a simple python application which expose an example service hello on dbus

example-dbus.py

#!/usr/bin/env python3
"""

dbus-send --session --dest=com.example.HelloService \
    --type=method_call --print-reply \
    /com/example/HelloService org.freedesktop.DBus.Introspectable.Introspect


dbus-send --session --dest=com.example.HelloService \
    --type=method_call --print-reply \
    /com/example/HelloService \
    com.example.HelloService.say_hello \
    string:"John"
"""


import dbus
import dbus.service
import dbus.mainloop.glib
from gi.repository import GLib

# Define the D-Bus interface name and object path
DBUS_INTERFACE = "com.example.HelloService"
DBUS_PATH = "/com/example/HelloService"

class HelloService(dbus.service.Object):
    def __init__(self):
        # Initialize the D-Bus main loop
        dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
        
        # Get the session bus
        bus = dbus.SessionBus()
        
        # Define the bus name
        bus_name = dbus.service.BusName(DBUS_INTERFACE, bus=bus)
        
        # Initialize the D-Bus service object
        super().__init__(bus_name, DBUS_PATH)

    # Define a D-Bus method that can be called by clients
    @dbus.service.method(DBUS_INTERFACE,
                        in_signature='s',  # Input parameter signature (string)
                        out_signature='s') # Output parameter signature (string)
    def say_hello(self, name):
        """
        A simple method that takes a name and returns a greeting
        """
        return f"Hello, {name}!"

    # Define a D-Bus signal that can be emitted
    @dbus.service.signal(DBUS_INTERFACE,
                        signature='s')
    def greeting_signal(self, message):
        """
        A signal that can be emitted with a message
        """
        pass

def main():
    # Create an instance of the service
    service = HelloService()
    
    # Create the main loop
    loop = GLib.MainLoop()
    
    print(f"Service running on D-Bus interface {DBUS_INTERFACE}")
    print("Press Ctrl+C to exit")
    
    try:
        # Run the main loop
        loop.run()
    except KeyboardInterrupt:
        loop.quit()
        print("\nService stopped")

if __name__ == '__main__':
    main()