Chapter 1 Introduction to Web Development

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Chapter 1


Introduction to Web

Development


PHP Programming with MySQL


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PHP Programming with MySQL

Introduction to Web Development


In 1990 and 1991,Tim Berners
-
Lee created the
World Wide Web at the European Laboratory for
Particle Physics (CERN) in Geneva, Switzerland


The original purpose of the
World Wide Web

(WWW)

was to provide easy access to cross
-
referenced documents that existed on the CERN
computer network


Hypertext

linking

allows you to quickly open
other Web pages


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PHP Programming with MySQL

Introduction to Web Development
(continued)


A document on the Web is called a
Web page


A Web page is identified by a unique address
called the Uniform Resource Locator (
URL
)


A URL is also commonly referred to as a
Web
address


A URL is a type of Uniform Resource Identifier
(
URI
)


A

Web site

refers to the location on the Internet
of the Web pages and related files


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PHP Programming with MySQL

Introduction to Web Development
(continued)


Web pages are displayed using a program
called a
Web browser


A
Web server

is a computer that delivers Web
pages


The most popular Web server software is
Apache HTTP Server (
Apache
)


The second most popular Web server is
Microsoft Internet Information Services (
IIS
) for
Windows


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PHP Programming with MySQL

HTML Documents


Web pages are created using Hypertext Markup
Language

(HTML)


Web pages are commonly referred to as
HTML

pages

or
documents


A
markup language

is a set of characters or
symbols that define a document’s logical
structure


HTML is based on an older language called
Standard Generalized Markup Language

(SGML)


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PHP Programming with MySQL

HTML Documents (continued)


Like

SGML, HTML

was originally designed as a
way of defining the elements in a document
independent of how they would appear


HTML

has evolved into a language that defines
how elements should appear in a Web browser


Understanding HTML is critical in learning how
to write a web application along with the server
programming


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PHP Programming with MySQL

Basic HTML Syntax


HTML

documents

are text documents that contain
formatting instructions called
tags


HTML tags include:


Formatting commands (
boldface

or
italic
)


Controls that allow user input (option buttons or check
boxes)


Tags are enclosed in brackets
(< >)

and consist of
an opening tag and a closing tag


Tutorial for learning HTML


http://www.htmldog.com/


http://www.w3schools.com/html/DEFAULT.asp




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PHP Programming with MySQL

Web Communication Protocols


A Web page is identified by a unique address
called the
URL


Each URL consists of two basic parts:


A
protocol

(usually HTTP) and


Either the
domain name

for a Web server or a
Web server’s
Internet Protocol address


Hypertext Transfer Protocol (
HTTP
) manages
the hypertext links that are used to navigate the
Web




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PHP Programming with MySQL

Web Communication Protocols
(continued)


A
host

refers to a computer system that is being
accessed by a remote computer


A
domain name

is a unique address used for
identifying a computer such as a Web server on
the Internet


The
domain identifier

identifies the type of
institution or organization (.biz, .com, .edu, .org)


An
Internet Protocol
, or
IP address
, is another
way to identify computers or devices connected
to the Internet


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PHP Programming with MySQL

Web Communication Protocols
(continued)


An IP address consists of a series of four groups
of numbers separated by periods


Each Internet domain name is associated with a
unique IP address


HTTP is a component of Transmission Control
Protocol/Internet Protocol (
TCP/IP
)


Hypertext Transfer Protocol Secure (
HTTPS
)
provides secure Internet connections for
transactions that require security and privacy


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PHP Programming with MySQL

Web Communication Protocols
(continued)



http://www.google.com/help/index.html






Protocol Domain name Directory Filename




Figure 1
-
4 Sample URL


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PHP Programming with MySQL

Publishing Your Web Site


Web Hosting:


The publication of a Web site for public access


Internet access (cable modem, DSL, satellite,
dial
-
up modem, ISP)


Internet Service Provider

(
ISP
):


Provides access to the Internet along with other
types of services such as e
-
mail


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PHP Programming with MySQL

Publishing Your Web Site
(continued)


ISP advantages to hosting a Web site:


Extremely fast Internet connections using
advanced fiber
-
optic connections


Large and powerful Web servers and the
expertise and manpower to maintain and manage
them


A

domain name

is a unique address used for
identifying a computer, such as a Web server on
the Internet


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PHP Programming with MySQL

Publishing Your Web Site

(continued)


Domain name registration


Pick a domain name that is similar to your
business name or that describes your Web site


You cannot use a domain name that is already in
use or a trademarked name


Contact a
domain name registrar
to

find out the
availability of a domain name and register it


Domain names are stored in a master database
that is maintained by the InterNIC


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PHP Programming with MySQL

Publishing Your Web Site

(continued)


Domain name registration
(continued)


For a fee, domain names can be registered for a
specified period of time


Most hosting sites provide registration service for
you


After you register your domain name, notify your
ISP of your domain information



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PHP Programming with MySQL

Publishing Your Web Site

(continued)


File Transfer Protocol

(FTP)


Is a
TCP/IP protocol

used for transferring files
across the Internet


Transfers files between an
FTP

client

(your
computer) and an
FTP server

(a server capable
of running FTP)


The vehicle that allows you to get your Web page
files to the Web server


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PHP Programming with MySQL

Publishing Your Web Site

(continued)


File Transfer Protocol
(continued)


Your ISP provides a username and password to
log on to the FTP site and upload files to the FTP
server


Examples of FTP clients include Firefox and
Internet Explorer and WinScp


Use your browser to log on to an FTP server and
upload your files


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PHP Programming with MySQL

Working with Well
-
Formed

Web Pages


HTML became an Internet standard in 1993 with
the release of version 1.0


The current version of HTML (4.01) was
released in 1999


HTML 4.01 is the last version of the HTML
language and is being replaced with
extensible
hypertext markup language

(
XHTML)


HTML is not suitable for user agents other than
Web browsers



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PHP Programming with MySQL

XHTML Document Type Definitions
(DTDs)


A well
-
formed document must include:


<!DOCTYPE>

declaration


<html>
,
<head>,

and
<body>

elements


A
document type definition
(
DTD
) defines:


The elements and attributes that can be used in

a document


The rules that a document must follow when it
includes them


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PHP Programming with MySQL

XHTML Document Type Definitions
(DTDs) (continued)


There are three types of DTDs with XHTML
documents:


transitional


strict


frameset


The World Wide Web Consortium (
W3C
) was
established in 1994 at MIT to oversee the
development of Web technology standards



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PHP Programming with MySQL

XHTML Document Type Definitions
(DTDs) (continued)


The
W3C
:


Decided some common HTML elements and
attributes for display and formatting would not be
used in
XHTML 1.0


Recommended using
Cascading Style Sheets
(CSS)
instead of HTML elements and attributes
for displaying and formatting Web pages


Elements and attributes that are considered
obsolete and will eventually be eliminated are
said to be
deprecated


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PHP Programming with MySQL

XHTML Document Type Definitions
(DTDs) (continued)











Table 1
-
2 HTML elements that are deprecated in XHTML 1.0



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PHP Programming with MySQL

XHTML Document Type Definitions
(DTDs) (continued)


Transitional DTD:


Allows you to use deprecated style elements in
your XHTML documents


Use only if you need to create Web pages that
use the deprecated elements


Frameset DTD:


Identical to the transitional DTD, except that it
includes the <frameset> and <frame> elements


Allows you to split the browser window into two or
more frames


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PHP Programming with MySQL

XHTML Document Type Definitions
(DTDs) (continued)


Strict DTD:



Eliminates the elements that were deprecated in
the transitional DTD and frameset DTD


The <!DOCTYPE> declaration for the strict DTD
is as follows:


<!DOCTYPE html PUBLIC


"
-
//W3C//DTD XHTML 1.0 Strict//EN"


"http://www.w3.org/TR/xhtml1/DTD/xhtml1
-
strict.dtd">


Always try to use the strict DTD


http://www.webstandards.org/learn/reference/tem
plates/


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PHP Programming with MySQL

Writing Well
-
Formed Documents


Include a <!DOCTYPE> declaration and the
<html>, <head>, and <body> elements


All XHTML documents must use <html> as the
root element


XHTML is case sensitive


All XHTML elements must have a closing tag


Attribute values must appear within quotation
marks


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PHP Programming with MySQL

Writing Well
-
Formed Documents
(continued)


Empty elements must be closed


XHTML elements must be properly nested


Nesting

refers to how elements are placed
inside other elements



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PHP Programming with MySQL

Cascading Style Sheets


A single piece of CSS formatting information,
such as text alignment, is referred to as a
style


The term
cascading

refers to the ability for Web
pages to use CSS information from more than
one source



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PHP Programming with MySQL

Cascading Style Sheets
(continued)


CSS properties:


CSS styles are created with two parts separated
by a colon


The
property

refers to a specific CSS style


The
value

assigned to it determines the style’s
visual characteristics


Together, a CSS property and the value assigned
to it are referred to as a
declaration

or
style
declaration


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PHP Programming with MySQL

Cascading Style Sheets
(continued)


Inline Styles


Allow you to add style information to a single
element in a document


Internal Style Sheets


Create styles that apply to the entire document

P { color : blue }

selector property value


External Style Sheets


A separate text document containing style
declarations that are used by multiple documents
on a Web site


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PHP Programming with MySQL

The Content
-
Type <meta> Element


Create a content
-
type
<meta>

element to
specify a content type that the document uses


The <meta> element provides information about
the information in a Web page


The <meta> element is nested within the <head>
section of the Web page


The three primary attributes in the <meta>
element are: name, content, and http
-
equiv



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PHP Programming with MySQL

Validating Web Pages


A
validating parser

is a program that checks
whether an XHTML document is well
-
formed
and conforms to a specific DTD


Validation verifies that your XHTML document is
well formed and that the elements in your
document are correctly written


Validation can help you spot errors in your code


XHTML validating services can be found online


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PHP Programming with MySQL

Understanding Web Development


Web development
, or Web programming, refers
to the design of software applications for a Web
site


The
Webmaster

is responsible for:


The day
-
to
-
day maintenance of a Web site


Monitoring Web site traffic and ensuring that the
Web site’s hardware and software are running
properly


Knowledge of Web page design, authoring, and
development



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PHP Programming with MySQL

Client/Server Architecture


Server (“back end”):


A database from which a client requests
information


Fulfills a request for information by managing the
request or serving the requested information to
the client


Responsible for data storage and management


A system consisting of a client and a server is
known as a
two
-
tier system


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PHP Programming with MySQL

Client/Server Architecture
(continued)


Client (“front end”):


Presents an interface to the user


Gathers information from the user, submits it to a
server, then receives, formats, and presents the
results returned from the server


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PHP Programming with MySQL

Client/Server Architecture
(continued)


A
three
-
tier
, or multi
-
tier, client/server system
consists of three distinct pieces:


Client tier
, or user interface tier, is the Web
browser


Processing tier
, or middle tier, handles the
interaction between the Web browser client and
the data storage tier


Performs necessary processing or calculations
based on the request from the client tier


Handles the return of any information to the client
tier


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PHP Programming with MySQL

Client/Server Architecture
(continued)

Figure 1
-
16 The design of a three
-
tier client/server system


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PHP Programming with MySQL

JavaScript and Client
-
Side
Scripting


JavaScript

is:


A client
-
side scripting language that allows Web
page authors to develop interactive Web pages
and sites


Used in most Web browsers including Firefox and
Internet Explorer


Client
-
side scripting

is a language that runs on
a local browser (on the client tier) instead of on a
Web server (on the processing tier)


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PHP Programming with MySQL

JavaScript and Client
-
Side
Scripting (continued)


JavaScript allows you to:


Turn static Web pages into applications such as
games or calculators


Change the contents of a Web page after a
browser has rendered it


Create visual effects such as animation


Control the Web browser window itself


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PHP Programming with MySQL

Server
-
Side Scripting and PHP


Server
-
side scripting

refers to a scripting language that
is executed from a Web server


Hypertext Preprocessor (PHP)

is a server
-
side
scripting language that is used to develop interactive
Web sites


Is easy to learn


Includes object
-
oriented programming capabilities


Supports many types of databases (MySQL, Oracle,
Sybase, ODBC
-
compliant)




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PHP Programming with MySQL

Server
-
Side Scripting and PHP
(continued)


PHP (continued):


PHP is an
open source

programming language


Open source refers to software where source

code can be freely used and modified


Can’t access or manipulate a Web browser like
JavaScript


Exists and executes solely on a Web server,
where it performs various types of processing or
accesses databases




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PHP Programming with MySQL

Server
-
Side Scripting and PHP
(continued)







General rule: Use client
-
side scripting to handle
user interface processing and light processing,
such as validation; use server
-
side scripting for
intensive calculations and data storage

Figure 1
-
17 How a Web server processes a PHP script


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PHP Programming with MySQL

Summary


In 1990 and 1991,Tim Berners
-
Lee created the
World Wide Web at the European Laboratory for
Particle Physics (CERN)


Transmission Control Protocol/Internet Protocol
(TCP/IP) is a large collection of communication
protocols used on the Internet


A Document Type Definition (DTD) defines the
elements and attributes that can be used in a
document



43

PHP Programming with MySQL

Summary (continued)


Cascading Style Sheets (CSS) are a standard
set by the W3C for managing the design and
formatting of Web pages in a Web browser


A system that consists of a client and a server is
known as a two
-
tier system


A three
-
tier client/server system consists of the
client tier, the processing tier, and the data
storage tier


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PHP Programming with MySQL

Summary (continued)


JavaScript is a client
-
side scripting language that
allows Web page authors to develop interactive
Web pages and sites


Hypertext Preprocessor (PHP) is a server
-
side
scripting language that is used for developing
interactive Web sites


Open source refers to software for which the
source code can be freely used and modified