This is our first CGI-Perl example <a href = ""> Click here to run the CGI program, reply.pl </a> </body> </html> - The connection from a CGI program back to the requesting browser is through standard output, usually through the server - The HTTP header needs only the content type, followed by a blank line, as is created with: print "Content-type: text/html \n\n"; #!/usr/local/bin/perl # reply.pl – a CGI program that returns a # greeting to the user print "Content-type: text/html \n\n", "<html> <head> \n", "<title> reply.pl example </title>", " </head> \n", "<body> \n", "<h1> Greetings from your Web server!", " </h1> \n </body> </html> \n"; Query string format
Programming the WEB 10CS73 DEPT. OF CSE, SJBIT Page 152 In World Wide Web , a query string is the part of a Uniform Resource Locator (URL) that contains data to be passed to web applications such as CGI programs. The Mozilla URL location bar showing an URL with the query string title=Main_page&action=raw When a web page is requested via the Hypertext Transfer Protocol , the server locates a file in its file system based on the requested URL . This file may be a regular file or a program. In the second case, the server may (depending on its configuration) run the program, sending its output as the required page. The query string is a part of the URL which is passed to the program. Its use permits data to be passed from the HTTP client (often a web browser ) to the program which generates the web page. Structure A typical URL containing a query string is as follows: When a server receives a request for such a page, it runs a program (if configured to do so), passing the query_string unchanged to the program. The question mark is used as a separator and is not part of the query string. A link in a web page may have a URL that contains a query string. However, the main use of query strings is to contain the content of an HTML form, also known as web form . In particular, when a form containing the fields field 1 , field 2 , field 3 is submitted, the content of the fields is encoded as a query string as follows: field 1 =value 1 &field 2 =value 2 &field 3 =value 3 ... The query string is composed of a series of field-value pairs. The field-value pairs are each separated by an equal sign . The series of pairs is separated by the ampersand , '&' or semicolon , ';'. For each field of the form, the query string contains a pair field=value. Web forms may include fields that are not visible to the user; these fields are included in the query string when the form is submitted This convention is a W3C recommendation. W3C recommends that all web servers support semicolon separators in the place of ampersand separators.
Programming the WEB 10CS73 DEPT. OF CSE, SJBIT Page 153 Technically, the form content is only encoded as a query string when the form submission method is GET . The same encoding is used by default when the submission method is POST , but the result is not sent as a query string, that is, is not added to the action URL of the form. Rather, the string is sent as the body of the request.
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- Winter '17
- Shwetha CH
- World Wide Web