Week Thirteen Notes

Announcements

• We are doing 'self-service' roll call today. Please mark the appropriate box with an 'X'. Please tell me if your name is missing from the sheet.
• Wednesday: E-mail of source code for web page assignment is due Friday: File Transfer of web page to server is due. Come to class for information. Also see the e-mail sent to the class recently:
  http://www.cs.csustan.edu/~john/Classes/CS4000/Msg_Re_Web_Pg_Asg.pdf
• We are reading chapter nine this week.
• We study how to make PowerPoint presentation this week.
  The assignment is now in the class web space. Also, I've moved the due date back to Friday, December 08 so we will have more time to discuss things.

Chapter Nine -- Inside the Internet and the World Wide Web

• The development of the Internet may be traced at least as far back in time as August 1962. The Internet Society maintains an authoritative history page of the Internet, with links to other histories and related pages.
• The researchers who performed the work getting the Internet started were primarily interested in sharing computing resources, software, and data.
• It was a major concern of the Department of Defense, who funded the early research and development, to create a network that could continue to function even if some of the nodes were destroyed.
• The Advanced Research Projects Agency (ARPA) of the Department of Defense that sponsored the program, which was called the ARPA net.
• The early growth of the ARPA net took place primarily at military installations and universities.
• Packet Switching was a very important innovation employed by the ARPA net. Instead of using dedicated circuits for the duration of a communication session, as in a telephone conversation, the new network broke large messages into numerous pieces called packets and sent them individually. This technology allows many users to share a communication channel concurrently. No user has to wait very long for an opportunity to send another packet. Each packet is acknowledged by the receiver. If there is a communication failure, the sender has to re-send only the packets that did not arrive.
• The Internet is somewhat "chaotic." No one owns it. No one is responsible for all of it. It's hard to say how big it is, since it is changing constantly and parts of it are difficult to detect.
• Technically, the Internet is the collection of networks that interoperate through the use of a set of networking protocols called Transmission Control Protocol/Internet Protocol (TCP/IP).
• The protocols are sets of rules for how information is transferred. Protocols determine the exact structure of packets, network address formats, routing procedures, error control, flow control, and other such technical aspects. The form of domain names (e.g. splendor.csustan.edu) and URL's (e.g. http://www.tuvaluislands.com/) are specified by TCP/IP.
• Internet connection technologies include: T1 (1.5 Mbps), T3(45 Mbps), modem (up to 56 Kbps), Digital Subscriber Line (DSL - 128 Kbps to 3 Mbps), Cable Modem (uploads from 128 Kbps to 768 Kbps, downloads perhaps 1 to 6 Mbps), satellite (download @ 200 to 400 Kbps, upload with modem @ 50 Kbps), and wireless broadband (maybe 5 to 20 Mbps). These speeds are meant to indicate what is possible - often ISP's restrict bandwidth.
• There is considerable interest in providing fiber optic cable to the typical residence. This might allow 100 Mbps access in homes, or more.
• Many Internet services are provided via the client-server model: e-mail world wide web, file service, file transfer, and applications.
• The world wide web servers transmit HTML (and other) documents to clients. The web browsers of the clients use the HTML as directions to render displays.
• A web log also known as a blog is a web-based journal, According to the Merriam-Webster online dictionary, a blog is "a Web site that contains an online personal journal with reflections, comments, and often hyperlinks provided by the writer." Originally the term "blog" applied only to journals of events on the world wide web. Nowadays most anything can be the subject of a blog. Blog authoring has become very popular. There are easy-to-use online tools for creating and maintaining them.
• Web browsers can display text, graphics, audio, and video in various formats. Plugins are software extensions that enable browsers to display new kinds of content. A browser may launch a helper application to display some types of content.
• HTML is not the only language used to create web pages. Examples: Perl, Java, .NET, ASP, JavaScript, ActiveX, XML, XHTML, and SMIL.
• Is there a single best search engine for all purposes? If not how does one decide which search software to use? Where do I find information about search engines?
• Check out what you read on the web. A significant portion of what you will see will be misleading or false. Don't give away information about yourself heedlessly. Be aware of ways that web publishers are able to get information about you. Use services such as mySimon, bizrate, and PayPal to protect your interests.
• Search engines typically create a database using information gathered by web crawlers (spiders). They answer queries by returning saved information from the database. Different search engines rank the material in different ways ... for example prominence of keywords, number of referring links, and ratings by human reviewers.
• Meta-search engines such as MetaCrawler, OneSeek, and Sherlock search several engines in parallel.
• Portals are web pages with lots of links to other pages and services. They serve as useful starting points for web browsers.
• Peer-to-peer (P2P) technology enables computer users to get access to data stored on each other's hard drives. This is a convenience but can lead to illegal copying.
• Grid computing is a technology that allows computer owneres on the Internet to cooperate working on a large computer project. Examples include SETI@Home and fightaidsathome.com.
• An intranet works like the Internet but it is not accessible except to a specific group of people, such as the workers at a particular company.
• An extranet is similar to an intranet, but it is designed for people to interact with an organization from the outside, as when customers do online shopping or when suppliers check inventory.
• Internet2 and Next Generation Internet are designed to be "alternative internets" - separate nets with plenty of bandwidth for research and academic purposes.
• Various societies feel the need to censor Internet content. There is large range of motivations and subject areas. Types of censored content include pornography, online gambling, Nazi-ism, Middle Eastern politics, religious organizations, women's health, sexuality, gay rights, Taiwan, Tibet, and dissidents.
• Access to Internet technology tends to separate society into "have's" and "have not's" ... a digital divide.