Waiting for a DBus service to become available (outdated example)

using DBus;

// [DBus (name = "org.gnome.evolution.metadata.Manager")]
// public interface Manager : GLib.Object {
//    public abstract void Register (DBus.ObjectPath registrar_path, uint last_checkout);
// }

[DBus (name = "org.gnome.evolution.metadata.Registrar")]
public class Registrar: GLib.Object {

    public void Set (string subject, string[] predicates, string[] values) {
        print ("set: %s\n", subject);
    }

    public void Cleanup () {
        print ("cleanup\n");
    }

    public void SetMany (string[] subjects, string[][] predicates, string[][] values) {


        uint len = subjects.length;
        uint i;

        print ("setmany: %d\n", subjects.length);


        for (i = 0; i < len; i++) {
                message ("setmany: " + subjects[i]);
//
//              There's a bug in Vala that makes lengths of inner arrays of a 
//              stacked array being wrong (apparently the inner array is no 
//              longer NULL terminated after demarshalign, which makes calcu-
//              lating the length impossible)
//
//              uint plen = 7; // strv_length (predicates[i]); 
//              uint y;
//
//              for (y = 0; y < plen; y++) {
//                      if (predicates[i][y] != null && values[i][y] != null) {
//                              print ("\t%s=%s\n", predicates[i][y], values[i][y]);
//                      }
//              }
        }
 
   }

    public void UnsetMany (string[] subjects) {
        print ("unsetmany %d\n", subjects.length);

    }

    public void Unset (string subject) {
        message ("unset: %s\n" + subject);
    }
}

public class MyApplication : GLib.Object {

    public uint stored_time;
    private DBus.Connection conn;
    private Registrar registrar;
    private dynamic DBus.Object bus;

    private void on_reply (GLib.Error e) {
    }

    private void deactivate () {
        registrar = null;
    }

    private void activate () {
        dynamic DBus.Object obj;

        DBus.ObjectPath path;

        registrar = new Registrar ();

        conn = DBus.Bus.get (DBus.BusType .SESSION);

        path = new DBus.ObjectPath ("/my/application/evolution_registrar");

        obj = conn.get_object ("org.gnome.evolution",
                               "/org/gnome/evolution/metadata/Manager",
                               "org.gnome.evolution.metadata.Manager");

        conn.register_object (path, registrar);

        try {
                obj.Register (path, stored_time, on_reply);
        } catch (GLib.Error e) {
                message ("Can't register: %s", e.message);
        }
    }

    private void on_name_owner_changed (DBus.Object sender, string name, string old_owner, string new_owner) {
        if (name == "org.gnome.evolution") {
                if (new_owner != "" && old_owner == "")
                        activate ();
                if (old_owner != "" && new_owner == "")
                        deactivate ();
        }
    }

    private void list_names_reply_cb (string[] names, GLib.Error e) {
        foreach (string name in names) {
                if (name == "org.gnome.evolution") {
                        activate();
                        break;
                }
        }
    }

    private bool on_ready () {

        try {
                print ("...\n");
                bus.list_names (list_names_reply_cb);
        } catch (GLib.Error e) {
                message ("Can't list: %s", e.message);
        }

        return false;
    }

    public void setup (uint stored_time) throws DBus.Error, GLib.Error {

        this.stored_time = stored_time;

        conn = DBus.Bus.get (DBus.BusType. SESSION);

        bus = conn.get_object ("org.freedesktop.DBus",
                               "/org/freedesktop/DBus",
                               "org.freedesktop.DBus");

        bus.NameOwnerChanged += on_name_owner_changed;

        Idle.add (on_ready);
    }

    static int main (string[] args) {
        var loop = new MainLoop (null, false);

        var app = new MyApplication ();

        try {
            uint a = 0;

            if (args.length > 1)
                a = (uint) args[1].to_ulong();
            else
                a = 0;

            app.setup (a);

        } catch (DBus.Error e) {
            stderr.printf ("Failed to initialise");
            return 1;
        } catch {
            stderr.printf ("Dynamic method failure");
            return 1;
        }

        loop.run ();

        return 0;
    }
}