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Programming The Web10CS73VTU Question Paper Solution UNIT – 1 Introduction to Web, XHTML-1 1.Explain HTTP. (06 Marks) (Jan-2014, July-2013) 1. HTTP method Domain part of the URL HTTP version 2. Header fields 3. Blank line 4. Message body The following is an example of the first line of an HTTP request: GET /storefront.html HTTP/1.1 Only a few request methods are defined by HTTP, and even a smaller number of these are typically used. Table 1.1 lists the most commonly used methods. Table 1.1 HTTP request methods Among the methods given in Table 1.1, GET and POST are the most frequently used. POST was originally designed for tasks such as posting a news article to a newsgroup. Its most Dept, of CSE, SJBITPage 1
Programming The Web10CS73common use now is to send form data from a browser to a server, along with a request to execute a program on the server that will process the data. Following the first line of an HTTP communication is any number of header fields, most of which are optional. The format of a header field is the field name followed by a colon and the value of the field. There are four categories of header fields: 1. General: For general information, such as the date 2. Request: Included in request headers 3. Response: For response headers 4. Entity: Used in both request and response headers One common request field is the Accept field, which specifies a preference of the browser for the MIME type of the requested document. More than one Accept field can be specified if the browser is willing to accept documents in more than one format. For example; we might have any of the following: Accept: text/plain Accept: text/html Accept: image/gif A wildcard character, the asterisk (*), can be used to specify that part of a MIME type can be anything. For example, if any kind of text is acceptable, the Accept field could be as follows: Accept: text/* The Host: host name request field gives the name of the host. The Host field is required for HTTP 1.1. The If-Modified-Since: date request field specifies that the requested file should be sent only if it has been modified since the given date.