Using Server Variables


Introduction.  In any web interaction there is a large variety of information that is passed.  When a developer wants to access this information it is usually identified by using the name Server Variables.

This information or server variables is usually classified into two major categories

  • HTTP Headers are pieces of information that are sent from the client to the server when requesting a piece of information or from the server to the client when responding to a page request.  For example,
    • the hostname of the client computer
    • the browser type and version of the client
    • the operating system of the client
    • the type of connection established between the client and the web server


  • Environment Variables are bits of information that the web server makes available to any program that requests them.  For example,
    • the URL of the ASP page
    • the entire physical path of the currently executing ASP
    • the root directory of the web
    • the web servers computer name
    • the web server's software

This information can be accessed within an ASP by using an appropriate Request.ServerVariables command.  The names of the Server Variables are given in the following two tables.


HTTP Header


HTTP_ACCEPT A list of the MIME types the client will accept
HTTP_ACCEPT_LANGUAGE What type of languages the browser expects.  These are human languages such as en-us to represent English, United States.
HTTP_CONNECTION The type of connection established between the client and the web server.
HTTP_HOST The hostname of the web server.
HTTP_USER_AGENT The browser type and version, and operating system of the client.
HTTP_REFERER The full URL of the web page containing the hyperlink used to reach the currently executing ASP page.
HTTP_COOKIE The cookies sent from the browser.


Environment Variable


URL The URL of the ASP page between and any query string.
PATH_INFO The same as the URL environment variable.
PATH_TRANSLATED The full, physical path of the currently executing ASP.
APPL_PHYSICAL_PATH The physical address of the web's root directory.
QUERY_STRING The querystring.
SERVER_NAME The web server's computer name.
SERVER_SOFTWARE The name of the web server software.


HTTP Headers.  Now we want to develop a small ASP that requests some of the HTTP headers and displays them.  So you want to copy the following code into a file called SomeHTTPHeaders.asp and upload it back to your ASP web.


<%@ Language=VBScript %>
<% Option Explicit %>

<font size=4>
<P>All of the MIME types the client will accept = <%= request.servervariables("HTTP_ACCEPT") %> </P>
<P>All languages the browser accepts = <%= request.servervariables("HTTP_ACCEPT_LANGUAGE") %> </P>
<P>The type of connection = <%= request.servervariables("HTTP_CONNECTION") %> </P>
<P>The hostname of the client = <%= request.servervariables("HTTP_HOST") %> </P>
<P>The client's type of browser and operating system = <%= request.servervariables("HTTP_USER_AGENT") %> </P>
<P>The URL of the referring page = <%= request.servervariables("HTTP_REFERER") %> </P>



The meaning of the code will be discussed in class.

Now you would get something like the following screen when you view the page.



Environment Variables.  Now we want to develop a similar ASP for displaying some important Environment Variables.  You should create a file called SomeEnvironmentVariables.asp and copy in the following code.



<%@ Language=VBScript %>
<% Option Explicit %>

<font size=4>

<P>Physical path to the Webs Root Directory = <%= request.servervariables("APPL_PHYSICAL_PATH") %> </P>
<P>Physical Path to the folder of the ASP that is currently running = <%= request.servervariables("PATH_TRANSLATED") %> </P>
<P>The web server's computer name = <%= request.servervariables("SERVER_NAME") %> </P>
<P>The web server's operating system = <%= request.servervariables("SERVER_SOFTWARE") %> </P>


The meaning of the code will be discussed in class.

You should get a screen that looks something like the following.