glib/docs/reference/gio/migrating-gdbus.xml

<chapter>
  <title>Migrating from dbus-glib to GDBus</title>

  <section>
    <title>Conceptual differences</title>

    <para>
      The central concepts of D-Bus are modelled in a very similar way
      in dbus-glib and GDBus. Both have a objects representing connections,
      proxies and method invocations. But there are some important
      differences:
      <itemizedlist>
        <listitem><para>
          dbus-glib uses libdbus, GDBus doesn't. Instead, it relies on GIO
          streams as transport layer, and has its own implementation for the
          the D-Bus connection setup and authentication. Apart from using
          streams as transport, avoiding libdbus also lets GDBus avoid some
          thorny multithreading issues.
        </para></listitem>
        <listitem><para>
          dbus-glib uses the GObject type system for method arguments and
          return values, including a homegrown container specialization
          mechanism. GDBus relies uses the #GVariant type system which is
          explicitly designed to match D-Bus types.
        </para></listitem>
        <listitem><para>
          The typical way to export an object in dbus-glib involves generating
          glue code from XML introspection data using <command>dbus-binding-tool</command>. GDBus does not (yet?) use code generation; you are expected to
          embed the introspection data in your application code.
        </para></listitem>
      </itemizedlist>
    </para>
  </section>

  <section>
    <title>Dbus-glib API conversion</title>

    <table id="dbus-glib-vs-gdbus">
      <title>dbus-glib APIs and their GDBus counterparts</title>
      <tgroup cols="2">
        <thead>
           <row><entry>dbus-glib</entry><entry>GDBus</entry></row>
        </thead>
        <tbody>
          <row><entry>#DBusGConnection</entry></entry>#GDBusConnection</entry></row>
          <row><entry>#DBusGProxy</entry></entry>#GDBusProxy</entry></row>
          <row><entry>#DBusGMethodInvocation</entry></entry>#GDBusMethodInvocatoin</entry></row>
          <row><entry>dbus_g_bus_get()</entry><entry>g_bus_get_sync(), also see
               g_bus_get()</entry></row>
          <row><entry>dbus_g_proxy_new_for_name()</entry><entry>g_dbus_proxy_new_sync(), also see
               g_dbus_proxy_new()</entry></row>
          <row><entry>dbus_g_proxy_add_signal()</entry><entry>not needed, use the generic #GDBusProxy::g-signal</entry></row>
          <row><entry>dbus_g_proxy_connect_signal()</entry><entry>use g_signal_connect() with #GDBusProxy::g-signal</entry></row>
          <row><entry>dbus_g_connection_register_g_object()</entry><entry>g_dbus_connection_register_object()</entry></row>
          <row><entry>dbus_g_connection_unregister_g_object()</entry><entry>g_dbus_connection_unregister_object()</entry></row>
          <row><entry>dbus_g_object_type_install_info()</entry><entry>introspection data is installed while registering
               an object, see g_dbus_connection_register_object()</entry></row>
          <row><entry>dbus_g_proxy_begin_call()</entry><entry>g_dbus_proxy_call()</entry></row>
          <row><entry>dbus_g_proxy_end_call()</entry><entry>g_dbus_proxy_call_finish()</entry></row>
          <row><entry>dbus_g_proxy_call()</entry><entry>g_dbus_proxy_call_sync()</entry></row>
          <row><entry>dbus_g_error_domain_register()</entry><entry>g_dbus_error_register_error_domain()</entry></row>
          <row><entry>dbus_g_error_has_name()</entry><entry>no direct equivalent, see g_dbus_error_get_remote_error()</entry></row>
          <row><entry>dbus_g_method_return()</entry><entry>g_dbus_method_invocation_return_value()</entry></row>
          <row><entry>dbus_g_method_return_error()</entry><entry>g_dbus_method_invocation_return_error() and variants</entry></row>
          <row><entry>dbus_g_method_get_sender()</entry><entry>g_dbus_method_invocation_get_sender()</entry></row>
        </tbody>
      </tgroup>
    </table>
  </section>
</chapter>