A native erlang implementation of D-Bus



A native erlang implementation of D-Bus

D-Bus is now largely used in a lot of applications for language-independant, object-oriented RPC system.

The erlang platform needs an erlang native implementation.

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Usage as Client

This example is making a dbus call to the org.freedesktop.DBus system service (under linux) and a list of registered services.

  {ok, Bus} = dbus_bus_reg:get_bus(session),
  {ok, Service} = dbus_bus:get_service(Bus, 'org.freedesktop.DBus'),
  {ok, RemoteObject} = dbus_remote_service:get_object(Service, '/org/freedesktop/DBus'),
  {ok, Iface} = dbus_proxy:interface(RemoteObject, 'org.freedesktop.DBus'),
  {ok, Names} = dbus_proxy:call(Iface, 'ListNames', []),
  io:format("ListNames: ~p~n", [lists:sort(Reply1)]),
  ok = dbus_remote_service:release_object(Service, RemoteObject),
  ok = dbus_bus:release_service(Bus, Service),

Usage as Service

In the demo folder there is a bigger example, but is a minimal service callback module:


%% api

%% dbus object callbacks

%% gen_dbus callbacks

-record(state, {}).

start_link() ->
  gen_dbus:start_link({local, ?MODULE}, ?MODULE, [], []).

init([Service, Path]) ->
  State = #state{},
  Methods = ['HelloWorld'],
  {ok, {"com.example.MyService", '/SomeObject', [
    {interface, 'com.example.MyInterface'},
    {methods, Methods},
    {signals, []}
    ]}, State}.

'HelloWorld'(dbus_info) ->
  [{interface, 'com.example.MyInterface'},
    {signature, [string], [{array, string}]}].

'HelloWorld'([HelloMessage], From, State) ->
  {reply, ["Hello from Erlang"], State}.

handle_info(Info, State) ->
  error_logger:warning_msg("Unhandled info: ~p~n", [Info]),
  {noreply, State}.

When the dbus application is running you can start this service with my_module:start_link(). or add it to your supervision tree.

Caveat at the moment the service creation does not open a dbus connection and as a result the service will not be visible until you create the first dbus connection e.g. via dbus_bus_reg:get_bus(session).


Current status

The status:

  • Consuming D-Bus services: ok
  • Providing D-Bus services: ok
  • Tests for both are working!
  • Connect through TCP and UNIX socket: ok