Chapter 12 The Internet and How It Works Learning Objectives This lesson introduces students to Internet basics. At the end of the lesson, the students will be able to: Discuss the origins of the Internet. Define what a computer network is, and how networks are conceptually structured. Describe how the Domain Name System (DNS) manages the identities of computers connected to the Internet. Define bandwidth and discuss how bandwidth limitations govern the delivery of multimedia over the Internet. Define the most common protocols used on the Internet. Define how protocols, MIME-types and URLs are used to identify, serve, and deliver multimedia. Discuss the World Wide Web, HTML, the limitations of HTML, and how various technologies are stretching the limitations of HTML. Estimated Time for Module: 2 hours Technology experts report that the Internet has been the greatest revolution in communications revolution during of the last several decades. Hundreds of millions of users across the world connect to the online realm to share information and ideas. The Internet is also a medium of growing interest for multimedia designers, and is sure to become one of the most important means of multimedia delivery in the coming years. This lesson introduces students to Internet basics as they relate to multimedia design and delivery. 000-2 12-1
Preparing for Class Ideally, this class should be conducted in a computer lab with Internet access and multimedia authoring software installed. Some exercises and projects in this lesson assume that Internet access is available in class. Prerequisites for Class Before coming to class, students should: Have read Lesson 12 in their textbooks. Be familiar with all previous material. Class Preparation Notes PowerPoint slides to accompany the lesson plan can be found on the CD. You will also find the figures for Lesson 12 as JPEGs on the CD. Before class, identify a Web page that can be used for the second exercise in this lesson. The page should be relatively simple so that students can view the source HTML and understand what it means. General Teaching Tips This lesson provides an overview of the Internet, focusing on issues that are important to multimedia designers. To achieve the primary objectives: Cover Internet basics even though many of your students are probably already familiar with aspects of the Internet. Omit the project if time is short and all students are familiar with the Internet. Discuss bandwidth issues, as they are especially important. Bandwidth affects online multimedia design and delivery more than any other factor. Key Terms Advanced Research Projects Agency (ARPA) ARPANET 000-2 12-2
Bandwidth Daemon Domain Name System (DNS) extensible Markup Language (XML) File Transfer Protocol (FTP) Hypertext Transfer Protocol (HTTP) Internet Internet Service Provider (ISP) IP address Local area network (LAN) Multipurpose Internet Mail Extensions (MIME-type) Network Points of Presence (POP) Point-to-Point Protocol (PPP) Top-level domain (TLD) Transmission Control Protocol/Internet Protocol (TCP/IP) Uniform Resource Locator (URL) Wide area network (WAN) Lecture Notes The Internet is already a popular medium for multimedia delivery, and its popularity is likely to grow. This lesson introduces students to Internet basics, focusing on aspects that specifically relate to multimedia design and development. I. History Teaching Tip 000-2 12-3
It should be mentioned that a complete introduction and primer to the Internet is beyond the scope of this course. Suggest some other resources (such as other classes at your school) that students can use to learn more about the Internet, Web design, and Web technology. A. ARPANET 1. The Internet began as a research network funded by the Advanced Research Projects Agency (ARPA). a) ARPA was part of the US Department of Defense. b) The first node of ARPANET was installed at the University of California in 1969. 2. The ARPANET grew as it networked universities, military sites, and government agencies. 3. In 1985, the National Science Foundation (NSF) used ARPANET to connect supercomputers and computer science centers. a) Management of the ARPANET officially passed to the NSF in 1989. 4. Commercial use of the Internet began in 1992. a) Commercial use now dominates Internet traffic. Exercise Have the students head to http://digitallyimported.com/timeline.php to browse through a timeline story of a growing Web-based organization. Suggest that they start with the last entries and move forward through time to the most recent one at the beginning for a chronological development of a Web-delivered music service. Ask them to determine (1) how old the organization is; (2) what is their service; (3) what were their challenges over time; and (4) what kind of growth did they experience as a Web enterprise? II. Internetworking A. Networking basics 000-2 12-4
1. Two or more computers connected to each other make a network. 2. A local network is called a local area network (LAN). 3. Distant LANs can be connected via phone lines or another medium to form a wide area network (WAN). 4. LANs, WANs, and individual computers can also connect to the Internet through a server. a) A server is permanently connected to the Internet through a highbandwidth physical connection. Teaching Tip If your classroom has computers, chances are they are part of a LAN or WAN, and that the network is probably connected to the Internet. Use the computers in your class to illustrate the teaching points. B. Internet addresses 1. Address syntax a) Internet addresses use the following syntax: [protocol]://[domain name]/[path]/[file name] b) The server directory path and file name are often left out c) The protocol usually does not need to be typed. d) The protocol is also often hidden, such as: (1) mailto (2) news 2. Top-level domains (TLDs). a) The current Domain Name System (DNS) was developed in 1983 to assign names and addresses to computers connected to the Internet. b) TLDs were established as categories for all users of the Internet. c) The TLD is part of the domain name, such as: 000-2 12-5
(1).com (2).net (3).gov (4).mil (5) Two-letter country codes. Teaching Tip The most common TLDs are listed in the Internet Addresses section of the lesson in the textbook. d) TLDs are still used, although DNS naming conventions have been loosened considerably. (1) TLDs no longer provide a reliable indication of what kind of service the site is, or where it is located. Exercise If Internet access is available in the class, have students visit several Web sites that defy traditional TLD naming conventions. For example, the Web site of the US House of Representatives can be reached using www.congress.com, even though the House of Representatives is arguably not a commercial enterprise. 3. IP addresses and data packets. a) The Internet transmits data using the Transmission Control Protocol (TCP). (1) Data is broken up into packets. b) The Internet Protocol (IP) transmits the packets. (1) Packets can travel along various paths and are reassembled at the receiving end. (2) Destinations are identified by numeric IP addresses such as: 140.174.162.10 000-2 12-6
(3) The domain name servers look up these addresses. C. Connections 1. To connect to the Internet, a computer or network needs: a) A data connection to a server. (1) The data connection can be wireless or a land line. (2) You usually need an account with the server. (3) Most people access a server through an Internet Service Provider (ISP). b) TCP/IP software (1) Your operating system may need to be configured to connect to the server and use TCP/IP software. c) Internet software includes: (1) E-mail programs (2) Web browsers (3) FTP software (4) Newsreaders Insider Information Many Web programs serve multiple purposes. For example, most Web browsers can also access FTP servers, although depending on the FTP server, a dedicated FTP program may still be required. Some e-mail programs, such as Microsoft Outlook Express and Netscape Messenger, also function as newsreaders. 2. The bandwidth bottleneck. a) Bandwidth is measured in bits per second (bps). b) Available bandwidth greatly affects how a person can use the Internet. Teaching Tip 000-2 12-7
Table 12-1 of the textbook lists common connection methods with their respective bandwidth speeds and capabilities. c) Users with slow connections will have a difficult time using multimedia over the Internet. d) To accommodate low-bandwidth users (1) Compress data when possible. (2) Take advantage of the browser s cache. (3) Design each multimedia element for download efficiency. (4) Design alternate sites for low- and high-bandwidth users. (5) Consider using streaming technology. Discussion Point Web designers should remember that many Internet users still connect at speeds that are significantly slower than 56 Kbps. Consider doing a quick, informal survey of your class to see who is connecting to the Internet with a slow dial-up connection versus who has a high-speed connection such as a Digital Subscriber Line (DSL) or a cable modem. D. Internet services 1. Services include HTTP, FTP, Usenet, SMTP, and others. a) Some services such as Gopher are almost forgotten. Teaching Tip A complete list of services can be found in the Internet Services section in the lesson in the textbook. 2. Multipurpose Internet Mail Extensions (MIME)-types a) Files used online must conform to Internet protocols. b) Data types are identified using MIME-types. c) File types must be recognized by servers to be used on the Internet. 000-2 12-8
Teaching Tip Table 12-2 in the textbook lists common MIME-types. III. The World Wide Web and HTML A. Web history 1. Tim Berners-Lee of CERN (the European Particle Physics Laboratory) developed the Web s hypertext system in 1989. a) The Hypertext Transfer Protocol (HTTP) was designed as a means for sharing documents over the Internet. b) The Hypertext Markup Language (HTML) is the markup language of the Web. c) Cross-platform compatibility was a design goal. Exercise Instruct students to visit a Web page, such as a page hosted by your school. In their Web browser, instruct students to select View Source (Internet Explorer) or View Page Source (Netscape). Students can view the HTML used to create the page they are viewing. Draw attention to key elements, showing how certain HMTL tags affect the on-screen presentation. B. Dynamic Web pages and XML. 1. Advanced tools can be used to make a Web page dynamic. a) Dynamic technologies include: (1) ColdFusion (2) Hypertext Preprocessor (PHP) (3) Active Server Pages (ASP) b) Dynamic pages work in conjunction with database applications to look up data. Discussion Point 000-2 12-9
Have students list some examples of dynamic pages. For example, they might list search engine results pages, personalized online forums, or online shopping carts. 2. extensible Markup Language (XML) a) This markup language allows developers to define their own styles and elements. Project 1 Visit the Web addresses listed below. www.navy.com/ www.sigov.si/ www.w3.org/markup/guide/style.html For each address, answer the following questions: 1. What is the title of the Web page? 2. Briefly describe the contents of the Web page. 3. What is a noticeable aspect of the URL? Allow approximately 30 minutes for this project. Project 1 Solution Because of the constantly changing nature of the Internet, review the URLs before class to ensure that they are still valid. In the last Web address mentioned above, the address is case-sensitive, so capitalization within the address is important for finding the Web page. Add additional URLs or replace the ones listed above if desired. The URLs listed above are: www.navy.com/ NAVY.COM: United States Navy. This page is usually packed with multimedia elements. At the time of writing, it offered a Flash movie incorporating elements from Navy recruitment advertisements. Note that even though this is a government-owned site, the TLD in the URL is.com 000-2 12-10
www.sigov.si/ Republika Slovenija. This site contains government and cultural information about the Republic of Slovenia. Note that the country is identified by the TLD in the URL. www.w3.org/markup/guide/style.html Dave Raggett s Introduction to CSS. This site is primarily text, but it includes a portrait of the author. The URL includes directories and a file name. Project 2 You are a college student looking for Web-based resources for a class report about Information Technology. You have heard about the Multimedia Educational Resource for Learning and Online Teaching (MERLOT) especially targeted at higher education users. You head to MERLOT at www.merlot.org and go to the Communities tab near the top. In the communities area you choose the Information Technology link. MERLOT gives you a list of Web-based learning materials on Information Technology. Look through just the list of links next to the Location labels, paying attention to the Web addresses, particularly the top-level domain names. What kind of top-level domain names do you identify in the list? Before you visit any of the links, jot down what the domain names, along with the resource titles, might imply about the nature of the resources posted at those addresses. Next, choose one or two links from each domain category to visit, and see if your assumptions are supported. Note whether they were, and be ready to report what you suspected and what you found. Allow approximately 30 minutes for this project. Students could also work in pairs and make this a collaborative project. Project 2 Solution Students may identify such top-level domain names as.edu,.com,.org and.mil. They may make assumptions that the.edu sources might be more academic and oriented toward drills or tutorials, that the.com sources may be more flashy and oriented toward a particular product, and that a.org may be oriented toward public service perspective. Many of the MERLOT resource links note that they can be used free for educational 000-2 12-11
purposes even though they hold copyrights. Students may however come to a few sources that ask for a membership or fee arrangement. They can move on to another source during class if that occurs. Ask several students to report what they found to the class. Review This lesson introduced students to Internet basics. Objectives included: Discussing the origins of the Internet. Defining what a computer network is and how networks are conceptually structured. Describing how the Domain Name System (DNS) manages the identities of computers connected to the Internet. Defining bandwidth and discussing how bandwidth limitations govern the delivery of multimedia over the Internet. Defining the most common protocols used on the Internet. Defining how protocols, MIME-types and URLs are used to identify, serve, and deliver multimedia. Discussing the World Wide Web, HTML, the limitations of HTML and how various technologies are stretching the limitations of HTML. Assessment Quiz Produce a handout and have students answer the following questions. Questions 1. Who took over the management of the ARPANET from the Department of Defense in 1989? 2. List three common top-level domains. 3. What is the name of the protocol used for transmitting data over the Internet? 4. Which factor most affects the way people use the Internet? 000-2 12-12
5. List three types of services on the Internet. 6. How are file types identified by Web servers? 7. Which language does the World Wide Web use for formatting and delivering content? 8. Fill in the blank: Web pages that change based on user and database input are called pages. 9. Fill in the blank: The Internet began in 1969 as the. 10. Fill in the blank: Data is broken up into before it is transmitted over the Internet. 11. True or false? Most people still connect to the Internet at speeds slower than 56Kbps. Answers 1. The National Science Foundation (NSF) took over the management of the ARPANET from the Department of Defense in 1989. 2. Common top-level domains include.com,.net,.edu,.gov,.org,.mil, and others. 3. The name of the protocol used for transmitting data over the Internet is the Transmission Control Protocol/Internet Protocol (TCP/IP). 4. The factor that most affects the way people use the Internet is available bandwidth. 5. Services on the Internet include HTTP, HTTPS, POP, FTP, Gopher, Usenet, Telnet, IRC, SMTP, and MUD. 6. File types are identified by Web servers using MIME-types. 7. The World Wide Web uses the Hypertext Markup Language (HTML) for formatting and delivering content. 8. Web pages that change based on user and database input are called dynamic pages. 000-2 12-13
9. The Internet began in 1969 as the ARPANET. 10. Data is broken up into packets before it is transmitted over the Internet. 11. True. Most people still connect to the Internet at speeds slower than 56 Kbps. 000-2 12-14