Page 261 - DCAP408_WEB_PROGRAMMING

Unit 11: Using Request Objects

Notes

Notes

1. Must prefix the name of the header with HTTP
2. How Request.ServerVariables (“ALL_HTTP) formats the list of HTTP headers. All
header names are capitalized and prefixed by HTTP_also, all dashes in the header
names are replaced with underscores, and the space between the colons at the value
of the header is removed. Request.ServerVariables (“ALL_RAW”) performs no
formatting to the request headers.
3. Reference header is present if the page has reached through a hyperlink on a different
web page.

Task Give answers to following questions:
1. Explain what a HTTP header is. Name some of the standard HTTP headers.

2. Explain how HTTP headers are read with Request.ServerVariables.

11.2 Accessing Environmental Variables

Useful Environment Variables, Reading the Environment Variables, Using Request,
ServerVariables.

The HTTP headers are useful for obtaining information about the current visitor but tell nothing
about the web server or the asp page that is being requested by the client.
Environmental variables are bits of information that the web server makes available to any
program that requests them. Environmental variables contain information such as the name of
the web server, the URL of the currently processing ASP page, or the name of the name of the
web server software being used.

Commonly used Environment Variables

Environment Variables Description
URL the URL of the ASP page from after
http\\www.your.webserver.com/up to the query string.
Path_info the same as the URL environment variable
Path_translated the full, physical path of the currently executing ASP page.
Appl_physical_path the physical address of the web’s root directory
Query_string the query string (equivalent to request every string)
Server_name the web server’s computer name
Server_software the name of the web software

Reading Environmental Variables using Request. Server Variables

The environmental variables are accessed much like the HTTP headers. The Request.
ServerVariables collection is used in the following format:

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