needs to have a persistent connection set up for the exchange of data, to
support congestion control

  should support establishment of a session key for authentication and
integrity; confidentiality is optional but helpful

  should support a keepalive, so that the LS can learn that the gateway has
failed. The keepalive should be fast, on the order to seconds, and not
require a lot of bandwidth (i.e., shouldn't have to refresh the entire set
of attributes as part of the keepalive)

  should support negotiation of the keepalive interval. The specific
requirement is for the server to tell the gateway what to use.

  should support partial updates, so that when a specific dynamic attribute
changes, only that attribute is sent