Overview

This is a DBus integration addon for NodeJS. It developed for performance and stability, ease of using and supporting.

It uses a libdbus only and doesn't depends from other libraries, like GLib and etc.

Why?

When I needed to use DBus in my projects, I tried to use all found DBus modules, but nothing of it worked properly for me.

• DBus addon by Shogun has strange and inconvenient API. Asynchronous operations fails to work for me. Also I cannot receive signals and implement service method calls. In early stage I tries to fix that behavior, but internal implementation looks like too tricky to support it.

• DBus addon by Motorola-Mobility is too low-level implementation, in fact it's almost a libdbus bindings. So high-level wrapper required to make it more convenient and easy for use. I tried to launch with it, but I don't agree what stuff like manipulating with DBus messages on JS-side is a good idea.

• Native implementation by Sidorares works more properly, but it have some serious problems with introspection and marshaling.

  Of course, using native implementation also is a not good idea for performance reasons.

How?

Internally this addon uses libuv for handling incoming data, so all interaction occurs in same thread with node and v8.

Installation

#!shell

$ npm install ndbus

Usage

#!javascript

var DBus = require('ndbus');
...

var session_bus = DBus();
var system_bus = DBus(true);
var custom_bus = DBus("custom_bus_name");

High-Level API

Interfacing with proxies

Objects must be introspectable to be able interact with its through proxies.

#!javascript

// binding object through proxy
bus.proxy("org.awesome.Service", "/path/to/object", "org.awesome.Interface",
function(err, some_object){
  // we need to handle errors
  ...
  // calling method of proxied object
  some_object.SomeMethod(arg0, arg1, ..., argN, function(err, ret0, ret1, ..., retN){
    // we need to handle errors
    ...
  });
  // binding to signal of proxied object
  function someListener(arg0, arg1, ..., argN){
    ...
  }
  some_object.SomeSignal.on(someListener);
  // unbinding from signal of proxied object
  some_object.SomeSignal.off(someListener);
  // binding to signal of proxied object only for one time
  some_object.SomeSignal.once(someListener);
  ...
  // removing proxy
  some_object.$();
});

Creating services

To create service you need to provide specification in simplified JSON-like format.

#!javascript

// creating service on the bus
bus.service("org.awesome.Service", function(err, some_service){
  // we need to handle errors
  ...
  // creating node with callback
  some_service.node("/path/to/object", function(err, node){
    // providing interface with callback
    node.iface("org.awesome.Interface", {
      // interface specification
      method: {
        // methods
        SomeMethod: {
          arg: {
            // in arguments
            arg0Name: arg0Signature,
            arg1Name: arg1Signature,
            ...
            argNName: argNSignature
          },
          res: {
            // out arguments
          }
        },
        AnotherMethod: {
          arg: [ arg0Signature, arg1Signature, ..., argNSignature ],
          $: {
            // method annotations
            annotationName: annotationValue
          }
        }
      },
       signal: {
        // signals
        someSignal: {
          arg: {
            // signal arguments
          },
          $: {
            // signal annotations
          }
        }
      },
      attrib: {
        // attributes (properties)
      },
      $: {
        // interface annotations
      }
    }, function(err, iface){
      // we need to handle errors
      ...
      // implementing method
      iface.SomeMethod(function(arg0, arg1, ..., argN, result){
        ...
        // emiting signal
        iface.SomeSignal(arg0, arg1, ..., argN);
      });
    });
    // providing interface with callback and object
    node.iface("org.awesome.Interface", {
      // interface specification
      ...
    }, {
      SomeMethod: function(arg0, arg1, ..., argN, result){
         ...
        // emiting signal
        this.SomeSignal(arg0, arg1, ..., argN);
      }
    }, function(err, iface){
      // we need to handle errors
      ...
      // removing interface
      iface.$();
    });
    ...
    // deleting node
    node.$();
  });
  ...
  // deleting service
  service.$();
});

Low-Level API

You need to use this only for extending High-Level API and in some special cases.

#!javascript

var nDBus = require('ndbus').internal;
...
var some_connection = nDBus.Connection(); // like DBus()
var some_interface = nDBus.Interface(some_connection); // like bus.proxy()
var some_method = nDBus.Method(some_interface, "MethodName", "in signature", "out signature");
var some_signal = nDBus.Signal(some_interface, "SignalName", "signature");
...
// call method
some_method.call([arg0, arg1, ..., argN], function(err, returns){
  var ret0 = returns[0], ret1 = returns[1], ..., retN = returns[N];
  ...
});
// register method callback
some_method.reg(function(args, result){
  var arg0 = args[0], arg1 = args[1], ..., argN = args[N];
  ...
  // asynchronous return case
  result([ret0, ret1, ..., retN]);
  // synchronous return case
  return [ret0, ret1, ];
});
// get registered method callback
var callback = some_method.reg();
// unregister method callback
some_method.reg(null);
...
// emit signal
some_signal.emit([arg0, arg1, ..., argN]);
// register signal listener
some_signal.reg(function(args){
  var arg0 = args[0], arg1 = args[1], ..., argN = args[N];
  ...
});
// get registered signal listener
var listener = some_signal.reg();
// unregister signal listener
some_signal.reg(null);

Licensing

This addon are available under GNU General Public License version 3.

ndbus — DBus integration addon for NodeJS.

Copyright © 2013 Kayo Phoenix [email protected]

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.