samples: add client for python, perl, and bash

samples/dbus_client.pl

+#!/usr/bin/env perl
+
+use Net::DBus;
+use Net::DBus::Reactor;
+
+my $bus = Net::DBus->system;
+
+# Get a handle to the 'knotd' service
+my $knotd = $bus->get_service("cz.nic.knotd");
+
+# Get the device manager
+my $knotd_interface = $knotd->get_object("/cz/nic/knotd", "cz.nic.knotd.events");
+
+$knotd_interface->connect_to_signal('zone_updated', sub
+{
+    my ($zone, $serial) = @_;
+    print "Zone $zone updated, SOA serial $serial\n";
+});
+
+
+# Main loop
+Net::DBus::Reactor->main->run();
+
+exit 0

samples/dbus_client.py

+#!/usr/bin/env python3
+
+import dbus
+import dbus.mainloop.glib
+import signal
+from gi.repository import GLib
+
+def sigint_handler(sig, frame):
+    if sig == signal.SIGINT:
+        loop.quit()
+    else:
+        raise ValueError("Undefined handler for '{}'".format(sig))
+
+def on_xfr_done(*args, **kwargs):
+    (zone, serial) = args
+    print("Zone %s updated, SOA serial %d" % (zone, serial))
+
+if __name__ == '__main__':
+    signal.signal(signal.SIGINT, sigint_handler)
+
+    loop = dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
+    bus = dbus.SystemBus()
+    knotd = bus.get_object('cz.nic.knotd', '/cz/nic/knotd')
+    events_iface = dbus.Interface(knotd, dbus_interface='cz.nic.knotd.events')
+    events_iface.connect_to_signal("zone_updated", on_xfr_done)
+    loop = GLib.MainLoop()
+    loop.run()

samples/dbus_client.sh

+#!/usr/bin/env bash
+
+cb() {
+	echo "$1 [${@:2}]"
+}
+
+gdbus monitor --system --dest cz.nic.knotd --object-path /cz/nic/knotd \
+	| awk '/^\/cz\/nic\/knotd/ {
+		gsub("cz.nic.knotd.events.", "", $2);
+		tmp="";
+		for(i=3;i<=NF;++i) {
+			if( $i ~ /[\),]$/ ) tmp=tmp$i;
+		}
+		gsub("(^\()|(\)$)", "", tmp);
+		split(tmp, args, ",");
+		printf "%s ", $2;
+		for (i in args) printf "%s ", args[i];
+		print "";
+		fflush(stdout); }' \
+	| while read line; do \
+			cb ${line[@]}; \
+		done