# File lib/metacat.rb, line 141
  def login(username, password)  
    response = metacat_get({
      'action'    =>  'login',
      'qformat'   =>  'xml',
      'username'  =>  username,
      'password'  =>  password
    })
    if(response.content_type == 'text/xml')
      doc = REXML::Document.new(response.read_body)
      if(doc.root.name == 'login')
        @cookie = response.response['set-cookie']
        @logged_in = true
      else
        raise MetacatPermissionDenied, "login error: "+doc.root.elements['message'].text
      end
    else
      raise MetacatResponseError
    end
  end