[Nepomuk] Re: same nepomuk db for several users

[Evgeny Egorochkin]

On Sunday 05 December 2010 18:54:03 Markus Leuthold wrote:
> > On 12/02/2010 01:24 AM, Markus Leuthold wrote:
> > > Hello list
> > > 
> > > We share our computer among several persons, each with a separate user
> > > account. We want to have a shared nepomuk database. What's the best way
> > > to do this? Creating a symlink of ~/.kde/share/apps/nepomuk to a shared
> > > folder?
> > > 
> > > best regards
> > > Kusi
> > 
> > This is tricky. It could be hacked with links indeed. But then no two
> > users could ever be logged in at the same time.
> > Why do you want to share the database?
> > 
> > Cheers,
> > Sebastian
> 
> There are many possible use-cases for sharing tags. Some real-world
> examples:
> 
> - me and my girlfriend are planning our vacation. She's tagging documents,
> pictures etc with the tag "vacation-2010". In my account, I'd like to see
> now what is already available when I'm organizing our vacations in my
> account.
> 
> - we're preparing a playlist for a party. We'd like to set the tag "party-
> playlist" in dolphin, running in each one's account. Since we're in a
> hurry, we're tagging the music at the same time on two different
> computers. So it should be possible to have the nepomuk db on a remote
> location.
> 
> As mentioned later in this thread, not all tags should be shared. It would
> be nice to have several nepomuk-dbs (private/shared). I understand that
> it's quite tricky to get the sharing right: It doesn't make sense to share
> tags for object which are not shared.
> You could say that tags of files which are readable by both accounts should
> also be saved in a shared nepomuk-db. Probably best would be an extended
> user interface where the user can choose the nepomuk location.
> 
> I'd like to mention that the workflow in digikam works excellent! We have
> all our photos in a shared directory. The sqlite3 file digikam4.db is
> read/write for all users, so each of us can tag photos (even concurrently)
> in digikam in our own accounts.
> 
> Talking about concurrent access: are you sure 2 nepomuk clients cannot
> access the db at the same time? It works with digikam. You can have two
> running instances of digikam (in two accounts), and when you change
> metadata located in digikam4.db, the change is immediately visible in the
> other running instance of digikam

You probably misunderstood Sebastian. He wasn't arguing against sharing 
data(keeping several databases or parts in sync), only against sharing the 
database itself.

I have already explained in my previous emails why we think sharing data is a 
much higher priority than sharing the database.

A less technical explanation:
 * we want users to be able to share data in many ways, including network.
 * 2 users on the same comp is just a special case.
 * having 2 copies of your and your girlfriend's tags on the same machine is a 
non-issue due to very small amount of data
 * without network sharing, you won't get large enough datasets(tag coulds, 
annotation) to make performance issues important.


-- 
Evgeny