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Chapter 1
Introduction to Web Development
2
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
3
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
4
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
5
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)
6
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
7
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
8
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
9
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
10
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
11
Web Communication Protocols (continued)
http://www.google.com/help/index.html
Protocol Domain name Directory Filename
Figure 1-4 Sample URL
12
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
13
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
14
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
15
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
16
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
17
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
18
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
19
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
20
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
21
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
22
XHTML Document Type Definitions (DTDs) (continued)
Table 1-2 HTML elements that are deprecated in XHTML 1.0
23
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
24
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
25
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
26
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
27
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
28
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
29
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 documentP { 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
30
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
31
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
32
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
33
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
34
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
35
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
36
Client/Server Architecture (continued)
Figure 1-16 The design of a three-tier client/server system
37
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)
38
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
39
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)
40
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
41
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
42
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
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
44
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
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