CS302: Software Engineering

Introduction

When studying Software Engineering, there is a number of preliminary basic knowledge a student/learner needs to have. This unit reviews some of this basic knowledge. The unit starts by reviewing system analysis and design. It describes the general overview of the computer systems, types of systems, roles of users participating in system development life-cycle. The unit also explains basics in programming, which include: cycle of data processing, steps needed to create a program and structured programming. The purpose of this unit is to determine your grasp of knowledge related to this course.

Objectives

Upon completion of this unit you should be able to:

• Define computer system and Describe types of systems 
• Identify major players or participants in the software development 
• Practice IPO data processing 
• Elaborate steps in program creation 
• Use structured programming in solving real problems 
• Elaborate steps in program creation 
• Use structured programming in solving real problems

Key Terms

A System: 

A system is a collection of components that work together to realize some objective forms of a system. 

IPO: 

This is Input, Process and Output (IPO), the most basic design cycle of data processing of a program.

Computer Systems 

Systems are created to solve problems. One can think of the systems approach as an organized way of dealing with a problem. In this dynamic world, the subject System Analysis and Design (SAD) mainly deals with software development activities.

What is a System?

From Tran Thi Phien, (2006), A system can generally be defined as a collection of components that work together to realize some objective forms of a system. A system may include software, mechanical, electrical and electronic hardware and be operated by people. Basically there are three major components in every system, namely input, processing and output. In a system the different components are connected with each other and they are interdependent, for example:

• Human body represents a complete natural system 
• We are also bound by many national systems such as political system, economic system, educational system and so forth 
• The objectives of the system demand that some output is produced as a result of processing the suitable inputs

Types of Systems 

As stated by Tran Thi Phien, (2006), there are many types of systems that we come into contact with everyday. The one we are interested with is an automated, computerized information system. Automated systems are the man-made systems that interact with or are controlled by one or more computers. We can distinguish many different kinds of automated systems, but they all tend to have five basic components:

Infrastructure: The physical and hardware system components, e.g. servers, computer hardware: CPUs, disks, terminals, etc 

Computer software: The programs and operating software of a system, including operating systems, database systems, utilities, and applications (financial systems) 

People: to operate the system, to provide its inputs and consume its outputs, and to provide manual processing activities in a system. E.g. programmers, operators, users of the systems and management 

Data: The information captured, used, and supported by a system, including files and databases. The information that the system remembers over a period of time.

Procedures: The programmed and manual guidelines, instructions, and steps involved in operating systems, including information technology (IT) procedures for backup and maintenance. Formal policies and instructions for operating the system. 

Business systems use these system components to transform data inputs into information outputs. 

Participants to System Development

In a typical systems development project, there are the following major categories of players:

User 

The most important player in the systems is the person (or group of people) for whom the system is being built. He or she is the person who will be interviewed, often in great detail, to learn what features the new system must have to be successful. The user is the “owner” in the sense that he or she receives, or inherits-and thus owns- the system when it is finally built. The user is also the “customer” in at least two important respects: 

As in so many other professions, “the customer is always right”, regardless of how demanding, unpleasant, or irrational he or she may seem. 

The customer is ultimately the person paying for the system and usually has the right and/or the ability to refuse to pay if he or she is unhappy with the product received.

Management 

Management is a rather loose term. There are several different kinds of managers: 

User managers: managers in charge of several people in the operational area where the new system will be used. These are usually middle-level managers who want systems that will produce a variety of internal reports and short-term trend analyses.

Executive development project (EDP)/MIS managers: the person in charge of the systems development project itself, and the higher-level managers who are concerned with the overall management and allocation of resources of all the technical staff in the systems development organization.

General management: top-level managers who are not directly involved in the EDP organization or in the user organization. This might include the president and/ or chairman of the organization.

Systems analysts 

The system analyst is a key member of any systems development project. In a broader sense, the systems analyst plays several roles:

Archaeologist and scribe: As a systems analyst, one of the main jobs is to uncover detail and to document business policy that may exist only as "tribal tradition", passed down from generation to generation of users. 

Innovator: The systems analyst must separate the symptoms of the user's problem from the true causes. With his or her knowledge of computer technology, the analyst must help the user explore useful, new applications of computers. 

Mediator: The systems analyst who often finds himself in the middle of users, managers, programmers, auditors, and various other players, all of whom frequently disagree with one another. 

Project leader: Because the systems analyst is usually more experienced than the programmers on the project, and since he is assigned to the project before the programmers begin working, there is a natural tendency to assign project management responsibilities to the analyst.

Systems designers 

The systems designer is the person (or group of people) who will receive the output of the systems analysis work. His or her job is to transform a technology-free statement of user requirements into a high-level architectural design that will provide the framework within which the programmer can work. In many cases, the systems analyst and the systems designer are the same person, or member of the same unified group of people. It is important for the systems analyst and systems designer to stay in close touch throughout the project.

Programmers 

Particularly on large systems development projects, the systems designers are likely to be a "buffer" between the systems analysts and the programmers. The systems analysts deliver their product to the system designers, and the system designers deliver their product to the programmer. The systems analyst and the programmer may have little or no contact with each other because work is often performed in a strictly serial sequence in many systems development projects. The work of systems analysis takes place first and it has to be completely finished before the work of programming begins.

Operations personnel 

The operations personnel are responsible for the computer center, telecommunications network, security of the computer hardware and data, as well as the actual running of computer programs, mounting of disk packs, and handling of output from computer printers. This happens after a new system has not only been analyzed and designed, but has also been programmed and tested.

Source: Ellen Ambakisye Kalinga
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