[packagekit] [Q] How "GetDepends" connect with "get_depends"

[NZzi]

hi all:

i wonder how "pkcon get-updates package" implement,
so i browse packagekit code, but i know little
about dbus, so after a whole day, i still can not
understand how "GetDepends" connect with "get_depends".

i browse from pk-console.c:

} else if (strcmp (mode, "get-depends") == 0) {
	...
	ret = pk_console_get_depends (client, filters, value, &error);
}

pk_console_get_depends()->pk_client_get_depends()->
ret = dbus_g_proxy_call (client->priv->proxy, "GetDepends", error,...)

i study some dbus docs, i konw dbus_g_proxy_call() call
"GetDepends" method through proxy object(client->priv->proxy),
but the "real" dependency-process function is get-depends() in
yumBackend.py. and i found it's backend_get_depends()(in
pk-backend-yum.c) invokd the get-depends().

but i don't know how dbus_g_proxy_call (client->priv->proxy, 
"GetDepends"...)
invoke backend_get_depends()(in pk-backend-yum.c)

can anyone give me some hints, thanks advance