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With dbus-glib, exporting an object over D-Bus works by generating a bunch of glue code from your introspection XML with dbus-binding-tool. The glue code gets included in your source, and you need to call
  dbus_g_object_type_install_info (TYPE_MYOBJECT,
                                   &dbus_glib_myobject_object_info);
      
      in your class_init() function to tell dbus-glib about your type.
      To actually export an instance, you call
      
  dbus_g_connection_register_g_object (system_bus_connection,
                                       my_object_path,
                                       G_OBJECT (my_object));
      
      The GDBus way of exporting an object works by embedding the
      introspection XML in the source, creating introspection data
      structures from it with g_dbus_node_info_new_for_xml(), and
      passing that along when you register the object:
      
  static const gchar introspection_xml[] =
    "<node>"
    "  <interface name='org.gtk.GDBus.TestPeerInterface'>"
    "    <method name='HelloWorld'>"
    "      <arg type='s' name='greeting' direction='in'/>"
    "      <arg type='s' name='response' direction='out'/>"
    "    </method>"
    "  </interface>"
    "</node>";
  /* parse introspection data */
  introspection_data = g_dbus_node_info_new_for_xml (introspection_xml, NULL);
  /
  id = g_dbus_connection_register_object (connection,
                                          "/org/gtk/GDBus/TestObject",
                                          "org.gtk.GDBus.TestPeerInterface",
                                          introspection_data->interfaces[0],
                                          &interface_vtable,
                                          NULL,  /* user_data */
                                          NULL,  /* user_data_free_func */
                                          NULL); /* GError** */
    
      The actual implementation of the exported object is done by specifying
      a GDBusInterfaceVTable that has method_call(), get_property() and
      set_property() methods. There is no direct support beyond that for
      exporting GObjects, so there is quite a bit of manual work involved,
      as you can see in the following example.
    
      Since the VTable methods don't have any direct GObject support, we
      pass the exported object as user_data. Also note that we have to handle
      the emission of the PropertiesChanged signal ourselves, by connecting
      to ::notify.
    
Example 14. Exporting a GObject
#include <gio/gio.h>
#include <stdlib.h>
/* ---------------------------------------------------------------------------------------------------- */
/* The object we want to export */
typedef struct _MyObjectClass MyObjectClass;
typedef struct _MyObject MyObject;
struct _MyObjectClass
{
  GObjectClass parent_class;
};
struct _MyObject
{
  GObject parent_instance;
  gint count;
  gchar *name;
};
enum
{
  PROP_0,
  PROP_COUNT,
  PROP_NAME
};
G_DEFINE_TYPE (MyObject, my_object, G_TYPE_OBJECT);
static void
my_object_finalize (GObject *object)
{
  MyObject *myobj = (MyObject*)object;
  g_free (myobj->name);
  G_OBJECT_CLASS (my_object_parent_class)->finalize (object);
}
static void
my_object_init (MyObject *object)
{
  object->count = 0;
  object->name = NULL;
}
static void
my_object_get_property (GObject    *object,
                        guint       prop_id,
                        GValue     *value,
                        GParamSpec *pspec)
{
  MyObject *myobj = (MyObject*)object;
  switch (prop_id)
    {
    case PROP_COUNT:
      g_value_set_int (value, myobj->count);
      break;
    case PROP_NAME:
      g_value_set_string (value, myobj->name);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}
static void
my_object_set_property (GObject      *object,
                        guint         prop_id,
                        const GValue *value,
                        GParamSpec   *pspec)
{
  MyObject *myobj = (MyObject*)object;
  switch (prop_id)
    {
    case PROP_COUNT:
      myobj->count = g_value_get_int (value);
      break;
    case PROP_NAME:
      g_free (myobj->name);
      myobj->name = g_value_dup_string (value);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}
static void
my_object_class_init (MyObjectClass *class)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (class);
  gobject_class->finalize = my_object_finalize;
  gobject_class->set_property = my_object_set_property;
  gobject_class->get_property = my_object_get_property;
  g_object_class_install_property (gobject_class,
                                   PROP_COUNT,
                                   g_param_spec_int ("count",
                                                     "Count",
                                                     "Count",
                                                     0, 99999, 0,
                                                     G_PARAM_READWRITE));
  g_object_class_install_property (gobject_class,
                                   PROP_NAME,
                                   g_param_spec_string ("name",
                                                        "Name",
                                                        "Name",
                                                        NULL,
                                                        G_PARAM_READWRITE));
}
/* A method that we want to export */
void
my_object_change_count (MyObject *myobj,
                        gint      change)
{
  myobj->count = 2 * myobj->count + change;
  g_object_notify (G_OBJECT (myobj), "count");
}
/* ---------------------------------------------------------------------------------------------------- */
static GDBusNodeInfo *introspection_data = NULL;
/* Introspection data for the service we are exporting */
static const gchar introspection_xml[] =
  "<node>"
  "  <interface name='org.myorg.MyObject'>"
  "    <method name='ChangeCount'>"
  "      <arg type='i' name='change' direction='in'/>"
  "    </method>"
  "    <property type='i' name='Count' access='read'/>"
  "    <property type='s' name='Name' access='readwrite'/>"
  "  </interface>"
  "</node>";
static void
handle_method_call (GDBusConnection       *connection,
                    const gchar           *sender,
                    const gchar           *object_path,
                    const gchar           *interface_name,
                    const gchar           *method_name,
                    GVariant              *parameters,
                    GDBusMethodInvocation *invocation,
                    gpointer               user_data)
{
  MyObject *myobj = user_data;
  if (g_strcmp0 (method_name, "ChangeCount") == 0)
    {
      gint change;
      g_variant_get (parameters, "(i)", &change);
      my_object_change_count (myobj, change);
      g_dbus_method_invocation_return_value (invocation, NULL);
    }
}
static GVariant *
handle_get_property (GDBusConnection  *connection,
                     const gchar      *sender,
                     const gchar      *object_path,
                     const gchar      *interface_name,
                     const gchar      *property_name,
                     GError          **error,
                     gpointer          user_data)
{
  GVariant *ret;
  MyObject *myobj = user_data;
  ret = NULL;
  if (g_strcmp0 (property_name, "Count") == 0)
    {
      ret = g_variant_new_int32 (myobj->count);
    }
  else if (g_strcmp0 (property_name, "Name") == 0)
    {
      ret = g_variant_new_string (myobj->name ? myobj->name : "");
    }
  return ret;
}
static gboolean
handle_set_property (GDBusConnection  *connection,
                     const gchar      *sender,
                     const gchar      *object_path,
                     const gchar      *interface_name,
                     const gchar      *property_name,
                     GVariant         *value,
                     GError          **error,
                     gpointer          user_data)
{
  MyObject *myobj = user_data;
  if (g_strcmp0 (property_name, "Count") == 0)
    {
      g_object_set (myobj, "count", g_variant_get_int32 (value), NULL);
    }
  else if (g_strcmp0 (property_name, "Name") == 0)
    {
      g_object_set (myobj, "name", g_variant_get_string (value, NULL), NULL);
    }
  return TRUE;
}
/* for now */
static const GDBusInterfaceVTable interface_vtable =
{
  handle_method_call,
  handle_get_property,
  handle_set_property
};
static void
send_property_change (GObject         *obj,
                      GParamSpec      *pspec,
                      GDBusConnection *connection)
{
  GVariantBuilder *builder;
  GVariantBuilder *invalidated_builder;
  MyObject *myobj = (MyObject *)obj;
  builder = g_variant_builder_new (G_VARIANT_TYPE_ARRAY);
  invalidated_builder = g_variant_builder_new (G_VARIANT_TYPE ("as"));
  if (g_strcmp0 (pspec->name, "count") == 0)
    g_variant_builder_add (builder,
                           "{sv}",
                           "Count", g_variant_new_int32 (myobj->count));
  else if (g_strcmp0 (pspec->name, "name") == 0)
    g_variant_builder_add (builder,
                           "{sv}",
                           "Name", g_variant_new_string (myobj->name ? myobj->name : ""));
  g_dbus_connection_emit_signal (connection,
                                 NULL,
                                 "/org/myorg/MyObject",
                                 "org.freedesktop.DBus.Properties",
                                 "PropertiesChanged",
                                 g_variant_new ("(sa{sv}as)",
                                                "org.myorg.MyObject",
                                                builder,
                                                invalidated_builder),
                                 NULL);
}
static void
on_bus_acquired (GDBusConnection *connection,
                 const gchar     *name,
                 gpointer         user_data)
{
  MyObject *myobj = user_data;
  guint registration_id;
  g_signal_connect (myobj, "notify",
                    G_CALLBACK (send_property_change), connection);
  registration_id = g_dbus_connection_register_object (connection,
                                                       "/org/myorg/MyObject",
                                                       introspection_data->interfaces[0],
                                                       &interface_vtable,
                                                       myobj,
                                                       NULL,  /* user_data_free_func */
                                                       NULL); /* GError** */
  g_assert (registration_id > 0);
}
static void
on_name_acquired (GDBusConnection *connection,
                  const gchar     *name,
                  gpointer         user_data)
{
}
static void
on_name_lost (GDBusConnection *connection,
              const gchar     *name,
              gpointer         user_data)
{
  exit (1);
}
int
main (int argc, char *argv[])
{
  guint owner_id;
  GMainLoop *loop;
  MyObject *myobj;
  g_type_init ();
  /* We are lazy here - we don't want to manually provide
   * the introspection data structures - so we just build
   * them from XML.
   */
  introspection_data = g_dbus_node_info_new_for_xml (introspection_xml, NULL);
  g_assert (introspection_data != NULL);
  myobj = g_object_new (my_object_get_type (), NULL);
  owner_id = g_bus_own_name (G_BUS_TYPE_SESSION,
                             "org.myorg.MyObject",
                             G_BUS_NAME_OWNER_FLAGS_NONE,
                             on_bus_acquired,
                             on_name_acquired,
                             on_name_lost,
                             myobj,
                             NULL);
  loop = g_main_loop_new (NULL, FALSE);
  g_main_loop_run (loop);
  g_bus_unown_name (owner_id);
  g_dbus_node_info_unref (introspection_data);
  g_object_unref (myobj);
  return 0;
}