Nepomuk in 4.13 and beyond

Vishesh Handa me at
Thu Dec 12 17:16:49 GMT 2013

On Thursday 12 Dec 2013 12:34:40 Ivan Čukić wrote:
> Aloha,
> > - Resource Description Framework (RDF)
> > The biggest problem with RDF is that it raises the knowledge needed 
> I'm not sure this was *the* problem with nepomuk adoption, but lets 
> that for a moment :)
> So, nepomuk was based on rdf and sparql. Essentially, a simple and
> standardized yet really slow (and overly academic) technology that (in 
> case) introduced quite a few issues, as you already stated.
> What is a replacement for sparql in baloo? (the wiki page is quite
> underwhelming)
> Things here seem to be quite separated. Are the different 'stores' at 
> sharing a same instance of a database? (aka, are akonadi, and other 
> going to share a single instance of **sql)

If we all decide to store stuff in sqlite, then it doesn't matter if they are 
separate database files or the same one.

Currently, for files, I do not use a sql store except for mapping the file url 
to a unique identifier.

> How are the following things going to be implemented (some use-cases 
> come to mind):
>  - telepathy and akonadi contacts (kpeople implementation)

KPeople currently use their own sqlite db to map akonadi and telepathy 
contacts into people. At some point an API for exposing these details will 
need to be provided.

>  - linking a contact (kpeople vs akonadi) to an activity

I'm hoping you'll have something along the lines of an Activity relation 
which can be used to map any id with an activity. How you store it is up to 

>  - linking a file to an activity

Same as contacts. You map an activity id with a file identifier.

>  - linking an application to an activity

I haven't thought about applications, but if you have a unique identifier for 
an application, it should be fairly straightforward.

>  - getting emails of contacts that are linked to an activity

1. Fetch the contacts related to that activity
2. Do a query on the Email Store with a from/to/cc/bcc with those contacts

>  - getting emails with attachments of contacts that are linked to an
> activity

1. Same
2. Do a query on the Email Store with a from/to/cc/bcc with those contacts, 
but set the attachment flag to true.

This would arguable be inferior to have everything in one database where 
the database does the whole query for you. However, if the need arises we 
can merge databases are required.

> > Additionally, RDF is a very flexible way to store data, it is however not
> > the most efficient way. Data is generally completely normalized even
> > though
> Agreed. RDF stores are usually slow because they focus on flexibility as a
> most common use-case which it is not.
> > you've read the basic ideas behind Baloo [2]
> As I said, the basic ideas are overly basic when you come from outside 
> and don't know what is written between the lines. :)
> Ch!

Vishesh Handa
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