Technology Infrastructure: The Internet and the World Wide Web

1. Chapter 2 Technology Infrastructure: The Internet and the World Wide Web

3. Learning Objectives How HTML tags and links work on the World Wide Web The differences among internets, intranets, and extranets Options for connecting to the Internet, including cost and bandwidth factors Internet2 and Semantic Web

4. Technology Overview Computer networks and the Internet form the basic technology structure for electronic commerce. The computers in these networks run such software as: Operating systems, database managers, encryption software, multimedia creation and viewing software, and the graphical user interface

5. Technology Overview The Internet includes: The hardware that connects the computers together and the hardware that connects the networks together Rapid change in these technologies requires businesses to be flexible.

6. Packet-Switched Networks A local area network (LAN) is a network of computers close together. A wide area network (WAN) is a network of computers connected over a great distance. Circuit switching is used in telephone communication. The Internet uses packet switching Files are broken down into small pieces (called packets) that are labeled with their origin, sequence, and destination addresses.

7. Routing Packets The computers that decide how best to forward each packet in a packet-switched network are called ‘routers’. The programs on these routers use ‘routing algorithms’ that call upon their ‘routing tables’ to determine the best path to send each packet. When packets leave a network to travel on the Internet, they are translated into a standard format by the router. These routers and the telecommunication lines connecting them are referred to as ‘the Internet backbone’.

8. Routing Packets

9. Internet Protocols A protocol is a collection of rules for formatting, ordering, and error-checking data sent across a network. ARPANET is the earliest packet-switched network. The open architecture of this experimental network used Network Control Protocol (NCP) which later became the core of the Internet.

10. Internet Protocols This open architecture has four key rules that have contributed to the success of the Internet. Independent networks should not require any internal changes to be connected to the network. Packets that do not arrive at their destinations must be retransmitted from their source network. Router computers act as receive-and-forward devices; they do not retain information about the packets that they handle. No global control exists over the network.

11. Internet Protocols The Transmission Control Protocol (TCP) and the Internet Protocol (IP) are the two protocols that support the Internet operation (commonly referred to as TCP/IP). The TCP controls the disassembly of a message into packets before it is transmitted over the Internet and the reassembly of those packets when they reach their destination. The IP specifies the addressing details for each packet being transmitted.

12. IP Addresses IP addresses are based on a 32-bit binary number that allows over 4 billion unique addresses for computers to connect to the Internet. IP addresses appear in ‘dotted decimal’ notation (four numbers separated by periods). They are assigned by three not-for-profit organizations (ARIN, RIPE, and APNIC).

13. IP Addresses Approximately two billion IP addresses are either in use or unavailable for use. Private IP addresses are a series of IP numbers that have been set aside for subnet use and are not permitted on the Internet. IPv6 is a possible solution that uses a 128-bit hexadecimal number for addresses.

14. Domain Names To make the numbering system easier to use, an alternative addressing method that uses words was created. An address, such as www.course.com, is called a domain name. The last part of a domain name (i.e., ‘.com’) is the most general identifier in the name and is called a ‘top-level domain’ (TLD).

15. Top-level Domain Names

16. Web Page Delivery Hypertext Transfer Protocol (HTTP) is the set of rules for delivering Web pages over the Internet. HTTP uses the client/server model A user’s Web browser opens an HTTP session and sends a request for a Web page to a remote server. In response, the server creates an HTTP response message that is sent back to the client’s Web browser. The combination of the protocol name and the domain name is called a uniform resource locator (URL).

17. SMTP, POP, MIME, and IMAP E-mail sent across the Internet must also be formatted to a common set of rules, otherwise e-mail created by one company (or Web site) could not be read by a person at another company. Simple Mail Transfer Protocol (SMTP) specifies the exact format of a mail message and describes how mail is to be administered at the Internet and network level.

18. SMTP, POP, MIME, and IMAP An e-mail program running on a user’s computer can request mail from the company’s main e-mail computer using the Post Office Protocol (POP). Multipurpose Internet Mail Extensions (MIME) allow the user to attach binary files to e-mail. The Interactive Mail Access Protocol (IMAP) performs the same basic functions as POP, but includes additional features.

19. Markup Languages and the Web Web pages are marked with tags to indicate the display and formatting of page elements. SGML is a meta language, which is a language that can be used to define other languages. HTML and XML are both derivatives of SGML.

20. Standard Generalized Markup Language SGML offers a system of marking up documents that is independent of any software application. Advantages of SGML include its long-term viability, it is nonproprietary and platform-independent, and it supports user-defined tags and architectures. Disadvantages of SGML include a costly and complicated set up, expensive tools, creating document-type definitions that are time consuming, and extensive learning time.

21. Hypertext Markup Language HTML is a simplified subset of SGML that includes tags defining the format and style of text elements in a document. HTML is an instance of one particular SGML document type. HTML now includes tags for tables, frames, and other features that help Web designers create more complex page layouts.

22. Extensible Markup Language Unlike HTML, XML uses markup tags to describe the meaning of the text rather than its display characteristics. XML uses paired start and stop tags in much the same way as database software defines a record structure. An XML document can be embedded within an HTML document. XML allows a user to ‘extend’ the language by creating their own tags.

23. Markup Languages and the Web

24. HTML Tags An HTML document contains both document text and elements. Tags are codes that are used to define where an HTML element starts and (if necessary) where it ends. In an HTML document, each tag is enclosed in brackets (<>). A two-sided tag set has an opening tag and a closing tag.

25. HTML Links Hyperlinks are bits of text that connect the current document to: another location in the same document another document on the same host machine another document on the Internet Hyperlinks are created using the HTML anchor tag. Two popular link structures are: Linear hyperlink structure Hierarchical hyperlink structure

26. Scripting Language and Style Sheet Capabilities Web designers can use the OBJECT tag to embed scripting language codes in HTML pages (this is also called client-side scripting). Scripts can execute programs on computers that display those pages. Cascading Style Sheets (CSS) let designers define formatting styles that can be reapplied to multiple Web pages.

27. HTML Editors HTML documents can be created in any general-purpose text editor or word processor.  Sophisticated editors can create full-scale, commercial-grade Web sites with database access, graphics, fill-in forms, and display the Web page along with the HTML code. Microsoft FrontPage and Macromedia Dreamweaver are examples of Web site builders.

28. HTML Editors

29. Intranets and Extranets Intranets An intranet is an interconnected network (or internet – small “i” intended) that does not extend beyond the organization that created it.  Intranets are an extremely popular and low-cost way to distribute corporate information. An intranet uses Web browsers and Internet-based protocols (including TCP/IP, FTP, Telnet, HTML, and HTTP) and often includes a firewall.

30. Intranets and Extranets Extranets Extranets are intranets that have been extended to include specific entities outside the boundaries of the organization (business partners, suppliers, etc.). An extranet can be a public network, a secure (private) network, or a virtual private network (VPN).

31. Intranets and Extranets A public network is any computer or telecommunications network that is available to the public. A private network is a private, leased-line connection between two companies that physically connects their intranets to one another. A VPN extranet is a network that uses public networks and their protocols to send sensitive data to partners, customers, suppliers, and employees using a system called ‘IP tunneling’ or ‘encapsulation’.

32. Internet Connection Options The Internet is a set of interconnected networks. Large firms that provide Internet access to other businesses are called Internet Access Providers (IAPs) or Internet Service Providers (ISPs).

33. Connectivity Overview The most common connection options that ISPs offer to the Internet are telephone, broadband, leased-line, and wireless. Bandwidth is the amount of data that can travel through a communication line per unit of time. Bandwidth can differ for data traveling to or from the ISP.

34. Voice-Grade Telephone Connections The most common way to connect to an ISP is through a modem connected to your local telephone service provider. POTS uses existing telephone lines and an analog modem to provide a bandwidth of 28-56 Kbps. ISDN uses the DSL protocol suite to offer bandwidths between 128-256 Kbps.

35. Broadband Connections Connections that operate at speeds of greater than 200 Kbps are called broadband services. ADSL uses the DSL protocol to provide bandwidths between 100-640 Kbps upstream and 1.5-9 Mbps downstream. Cable modems provide transmission speeds between 300 Kbps-1 Mbps from the client to the server and a downstream rate as high as 10 Mbps. Satellite microwave transmissions handle Internet downloads at speeds around 500 Kbps.

36. Leased-Line Connections Large firms can connect to an ISP using higher-bandwidth connections that they can lease from telecommunications carriers. A ‘T1’ line operates at 1.544 Mbps and a ‘T3’ line operates at 44.736 Mbps.

37. Wireless Connections Many researchers and business managers see great potential for wireless networks and the devices connected to them. The term m-commerce (mobile commerce) is used to describe the kinds of resources people might want to access using devices that have wireless connections.

38. Internet Options

39. Internet2 Internet2 is an experimental test bed for new networking technologies that is separate from the original Internet. 200 universities and a number of corporations joined together to create this network. It has achieved bandwidths of 10 Gbps. Internet2 promises to be the proving ground for new technologies and applications of those technologies that will eventually find their way to the Internet.