# File lib/openid/server.rb, line 283
      def AssociateRequest.from_query(query)
        session_type = query['openid.session_type']
        if session_type == 'DH-SHA1'
          session = DiffieHellmanServerSession.from_query(query)
        elsif session_type.nil?
          session = PlainTextServerSession.from_query(query)
        else
          raise ProtocolError.new(query,
                                  "Unknown session_type #{session_type}")
        end
        
        return new(session)
      end