Hi Andrew,

On 01/22/2016 08:59 PM, Andrew Zaborowski wrote:
> org.freedesktop.* service implementations don't seem to report any
> interfaces on non-object paths in the tree, neither does bluez.
> http://dbus.freedesktop.org/doc/dbus-specification.html#standard-interfaces-introspectable
> doesn't say much about this so this is up for discussion.
> ---
>   ell/dbus-service.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
>

You're correct, most org.freedesktop implementations don't do this.
However, its a bit bizarre to me that this behavior exists.  Just think 
about it, you're calling Introspect on an object and that object doesn't 
say it supports Introspect.

e.g.

dbus-send --session --dest=org.PulseAudio1 --type=method_call 
--print-reply / org.freedesktop.DBus.Introspectable.Introspect
method return sender=:1.15 -> dest=:1.69 reply_serial=2
    string "<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object 
Introspection 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
   <node name="org"/>
</node>
"

The Qt implementations seem to always include Introspect.  Maybe because 
they add a bunch of extra interfaces by default.  E.g.:

dbus-send --session --dest=org.ofono.phonesim --type=method_call 
--print-reply /some/deep org.freedesktop.DBus.Introspectable.Introspect
method return sender=:1.73 -> dest=:1.76 reply_serial=2
    string "<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object 
Introspection 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
   <interface name="org.freedesktop.DBus.Introspectable">
     <method name="Introspect">
       <arg name="xml_data" type="s" direction="out"/>
     </method>
   </interface>
   <interface name="org.freedesktop.DBus.Peer">
     <method name="Ping"/>
     <method name="GetMachineId">
       <arg name="machine_uuid" type="s" direction="out"/>
     </method>
   </interface>
   <node name="path"/>
</node>
"

In the end I think having it is more correct than not, but I'm fine 
going either way.

Regards,
-Denis