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Introduction to Web DevelopmentIn 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

Introduction to Web Development (continued)A document on the Web is called a Web pageA Web page is identified by a unique address

called the Uniform Resource Locator (URL)A URL is also commonly referred to as a Web

addressA 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

Introduction to Web Development (continued)Web pages are displayed using a program

called a Web browserA Web server is a computer that delivers

Web pagesThe most popular Web server software is

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

Microsoft Internet Information Services (IIS) for Windows

GoalTo provide information to the user:-

Files holding information must be createdThese file must be store at a central location on

computerWhen required the user should be allowed to

access these file using there desktop computers

A network link must be establish between the desktop computer and the computer serving information at a central location.

Web Communication ProtocolsA Web page is identified by a unique address

called the URLEach 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 addressHypertext Transfer Protocol (HTTP)

manages the hypertext links that are used to navigate the Web

Web Communication Protocols (continued)A host refers to a computer system that is

being accessed by a remote computerA 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

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 (may be shared).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

Web Communication Protocols (continued)

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

Protocol Domain name Directory Filename

Client/Server ArchitectureServer (“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 managementA system consisting of a client and a server is

known as a two-tier system

Client/Server Architecture (continued)Client (“front end”):

Presents an interface to the userGathers information from the user, submits it

to a server, then receives, formats, and presents the results returned from the server

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

Client/Server Architecture (continued)

HTML DocumentsWeb pages are created using Hypertext

Markup Language (HTML)Web pages are commonly referred to as

HTML pages or documentsA 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)

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

Cascading Style SheetsA 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

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 characteristicsTogether, a CSS property and the value

assigned to it are referred to as a declaration or style declaration

Cascading Style Sheets (continued)Inline Styles

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

Internal Style SheetsCreate styles that apply to the entire document

P { color : blue }selector property value

External Style SheetsA separate text document containing style

declarations that are used by multiple documents on a Web site

JavaScript and Client-Side ScriptingJavaScript 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)

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 animationControl the Web browser window itself

Server-Side Scripting and PHPServer-side scripting refers to a scripting

language that is executed from a Web serverHypertext Preprocessor (PHP) is a server-

side scripting language that is used to develop interactive Web sitesIs easy to learnIncludes object-oriented programming capabilitiesSupports many types of databases (MySQL, Oracle,

Sybase, ODBC-compliant)

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 modifiedCan’t access or manipulate a Web browser like

JavaScriptExists and executes solely on a Web server,

where it performs various types of processing or accesses databases

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