DPB20043 MIS Electronic Flip Book

People In Information Systems • Roles of people in designing, development and the user of information system. a. Systems analyst b. Programmer c. Chief Information Officer d. End user



CHAPTER 5 INFORMATION SYSTEM DEVELOPMENT 1

Alternative System Building Approaches There are alternative methods for building an information system. They include: • Systems Life Cycle • Prototyping • End-user development • Application software packages and Outsourcing



1. System Life Cycle It is a traditional methodology that uses a phased approach to build a system, dividing systems development into formal stages, and corresponding to the stages of systems development. Each stage consists of basic activities that must be performed before the next stage can begin.

Systems Life Cycle

System Development Life Cycle • System Development Life Cycle or SDLC is an standard industry term used in systems engineering, information systems and software engineering to describe a process for planning, creating, testing, and deploying an information system.

2. Prototyping



Steps in Prototyping Step 1: Identify the user’s basic requirements. Step 2: Develop an initial prototype. Step 3: Use the prototype. Step 4: Revise and enhance the prototype.















4. End-user development • End-User Development can be defined as a set of methods, techniques, and tools that allow users of software systems, who are acting as non-professional software developers, at some point to create, modify or extend a software artifact.









4. Application software packages















What is a computer program? ➢ Set of instructions that directs computer to perform tasks • Programming language-used to write instructions

What is a Programming Language • A programming language allows people to create programs that tell machines (computers) what to do. • A programming language is a tool for developing executable models for a class of problem domains.



What are low-level languages and high-level languages?

Levels of Programming Languages



Programming Languages • Computers can not use human languages, and programming in the binary language of computers is a very difficult, tedious process • Therefore, most programs are written using a programming language and are converted to the binary language used by the computer • Three major categories of programming languages: • Machine Language • Assembly Language • High level Language

Machine Language • Natural language of a particular computer • Primitive instructions built into every computer • The instructions are in the form of binary code • Any other types of languages must be translated down to this level



Assembly languages • English-like Abbreviations used for operations (Load R1, R8) • Assembly languages were developed to make programming easier • The computer cannot understand assembly language - a program called assembler is used to convert assembly language programs into machine code



• So here is a snippet of assembly language:

Differences between Machine Language and Assembly Language MACHINE LANGUAGE ASSEMBLY LANGUAGE Machine langugae is only understand by the Assembly language is only understand by human computers. beings not by the computers. In machine language data only represented with In assembly language data can be represented the help of binary format(0s and 1s), with the help of mnemonics such as Mov, Add, hexadecimal and octadecimal. Sub, End etc. Machine language is very difficult to understand Assembly language is easy to understand by the by the human beings. human being as compare to machine language. Modifications and error fixing cannot be done in Modifications and error fixing can be done in machine language. assembly language.

Interpreter, Compiler, Assembler



High Level Languages • English-like and easy to learn and program • Common mathematical notation • Total Cost = Price + Tax; • area = 5 * 5 * 3.1415; • Java, C, C++, FORTRAN, VISUAL BASIC, PASCAL

Compiling Source Code A program written in a high-level language is called a source program (or source code). Since a computer cannot understand a source program. Program called a compiler is used to translate the source program into a machine language program called an object program. The object program is often then linked with other supporting library code before the object can be executed on the machine.

Methods of Programming • Procedural • Defining set of steps to transform inputs into outputs • Translating steps into code • Constructed as a set of procedures • Each procedure is a set of instructions • Object-Oriented • Defining/utilizing objects to represent real-world entities that work together to solve problem • Basic O-O Programming Components • Class • Object/Instance • Properties • Methods