[Nepomuk] Sync KDE-Nepomuk to online db

[PierreL]

> Message: 3
> Date: Mon, 5 Sep 2011 23:32:49 +0530
> From: Vishesh Handa <handa.vish at gmail.com>
> To: PierreL <pierrelud at yahoo.com>
> Cc: nepomuk at kde.org
> Subject: Re: [Nepomuk] Sync KDE-Nepomuk to online db
> Message-ID:
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> <CAKb-1oc8no7hmpLQEbRYu9dP1OtuHZjhk+HgtmxZvODSsnfUiw at mail.gmail.com>
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>
> Hey Pierre
>
> On Mon, Sep 5, 2011 at 11:00 PM, PierreL <pierrelud at yahoo.com>
> wrote:
>
> > Hi,
> >
> > I need to sync the KDE-Nepomuk quad-store to an online
> quad-store probably
> > with the help of http://en.wikipedia.org/wiki/SyncML
>
>
> I want the same thing. I would actually like OwnCloud to
> have a quad store.
>
Nice. The current problem we have with own cloud is that is does not use all the Nepomuk ontologies and we want to use some extended Nepomuk ontologies. So no data loss.

>
> >
> > I understand a year ago there was a hacking session on
> a ShareServie and
> > work done during GSOC on this service. I also
> understand Telepathy has/will
> > have some interest in this. I do not know of where
> this work stands and what
> > are the current problems.
> >
>
> That was done by me. The project was "Nepomuk Backup, Sync
> and Sharing". The
> backup and synchronization worked, but the design wasn't
> great, and it was
> only in hindsight that we realized all kinds of problems.
> Fortunately, most
> of my work was used to develop the Data Management service,
> which is the
> core part of Nepomuk 2.0.
>
Where can I read more on this and is this code available?

>
> Right now, some parts of backup and synchronization needs
> to be rewritten,
> and they need to be merged with the Storage service. It's
> not a big job, it
> involves throwing a lot of code away and I should get down
> to it. The
> complex code which does the identification of duplicates
> and merges triples
> into the repository is already there. And it has been
> tested thoroughly.
>
Is there anything available to use or look at, at the moment? 

> The sharing service is still just a prototype. However,
> we're going to be
> working on it during the Telepathy sprint (15th-18th
> September)
>
Where will this take place?
>
> > I will of cause want to re-use as much as possible, so
> if something is
> > available now please let me know or just any
> information you can share.
> >
>
> Of course. We would like that as well.
>
So I will need some prototype very soon, so the plan is the following: For now as a simple use case just sync notes from SemNotes as a start. All notes are stored in Nepomuk which makes it easier than if there was no links to files etc.

Terminology:
Online store = Hosted online store
Client = KDE-Nepomuk store

We store this as a pimo:Note in the online store in a graph g1 and add provenance in a meta-data graph g2 for g1 of the client's containing uri and device name/id as metadata and add more client's provenance data as neded for the same note. The client's will not store any online store info. 

On the syncing part for now and just for now, on the client side maybe SemNotes can send a signal that it created/updated/deleted a note and a new Nepomuk service call it SyncN will push this to the online store. The logic in the online store service SyncO will then check if the note provenance uri exists and then take action on what was done on the client. Also SyncO logic will check for other provenance uris for that note in g2
and send that action to these clients.

Yes, questions arise like what if client is offline or what if this note is being edited by other client/s at the same time. The first answer is easy, the client check the online store when it comes online and take action. The second answer is harder..
  
>
> I'm not really familiar with SyncML. I'll take some time
> and read up about
> it.
>
> Till then could you tell what your plans were?
>
So my plan is to start implementing something in the line of this notes use case to start with at least. Is there anything I can reuse now and can I access it?

Also can you share any lessons learned etc. etc.

What are you plans and in what time-lines are you planning this? It will b very very nice if our efforts can compliment each other rather that to just redo a lot that you have done, so some kind of co-ordination will be needed for this interaction. 

Cheers,
Pierre

>
> >
> > Thanks,
> > Pierre
> > _______________________________________________
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> > Nepomuk at kde.org
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> >
>
>
>
> --
> Vishesh Handa
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