Migrating to GDBus: GIO Reference Manual

## Migrating to GDBus

## Conceptual differences

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:

- dbus-glib uses the libdbus reference implementation, GDBus doesn't. Instead, it relies on GIO streams as transport layer, and has its own implementation for the D-Bus connection setup and authentication. Apart from using streams as transport, avoiding libdbus also lets GDBus avoid some thorny multithreading issues.

- dbus-glib uses the GObject type system for method arguments and return values, including a homegrown container specialization mechanism. GDBus relies on the GVariant type system which is explicitly designed to match D-Bus types.

- dbus-glib models only D-Bus interfaces and does not provide any types for objects. GDBus models both D-Bus interfaces (via the GDBusInterface, GDBusProxy and GDBusInterfaceSkeleton types) and objects (via the GDBusObject, GDBusObjectSkeleton and GDBusObjectProxy types).

- GDBus includes native support for the org.freedesktop.DBus.Properties (via the GDBusProxy type) and org.freedesktop.DBus.ObjectManager D-Bus interfaces, dbus-glib doesn't.

- The typical way to export an object in dbus-glib involves generating glue code from XML introspection data using dbus-binding-tool. GDBus provides a similar tool called gdbus-codegen that can also generate Docbook D-Bus interface documentation.

- dbus-glib doesn't provide any convenience API for owning and watching bus names, GDBus provides the `g_bus_own_name()` and `g_bus_watch_name()` family of convenience functions.

- GDBus provides API to parse, generate and work with Introspection XML, dbus-glib doesn't.

- GTestDBus provides API to create isolated unit tests GDBus Test Scaffolding.