gene.heskett at verizon.net
Mon Nov 23 16:56:59 UTC 2009
On Monday 23 November 2009, Bob Ham wrote:
>On Sat, 2009-11-21 at 09:45 -0500, Paul Davis wrote:
>> I don't really care at all about the technology inside a Linux session
>> handling "toolkit", although clearly it would be nicer if it worked on
>> all Linux systems. What I care about is the complete lack of any
>> stable API that a developer of an application that would participate
>> in this could use and have some confidence in. Do I believe that using
>> dbus as an IPC mechanism makes sense in this case, and that therefore
>> "the API" is really just a set of dbus names and semantics? Well, i'm
>> agnostic about that
>I'd like to comment on this issue in order to clarify and also to
>explain why, as Nedko stated in his original email, I gave no support to
>One of the goals of LADCCA, LASH and even LADISH is to enable
>network-wide session management. A D-Bus connection enables
>communication between remote objects on a single bus. However, that bus
>is limited to a single host. Buses cannot span hosts. In order to
>implement a network-aware session management system using D-Bus, there
>must necessarily be one of only two approaches.
>The first approach is to have one bus on one host which all clients and
>servers on all hosts connect to. This is a star topology which has
>inherent weaknesses in terms of resilience. I believe the robustness
>needed for a usable networked audio session cannot be provided using an
>IPC mechanism with a single point of failure.
>The second option is to have multiple buses; for each session client and
>server to open multiple D-Bus connections. However, this introduces
>another layer of addressing. In order for messages to be passed to a
>remote object, not only must you know the address of the object but the
>address of the bus to which it is connected. This completely undermines
>the use of D-Bus. D-Bus is an IPC mechanism for communication with
>remote objects that doesn't allow communication with remote objects on
>I have never understood why D-Bus was even considered for a network-wide
>audio session system. It seems to me to be a case of all problems
>looking like a nail when you have a hammer.
Hop hip hooray! Someone with an overview of the problem, and some
understanding of the issues.
I have only a very small oar in this water as I represent just another sample
of the fabled 'user'. One who has been lurking here for many years, hoping
someone will pluck his magic twanger and linux audio will Just Work(TM)
forevermore. As all of these lists readers are aware of, that hasn't
But what I see all too often here are the clashes of personalities because
each one thinks his idea should trump all others and be universally adopted
by all. This D-Bus thing is typical. And when someone points out its
weaknesses, he is more likely to be treated like somebody burning a religious
book than as someone trying to steer to progress of this stateless ship.
So, I suggest that at the next audio summit, the discussion MUST be centered
on the design of a messaging bus/protocol that is usable by all if enough
pride can be swallowed by the protagonists, lay out the structures needed so
that _everyone_ has a usable tool, and come home and write it!
The present situation, while far better than it was in 1997-8 when I did my
first linux install, is still nowhere near a Just Works(TM) condition. And
what I read in my lurking here for much of a decade, is scarey. So little
mention of the system the top distros are shoving down our throats,
pulseaudio, as if its being somehow profane to even mention it. Hey, we all
live on this same planet, remember?
So little co-operation and so much time spent whipping the horses that are
trying to draw and quarter this thing called linux audio, each somehow
thinking that when their team has pulled off its little piece, it will
somehow be converted to a majority holding. Like a 2nd place winner in a
gunfight, it won't happen.
So lets start from scratch and build this universal bus, one that can handle
a system with more than one piece that claims to be audio capable, in
addition to being _local_ network transparent. And then all the rest of the
various factions here should get on this bus and use it.
You can, and probably will, ignore me. In fact I expect it based on my
observations so far.
Just an old (75) farts $0.02, who hopes he lives long enough to see it work.
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