Lesson 3: Reading an HTTP Request

The Request Object

The Request object provides access to any information that is passed to the Web server by the HTTP request message.

Request Object Collections

The Request object contains five collections that you can use to extract information from an HTTP request.

The following table lists and describes these five collections.

---

Collection	Description
QueryString	The values of variables in the HTTP query string, specifically the values following the question mark ( ? ) in an HTTP request.
Form	The values of form elements posted to the body of the HTTP request message by the form's Post method.
Cookies	The values of cookies sent in the HTTP request.
ClientCertificate	The values of the certification fields in the HTTP request.
ServerVariables	The values of predetermined Web server environment variables.

---

Using the Request Object

Each collection of the Request object contains variables that you can use to retrieve information from an HTTP request.

---

Note

For a complete listing of the predetermined environment variables, see the Active Server Page Roadmap that is installed with ASP.

---

Example

This example uses the SERVER_NAME variable of the ServerVariables collection to retrieve the name of the Web server:

 Request.ServerVariables("SERVER_NAME") 

You can use the values of these variables to create dynamic HTML to return to the user .

Example

This example uses the name of the Web server to create a hyperlink to a Web page on the same server:

 <A HREF="http://<%= Request.ServerVariables("SERVER_NAME")%> /MyPage.asp">Link to MyPage</A> 

You can also access a variable directly without specifying the name of the collection.

Example

This example accesses a server variable directly:

 Request("SERVER_NAME") 

If you access a variable directly, the Web server searches for the variable in a collection in the following order:

• QueryString
• Form
• Cookies
• ClientCertificate
• ServerVariables

If a variable with the same name exists in more than one collection, the first instance encountered is used.