信息处理技术

信息处理技术信息处理技术

Chapter 6: Web Pages, Web Sites, and E-Commerce 2111Chapter 4: File Management, Virus Protection, and Backup

1Chapter 1: Computer, Internet, Web, and E-Mail Basics

Chapter 6: Web Pages, Web Sites, and E-Commerce 3

After this chapter, you should be able to:– Describe the roles that HTML, XHTML, HTTP,

URLs, browsers, and Web servers play in bringing Web pages to your desktop

– Explain why cookies are useful in an environment that is based on a stateless protocol, and provide some concrete examples of their use

– Identify some Web page design tools and discuss their advantages and disadvantages

– Describe how HTML tags, cascading style sheets, links, buttons, hot spots, frames, forms, and tables are used in the design and creation of Web pages

– Identify the elements that typically form a Web page

Chapter 6 Preview


– Explain how to test and post Web pages– Describe how DHTML, XML, and XSL technologies work

to enhance Web pages– List some advantages and disadvantages of using

JavaScript, VBScript, Java applets, and ActiveX controls– Discuss why e-commerce has become so popular with

consumers and merchants– List some threats to the security of credit card numbers

and other sensitive data during e-commerce transactions– Describe how the following e-commerce technologies

work: shopping carts, SSL, one-time use credit cards, electronic wallets, and person-to-person payment systems

Chapter 6 Preview


Chapter 6 Outline

• Section A– Web Technology

• Section B– Basic Web Page Authoring

• Section C– Web Page Extensions, Scripts, and

Programs

• Section D– E-Commerce

Computer Concepts 8th Edition

Chapter 6Web Pages, Web Sites, and E-Commerce

网页、网站及电子商务Section A: Web Technology

WEB技术


• The Internet is a communications network

• The Internet carries text, graphics, and audio data that forms Web pages

• The Web is an interlinked collection of information that flows over the Internet

The Web, The Net, and Hypertext: What’s the difference between the Web and the Internet?

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• Two of the most important elements of the Web– Hypertext Transfer Protocol (HTTP)– Hypertext Markup Language (HTML)

• Hypertext – text linked together in non-linear form

• Hypertext link – clickable text that lets you access related documents

What is hypertext and what does it have to do with the Web?

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What is hypertext and what does it have to do with the Web?

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• Web pages are written in HTML

• HTML document – plain text, or ASCII, document with embedded HTML tags

• HTTP communications protocol is used by Web browser when requesting specific pages

How does the Web work?

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How does the Web work?

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• HTML (Hypertext Markup Language)– is a set of specifications for creating documents– Tags specify how the document should

appear – World Wide Web Consortium (W3C) –

organization that reviews and revises HTML standard

• XHTML is the follow-up version to HTML 4

HTML and XHTML: What is HTML?

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HTML and XHTML: What is HTML?

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• HTML document is like a screenplay

• Web browser is like a director

• Web page exists only for the duration of the performance

So HTML documents look a lot different than Web pages, right?

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Can I see the HTML tags used to create a Web page?

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• Formatting tags

• Link tags

• Media tags

• Operational tags

What are the most commonly used HTML tags?

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• Browser plays two roles:– Uses HTTP to send messages to a Web

Server– Interprets the HTML tags from the Web

server in order to display the requested Web page

Web Browsers: Why do I need a web browser to access the Web?

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What are some of today’s most popular browsers?

• Netscape

• Internet Explorer

• Opera

• Mozilla Firefox

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• It is a good idea to upgrade when a new version comes out– Contains up-to-date functionality– Some Web pages depend on new HTML

features supported by newer versions of a browser

– Upgrades are generally free

Should I upgrade my browser when new versions become available?

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• The native file formats for early browsers typically were limited to documents in HTML format and graphics files in GIF and JPEG formats

• Files that are not handled by the browser sometimes require you to download helper application, plug-in, or player in order to handle the files

Helper Applications, Plug-Ins, Players: Why do I have to download software to view some Web pages?

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• A program that extends a browser’s ability to work with file formats– Updates your system so browser can

automatically open helper application that works with a specific file format

– Used by browser to open non-HTML file format

What is a helper application?

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• Plug-in – type of helper application that can be activated by the EMBED tag inserted in an HTML document

• Player – any helper application or plug-in that helps a browser display a particular file format

Is a plug-in the same as a helper application?

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HTTP: How does HTTP work?

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• Yes

• HTTP is classified as a stateless protocol– One request and response per session– Assembly of one page requires one

request per element on the page

Does a browser have to request each Web page element separately?

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What if a Web server cannot find the file a browser requested?

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• Web server is configured to include HTTP software– Always running when server is “up” and

ready to fulfill requests– One port is dedicated to “listening” for

HTTP requests• Traditionally port 80

Web Servers: How does a Web server understand HTTP requests?

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• Not necessarily – server can house many sites or just one, and one site may cover several servers– www.hotmail.com – housed on several

identically configured file servers

Is a Web server the same as a Web site?

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• A small chunk of data generated by a Web server and stored in a text file on your computer

• Web sites use cookies to:– Track your path through a site– Provide information that allows the Web site to

present you with ad banners– Retain any personal information that you type

into a Web page form

Cookies: What is a “cookie”?

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What is a “cookie”?

A cookie is created by a Web server and stored on your computer’s hard disk

5


• Cookies are a relatively safe technology– Data, not computer program– Can only be accessed by site that created

it– Contain only information you disclose while

using the site– Uses a randomly generated number

instead of your name

Are cookies safe and private?

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Does my computer have to accept cookies?

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• A Web programmer can program a cookie to “time out”

• You can delete the cookies– Netscape uses Cookies.txt or Magiccookie– IE stores each in a separate file

How long do cookies stay on my computer?

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Section B: Basic Web Page Authoring网页设计基础


• Text editor – most difficult as you have to create everything from scratch

Web Page Authoring Tools:网页设计工具

What tools can I use to create Web pages?

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• Conversion option available in many software applications– Microsoft Word

• File menu’s Save As Web Page

• Online Web authoring tools– Provided by some ISPs– Type, select, drag, and drop elements onto

Web page

What is an HTML conversion tool?什么是 HTML转换工具？

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• Web authoring software – provides tools for creating web pages– Microsoft FrontPage

– Macromedia Dreamweaver

What’s Web authoring software?什么是网页设计软件？

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What’s Web authoring software?

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What are the components of a Web page?

网页页面的组成

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• In Web page authoring software, highlight and then format

• With a text editor, use tags such as:

Formats, Styles, and Style Sheets: How do I format the text on a Web page?

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• A style is the same as in the world of word processing– Bold, italic, green, and Arial

• Don’t get carried away, choose base font for paragraphs; consistent style for headers

What is a style?

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• Cascading style sheet (CSS) – acts as a template that can control the layout and design of Web pages– Internal – placed near the beginning of html

document (<style> tag within <head> section)

– External style sheet – contains formatting specifications for a group of Web pages; a separate file contains the styles

What is a style sheet?

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How are graphics incorporated into Web pages?

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What about video and animation?

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• A link appears as underlined, blue text (color depends upon settings)

• Can also be a button or a graphic

• The HTML has two parts– Destination, Label

Links, Buttons, and Hot Spots: How do links work?

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• Instead of text label, you can use an image as a clickable link– Can connect to graphics or other Web

pages– Can look like buttons, complete with labels

and icons

How can I turn a graphic into a link?

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• Internal link – links to other pages on same site

• External link – links to pages outside of the site

• Intrapage link – jumps to a location within same page

• Mailto link – automatically opens pre-addressed e-mail form that can be filled in and sent

What kinds of links can I add to a page?

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HTML Forms: What is an HTML form?

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• Your information is stored in memory on your computer

• When you click a Submit button, information is gathered and submitted via a specially designated program on an HTTP server

What happens to the data that’s entered into a form?

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• CGI (Common Gateway Interface) – set of specifications or standards for how servers can handle a variety of HTTP requests

• ASP (Active Server Pages) – server-side technology developed by Microsoft that offers an alternative to CGI– Runs on server and deals with data submitted– Can be written in any scripting language

• CGI and ASP specify how the server should deal with the data

What happens to my data after it arrives at a server?

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Why are tables such an integral part of many Web pages?

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• Easy to use when created with Web authoring software

• Text editors are more complicated when creating tables– To view table, must preview page using

your browser

How flexible are tables?

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Frames: What’s a frame?

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Testing and Posting Web Pages

• Test each page locally

• Transfer pages to a Web server

• Test all pages and links

• Update your site to keep it current

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Section C: Web Page Extensions, Scripts, and Programs网页的扩展名、脚本、程序


What is DHTML?

DHTML effects usually activate as a result of a“mouseover”. In this example, moving the mouse

over the map zooms the map to a larger size

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• No

• DHTML is just a term that is used to describe a method for using HTML in combination with a few other technologies

Is DHTML a replacement for HTML?

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• XML (eXtensible Markup Language) – method for putting structured data into a text file– Uses tags and attributes– Defines fields of data– <part number>, <price>, <weight>

XML and XSL: What is XML?

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• XSL (eXtensible Stylesheet Language) – creates customized tags that control the display of the data that’s contained in an XML document

What is XSL?

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• Yes, to perform complicated tasks and respond to user actions

• Script – allows designers to embed simple program instructions (scripting statements)

JavaScript and VBScript: Is it possible to add programs to a Web page?

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• Scripting languages allow pages to become more interactive– Allows e-commerce sites to verify credit

card information– Makes interactive pages like loan payment

calculators

How would a Web page author use a scripting language?

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• JavaScript

• VBScript

• Alternatives– PerlScript– Python– REXX– Awk

What are the most popular scripting languages?

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• Client-side scripts – consist of scripting statements embedded in HTML document– Execute in browser on client

• Server-side scripts – consist of statements that are executed on server– Typically accept data submitted by a form

How do scripts work?

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• Occurs when a browser or server cannot execute one or more statements in a script– Syntax errors– Script command not supported

What’s a Scripting Error?

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• Java is a high-level programming language developed by Sun Microsystems

• Small Java applications are called Java applets– Input forms, rotating images, interactive

animation

Java Applets: What’s a Java applet?

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How do applets work?

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• Compiled computer program that can be referenced from within an HTML document– Can be used on client-side or server-side

ActiveX controls: What is an ActiveX control?

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• Digital certificate – electronic attachment to a file that verifies the identity of its source

• Certificate authority – company that supplies digital certificates

What is a digital certificate?

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How does a digital certificate work?

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Section D: E-Commerce电子商务


• E-commerce describes financial transactions that are conducted electronically over a computer network– Includes physical products, digital products, and

services– Digital products such as News, music, video,

databases, software, and all types of knowledge-based items

– Peddle services, such as arranging trips, online medical consultation, and remote education

– Carried out by computer or require human agents

E-Commerce Basics: What is e-commerce?

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• Demographics not yet stabilized– In 1995, 30-something white male– Now, females and teens have entered the

online shopping fray in droves– B2C (business-to-consumer) e-commerce

– typical e-commerce activities that the typical Web surfer enjoys

– C2C (consumer-to-consumer) – includes online auctions and rummage sales

Who is the typical e-commerce customer?

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• B2B (business-to-business) e-commerce – involves one enterprise buying goods and services from another enterprise

• B2G (business-to-government) e-commerce – aims to help businesses sell to governments

Who is the typical e-commerce customer?

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How does an e-commerce store work?

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• Cyberspace version of the good old metal cart that you wheel around a store and fill up with merchandise

Shopping Carts: What’s an online shopping cart?

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• Shopper browses Web site, and then adds products using a “Buy” or “Add to Cart” button

• Uses cookies to store information about your activities on Web site

How do shopping carts work?

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• Spyware is often used to gather information secretly and relay it to advertisers or other interested parties

• Ad-serving cookies track your activities at any site containing banner ads from the third party (who supplied the cookie)

Transaction Privacy and Security: How does e-commerce affect my privacy?

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What is an electronic wallet?

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• Customer opens an account

• Some services require you to deposit some money into your account

• Customer receives user ID and password

• Money can be sent to anyone who has an e-mail account

How does a person-to-person payment work?

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You should now be able to:– Describe the roles that HTML, XHTML, HTTP,

URLs, browsers, and Web servers play in bringing Web pages to your desktop

– Explain why cookies are useful in an environment that is based on a stateless protocol, and provide some concrete examples of their use

– Identify some Web page design tools and discuss their advantages and disadvantages

– Describe how HTML tags, cascading style sheets, links, buttons, hot spots, frames, forms, and tables are used in the design and creation of Web pages

– Identify the elements that typically form a Web page

Conclusion


– Explain how to test and post Web pages– Describe how DHTML, XML, and XSL technologies work

to enhance Web pages– List some advantages and disadvantages of using

JavaScript, VBScript, Java applets, and ActiveX controls– Discuss why e-commerce has become so popular with

consumers and merchants– List some threats to the security of credit card numbers

and other sensitive data during e-commerce transactions– Describe how the following e-commerce technologies

work: shopping carts, SSL, one-time use credit cards, electronic wallets, and person-to-person payment systems

Conclusion

信息处理技术

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