JENNIFER T. ANGIWOT

OOC

BOOK: SYSTEM ANALYSIS AND DESIGN

AUTHOR: KENNETH E. KENDALL

                   JULIE E. KENDALL

CHAPTER 1

REFERENCE No.QA 76.9 S88 K45 1995

 

 

THE SYSTEMS DEVELOPMENT LIFE CYCLE

                

           

Systems Analysis Life Cycle is a phased approach to analysis and design which holds that systems are best developed through the use of a specific cycle of analyst and user activities.

 

SEVEN PHASE OF SDLC

 

Identify Problems, Opportunities and Objectives

            In this first phase of the systems analysis life cycle development life cycle, the analyst is concerned with identifying problems, opportunities and objectives. This stage is critical to the success of the rest of the project.

 

            In this phase the analyst see who, what, when, how of the project will be carried. Opportunities are the situations that the analyst believes can be improved through the use of computerized information systems. Identifying objectives is also an important component of the first phase. First the analyst must discover what the business is trying to do.

 

            The persons involved here are the users, analysts and system managers coordinating the project.

 

Determining Information Requirements

 

The next phase that the analyst enters is that of determining information requirements for the particular users involved. Among the tools used to define information requirements in the business are; sampling and investigating hard data, interviewing, questioners, observing decision makers and office environments and even prototyping.

 

In this phase, the analyst is striving to understand what information users need to perform their jobs. This phase serves to fill in the pictures that the analyst has of the organization and its objectives.

 

The people involve in this phase are the analyst and users, typically operations managers and operation workers.

 

Analyzing System Needs

 

The next phase that the system analyst undertakes involves analyzing system needs. Special tools and techniques help the analyst make requirements determinations. One such tool is the use of data flow diagrams to chart the input, processes and out put of the business functions in a structural graphical form. During this phase the systems analyst also analyzes the structural decision made.

 

There are three major methods for analysis of structured decisions: structured English, decision tables and decision trees. Not all decisions in organizations are structured, but it is still important for the systems analyst to understand them.

 

At this point in the systems development life cycle, the systems analysts prepares a systems proposal that summarizes what has been found, provides cost/ benefit analyses of alternatives and make recommendation on what should be done.

 

Designing the Recommended System

 

            In this phase, the systems analyst uses the information collected earlier to accomplish the logical design of the information system. The analyst designs accurate data- entry procedures so that data going into the information system are correct. The analyst also provides for effective input to the information system by using techniques of good form and screen design.

 

            Part of the logical design of the information system is devising the user interface. The user interface connects the user with the system and is thus extremely important. The design phase also includes designing files or data bases that will store much of the data needed by decision makers in the organization.

 

            The analyst must design controls and back up procedure program specification packets for programmers.

 

Developing and Documenting Software

 

In this fifth phase of the systems development life cycle, the analyst works with the programmers to develop any original software that is needed. Some of the structured techniques for designing and documenting software include structure charts, the HIPO method, flowcharts, vassi –shneiderman charts,warnier or diagrams and pseudo code.

 

During this phase the analyst also works with users to develop effective documentation for software, including procedure manuals. Documentation tells users how to use software and also what to do if software problems occur.

 

To ensure quality, a programmer may conduct either a design or a code walk trough, explaining complex portions of the program to a team of other programmers.

 

Testing and Maintaining the System

 

Before the information system can be used, it must be tested.

 

It is much less costly to catch problems before the system is signed over to users. Some of the testing is completed by programmers alone, some of it by systems analyst in conjunction with programmers.

 

Maintenance of the system and its documentation begins in this phase and is carried out routinely through out the life of the information system. Many of the systematic procedures the analyst employs through out the systems development life cycle can help ensure that maintenance is kept to a minimum.

 

Implementing and Evaluating the System

 

            In this last phase of system development life cycle, the analyst helps implement the information system. This involves training users to handle the system. Some training is done by vendors, by over sight of training is the responsibility of the systems analyst. The analyst needs to plan for a smooth conversation from the old formats to new ones or building a data base, installing equipment and bringing the new system into production.

 

            Evaluation is shown as a part of this final phase of the systems development life cycle mostly for the sake of discussion. A key criterion that must be satisfied is whether the intended users are indeed using the system.

 

            When an analyst finishes one phase of system development and proceed to the next, the discovery of a problem may force the analyst to return to the previous phase, and modify the work done there.

 

            In either event, the program must be modified, and the analyst may have to change some of the system design material. Intern, this may necessitate that the analyst meet with the user and re investigate how a specific business activity functions