The world wide database of domain names and corresponding IP addresses is called

The Internet is based on the TCP/IP networking protocol suite described earlier in this chapter. Every computer on the Internet is assigned a unique Internet Protocol (IP) address, which currently is a 32-bit number represented by four strings of numbers and ranging from 0 to 255. For instance, the IP address of www.microsoft.com is 207.46.250.119.

           When a user sends a message to another user on the Internet, the message is first decomposed into packets using the TCP protocol. Each packet contains its destination address. The packets are then sent from the client to the network server, and from there onto as many other servers as necessary to arrive at a specific computer with a known address. At the destination address, the packets are reassembled into the original message.

Because it would be incredibly difficult for Internet users to remember strings of 12 numbers, a Domain Name System (DNS) converts IP addresses to domain names. The domain name is the English-like name that corresponds to the unique 32-bit numeric Internet Protocol (IP) address for each computer connected to the Internet. DNS servers maintain a database containing IP addresses mapped to their corresponding domain names. To access a computer on the Internet, users need only specify its domain name.

           DNS has a hierarchical structure (see Figure 8-9). At the top of the DNS hierarchy is the root domain. The child domain of the root is called a top-level domain, and the child domain of a top-level domain is called a second-level domain. Top-level domains are two-and three-character names you are familiar with from surfing the Web, such as .com, .edu, gov, and the various country codes such as .ca for Canada or .it for Italy. Second-level domains have two parts, designating a top-level name and a second-level name�such as buy.com, nyu.edu, or amazon.ca. A host name at the bottom of the hierarchy designates a specific computer on either the Internet or a private network.

FIGURE 8-9 The Domain Name System
The Domain Name System is a hierarchical system with a root domain, top-level domains, second-level domains, and host computers at the third level.

How many unique addresses are there on the Internet if over 600 million people are connected? The Internet addressing convention described earlier is called Internet Protocol version 4 (IPv4). This �dotted quad� addressing scheme (a 32-bit string of numbers organized into four sets of numbers ranging from 0 to 255) contains up to 4 billion addresses (2 to the 32nd power).

           Because many corporations and governments have been given large blocks of millions of IP addresses to accommodate current and future workforces, and because of sheer Internet population growth, the world is running out of available IP addresses using this scheme. A new version of the IP addressing scheme being developed is called Internet Protocol version 6 (IPv6) and contains 128-bit addresses (2 to the power of 128), or over a quadrillion possible unique addresses (National Research Council, 2000).

Internet data traffic courses over transcontinental high-speed backbone networks that generally operate today in the range of 45 Mbps to 2.5 Gbps (Figure 8-10). These trunk lines are typically owned by long-distance telephone companies (called network service providers) or by national governments. Local connection lines are owned by regional telephone and cable television companies in the United States that connect retail users in homes and businesses to the Internet. The regional networks lease access to ISPs, private companies, and government institutions.

FIGURE 8-10 Internet network architecture
The Internet backbone connects to regional networks, which in turn provide access to Internet service providers, large firms, and government institutions. Network access points (NAPs) and metropolitan area exchanges (MAEs) are hubs where the backbone intersects regional and local networks and where backbone owners connect with one another.

No one �owns� the Internet, and it has no formal management organization per se. However, worldwide Internet policies are established by a number of different organizations and government bodies including the following:

           Each organization pays for its own networks and its own local Internet connection services, a part of which is paid to the long-distance trunk line owners through monthly charges for telephone and Internet services. Consequently, the costs of e-mail and other Internet connections tend to be far lower than equivalent voice, postal, or overnight delivery, making the Internet a very inexpensive communications medium. It is also a very fast method of communication, with messages arriving anywhere in the world in a matter of seconds, or after a minute or two at most.

Internet Services

The Internet is based on client/server technology. Individuals using the Internet control what they do through client applications on their computers, such as Web browser software. All the data, including e-mail messages and Web pages, are stored on servers. A client uses the Internet to request information from a particular Web server on a distant computer, and that server sends the requested information back to the client over the Internet. Chapters 6 and 7 describe how Web servers can also work with application servers and database servers to access information from an organization�s internal information systems applications and their associated databases.

           Client platforms today include not only PCs and other computers but also cell phones, small handheld digital devices, and other information appliances. An information appliance is a device, such as an Internet-enabled cell phone or a TV Internet receiver for Web access and e-mail, that has been customized to perform a few specialized computing tasks well with minimal user effort. People are increasingly relying on these easy-to-use specialized information appliances to connect to the Internet.

           A client computer connecting to the Internet has access to a variety of services. These services include e-mail, electronic discussion groups (Usenet newsgroups and LISTSERVs), chatting and instant messaging, Telnet, File Transfer Protocol (FTP), and the World Wide Web. Table 8-6 provides a brief description of these services.

TABLE 8-6 Major Internet Services

           Each Internet service is implemented by one or more software programs. All of the services may run on a single server computer, or different services may be allocated to different machines. Only one disk drive may store the data for these services, or multiple disks may store data for each type, depending on the amount of information being stored. Figure 8-11 illustrates one way that these services might be arranged in a multitiered client/server architecture.

FIGURE 8-11 Client/server computing on the Internet
Client computers running Web browser and other software can access an array of services on servers over the Internet. These services may all run on a single server or on multiple specialized servers.

The Internet and Business Value

The Internet is unique and very different from any other networking technology developed in the past (Table 8-7). These unique features translate directly into business value for all businesses, worldwide, whether they are small or large.

TABLE 8-7 Seven Unique Features of Internet Technology

The World Wide Web

The World Wide Web (the Web) is the most popular Internet service. It is a system with universally accepted standards for storing, retrieving, formatting, and displaying information using a client/server architecture. Web pages are formatted using hypertext with embedded links that connect documents to one another and that also link pages to other objects such as sound, video, or animation files. When you click a graphic and a video clip plays, you have clicked a hyperlink.

           The Web was invented in the period from 1989 to 1991 by Dr. Tim Berners-Lee and his associates at the European Particle Physics Laboratory, better known as CERN. Information shared on the Web remained text-based until 1993, when Marc Andreessen and others at the National Center for Supercomputing Applications (NCSA) at the University of Illinois created a Web browser with a graphical user interface (GUI) called Mosaic that made it possible to view documents on the Web graphically�using colored backgrounds, images, and even primitive animations. In 1994, Andreessen and Jim Clark founded Netscape, which created the first commercial browser, Netscape Navigator. In August 1995, Microsoft Corporation released its own browser, called Internet Explorer (IE), which became the dominant Web browser.

HYPERTEXT

Web pages are based on a standard Hypertext Markup Language (HTML), which formats documents and incorporates dynamic links to other documents and pictures stored in the same or remote computers (see Chapter 6). Web pages are accessible through the Internet because Web browser software on your computer can request Web pages stored on an Internet host server using the Hypertext Transfer Protocol (HTTP). HTTP is the communications standard used to transfer pages on the Web. For example, when you type a Web address in your browser such as www.sec.gov, your browser sends an HTTP request to the sec.gov server requesting the home page of sec.gov.

           HTTP is the first set of letters at the start of every Web address, followed by the domain name, which specifies the organization�s server computer that is storing the document. Most companies have a domain name that is the same as or closely related to their official corporate name. The directory path and document name are two more pieces of information within the Web address that help the browser track down the requested page. Together, the address is called a Uniform Resource Locator (URL). When typed into a browser, a URL tells the browser software exactly where to look for the information. For example, in the following URL:

            http://www.megacorp.com/content/features/082602.html

           http names the protocol used to display Web pages, www.megacorp.com is the domain name, content/features is the directory path that identifies where on the domain Web server the page is stored, and 082602.html is a document name and the format of the document (it is an HTML page).

WEB SERVERS

A Web server is software for locating and managing stored Web pages. It locates the Web pages requested by a user client on the computer where they are stored and delivers the Web pages to the user�s computer. The most common Web server in use today is Apache HTTP Server, which controls 67 percent of the market. Apache is an open source product that is free of charge and can be downloaded from the Web (Figure 8-12). Microsoft�s Internet Information Services is the second most commonly used Web server with a 22 percent market share.

FIGURE 8-12 Major Web server providers
This figure illustrates the market share of each of the major Web server software providers.

Source: Based on data from Netcraft Web Server Survey, July 2004, www.serverwatch.internet.com/netcraft.

           A typical Web site is a collection of Web pages linked to a home page�a text and graphical screen display that usually welcomes the user and provides a brief description of the organization that has established the Web site. Most home pages offer a way to contact the organization or individual. The person in charge of an organization�s Web site is called a Webmaster.

SEARCHING FOR INFORMATION ON THE WEB

Locating information on the Web is a critical function. Billions of Web pages exist, and this number will quickly double. No comprehensive catalog of Web sites is available. The principal methods of locating information on the Web are Web site directories, search engines, intelligent agents, and broadcast or �push� technology.

           Search Engines and Web Site Directories Several companies have created directories of Web sites and their addresses, providing search tools for finding information. Yahoo! is an example. People or organizations submit sites of interest, which then are classified and ranked by human experts. To search the Yahoo! directory, you enter one or more keywords and then see displayed a list of categories and sites with those keywords in the title.

           Other search tools do not require Web sites to be preclassified and will search Web pages automatically. Such tools, called search engines, can find Web sites that may be little known. Search engines contain software that looks for Web pages containing one or more of the search terms, then they display matches ranked by a method that usually involves the location and frequency of the search terms. These search engines create indexes of the Web pages they visit. The search engine software then locates Web pages of interest by searching through these indexes.

           Some search engines are more comprehensive or current than others, depending on how their components are tuned, and some also classify Web sites by subject categories. Some search engines, such as AltaVista, seek to visit every Web site in existence, read the contents of the home page, identify the most common words or keywords, and create a huge database of domain names with keywords. Sometimes the search engines will only read the metatags and other keyword sections of the home page. The program that search engines unleash on the Web to perform this indexing function is called a spider or crawler. Because search engines do not always overlap, users may miss a page on one engine but pick it up on another.

           Google has become overwhelmingly the most popular Web search tool and is used for about 55 percent of all searches on the Web through its own site. Google works by sending �crawlers� across the Internet and using its 10,000 computers to update its index of about 8 billion Web pages. Google software indexes and ranks sites based on relevance measured by how prominently the user�s search terms appear on the pages that include them, the number of users who access these pages, and the number of outside links to a particular page.

Google is the most popular Web search engine. It offers search-based advertising. The listings displayed under �Sponsored Links� are links paid by advertisers. The unbiased results of the search are displayed under �Web�.

           Search engines are no longer simply search engines but instead have transformed themselves into major shopping tools by offering search-related advertising. When users enter search termat Google, MSN Search, Yahoo!, or any of the other sites serviced by these search engines, they receive two types of listings: sponsored links, for which advertisers have paid be listed (usually at the top of the search results page) and unsponsored search results. For firms who pay the search engine companies $2 billion a year for sponsored links, this feature represents a powerful new marketing tool called search-based advertising that precisely matches consumer interest and timing with an advertising message.

           Although the major search engines are used for locating general information of interest to users, they have also become a crucial tool within e-commerce sites. Customers can more easily search for the product information they want with the help of an internal search program; the difference is that within Web sites, the search engine is limited to finding matches from that one site.

           Intelligent Agent Shopping Bots Chapter 12 details the capabilities of software agents with built-in intelligence that can gather or filter information and perform other tasks to assist users. The Web crawler and spider software for searching the Web that we mentioned earlier is one type of intelligent software agent. Shopping bots are another type of intelligent agent software for searching the Internet for shopping information. Shopping bots can help people interested in making a purchase filter and retrieve information about products of interest, evaluate competing products according to criteria the users have established, and negotiate with vendors for price and delivery terms (Kocas, 2002�2003; Maes, Guttman, and Moukas, 1999). Many of these shopping agents search the Web for pricing and availability of products specified by the user and return a list of sites that sell the item along with pricing information and a purchase link. Table 8-8 compares various types of electronic commerce agents.

TABLE 8-8 Examples of Electronic Commerce Agents

           Broadcast and Push Technology Instead of spending hours surfing the Web, users can have the information in which they are interested delivered automatically to their desktops through push technology. This technology enables a computer to broadcast information of interest directly to the user, rather than having the user �pull� content from Web sites.

           Special client software enables the user to specify the categories of information he or she wants to receive, such as news, sports, financial data, and so forth, and how often this information should be updated. After finding the kind of information requested, push server programs serve it to the push client. The streams of information distributed through push technology are known as channels. Using push technology to transmit information to a select group of individuals is one example of multicasting. (LISTSERVs sending e-mail to members of specific mailing lists is another.)

MySimon features a shopping bot that can search Internet retailers for price and availability of products specified by the user. Displayed here are the results of a search of prices and sources for a high-definition television set.

           The Semantic Web Most of the Web�s content today is designed for humans to read and for computers to display, not for computer programs to analyze and manipulate. Search engines can discover when a particular term or keyword appears in a Web document, but they do not really understand its meaning or how it relates to other information on the Web. The Semantic Web is a collaborative effort led by the World Wide Web Consortium to make Web searching more efficient by reducing the amount of human involvement in searching for and processing Web information. Tim Berners-Lee wrote the road map for the Semantic Web in 1998.

           Although the Semantic Web is still in its infancy, it could eventually bring additional structure to the meaningful content of Web pages so that machines could make more sense of the Web and data in Web pages could be processed automatically. Two important technologies for developing the Semantic Web are Extensible Markup Language (XML), which we introduced in Chapter 6, and the Resource Description Framework (RDF). RDF goes beyond XML to describe data in terms of objects and their interrelationships. Once data on the Web have specific meanings and rules for reasoning about them, agent technology could be harnessed to unleash software agents roaming from page to page to automatically carry out sophisticated tasks for users.

           One prototype application is the Semantic Web Environmental Directory (SWED) in the United Kingdom. Instead of centralizing the storage, management, and ownership of information about environmental organizations and projects, SWED continually harvests data and uses these data to create the directory (Frauenfelder, 2004).

Intranets and Extranets

Organizations can use Internet networking standards and Web technology to create private networks called intranets. We introduced intranets in Chapter 1, explaining that an intranet is an internal organizational network that provides access to data across the enterprise. It uses the existing company network infrastructure along with Internet connectivity standards and software developed for the World Wide Web. Intranets can create networked applications that can run on many different kinds of computers throughout the organization, including mobile handheld computers and wireless remote access devices.

           Whereas the Web is available to anyone, an intranet is private and is protected from public visits by firewalls�security systems with specialized software to prevent outsiders from entering private networks. Intranet software technology is the same as that of the World Wide Web. Intranets use HTML to program Web pages and to establish dynamic, point-and-click hypertext links to other pages. The Web browser and Web server software used for intranets are the same as those on the Web. A simple intranet can be created by linking a client computer with a Web browser to a computer with Web server software using a TCP/IP network with software to keep unwanted visitors out.

EXTRANETS

A firm can create an extranet to allow authorized vendors and customers to have limited access to its internal intranet. For example, authorized buyers could link to a portion of a company�s intranet from the public Internet to obtain information about the costs and features of the company�s products. The company can use firewalls to ensure that access to its internal data is limited and remains secure; firewalls can also authenticate users, making sure that only authorized users can access the site.

           Both intranets and extranets reduce transaction and agency costs by providing additional connectivity for coordinating disparate business processes within the firm and for linking electronically to customers and suppliers. Private industrial networks (introduced in Chapter 4) are based on extranets because they are so useful for linking organizations with suppliers, customers, or business partners. Extranets often are employed for collaborating with other companies for supply chain management, product design and development, and training efforts.

Next-Generation Networks and Internet2

The public Internet was not designed to handle massive numbers of very large files flowing to and from hundreds of millions of host computers. Today�s Internet often has delays and does not guarantee any specific level of service. Experimental national research networks (NRNs) are developing high-speed, next-generation networks to address this problem. These private networks do not replace the public Internet, but they do provide test beds for leading-edge technology for research institutions, universities, and corporations that may eventually migrate to the public Internet. These national research networks include 6NET in Europe, the Asia Pacific Advanced Network (APAN), and CANARIE in Canada.

           In the United States, Internet2 and Next-Generation Internet (NGI) are NRN consortia representing 200 universities, private businesses, and government agencies that are working on a new, robust, high-bandwidth version of the Internet. The advanced networks provide an environment in which new technologies can be tested and enhanced. Several new networks have been established, including Abilene and vBNS (a WorldCom/ National Science Foundation partnership).

           Abilene and vBNS (short for very high performance backbone network service) are high-performance backbone networks with bandwidths ranging from 2.5 Gbps to 9.6 Gbps that interconnect the gigaPoPs used by Internet2 members to access the network. A gigaPoP is a regional gigabit Point of Presence, or point of access, to the Internet2 network that supports data transfers at the rate of 1 Gbps or higher. In February 2003, Internet2 announced it had successfully tested the Abilene network at more than 8 Gbps in a cross-country test that lasted 5 hours (www.internet2.edu, 2003).

           Internet2 research groups are developing and implementing new quality of service technologies that will enable the Internet to provide different levels of service, depending on the type and importance of the data being transmitted. Today�s Internet transmissions are considered �best effort��packets of data arrive without any regard to the priority of their contents. Different types of packets could be assigned different levels of priority as they travel over the network. For example, packets for applications such as videoconferencing, which must arrive simultaneously without any break in service, would receive higher priority than e-mail messages, which do not have to be delivered instantaneously.

           Other Internet2 projects include the development of more effective routing practices; standardized middleware that incorporates identification, authentication, and security services that today are often handled as a part of applications running on the Internet; and advanced applications for distributed computation, virtual laboratories, digital libraries, distributed learning, and tele-immersion.

           The most recent effort to revitalize the Internet is called PlanetLab. It is a grassroots group of nearly 100 computer scientists at academic institutions backed by leading hightech companies such as Intel and Hewlett-Packard. PlanetLab researchers are building an experimental overlay network on top of the Internet using computers called smart nodes attached to traditional Internet routers. Each smart node runs software that divides the machine�s resources among many users, vastly increasing processing power, data storage capacity, and the ability to track data and programs flowing over the Internet. The smart nodes could be used to create a much smarter and more flexible network than today�s Internet that could potentially monitor itself for damaging computer viruses, relieve bottlenecks automatically, and make users� personal computer programs and files portable to any Internet-connected terminal (Roush, 2003).

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