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Chapter 27 WWW and HTTP

The WWW today is a distributed client/server service, in which a client using a browser can access a service using a server. However, the service provided is distributed over many locations called sites. | Chapter 27 WWW and HTTP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 27. 27-1 ARCHITECTURE The WWW today is a distributed client/server service, in which a client using a browser can access a service using a server. However, the service provided is distributed over many locations called sites. Client (Browser) Server Uniform Resource Locator Cookies Topics discussed in this section: 27. Figure 27.1 Architecture of WWW 27. Figure 27.2 Browser 27. Figure 27.3 URL 27. 27-2 WEB DOCUMENTS The documents in the WWW can be grouped into three broad categories: static, dynamic, and active. The category is based on the time at which the contents of the document are determined. Static Documents Dynamic Documents Active Documents Topics discussed in this section: 27. Figure 27.4 Static document 27. Figure 27.5 Boldface tags 27. Figure 27.6 Effect of boldface tags 27. Figure 27.7 Beginning and ending tags 27. . | Chapter 27 WWW and HTTP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 27. 27-1 ARCHITECTURE The WWW today is a distributed client/server service, in which a client using a browser can access a service using a server. However, the service provided is distributed over many locations called sites. Client (Browser) Server Uniform Resource Locator Cookies Topics discussed in this section: 27. Figure 27.1 Architecture of WWW 27. Figure 27.2 Browser 27. Figure 27.3 URL 27. 27-2 WEB DOCUMENTS The documents in the WWW can be grouped into three broad categories: static, dynamic, and active. The category is based on the time at which the contents of the document are determined. Static Documents Dynamic Documents Active Documents Topics discussed in this section: 27. Figure 27.4 Static document 27. Figure 27.5 Boldface tags 27. Figure 27.6 Effect of boldface tags 27. Figure 27.7 Beginning and ending tags 27. Figure 27.8 Dynamic document using CGI 27. Figure 27.9 Dynamic document using server-site script 27. Dynamic documents are sometimes referred to as server-site dynamic documents. Note 27. Figure 27.10 Active document using Java applet 27. Figure 27.11 Active document using client-site script 27. Active documents are sometimes referred to as client-site dynamic documents. Note 27. 27-3 HTTP The Hypertext Transfer Protocol (HTTP) is a protocol used mainly to access data on the World Wide Web. HTTP functions as a combination of FTP and SMTP. HTTP Transaction Persistent Versus Nonpersistent Connection Topics discussed in this section: 27. HTTP uses the services of TCP on well-known port 80. Note 27. Figure 27.12 HTTP transaction 27. Figure 27.13 Request and response messages 27. Figure 27.14 Request and status lines 27. Table 27.1 Methods 27. Table 27.2 Status codes 27. Table 27.2 Status codes (continued) 27. Figure 27.15 Header format