The IRequest::get_ServerVariables method retrieves the ServerVariables collection of the Request object.
HRESULT get_ServerVariables(
  IRequestDictionary ** ppDictReturn  //pointer to an 
                                      // IRequestDictionary interface 
                                      // pointer that receives the 
                                      // ServerVariables collection
);
 You can iterate through the ServerVariables collection with the IRequestDictionary::get__NewEnum, or you can retrieve a specific ServerVariable with the IRequestDictionary::get_Item method.