. The programming stage results in actual software code for the system. The installation stage outputs the results of tests to assess the performance of the system. The post-implementation stage concludes with a post-implementation audit to measure the extent to which the new system has met its original objectives. We now describe the stages of the life cycle in detail. 


The project definition stage tries to answer the questions, “Why do we need a new system project?” and “What do we want to accomplish?” This stage determines whether the organization has a problem and whether that problem can be solved by building a new information system or by modifying an existing one. If a system project is called for, this stage identifies its general objectives, specifies the scope of the project, and develops a project plan that can be shown to management. 

The systems study stage analyzes the problems of existing systems (manual or automated) in detail, identifies objectives to be attained by a salutation to these problems, and describes alternative solutions. The systems study stage examines the feasibility of each solution alternative for review by management. This stage tries to answer the questions, “What do the existing systems do?” “What are their strengths, weakness, trouble spots, and problems?” “What user information requirements must be met by the solution?” “What alternative solution options are feasible?” “What are their costs and benefits?” 

Answering these questions requires extensive information gathering and research; sifting through documents, reports, and work papers produced by existing systems;  observing how these systems work; polling users with questionnaires; and conducting interviews. All of the information gathered during the systems study phase will be used to determine information system requirements. Finally, the systems study stage describes in detail the remaining life cycle activities and the tasks for each phase. 

The design stage produces the logical and physical design specification for the solution. Because the life cycle emphasizes formal specifications and paperwork, many of the design and documentation tools, such as data flow diagrams, structure charts, or system flowcharts are likely to be utilized.  

The programming stage translates the design specifications produced during the design stage into software program code. Systems analysts work with programmers to prepare specifications for each program in the system. These program specifications describe what each program will do, the type of programming language to be used, inputs and outputs, processing logic, processing schedules, and control statements such as those for sequencing input data. Programmers write customized program code typically using a conventional third-generation programming language such as COBOL or FORTRAN or a high-productivity fourth-generation language. Since large systems have many programs with hundreds of thousands of lines of program code, entire teams of programmers may be required. 

The installation stage consists of the final steps to put the new or modified system into operation: testing, training, and conversion. The software is tested to make sure it performs properly from both a technical and a functional business standpoint. Business and technical specialists are trained to use the new system. A formal conversion plan provides a detailed schedule of all of the activities required to install the new system, and the old system is converted to the new one. 

The post-implementation stage consists of using and evaluating the system after it is installed and is in production. It also includes updating the system to make improvements. Users and technical specialists will go through a formal post implementation audit that determines how well the new system has met its original objectives and whether any revisions or modifications are required. After the system has been fine-tuned it will need to be maintained while it is in production to correct errors, meet requirements, or improve processing efficiency. Over time, the system may require so much maintenance to remain efficient and meet user objectives that it will come to the end of its useful life span. Once the system’s life cycle comes to an end, a completely new system is called for and the cycle may begin again.

The above stages can be divided into three broad categories. 


Blog Widget by LinkWithin