module Dn_io: sig .. end
Returns this as factory for inclusion into 
Netplex_main.startup
val factory : unit -> Netplex_types.processor_factory
Returns this as factory for inclusion into Netplex_main.startup
val add_service : Dn_config.dn_config ->
       Netplex_types.config_file ->
       Netplex_types.address -> Netplex_types.controller -> unit
Adds the Dn_io service directly to the controller. This way, there is
      no need to configure it in the config file. This function is called
      from Dn_manager when Dn_manager is enabled in the config file.