dbus.js

D-Bus (short for "Desktop Bus") is a message-oriented middleware mechanism that allows communication between multiple processes running concurrently on the same machine. D-Bus was developed as part of the freedesktop.org project, initiated by GNOME developer Havoc Pennington to standardize services provided by Linux desktop environments such as GNOME and KDE Plasma.

https://en.wikipedia.org/wiki/D-Bus

dbus.js is a JavaScrpt library for D-Bus.

This is a fork of dbus-native that brings:

• replace callbacks with async / await
• migrate from commonjs to ESM
• replace abstract-socket dependency with Node.js builtin support
• update dependencies
• misleading EventEmitter API replaced
  • on/addListener -> subscribe()
  • off/removeListener -> unsubscribe()
  • emit -> signal()

npm install dbus.js

import dbus from "dbus.js";

const bus = dbus.sessionBus();
const service = bus.getService("org.freedesktop.Notifications");
const iface = await service.getInterface(
  "/org/freedesktop/Notifications",
  "org.freedesktop.Notifications",
);
console.log(iface);

await iface.subscribe("ActionInvoked", (...args) => {
  console.log("ActionInvoked", ...args);
});

await iface.subscribe("NotificationClosed", (...args) => {
  console.log("NotificationClosed", ...args);
});

const [id] = await iface.Notify(
  "exampl",
  0,
  "",
  "summary 3",
  "new message text",
  ["xxx yyy", "test2", "test3", "test4"],
  [],
  5,
);
console.log("Notificaton id", id);

setTimeout(() => iface.CloseNotification(id), 4000);

API

Low level messaging: bus connection

connection = dbus.createClient(options)

options:

• socket - unix socket path
• port - TCP port
• host - TCP host
• busAddress - encoded bus address. Default is DBUS_SESSION_BUS_ADDRESS environment variable. See http://dbus.freedesktop.org/doc/dbus-specification.html#addresses
• authMethods - array of authentication methods, which are attempted in the order provided (default:['EXTERNAL', 'DBUS_COOKIE_SHA1', 'ANONYMOUS'])
• ayBuffer - boolean (default:true): if true 'ay' dbus fields are returned as buffers
• ReturnLongjs - boolean (default:false): if true 64 bit dbus fields (x/t) are read out as Long.js objects, otherwise they are converted to numbers (which should be good up to 53 bits)

connection has only one method, message(msg)

message fields:

• type - methodCall, methodReturn, error or signal
• path - object path
• interface
• destination
• sender
• member
• serial
• signature
• body
• errorName
• replySerial

connection signals:

• connect - emitted after successful authentication
• message
• error

example:

import dbus from "dbus.js";
const conn = dbus.createConnection();
conn.message({
    path:'/org/freedesktop/DBus',
    destination: 'org.freedesktop.DBus',
    'interface': 'org.freedesktop.DBus',
    member: 'Hello',
    type: dbus.messageType.methodCall
});
conn.on('message', (msg) => {
  console.log(msg);
});

Note on INT64 'x' and UINT64 't'

Long.js is used for 64 Bit support. https://github.com/dcodeIO/long.js The following javascript types can be marshalled into 64 bit dbus fields:

• typeof 'number' up to 53bits
• typeof 'string' (consisting of decimal digits with no separators or '0x' prefixed hexadecimal) up to full 64bit range
• Long.js objects (or object with compatible properties)

By default 64 bit dbus fields are unmarshalled into a 'number' (with precision loss beyond 53 bits). Use {ReturnLongjs:true} option to return the actual Long.js object and preserve the entire 64 bits.

Links

• http://cgit.freedesktop.org/dbus - freedesktop reference C library
• https://github.com/guelfey/go.dbus
• https://github.com/Shouqun/node-dbus - libdbus
• https://github.com/Motorola-Mobility/node-dbus - libdbus
• https://github.com/izaakschroeder/node-dbus - libdbus
• https://github.com/agnat/node_libdbus
• https://github.com/agnat/node_dbus - native js
• https://github.com/cocagne/txdbus - native python + twisted
• http://search.cpan.org/~danberr/Net-DBus-1.0.0/ (seems to be native, but requires libdbus?)
• https://github.com/mvidner/ruby-dbus (native, sync)
• http://www.ndesk.org/DBusSharp (C#/Mono)
• https://github.com/lizenn/erlang-dbus/ - erlang
• https://github.com/mspanc/dbux/ - elixir
• http://0pointer.net/blog/the-new-sd-bus-api-of-systemd.html - Blog post about sb-bus and D-Bus in general