dbus object path

Thiago Macieira thiago at kde.org
Sat Mar 14 10:41:56 PDT 2009

Michael 'Mickey' Lauer wrote:
>Am Dienstag, den 10.03.2009, 14:38 +0300 schrieb Alexandr Lebedev:
>> Dear colleagues. Help me please. How I can receive the list of objects
>> under the service name?
>This is one of the missing features in dbus. You need to use
>introspection. Have a look at dbus-hlid @ http://git.freesmartphone.org
>which you can use for that.

No, you don't. Please read my email: unless you're writing a program whose 
purpose is to scan existing objects in D-Bus and show them to the user 
(i.e., a program that *is* a D-Bus browser), finding objects through 
introspection is always the wrong solution.

The correct thing is to:
1) know the path before-hand (via well-known path) or out-of-band 

or 2) request that the object reveal itself via signalling (one signal 
request, one reply or method call)

I have taken a look at http://git.freesmartphone.org/?p=dbus-
hlid.git;a=blob;f=src/obj.vala;hb=HEAD and I can tell that it probably 
works, but it is WRONG. Please do not introspect every object in a 
service. That's a lot of round-trips for what you could do with two (#2 
above) or zero (#1). 

Not to mention, of course, that some services do not like being 
introspected at all and may not reply, thus causing your code to hang for 
25 seconds while calling to /.

Also, you didn't use a proper XML parser. Some services may reply with 
introspections containing no new-lines, for instance, or with different 
whitespace count.

  Thiago Macieira  -  thiago (AT) macieira.info - thiago (AT) kde.org
    PGP/GPG: 0x6EF45358; fingerprint:
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