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Posts tagged with 'd-bus'

pitti

The current default D-BUS configuration (at least on Ubuntu) disallows monitoring method calls on the system D-BUS (dbus-monitor --system), which makes debugging rather cumbersome; this has worked years ago, but apparently got changed for security reasons. It took me a half an hour to figure out how to enable this for debugging, and as this has annoyingly little Google juice (I didn’t find any solution), let’s add some.

The trick seems to be to set a global policy to be able to eavesdrop any method call after the individual /etc/dbus-1/system.d/*.conf files applied their restrictions, for which there is already a convenient facility. Create a file /etc/dbus-1/system-local.conf with

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE busconfig PUBLIC
  "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
  "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">

<busconfig>
  <policy user="root">
    <!-- Allow everything to be sent -->
    <allow send_destination="*" eavesdrop="true"/>
    <!-- Allow everything to be received -->
    <allow eavesdrop="true"/>
    <allow send_type="method_call"/>
  </policy>
</busconfig>

Then sudo dbus-monitor --system displays everything. Needless to say that you don’t want this file on any production system!

Does anyone know an easier way? My first naive stab was to run dbus-monitor as root, but that doesn’t make any difference at all.

Update: Turns out this is already described in a better way at https://wiki.ubuntu.com/DebuggingDBus. Yay me for not finding that.. I updated above recipe to limit access to root, which is much better indeed.

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pitti

I just pushed out a new python-dbusmock release 0.6.

Calling a method on the mock now emits a MethodCalled signal on the org.freedesktop.DBus.Mock interface. In some cases this is easier to track than parsing the mock’s log or using GetMethodCalls. Thanks to Lars Uebernickel for this.

DBusMockObject.AddTemplate() and DBusTestCase.spawn_server_template() can now load local templates from your own project by specifying a path to a *.py file as template name. Thanks to Lucas De Marchi for this feature.

I also wrote a quite comprehensive template for systemd’s logind. It stubs out the power management functionality as well as user/seat/session objects, and is convincing enough for loginctl. Some bits like AttachDevice is missing, as this sounds unlikely to be required for D-BUS mock tests, but please let me know if you need anything else.

The mock processes now terminate automatically if their connected D-BUS goes down, as advertised in the documentation.

You can get the new tarball from Launchpad, and I uploaded it to Debian experimental now.

Enjoy!

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pitti

With python-dbusmock you can provide mocks for arbitrary D-BUS services for your test suites or if you want to reproduce a bug.

However, when writing actual tests for gnome-settings-daemon etc. I noticed that it is rather cumbersome to always have to set up the “skeleton” of common services such as UPower. python-dbusmock 0.2 now introduces the concept of “templates” which provide those skeletons for common standard services so that your code only needs to set up the particular properties and specific D-BUS objects that you need. These templates can be parameterized for common customizations, and they can provide additional convenience methods on the org.freedesktop.DBus.Mock interface to provide more abstract functionality like “add a battery”.

So if you want to pretend you have one AC and a half-charged battery, you can now simply do

  def setUp(self):
     (self.p_mock, self.obj_upower) = self.spawn_server_template('upower', {})

  def test_ac_bat(self):
     self.obj_upower.AddAC('mock_AC', 'Mock AC')
     self.obj_upower.AddChargingBattery('mock_BAT', 'Mock Battery', 50.0, 1200)

Or, if your code is not in Python, use the CLI/D-BUS interface, like in shell:

  # start a fake system bus
  eval `dbus-launch`
  export DBUS_SYSTEM_BUS_ADDRESS=$DBUS_SESSION_BUS_ADDRESS

  # start mock upower on the fake bus
  python3 -m dbusmock --template upower &

  # add devices
  gdbus call --system -d org.freedesktop.UPower -o /org/freedesktop/UPower \
      -m org.freedesktop.DBus.Mock.AddAC mock_ac 'Mock AC'
  gdbus call --system -d org.freedesktop.UPower -o /org/freedesktop/UPower \
      -m org.freedesktop.DBus.Mock.AddChargingBattery mock_bat 'Mock Bat' 50.0 1200

In both cases upower --dump or gnome-power-statistics will show you the expected devices (of course you need to run that within the environment of the fake $DBUS_SYSTEM_BUS_ADDRESS, or run the mock on the real system bus as root).

Iftikhar Ahmad contributed a template for NetworkManager, which allows you to easily set up ethernet and wifi devices and wifi access points. See pydoc3 dbusmock.templates.networkmanager for details and the test cases for how this looks like in practice.

I just released python-dbusmock 0.2.1 and uploaded the new version to Debian experimental. I will sync it into Ubuntu Raring in a few hours.

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David

Ubuntu App Developer Week – Day 3 Summary

Right into the middle of the week and still delivering the most diverse set of sessions from the most interesting technologies. QML, Cloud, D-Bus, Multitouch, Unity, Bazaar… Wednesday had a bit of everything. Most importantly, this sessions are for you all, so I was really glad to hear feedback on how people liked the content of App Developer Week! So here’s a new summary for all of those who couldn’t attend.

Qt Quick: QML the Language

By Jürgen Bocklage-Ryannel

In his first session, Jürgen gave a short intro to Qt Quick’s QML language and how to use it. The first steps were to install Qt and Qt Creator, followed by a description of what Qt Quick is and how developers came up with a declarative way, similar to CSS or JSON to write in the language. All that clear, he then started with the Qt Quick tutorial and code examples that could be run with qmlviewer, the qml interpreter. Onto the second part, he focused on the QML languate, and going into the detail on how to create custom QML components. There were also lots of pointers to the excellent Qt documentation.

Check out the session log here.

Make your applications work in the cloud with Ubuntu One

By Stuart Langridge

Stuart gave a great overview on how to add the cloud to existing apps and how to make new apps for the cloud, letting Ubuntu One do all the hard work for you: from managing identities, password renewal to sharing data between applications. And all that on the web, the desktop, mobile… all your stuff everywhere! He then showed us some simple code to sync playlists on the cloud, ready for streaming. File sync is also an important Ubuntu One feature apps can make use of for sharing, and he also went through a couple of the many cool ways you can use it. The last mention was on API documentation, something Stuart is working on in this cycle.

Check out the session log here.

Take control of your desktop easily with DBus

By Alejandro J. Cura

In this session Alejandro showed us in a hands-on and easy to follow way different bits and pieces of D-Bus, and how applications in the desktop can communicate through it. He went through real life examples to show how to do simple tasks and explained how they can be achieved with D-Bus.

Check out the session log here.

Touchégg: Bringing Multitouch Gestures to your Desktop

In the second multitouch session of the week, app developer José Expósito started showcasing Touchégg, how it works and its features: recognizing multitouch gestures and getting the most of multitouch devices. He then went on describing which gestures it supports, such as tap, drag, pinch or tap & hold, and the different actions that can be associated to gestures, showing us a really cool video of Touchégg in action. The second part of the talk focused on describing the technologies used to develop Touchégg: uTouch-GEIS, through its simplified interface, and Qt.

By José Expósito

Check out the session log here.

Unity: Integrating with Launcher and Places

By Mikkel Kamstrup Erlandsen

Mikkel used the intro of the talk to set a couple of things straight: “Places” are going to be called “Lenses” in the next cycle, and libunity does not yet guarantee API or ABI stability. He then followed with the Unity Launcher integration, and how applications can use static quicklists, and more advanced features such as count, progress bar, window flashing and dynamic quicklists. The second part were Places: remote databases that provide data for Unity to render. Through a Python code example he showed us in detail all the aspects of creating a Unity Place.

Check out the session log here.

Tracking Source Code History with Bazaar

By Jelmer Vernooij

Jelmer, in his experience of seasoned Bazaar hacker started off introducing what bzr is: a modern distributed version control system. He then went on with the basics with a hands-on example, going through the creation of a branch, the first commit, and describing several of the most handy bzr commands. As a wrap-up, he showcased more advanced features such as source recipes: scripts that combine branches and build daily Debian packages from them.

Check out the session log here.

The Day Ahead: Upcoming Sessions for Day 4

We’re featuring a Qt Quick Marathon today: 2 sessions in a row. Following that, how to do RAD with yet another framework: Quickly, how to get your applications in Ubuntu, and how to get them translated in Launchpad. Enjoy!

16:00 UTC
Qt Quick: Elements/Animations/States – Jürgen Bocklage-Ryannel
Another day and more featured Qt content: this time Jürgen will take us through different elements/animations and states Qt Quick provides, and will show us through examples how to make use of them.

17:00 UTC
Qt Quick: Rapid Prototyping – Jürgen Bocklage-Ryannel
If one session weren’t enough, here’s the continuation: more Qt goodness, this time a hands-on session to develop a small application from start to finish and experience the whole process from the front row.

18:00 UTC
Rapid App Development with QuicklyMichael Terry
Mike will show you how to write applications in no time with the power of Python and Quickly: bringing back the fun in programming.

19:00 UTC
Getting Your App in the Distro: the Application Review ProcessAllison Randal
A while back we created an easy process defining how to get applications into Ubuntu, so in order to be able to add them in a matter of weeks, rather than waiting for the next release. Allison, in her Ubuntu Technical Architect and Application Review Board member hat, will walk you through the Application Review Process

20:00 UTC
Adding Indicator Support to your AppsTed Gould
Join the man who knows most about indicators in a session that will teach you how to integrate your application even more into Ubuntu. They’re slick, robust and consistent: bringing indicator support to your apps.

21:00 UTC
Using Launchpad to get your application translatedHenning Eggers
One of the coolest features of Launchpad is that it helps growing a translation community around your project. You can make your application translatable in Launchpad and be able to deliver it into almost any language. Henning will teach you how to do this, picking up where the previous session on translations left.

Looking forward to seeing you all there!


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pitti

On the long flight back from UDS-Lucid I read the Vala tutorial on my ebook, and did some of the exercises. I was curious about Vala because it combines the speed and memory efficiency of C in a sane C#-like language with proper memory management, exceptions, and without the silly “close to the metal” faff that is usually required in C.

And indeed I wasn’t disappointed. It’s not as convenient as Python, but really not far from it, and it’s faaaast!

Today I finally got back to this and wrote my first D-Bus example in vala which does a call to DeviceKit-disks:

using DBus;

int main(string[] args)
{
    Connection con = Bus.get(BusType.SYSTEM);

    dynamic DBus.Object dk = con.get_object(
            "org.freedesktop.DeviceKit.Disks",
	    "/org/freedesktop/DeviceKit/Disks",
	    "org.freedesktop.DeviceKit.Disks");

    ObjectPath[] devs = dk.EnumerateDevices();
    foreach (ObjectPath o in devs)
	stdout.printf("%s\n", o);

    return 0;
}

Compile and run it with

valac --pkg dbus-glib-1 dbus-dk.vala && ./dbus-dk

and voila!

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