else on the Internet. Hyperlinking collectively comprises the World Wide Web. HTML anchor tags are used to create hyperlinks. Another popular application of HTML code is the HTML editors, which allow Web site designers to drag and drop objects such as graphics, buttons or lines onto a Web page. The Web site builder software uploads the pages to the Internet web server from the PC, which developed them. Commercially available Web site building software include Microsoft Front Page, Dreamweaver, and Storefront. 10.6.Web Clients and Servers When an Internet user connects to the World Wide Web, the user computer becomes a Web client in a worldwide client/server network. The Internet connects many different types of computers running different operating systems software and permits them to communicate effectively as well as exchange files that are publicly available through the Web server. The client/server model divides the work load responsibilities between the client and server in the network connection whether it is LAN’s, WAN’s or the Web. Typically, the client computer requests services such as information retrieval, database access or printing and the server processes the requests. These client/server responsibilities can be carried out using a two-tier or three-tier system of articulation. A two-tier system directs communications between the client on the Internet (Web browser) and the Web server on the other end. The Web server deciphers the request, locates the requested resources, processes the information and responds to the client. In contrast to a two-tier system, a three-tier system also involves communication with a database service that
- 76 -supplies applications and non-HTML information to the Web server on request. Electronic commercial sites often require a three-tier system with its own hardware and software to keep track of customer purchases/preferences; query inventory databases or updates their catalog. The database services, which comprise the third tier, are often referred to as the backend machines/programs. Communications between the Web server and the backend provider are facilitated by a protocol known as Common Gateway Interface. The backend servers provide programs that dynamically transform data into HTML so that Web browsers can display the results. 10.7.Internets, Intranets, and Extranets A firm with a commercial Internet presence may consider the development of a Web based private network that hosts Internet applications on a company wide or local area network. This private network, called an intranet, can be used to disseminate company information within the various locations of the firm. An extranet extends the intranet concept to network connections with business partners, suppliers or customers. The infrastructure for a private network should include a TCP/IP network, Web authoring software, Web server hardware and software, Web clients and a firewall server. Since many of these requirements are probably in place at a firm already using electronic commerce, additional cost can be minimized.