The Hypertext Transfer Protocol (HTTP) is a protocol used mainly to access data on the World Wide Web. HTTP functions like a combination of FTP and SMTP. This chapter provides knowledge of Hypertext Transfer Protocol (HTTP): HTTP transaction, request message, response message, header, examples, some other features. | Chapter 24 Hypertext Transfer Protocol (HTTP) CONTENTS HTTP TRANSACTION REQUEST MESSAGE RESPONSE MESSAGE HEADER EXAMPLES SOME OTHER FEATURES HTTP uses the services of TCP on well-known port 80. HTTP TRANSACTION Figure 24-1 HTTP transaction Figure 24-2 Message categories REQUEST MESSAGE Figure 25-3 Request message Figure 24-4 Request line Figure 24-5 URL RESPONSE MESSAGE Figure 24-6 Response message Figure 24-7 Status line Status code: Same format as FTP responses (three digits) HEADER Figure 24-8 Header format Figure 24-9 Headers EXAMPLES Example 1 This example retrieves a document. We use the GET method to retrieve an image with the path /usr/bin/image1. Figure 24-10 Example 1 Example 2 This example retrieves information about a document. We use the HEAD method to retrieve information about an HTML document (see Chapter 25) Figure 24-11 Example 2 Example 3 In this example, the client wants to send input data to the server. We use the POST method. Figure 24-12 Example 3 SOME OTHER FEATURES HTTP version specifies a persistent connection by default. | Chapter 24 Hypertext Transfer Protocol (HTTP) CONTENTS HTTP TRANSACTION REQUEST MESSAGE RESPONSE MESSAGE HEADER EXAMPLES SOME OTHER FEATURES HTTP uses the services of TCP on well-known port 80. HTTP TRANSACTION Figure 24-1 HTTP transaction Figure 24-2 Message categories REQUEST MESSAGE Figure 25-3 Request message Figure 24-4 Request line Figure 24-5 URL RESPONSE MESSAGE Figure 24-6 Response message Figure 24-7 Status line Status code: Same format as FTP responses (three digits) HEADER Figure 24-8 Header format Figure 24-9 Headers EXAMPLES Example 1 This example retrieves a document. We use the GET method to retrieve an image with the path /usr/bin/image1. Figure 24-10 Example 1 Example 2 This example retrieves information about a document. We use the HEAD method to retrieve information about an HTML document (see Chapter 25) Figure 24-11 Example 2 Example 3 In this example, the client wants to send input data to the server. We use the POST method. Figure 24-12 Example 3 SOME OTHER FEATURES HTTP version specifies a persistent connection by default. | Chapter 24 Hypertext Transfer Protocol (HTTP) CONTENTS HTTP TRANSACTION REQUEST MESSAGE RESPONSE MESSAGE HEADER EXAMPLES SOME OTHER FEATURES HTTP uses the services of TCP on well-known port 80. HTTP TRANSACTION Figure 24-1 HTTP transaction Figure 24-2 Message categories REQUEST MESSAGE Figure 25-3 Request message Figure 24-4 Request line Figure 24-5 URL RESPONSE MESSAGE Figure 24-6 Response message Figure 24-7 Status line Status code: Same format as FTP responses (three digits) HEADER Figure 24-8 Header format Figure 24-9 Headers EXAMPLES Example 1 This example retrieves a document. We use the GET method to retrieve an image with the path /usr/bin/image1. Figure 24-10 Example 1 Example 2 This example retrieves information about a document. We use the HEAD method to retrieve information about an HTML document (see Chapter 25) Figure 24-11 Example 2 Example 3 In this example, the client wants to send input data to the server. We use the POST method. Figure .
