IT_Chapter_13B

Programming Languages

• Used to generate source code

• Avoids using machine code

• Have strict rules of syntax

– Symbols and punctuation have meaning

– Spelling must be exact

• Code is converted into machine language

Language Categories

• First generation language

– Machine languages

– Written in binary

– Different for every CPU

• Second generation languages

– Assembly languages

– Statements that represent machine code

– Code converted by an assembler

– Still used to optimize video games

• Third generation languages (3GL)

– First higher level language

– Supports structured and OOP

• Code is reusable

• Code is portable

– Typically written in an IDE

– C/C++ creates games and applications

– Java creates web applets

– ActiveX creates Web and Windows applets

• Fourth generation languages (4GL)

– Easier to use than 3GL

– Coded in a visual IDE

– Tools reduce the amount of code

– Object oriented programming

– Microsoft .Net is a language

– Dream Weaver is an 4GL IDE

• Fifth generation language (5GL)

– Mystery language

– May not be created yet

– Will create software automatically

WWW Development Languages

• Markup languages

– Describe how the text is formatted

• Hyper Text Markup Language (HTML)

– Basis of all web pages

– Defines web structure using tags

– Easy to learn and use

– Created with a text editor

• Extensible Markup Language (XML)

– Stores data in a readable format

– Looks like HTML

– Allows developers to create tags

– Depends on HTML for formatting

• Extensible HTML (XHTML)

– Newer version of HTML

– Stricter rules

– Based on XML rules

• Extensible Style Sheet Language (XSL)

– Format and displays XML documents

– Rules that dictate formatting

– Create a standard web page

• Extensible HTML Mobile Profile

– XHTML MP

– Initially Wireless Markup Language (WML)

– Creates pages viewable on a handheld

• Cascading Style Sheets (CSS)

– Format HTML, XHTML and XSL

– Applies consistent formatting to all pages

• Web authoring environments

– Reduces tedium for creating pages

– Tools that simplify web site creation

– Macromedia Dream weaver

• Simplifies large sites

• CSS support is exceptional

– Microsoft FrontPage simplifies large sites

– Macromedia Flash creates web animations

• Scripting languages

– Create dynamic web pages

• Change based on user input

– HTML can create static pages

– Page is generated as needed

• JavaScript

– Developed by Netscape

– Works inside of HTML

– Page verification and simple animation

– Based on Java

• Active Server Pages (ASP)

– Developed by Microsoft

– Based on Visual Basic

– Good at connecting to Microsoft databases

– Runs only on Microsoft servers

• Perl

– Old UNIX language

– Found on all Windows and Linux servers

– Excellent web scripting language

• Hypertext Pre-Processor (PHP)

– Especially good at connecting to MySQL

– Very popular language

– Runs on UNIX and Windows

Systems Development Life Cycle

• SDLC

• Organized way to build programs

• Consists of five phases

• Phase 1: Needs Analysis

– Users identify a need

– Need is clearly defined using tools

• Phase 2: Systems design

– Solution to the need is defined

– Many tools are used

– Prototypes of the solution are built

• Phase 3: Development

– Solution to the problem is built

– Programmers write the solution

– Technical writers document the process

– Solution is continually tested

• Phase 4: Implementation

– The solution is installed

– Users are converted to the new system

– Trainers are important in this phase

• Phase 5: Maintenance

– IT professionals monitor the product

– Bugs are found and fixed

– New features are added