[LAD] Non-DAW's Session Handling Requirements

[Nedko Arnaudov]

malnourite at gmail.com writes:

> -+--- Overview - -    -
>
> The Non-DAW comprises a modular system. It would be convenient for
> the author and the users alike if the state of Non-DAW's components
> and other, entirely separate, programs could be managed together as a
> coherent whole.  The LASH system appears, at first glance, to support this
> kind of arrangement.  However, the current LASH API is overly complex and
> lacking in what this author considers to be a basic level of functional
> maturity. It is this confusion, I believe, which has resulted in the
> poor adoption of LASH and its subsequent stagnation.

I think almost everybody dislikes the current API so you got some
followers for sure ;)

> -+--- Basic Concerns - -    -
>
> Non-DAW, and other complex programs with large state which cannot
> be held in RAM all at once, require a few things that LASH doesn't
> currently provide.  These needs include the following:
>
>   1. The need to know the LASH project path the moment it first joins the
>   LASH session at startup. If this were so it could start a new Non-DAW
>   project under the LASH project path and new captures would go in their
>   right place without any intervention by the user. To clarify: there
>   must be no time when Non-DAW is connected to LASH without knowledge
>   of the path to the current LASH project directory.

Do you need to know LASH project path or you need to know the directory
path where your project data resides? I think there is nothing wrong
with providing the later.

>   2. The need to be informed of, or else be able to query at any time,
>   the LASH project name. If the LASH project path and the LASH project
>   name weren't different, we could get away with scanning the path for
>   the name, but this is unfortunately not the case.

I dont see anything wrong with this, we can have both query function and
signals. In fact we already have some signals to serve in the dbus branch.

> Additionally, the following would be required in order to fully integrate
> with LASH (transparently to the user).
>
>   1. Ability to initiate new projects, choosing among a list of previously
>   recorded templates.

planned already

>   2. Ability to save the current project as a template.

planned already

>   3. Ability to initiate a save of the entire LASH project.

even non-dbus implementation has this AFAIK

>   4. Ability to choose from a list of LASH projects to load.

already working. In dbus branch we have GetProjects method instead of
reading audio projects directory on client side.

> Some of the above are already possible to some extent with the current
> API, but complicated greatly by the artificial division of the API into
> client and control portions.

I think API division is right thing to have. However there should be no
artificial restriction of being both regular and control app. AFAIK it
is in Juuso's plans to remove this artificial restriction.

> Non-DAW and Non-Sequencer have the ability to change to a new project/song
> without restarting, but LASH makes no use of this--always restarting
> instances of these programs instead of reusing them.  Of course,
> Non-DAW and Non-Sequencer have extremely short startup times compared
> to other programs in their class, but still, I would like to avoid the
> distraction of many windows opening and closing at LASH project change
> time--it reflects poorly on my and any other programs which can change
> songs without crashing.

Maybe crazy idea, but we could have some of lash clients to export dbus
object to be controlled without restarting. And to make things even more
crazy, this matches my prefered "launch LASH apps only through lashd"
scenario. With apps being registered in database. So far we use existing
desktop entries infrastructure for launching apps through lashd. We
could use autolaunched dbus services too. Juuso, what you think?

> I would also like to see the preferred behavior of new/save/load
> operations in all clients specified by LASH so as to avoid confusion
> and potential data loss. Should any LASH client be permitted to save
> or load to/from disk /it's own state/ without informing LASH? This may
> seem harmless when the program state consists of a single file--as it
> is assumed that a copy of that file will be saved by the program in the
> LASH project directory whenever a LASH save is next performed. But now
> the user has two (differing) copies of his file--and he isn't sure which
> one he really edited--or where it is on disk.  The problem becomes even
> more serious when the program state includes a directory filled with
> gigabytes of audio sources...

I agree. These things need to be documented.

> Is it really advisable for LASH clients to operate on their state,
> which is supposedly under the control of LASH, as if it was theirs
> alone--without informing LASH of their activities? I don't necessarily
> know the answer to this question, but I do know that LASH needs to make
> a recommendation of some kind regarding the expected behavior--whatever
> it may be.

IMHO we should give recomendation but I'm against trying to force
things. We should the users participate in evolution instead of us
trying to enforce things as Gods of Code ;)

> -+--- Additional Thoughts - -    -
>
> There are also many things which LASH /could/ do to enhance the
> integration experience, but doesn't.
>
> These include, but are by no means limited to, the following:
>
>   * Templating and layering functionality.

already planned

>   * Project grouping (eg. all songs for an album) for easy management
>   of hundreds of projects. Please use subdirectories and/or symlinks
>   for this and not some XML junk.

already planned

>   * Global Undo/Redo functionality (simply sends a message to all clients
>   asking them to undo/redo and possibly providing feedback), additionally,
>   we can envision storing state diffs on disk for clients with no native
>   undo capability--something akin having the state in a git repo could
>   be used, reloading a reconstruction of prior state upon an 'undo'
>   request)--this is only viable if LASH can reuse program instances.

not that i dislike the idea, but i prefer to defer such functionality
for later incarnation of LASH. Unless someone is really motivated to
work on this now.

>   * Looser integration with/no direct dependance on JACK.

For LASH client or for lashd? I personally consider LASH tightly coupled
with JACK in the terms of user workflow. Thus I assume lashd and LASH
apps interacting directly with JACK. However, with jackdbus approach,
only LASH apps have direct dependance of JACK (i.e. are linked against
libjack). lashd uses jackdbus instead. LASH control app probably does
not interact with JACK server at all. The only possible exception I know
so far is to get JACK settings preset from JACK multiconfig object. But
I consider that separate module, not directly coupled with JACK itself.

I'll use this thread to announce the LADI project to this mailing
list. I maintain some documentation in my wiki:

http://nedko.arnaudov.name/wiki/moin.cgi/LADI

The above page has link to the "D-Bus interactions between components in
LADI system" diagram:

http://nedko.arnaudov.name/soft/ladi/ladi-dbus-interactions.png

There is also page dedicated to LASH in LADI system (LASH + D-Bus):

http://nedko.arnaudov.name/wiki/moin.cgi/lashdbus

-- 
Nedko Arnaudov <GnuPG KeyID: DE1716B0>
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