Systems Analysis & Programming

10.1 Systems Development10.2 Programming: A Five-Step Procedure10.3 5 Generations of Programming Languages10.4 Programming Languages Used Today10.5 Object-Oriented & Visual Programming10.6 Markup & Scripting Languages

Chapte

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Systems Development

Organizations can make mistakes, and big organizations can make really big mistakes

Murphy’s Law: Whatever can go wrong, will go wrong, and at the worst possible time

A system A collection of related components that interact to

perform a task in order to accomplish a goal Systems Development

6-phase process of gathering information about system requirements and using that to develop a new system that improves productivity

Warning! Road Out!

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Systems Development

The three kinds of “roles” (users) of a project are: Users

The new system must ALWAYS be developed in consultation with the people who will be using the completed system

Management Managers within an organization should be consulted

about the system, as they control the budget and resources

Technical staff The Information Systems or IT staff must be involved so

they can make sure the technology is there

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Systems Development

Systems Analyst An information specialist who performs

systems analysis, design, and implementation

His or her job is to study the information and communications needs of an organization and determine what changes are needed to deliver better information to the people who need it

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Systems Development

The 6 phases of systems analysis & design are:

Information systems are frequently revised and upgraded

Steps in the cycle often overlap

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Systems Development

Phase 1: Conduct a preliminary investigation Conduct a preliminary analysis Propose alternative solutions

Interview people within the organization Study what competitors are doing Decide to leave the system as is, improve it, or

develop a new system

Describe costs and benefits Submit a preliminary plan with

recommendations This should be a written report Get management approvals for next phase

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Systems Development

Phase 2: Analyze the system Gather data

Interview employees and managers Develop, distribute, analyze questionnaires Review current written documents Observe people and processes at work

Analyze the data Use system modeling tools Create a data flow diagram to show how data flows

through the system Write a report and get approvals for next phase

Document how the current system works Document problems with the current system Describe the requirements for the new system

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Systems Development

Phase 3: Design the system Notice that you don’t design the new system

until you have done phase 2 since that establishes the requirements it must meet!

Do a preliminary design Often involves prototyping

Do a detail design, showing: Input requirements Output requirements Storage requirements Processing requirements System controls Backup

Write a report and get approvals for next phase

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Systems Development

Phase 4: Develop the system Develop or acquire the software Acquire and integrate the hardware Test the system

Unit testing Systems testing with both analysts and end-

users End-user testing is critical, as they don’t

know the software and will show the developers where they forgot something

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Systems Development

Phase 5: Implement the system Choose a strategy to convert to the new

system Direct implementation Parallel implementation Phased implementation Pilot implementation

Train the users Document the system Give classes or train the trainers

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Systems Development

Phase 6: Maintain the system Perform periodic evaluations Make changes to the system based on

new conditions Document those changes

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Programming: A Five-Step Procedure

A program is a list of instructions that the computer must follow to process data into information

The five steps are1.Clarify/define the problem2.Design the program3.Code the program4.Test the program5.Document and maintain the program

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5 Generations of Programming Languages 1945 – 1st Generation – Machine Language

The basic language of the computer – all zeros and ones

Each CPU architecture had a different machine language

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5 Generations of Programming Languages 1945 – 1st Generation – Machine Language Mid-1950s – 2nd Generation – Assembly

Language Mnemonic version of machine language Faster to program in than machine language Each CPU architecture had a different

assembler

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5 Generations of Programming Languages 1945 – 1st Generation – Machine Language Mid-1950s – 2nd Generation – Assembly

Language Mid-1950s to 60s – 3rd Generation – High-

level Languages (procedural languages) such as FORTRAN, COBOL, BASIC, C These languages are portable (the same

across all CPUs) The programmer writes, then interprets or

compiles the programs The compiler or interpreter translates the

code into the CPU-specific assembler

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5 Generations of Programming Languages 1945 – 1st Generation – Machine Language Mid-1950s – 2nd Generation – Assembly Language Mid-1950s to 60s – 3rd Generation – High-level

Languages (procedural languages) such as FORTRAN, COBOL, BASIC, C

Early 1970s – 4th Generation – Problem-oriented Languages such as SQL, Intellect, NOMAD, FOCUS Easier to program in than 3rd generation languages Three types are:

Report generators Query languages Application generators

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5 Generations of Programming Languages 1945 – 1st Generation – Machine Language Mid-1950s – 2nd Generation – Assembly Language Mid-1950s to 60s – 3rd Generation – High-level Languages

(procedural languages) such as FORTRAN, COBOL, BASIC, C Early 1970s – 4th Generation – Problem-oriented Languages such

as Intellect, NOMAD, FOCUS

Early 1980s – 5th Generation – Natural Languages Programming languages that use human

language to give people a more natural connection with computers

Part of the field of artificial intelligence

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Programming Languages Used Today

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Object-Oriented What Is an Object?

Objects are key to understanding object-oriented technology.

Look around right now and you'll find many examples of real-world objects: your dog, your desk, your television set, your bicycle.

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Object-Oriented What Is an Object? Real-world objects share two

characteristics: They all have state and behavior.

Dogs have state (name, color, breed, hungry) and

behavior (barking, fetching, wagging tail).

Identifying the state and behavior for real-world objects is a great way to begin thinking in terms of object-oriented programming.

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Object-Oriented What Is an Object? Software objects are conceptually

similar to real-world objects: they too consist of state and related behavior.

An object stores its state in properties (fields, attributes or variables in some programming languages)

An object exposes its behavior through methods (functions in some programming languages).

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Object-Oriented What Is a Method? Methods operate on an object's

internal state and serve as the primary mechanism for object-to-object communication.

Hiding internal state and requiring all interaction to be performed through an object's methods is known as data encapsulation — a fundamental principle of object-oriented programming.

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Object-Oriented & Visual Programming

In Object oriented Programming (OOP) data and processing instructions are combined into an object that can be reused Object

Self-contained module consisting of reusable code

Message The instruction received by the object indicating it

is time to perform an action

Method The processing instructions within the object to

perform the specified action

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Object-Oriented & Visual Programming Black Box

Objects are like a black box in that the actions and the objects are specified, but the methods used are internal to the object This means the programmer that uses an object does

not need to know how the program inside the object does what it does

For example, Microsoft Excel is like an object Most of us use Excel without understanding what the

programmers at Microsoft did to make Excel work If we had to know that, it would take a lot longer to learn how to

use Excel! Programmers who use objects can write programs a lot faster,

because objects save so much work

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Object-Oriented & Visual Programming 3 basic concepts of OOP

Encapsulation One object contains (encapsulates) both

State Data (properties) Relevant processing instructions or behavior (methods)

Inheritance One object can be used as the foundation for other

objects Objects can be arranged in hierarchies – classes and

subclasses Objects can inherit actions and attributes from each

other Polymorphism

Allows a single definition to be used with different data types and different functions

Means a message produces different results depending on the object it is sent to

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Object-Oriented & Visual Programming

DoorsHave a Handle

openclose

Patio doorsHave a slider

slide openslide closed

Front doorsHave locks

Car doorsHave locks

Have windows

The “Door” classActions

performed by a door

(behavior)Subclasses of doors inherit from the door class, but also have their own unique actions and attributes

Notice we only list the actions & attributes when

they differ from those of class

Example of Inheritance Hierarchy with Specialization

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Object-Oriented & Visual Programming Visual Basic is an example of visual

programming Using a mouse, the programmer drags and

drops objects on screen The objects are arranged to make up the

graphical user interface for the program being written

By double-clicking on those objects, the programmer can get into a coding window and write the programs to control the actions and behaviors of those objects

This makes it fast and easy to build prototype user interfaces and get end-user approval before doing a lot of programming