Re: [LAD] Summercode 2008: LASH as a D-Bus service

On Wed, 2008-01-23 at 19:44 +0200, Juuso Alasuutari wrote:
> I'm getting the feeling that there have been some misunderstandings in this
> discussion. Let's see if I can help with them, or if I'll just end up
> confusing things more. :)
>
> On Wednesday 23 January 2008 00:18:48 Bob Ham wrote:
> > On Tue, 2008-01-22 at 21:11 +0200, Nedko Arnaudov wrote:
> > > Bob Ham <rah@email-addr-hidden> writes:
> > > > More generally, LASH isn't a frontend for JACK.
> > >
> > > What about the jack watchdog? What does get killed by it?
> >
> > A good example. What does the watchdog do, exactly? It isn't a
> > frontend. I doesn't try to work around jackd's crashing. It just
> > ensures that if something bad does happen, the computer as a whole isn't
> > brought down. This is massively different from what you're proposing.
> >
> > To try and work around a crash in jackd and present a system to the user
> > where crashes make no difference is to invite more problems. If you
> > can't get jackd to stay up, what makes you think you can get your new
> > system to stay up?
>
> I don't think Nedko's proposal is motivated by a desire to work around
> existing bugs.

It sounded suspiciously to me as though that was exactly what Nedko's
proposal was :-) As I understand it, the issue is that jackd crashes,
and when it does it tends to bring down the whole audio session which is
a nightmare from a usability perspective. Nedko's proposal is to create
some system outside of jackd that can account for those crashes and
maintain the audio session in spite of them.

I think this is wrong. It's saying "OK, jackd isn't robust and we're
going to take account of that in our JACK-dependent system" when what
should be said is "OK, jackd isn't robust so we're going to make it
robust."

> > A layer that abstracts away the incidental
> > obligations of being a JACK client would be good but that is very far
> > from the domain that LASH is intended to help with.
>
> If such a layer could be beneficial (which is my belief also), why do you
> think that it's outside the scope of LASH planned improvements?

There's no reason to add a system-specific API layer to LASH itself.
The abstraction could be done by a separate library entirely, eg
libeasyjack.

> > To view LASH as the centre of a linux audio system is to misunderstand
> > its purpose. It might be able to *facilitate* a unified system, along
> > with JACK and other APIs, but it isn't the unified system itself. Such
> > a role is intended for the much-loathed "server interface" distinguished
> > in the LASH API.
>
> I personally don't see LASH as the centre of the audio system, and I'm not
> sure that Nedko meant to say that either.

I must have been thrown off by Nedko's words "LASH should behave like
all-in-one app" ;-)

> > It seems that what you want is Patchage++. Unfortunately, LASH isn't
> > that and I think you're likely to run into problems if you try and turn
> > it into that.
>
> Yes, at least I would like to see the day when one application can manage
> everything that the concept of an "audio session" includes (Patchage is
> probably pretty good already). But you've misunderstood the purpose of this
> discussion. We're not out to turn LASH into a super daemon/application of the
> sort that you're worried about. What we are trying to do is to think of how
> the interfaces and features of LASH could better help support a controller
> application's operation.

The thing is, a lot of the problems that have been highlighted as
capable of being solved by LASH aren't really anything in LASH's domain
and *shouldn't* be solved by it.

For example, yes, you could add support for maintaining the specific
settings of the patch system (I'm referring not just to JACK here) but
that's not what LASH is concerned with. It only cares about patch
configurations and client state. If it's the case that LASH *has* to
control the settings of the patch system just to provide a usable
system, then it points to a problem with the patch system. If the user
wants to change settings on the fly then the patch system itself should
enable that.

IMHO, there is a lot of work to be done to properly provide the kind of
support that LASH is *trying* to provide, without going on and thinking
about what else it might be able to do. Here is the list of future LASH
work from a while back:

        1.0
                Client priorities
                Track naming
                Guaranteed save directory availability
>1.0
                Graded saves
                Networked audio
                User interface standard
                Automatic client installation

And I would add to that now:

        0.6
                Redesign client/server communication
                        Certificate based security/encryption
                        Use OSC
                Rework API
                        Genericify patch-system specifics
                        Provide more useful event system (callbacks, etc)
                Rewrite client library in gobject
                Rewrite server in C++

Bob

-- 
Bob Ham <rah@email-addr-hidden>

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