The basics an overview of the internet web technologies
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The Basics: An overview of the Internet & Web technologies Today’s Lecture Introduction to Computer networks and the WWW Web search study Break In-class activity – introduce your favorite/least favorite Web sites A Review of Last Week’s Lecture

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Today’s Lecture

  • Introduction to Computer networks and the WWW

  • Web search study

    Break

  • In-class activity – introduce your favorite/least favorite Web sites


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A Review of Last Week’s Lecture

  • The Internet began as a military research project

  • It grew to its current role as a global communications network linking more than a billion persons, businesses, organizations, and governments.

  • The Internet has made information available on a scale never before imagined.


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A Review of Last Week’s Lecture

  • The Internet is composed of interconnected client/server networks.

  • The Internet grew rapidly, especially after the Web became available as a new way of using the Internet.

  • There are several choices for bandwidth and pricing choices when connecting to the Internet.



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Computer Networks

  • Network Interface Card (NIC):a card used to connect a computer to a network of other computers.

  • Server: computer that accepts requests and shares some or all of its resources with computers it is connected to.

  • NICs connect to cables which connect to servers.


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The Internet

  • Computers connected to each other form a network.

  • LAN (localareanetwork): Networked computers physically near each other.

  • WAN (wideareanetwork): Networked computers not near each other.


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A Client/Server LAN

New Perspectives on The Internet, Sixth Edition—Comprehensive Appendix A

8


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The Internet

  • internet: networks connected to each other

  • Internet: a specific internet that connects computers all over the world using a common set of interconnection standards (TCP/IP).

  • WorldWideWeb (WWW): a subset of the computers on the Internet that use software to make their contents easily accessible to each other.


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The World Wide Web

  • Web servers: Computers connected to the Internet that contain files their owners have made available publicly through their Internet connections.

  • When you use your Internet connection to become part of the Web, your computer becomes a Webclient in a worldwide client/server network.

  • Web browser: software that you run on your computer to make it work as a Web client.


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Client/Server Structure of the World Wide Web

11

New Perspectives on The Internet, Sixth Edition—Comprehensive Tutorial 1


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Hypertext, Links, and Hypermedia

  • Hypertext Markup Language (HTML):standard language used on the Web to format documents.

  • HTML uses codes (tags) to tell the Web browser software how to display text.

  • <head> Heading new </head>

  • <body> This is the body text. </body>

  • HTML document: a text file that contains HTML tags.

  • When a Web browser displays an HTML document, it is referred to as a Webpage.


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Hypertext, Links, and Hypermedia

  • HTML anchor tag: enables Web designers to link HTML documents to each other. (<A…> & </A>)

  • Hypertext links:can connect HTML documents together; can also connect one part of HTML document to another part.

  • Hypermedia links: hyperlinks that connect to computer files that contain pictures, graphics, and media objects such as sound and video clips.


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Hypertext, Links, and Hypermedia

New Perspectives on The Internet, Sixth Edition—Comprehensive Tutorial 1

14


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Web Site Organization

  • Web site: a collection of linked Web pages with a common theme or focus.

  • Home page

    • the main page for a particular Web site.

    • the first page that opens when you start your Web browser; sometimes called start page.

    • the Web page that a Web browser loads the first time you use it; also sometimes called start page.


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Addresses on the Web

  • Internet Protocol Address (IP): unique id number given to each computer on the Web. (i.e., 144.214.5.218)

  • Domain name: unique name associated with specific IP address by a program that runs on an Internet host computer. (www.cityu.edu.hk)

  • Domain Name Software (DNS): coordinates IP addresses and domain names for all computers attached to it.

  • Domain name server: the host computer that runs DNS software.

  • The last part of domain name is called its top-level domain (TLD).


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Common Top Level Domains (TLDs)

New Perspectives on The Internet, Sixth Edition—Comprehensive Tutorial 1

17


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Uniform Resource Locators

Four-part addressing scheme tells the Web browser:

  • Transfer protocol to use when transporting the file.

  • Domain name of computer on which file resides.

  • Pathname of folder or directory on computer on which file resides.

  • Name of the file.


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Uniform Resource Locators

Structure of a Uniform Resource Locator (URL)


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Main Elements of Web Browsers

  • Title Bar

  • Scroll Bars

  • Status Bar

  • Menu Bar

  • Page Tab

  • Home Button


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Finding Information on the Web Using Search Engines & Web Directories

  • Web Search Engines: Web pages that conduct searches of the Web to find words or expressions you enter.

  • Web Directory: a Web page that contains a list of Web page categories like education or recreation. Can narrow the results returned for a particular search.

  • Web directory editors categorize the Web pages.


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Returning to Web Pages DirectoriesPreviously Visited

  • Using favorites and bookmarks

    • Internet Explorer - save the URL of a site you would like to revisit as a favorite in the Favorites folder.

    • Firefox - use a bookmark to save the URL of a specific page so you can return to it.

  • Using the History List

    • Back button

    • Forward button


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Returning to Web Pages DirectoriesPreviously Visited

  • Cookie

    • A small file that a Web server writes to the disk of the client computer.

    • Can contain information about the user such as login names and passwords.

    • Assists in performing functions such as automatic login.

    • User is often unaware that the files are being written to the computer’s disk drive.


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Reloading a Web Page and Stopping a Web Page Transfer Directories

  • The browser stores a copy of every Web page it displays on your computer’s hard drive in a cache folder.

  • Use the Refresh button in IE or the Reload button in Firefox to load the same Web page that appears in the browser window again.

  • Use the Stopbutton to halt the Web page transfer from the server.


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Printing and Saving Web Pages Directories

  • You can use a Web browser to print a Web page.

  • You can save copies of most Web pages as files that you can store on your computer’s hard disk, floppy disk, etc.

  • Some Web pages are written to make copying and saving difficult or impossible.


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Examining Additional Web Browser Choices Directories

  • Other Internet browsers began to make a dent in Microsoft’s dominant position in 2004.

  • Security flaws in Internet Explorer were increasingly exploited by virus and worm writers.

  • Organizations and individuals began to doubt reliability of a single browser.

  • http://en.wikipedia.org/wiki/Comparison_of_web_browsers


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Mozilla Project Directories

  • Mosaic

    • One of the first Web browsers

    • Developed in 1990s

  • NetscapeNavigator

    • First commercially successful Web browser

    • Created by Mosaic developers

    • Originally called “Mozilla,” short for “Mosaic killer”


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Mozilla Project Directories

  • Mozilla project

    • Started in 1999 after Netscape Navigator was turned over to a non-profit organization

    • They rebuilt the browser rendering engine (the internal workings of the browser)

  • Gecko engine: browser rendering engine used in Netscape Navigator, the Mozilla browser and Mozilla Firefox.


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Mozilla Suite Directories

  • A combination of software applications developed by the Mozilla open source project.

    • Web browser

    • E-mail client and newsreader – Mozilla Messenger

    • HTML editor – Mozilla Composer

    • Instant messaging chat client – ChatZilla

  • Time Warner’s AOL division distributes most of the Mozilla Suite as Netscape Navigator.


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Browsers for Hire: DirectoriesOpera and iRider

  • Internet Explorer, Navigator, Mozilla, and Firefox are all available at no cost.

  • Some browsers, such as Opera and iRider, charge a license fee


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Opera Directories

  • Started out as research project at Telenor, Norway’s state telecommunication company.

  • Program code written independently and is not affected by security flaws exploited by those attacking Gecko-based browsers or IE.

  • Free version available supported by advertising.


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Opera for Mobile Directories

  • Gives mobile device users a fully functional Web browser.

  • Users can view any Web site (not just those designed to display on mobile devices) using a mobile phone, PDA, or similar device.


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Opera Web Browser Main Screen Directories

New Perspectives on The Internet, Sixth Edition—Comprehensive Tutorial 1

33


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iRider Directories

  • Designed for power users.

  • Can view thumbnail images of multiple open Web pages displayed in a hierarchical map called a Page List.

  • Keeps all open Web pages in memory until the user deletes them.

  • User can run several searches simultaneously and compare the results.

  • Users can select multiple links on a page and iRider downloads the pages simultaneously.


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Multiple Searches in the DirectoriesiRider Web Browser

Hierarchy of thumbnail images (one for each Web page visited).

New Perspectives on The Internet, Sixth Edition—Comprehensive Tutorial 1

35


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Reproducing Web Pages and Copyright Law Directories

  • Copyright: Legal right of the author or other owner of an original work to control reproduction, distribution and sale of that work.

  • Laws govern the use of photocopies, audio or video recordings, and other reproductions of authors’ original work.

  • Comes into existence as soon as the work is placed into tangible form.

  • Exists even if the work does not contain a copyright notice.


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Reproducing Web Pages and Copyright Law Directories

  • Fair use is a provision that allows students to use limited amounts of copyrighted information in term papers and other reports in an academic setting.

  • Source must always be cited.

  • Commercial use of copyright more restricted.

  • Obtain permission from copyright holder before using anything you copy from a Web page.


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Checking Web Page Security (IE) Directories

  • A closed padlock symbol (security indicator button) appears in the status bar when Internet Explorer loads an encrypted Web page.

  • Encryption is a way of scrambling and encoding data transmissions that reduces the risk that a person who intercepts the Web page as it travels across the Internet will be able to decode and read the page’s contents.

  • To check some of the security elements of a Web page,

    • double-click the security indicator button

    • click File, Properties, and then click the Certificates button


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Using Internet Explorer to DirectoriesSave a Web Page

  • You can save entire Web pages, selected portions of Web page text, or particular graphics from a Web page to a disk.

  • You can save portions of Web page text so you can use it in other programs.

  • You can save a graphic from a Web page by right-clicking on the picture and clicking Save Picture As.


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Checking Web Page Security (Firefox) Directories

  • A closed padlock symbol (the security indicator button) appears in the status bar when Firefox loads an encrypted Web page.

  • Encryption is a way of scrambling and encoding data transmissions that reduces the risk that a person who intercepts the Web page as it travels across the Internet will be able to decode and read the page’s contents.

  • To check some of the security elements of a Web page,

    • double-click the security indicator button

    • click Tools, Page Info, and then click the Security tab


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Managing Cookies (Firefox) Directories

  • Firefox stores all cookies in one file and gives users a tool to manage that file.

  • Click Tools on the menu bar, click Options, click the plus sign next to Cookies.

  • Click the View Cookies button to view individual cookies.

  • Select a cookie, and then click the Remove Cookie button to delete it.

  • To delete all cookies that have been stored on your computer, click the RemoveAllCookies button.


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Using Firefox to Save Directoriesa Web Page

  • You can store entire Web pages, selected portions of Web page text, or particular graphics from a Web page to a disk.

  • You can save portions of Web page text so you can use it in other programs.

  • You can save a graphic from a Web page by right-clicking on the picture and clicking Save Image As.


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Summary Directories

  • Web pages and Web sites make up the World Wide Web.

  • The Web uses a client/server structure in which Web server computers make Web page files available to Web client computers that are running Web browser software.

  • Each server computer on the Internet has an IP address that is mapped to a domain name.

  • The domain name plus the Web page filename make up the Uniform Resource Locator (URL).


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Summary Directories

  • All Web browsers have the same basic elements and can be used to explore the Web in similar ways.

  • Web browsers display Web pages and maintain a history list that can be used to find pages previously visited.

  • Web browsers allow users to print and save Web pages and elements of Web pages.

  • Web browsers are currently available at no or low cost.


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Summary Directories

  • The two most widely used Web browsers are

    • Internet Explorer

    • Firefox


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Break… Directories


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How to access newmedia server Directories

  • http://newmedia.cityu.edu.hk/en3515/


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Exercise 1: my favorite Web sites Directories

My favorite sites

http://www.wikipedia.org

http://www.google.com

www.nytimes.com

www.flickr.com

hk.yahoo.com


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Exercise 2: Use WWW to Directoriesresearch following technologies

What should you do?

  • Form a group

  • Pick a topic from the list to the left

  • Using WWW to conduct a research on this topic and answer the following questions:

    • What is it?

    • How does it work?

    • What are some of the advantages of using it?

    • What are some of the disadvantages of using it?

    • Are there any social controversy associated with it?

    • What do you think about it?

      Note: keep detailed notes. Be prepared to give a presentation on the topic next week.

  • Wikis

  • Server side technologies

  • Dynamic Web sites

  • Widgets

  • Phishing

  • Podcasts

  • facebook.com

  • Ubiquitous computing

  • Search engine Bots/Spiders

  • PGP (Pretty Good Privacy)

  • W3C


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