Nepomuk in 4.13 and beyond

Shantanu Tushar Jha shaan7in at
Fri Dec 13 09:40:32 GMT 2013

Hi Vishesh,

While we're doing a "better Nepomuk", something that I'll personally love
improved is real-time[1] resource updates. We disabled resource watcher in
PMC a long time back because it used to slow down things a *lot*. I'd
envision something along the lines of signals which would notify the
resource IDs (or equivalent) that have changed. While the bare minimum
would be creation/deletion, notifications about changes to metadata will


On Fri, Dec 13, 2013 at 12:40 AM, Vishesh Handa <me at> wrote:

> On Thursday 12 Dec 2013 19:40:11 Ivan Čukić wrote:
> > > If we all decide to store stuff in sqlite, then it doesn't matter if
> they
> > > are separate database files or the same one.
> >
> > I might be missing a few things here, but asking questions is the road to
> > enlightenment :)
> >
> > - There is no way to query across different stores, which was the main
> > appeal of nepomuk? (I concluded this from the last mail)
> >
> There isn't one. Not right now. I'm open to ideas on how to do something
> like
> if it is required. I'm slightly skeptical if it actually is required.
> > - When querying, how do I get the properties of the results?
> You don't. You just get the identifier and some text. You can do a
> subsequent
> fetch job to get additional data.
> This is however just the generic Query API, if required we can design
> better
> APIs for something you have in mind. I have some specialized APIs for
> querying
> PIM data which are more useful in certain cases.
> >
> > When asking for the attachments sent by Alice, I don't care only about
> the
> > id, title and the icon of the result. I'd like to get the mimetype, size
> > etc. (for example, to group the results), or for further processing if I
> > have no desire to show the results directly to the user. Can I retrieve
> > those with baloo api? Do I need to make separate queries for those?
> >
> Attachments are a strange corner case, in Akonadi, where it isn't really a
> file
> since it does not have a url, and is not dereference-able. For normal
> files,
> you currently just get the url.
> >
> > The Result class looks like it was tailored only for displaying the
> results
> > to the user - KRunner style (design of it all looks quite similar to
> > KRunner to be honest).
> >
> It was designed for Runners, Dolphin, and Email Search. It wasn't designed
> to
> be a Nepomuk Query API replacement.
> > - We talked about asynchronous querying. Is it going to happen?
> >
> There is a QueryRunnable class which can be used to run queries in another
> thread. Most backends, do not seem to allow asynchronous queries, so there
> wasn't a way to run queries asynchronously by default.
> > I see a lot of KJobs for altering stuff, but Query and ResultIterator do
> not
> > look async.
> >
> > Just imagine a store that wants to query currently open windows (via dbus
> > connection to kwin), or currently open documents for an activity
> (requires
> > connection to both kamd and kwin). It can not be done sanely in a
> > synchronous way. One of the main things in libkactivities was to make
> > everything be totally async.
> >
> I'm open to suggestions on how to implement queries in an async manner.
> > - Database integration
> >
> > When we talked about the nepomuk successor at Akademy, one of the main
> > benefits I saw at the time was the possibility to integrate all dbs into
> one
> > (and shut up all the people who complain we like dbs too much :) ). Baloo
> > seems to go out of its way to accommodate the fact that everybody is
> using
> > different things (be it mysql, embedded mysql, sqlite, plain text etc.).
> >
> > From my POV, it would be much nicer if you forced a single db (as an
> actual
> > store, not as a cache like nepomuk is for akonadi) on the people, with
> the
> > option to have a few things runtime defined. It would ease the
> development
> > and would allow more fun queries which would be optimized unlike the
> manual
> > client-side joining of different query results.
> But what if one doesn't use SQL for storing data? IMO Xapian is much better
> suited that sqlite's FTS support (or mysql).
> I agree with you on the fun query bit, but I'm skeptical if those "fun
> queries" are genuinely required. How about we list down the use cases and
> then
> see?
> When planning Baloo, I've mostly taken a look at PIM, Dolphin, KRunner (and
> Milou), PMC, and KPeople. Perhaps something was missed?
> >
> >
> > Cheerio,
> > Ivan.
> --
> Vishesh Handa

Shantanu Tushar    (UTC +0530)
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