[Bluez-users] bluez and dbus - how to turn on discovery?

[Bluez-users] bluez and dbus - how to turn on discovery?

[Andrew Kohlsmith]

I've seen it in this list, but I can't find it now.

dbus is such a hairy pain in the ass, I hope that my opinion of it changes 
once I understand it more.

I would have thought that using a dbus "browser" such as kdbus I would have 
found a method to turn discovery on and off, as well as a bunch of other 
things.  However, browsing the system bus it I see

:1.0/org/bluez as an object (with nothing else)
org.bluez/org/bluez as an object (again with nothing else)

There isn't anything interesting in the session bus (at least not relating to 
Bluez, although I wasn't expecting to find anything.)

There is also an org.freedesktop.DBus interface in both the system and session 
busses with a ton of crap under it, but nothing bluez-related.

I haven't found much in the way of documentation on how to use this, yet we're 
all expected to use it.  Can someone assist in giving perhaps a crash course 
in controlling bluez through dbus?

-A.

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Re: [Bluez-users] bluez and dbus - how to turn on discovery?

[Marcel Holtmann]

Hi Andrew,

> dbus is such a hairy pain in the ass, I hope that my opinion of it changes 
> once I understand it more.
> 
> I would have thought that using a dbus "browser" such as kdbus I would have 
> found a method to turn discovery on and off, as well as a bunch of other 
> things.  However, browsing the system bus it I see
> 
> :1.0/org/bluez as an object (with nothing else)
> org.bluez/org/bluez as an object (again with nothing else)
> 
> There isn't anything interesting in the session bus (at least not relating to 
> Bluez, although I wasn't expecting to find anything.)
> 
> There is also an org.freedesktop.DBus interface in both the system and session 
> busses with a ton of crap under it, but nothing bluez-related.
> 
> I haven't found much in the way of documentation on how to use this, yet we're 
> all expected to use it.  Can someone assist in giving perhaps a crash course 
> in controlling bluez through dbus?

the session bus is not used by BlueZ at all. We only use the system bus.

I never used kdbus and so I can't tell you if that would work or not. I
always use the native interface from C or from Python. Some people use
dbus-send, but I can't remember the syntax.

So in general if your adapter has been found you should see org
org.bluez/org/bluez/hci0 object with the org.bluez.Adapter interface.
This interface on this path provides a SetMode method that can be used
to change the mode from "connectable" to "discoverable".

Since you speak about kdbus, I assume you don't use GNOME, but in that
case you could install bluez-gnome and use the bluetooth-properties
program to change the setting.

Regards

Marcel



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Re: [Bluez-users] bluez and dbus - how to turn on discovery?

[Andrew Kohlsmith]

On Monday 15 January 2007 8:24 am, Marcel Holtmann wrote:
> the session bus is not used by BlueZ at all. We only use the system bus.

Right, I figured that.  :-)

> So in general if your adapter has been found you should see org
> org.bluez/org/bluez/hci0 object with the org.bluez.Adapter interface.
> This interface on this path provides a SetMode method that can be used
> to change the mode from "connectable" to "discoverable".

dbus-send --system --dest=org.freedesktop.DBus --print-reply=1 /org/freedesktop/DBus 
org.freedesktop.DBus.ListNames
   array [
      org.freedesktop.DBus      :1.4      org.bluez      :1.9      :1.11   ]

I only have an org.bluez interface.  No org.bluez.Adapter, even though hci0 is 
up and running great (hcid is running, and hidd is running, my BT mouse works 
great)

> Since you speak about kdbus, I assume you don't use GNOME, but in that
> case you could install bluez-gnome and use the bluetooth-properties
> program to change the setting.

*nods* it looks like kdbus is working fine, as the dbus-send call itself is 
returning the exact same info... I just don't have a org.bluez.Adapter 
interface, nor do I have any hci0 object path.

Talking with the guys in FreeNode's #dbus channel too they say that this kind 
of return code is an error:

$ dbus-send --system --dest=org.bluez --print-reply=1 /org/bluez/hci0 
org.freedesktop.DBus.Introspectable.Introspect
   <!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 
1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
$

(/org/bluez also sends the exact same response) -- they claim that running 
that should give me some methods/interfaces, a child node or an error.

-A.

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Re: [Bluez-users] bluez and dbus - how to turn on discovery?

[Andrew Kohlsmith]

On Monday 15 January 2007 8:24 am, Marcel Holtmann wrote:
> I never used kdbus and so I can't tell you if that would work or not. I
> always use the native interface from C or from Python. Some people use
> dbus-send, but I can't remember the syntax.

For the archives, this is how you do it with dbus-send:

$ dbus-send --system --dest=org.bluez --print-reply=1 /org/bluez/hci0 
org.bluez.Adapter.SetMode string:discoverable

Howver... I see no hci0, I see no methods (i.e. Adapter isn't there, SetMode 
isn't there)...  it looks like the bluez 3.7 release does not have any kind 
of introspection or way of seeing what it provides programmatically.  Is this 
true?

-A.

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Re: [Bluez-users] bluez and dbus - how to turn on discovery?

[Ulisses Furquim]

On 1/15/07, Andrew Kohlsmith <akohlsmith-bluez@benshaw.com> wrote:
> dbus-send --system --dest=org.freedesktop.DBus --print-reply=1 /org/freedesktop/DBus
> org.freedesktop.DBus.ListNames
>    array [
>       org.freedesktop.DBus      :1.4      org.bluez      :1.9      :1.11   ]
>
> I only have an org.bluez interface.

Sorry, but this org.bluez is not an interface, but the bluez service.

> Talking with the guys in FreeNode's #dbus channel too they say that this kind
> of return code is an error:
>
> $ dbus-send --system --dest=org.bluez --print-reply=1 /org/bluez/hci0
> org.freedesktop.DBus.Introspectable.Introspect
>    <!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection
> 1.0//EN"
> "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
> $
>
> (/org/bluez also sends the exact same response) -- they claim that running
> that should give me some methods/interfaces, a child node or an error.

Yep, hcid is not answering the Introspect calls with the interface
methods and their signatures.

-- Ulisses

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Re: [Bluez-users] bluez and dbus - how to turn on discovery?

[Andrew Kohlsmith]

On Tuesday 16 January 2007 8:02 am, Ulisses Furquim wrote:
> Sorry, but this org.bluez is not an interface, but the bluez service.

I'm still trying to get my head around the dbus nomenclature.  It's a work in 
progress (my understanding, that is).  The various FAQs are helping, but it's 
taking some time yet.

> Yep, hcid is not answering the Introspect calls with the interface
> methods and their signatures.

The latest bluez (3.8) does return a grammatically correct XML response now 
(empty node).  I must ask again though -- how does one see which 
methods/properties bluez makes available through dbus?  How does one find out 
which bluetooth interfaces (hci0, hci1, etc.) are available?

I mean ok I can see how dbus is taking a lot of programming load off of the 
bluez IPC requirements, but it seems that the soul of dbus was removed in the 
bluez implementation.

-A.

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Re: [Bluez-users] bluez and dbus - how to turn on discovery?

[Marcel Holtmann]

Hi Andrew,

> > Sorry, but this org.bluez is not an interface, but the bluez service.
> 
> I'm still trying to get my head around the dbus nomenclature.  It's a work in 
> progress (my understanding, that is).  The various FAQs are helping, but it's 
> taking some time yet.

we all had our problems. You actually need to use it to understand how
it works.

> > Yep, hcid is not answering the Introspect calls with the interface
> > methods and their signatures.
> 
> The latest bluez (3.8) does return a grammatically correct XML response now 
> (empty node).  I must ask again though -- how does one see which 
> methods/properties bluez makes available through dbus?  How does one find out 
> which bluetooth interfaces (hci0, hci1, etc.) are available?

The introspection support is a problem and we know that. Mainly this is
because the low-level D-Bus API (which we use) makes it kinda hard to
easily support introspection. Especially if you have a lot of methods
and signals it is kinda horrible. And right now we simply haven't added
full introspection support. However we have a dbus-api.txt document in
the the source code that describes all methods and signals.

And to answer your question. You connect to the org.bluez service and
then you call org.bluez.Manager.ListAdapters() on the /org/bluez object
path. The return will be a list of object paths that implement the
org.bluez.Adapter interface. It sounds strange, but once you understood
it, it makes perfect sense.

> I mean ok I can see how dbus is taking a lot of programming load off of the 
> bluez IPC requirements, but it seems that the soul of dbus was removed in the 
> bluez implementation.

This has nothing to do with the soul of D-Bus. It is simply a big
difference if you use a high-level language or C with no additional
bindings.

Regards

Marcel



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Re: [Bluez-users] bluez and dbus - how to turn on discovery?

[Pierre-Yves Paulus]

Hello Andrew,

> The latest bluez (3.8) does return a grammatically correct XML response now 
> (empty node).  I must ask again though -- how does one see which 
> methods/properties bluez makes available through dbus?  How does one find out 
> which bluetooth interfaces (hci0, hci1, etc.) are available?

For now, have a look at

http://bluez.cvs.sourceforge.net/bluez/utils/hcid/dbus-api.txt?view=markup

You will find that there is a ListAdapters() method in the Manager 
hierarchy which will let you list current adapters, along the list of 
all other methods.

Regards,
Pierre-Yves


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