11. Application bus

0. Install (on the virtual machine) all the software required:

   • # apt-get install d-feet qt5-dbus python3-module-pydbus

1. Follow «DBus programming» lecture part.

H/W

1. Log in to sugon and create a folder named 11_ApplicationBus.

2. Finish all the tasks on VE
3. Listen to D-bus messages with 'dbus-monitor'. In the first terminal, run 'dbus-monitor' to listen to messages:

   andrewt@comp-core-i7-3615qm-0dbf32 ~ $ dbus-monitor | grep -A 10 -B 4 "Hello world"

   In the second terminal, send a notification:

   andrewt@comp-core-i7-3615qm-0dbf32 ~ $ notify-send "Hello world"

   Save what was recorded by 'dbus-monitor' to the 'notification.log' file and upload it to 'sugon'.
4. Listen to D-bus messages with 'dbus-monitor' to know the call that changes wallpaper.
   • Run 'dbus-monitor':

     andrewt@comp-core-i7-3615qm-0dbf32 ~ $ dbus-monitor | grep -A 10 -B 10 "last-image"

   • Change the desktop wallpaper.
   • Find the method call that changes wallpaper in the 'dbus-monitor' output.
   • Based on the call description from 'dbus-monitor' write a command that changes the wallpaper using 'qdbus'. Hint: andrewt@comp-core-i7-3615qm-0dbf32 ~ $ qdbus org.xfce.Xfconf bla-bla-bla
   • Save the command to the 'wallpaper.sh' file and upload it to sugon.

5. Modify the server.py service. Add a new method: Signature:

   <method name='MultiString'>
               <arg type='s' name='a' direction='in'/>
        <arg type='u' name='num' direction='in'/>
        <arg type='as' name='response' direction='out'/>
   </method>

   Body:

   • def MultiString(self, s, num):
         """returns n strings"""
         return s * num

   Call this method from 'dbus-send' (specify types of arguments as: string and uint32).

6. Save the program itself and the output (to the 'miltistring.log') and save it to sugon.