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Posted to users@jena.apache.org by Laura Morales <la...@mail.com> on 2020/12/13 17:05:04 UTC
Does Jena support RDF*?
I've only recently discovered the existence of RDF* and Turtle*. Looks like they were introduced around 2019. Does Jena have support for these in the current release?
Re: Does Jena support RDF*?
Posted by Jean-Marc Vanel <je...@gmail.com>.
The source code , with store and SPARQL to retrieve, and a few
explanations, is here:
https://github.com/jmvanel/semantic_forms/blob/master/scala/forms/src/main/scala/deductions/runtime/semlogs/TimeSeries.scala#L27
The trick used is to create a new URI for each modification of the main
database ( find
http://localhost:9000/ldp/1486136803523-89228787433384#1486136808956 in the
source code ) , that is used both as a subject for metadata, and as a graph
for the current modified triples.
It deserves more explanations I think.
Jean-Marc Vanel
<http://semantic-forms.cc:9112/display?displayuri=http://jmvanel.free.fr/jmv.rdf%23me>
+33
(0)6 89 16 29 52
Le lun. 14 déc. 2020 à 13:57, Laura Morales <la...@mail.com> a écrit :
> > This is an alternative to RDF* , AFAIK .
> > If someone is interested, I can document the structure of the secondary
> TDB
> > database.
>
> I don't want to abuse your time but yes, this would be helpful. Even just
> a sketch of it, just to get the idea.
>
Re: Does Jena support RDF*?
Posted by Laura Morales <la...@mail.com>.
> This is an alternative to RDF* , AFAIK .
> If someone is interested, I can document the structure of the secondary TDB
> database.
I don't want to abuse your time but yes, this would be helpful. Even just a sketch of it, just to get the idea.
Re: Does Jena support RDF*?
Posted by Jean-Marc Vanel <je...@gmail.com>.
I use on the SF (1) site (powered by (2) ) a secondary TDB database, not
exposed via SPARQL, which contains annotations on the primary data.
This enables to have roughly the equivalent of git; its records a history
of user edits.
Via web pages, only a bit of this data is exposed, allowing to show this
historic table view:
http://semantic-forms.cc:1952/history?limit=50
This is an alternative to RDF* , AFAIK .
If someone is interested, I can document the structure of the secondary TDB
database.
(1) SF site http://semantic-forms.cc:1952/
(2) SF software http://semantic-forms.cc:9112/ldp/semantic_forms
Jean-Marc Vanel
<http://semantic-forms.cc:9112/display?displayuri=http://jmvanel.free.fr/jmv.rdf%23me>
+33
(0)6 89 16 29 52
Le dim. 13 déc. 2020 à 20:35, Laura Morales <la...@mail.com> a écrit :
> > What's your interest in RDF*?
>
> There seems to have been this endless debate about triplestores vs
> property graphs since as far as I can remember. This new standard
> apparently promises to be the best of both world by supporting RDF plus
> what they call "richer types" (aka nodes, vertexes). "Richer" compared to
> the extremely atomic level of triples. So my interest is mostly to try it
> and see how it compares. Also from a storage point of view since everything
> that I've read claims that property graphs are faster to traverse because
> their storage is not "index-based" like triples. I've personally tried to
> use a couple of property graphs databases but I keep going back to
> triplestores for the only reason that they use more standardized
> technology. Every property graph instead seems to have its own way of doing
> things; I couldn't even find a standardized format for exporting/importing
> graphs or a standardized query language (although there are some efforts
> toward one called GQL). So if RDF* can combine the best parts of both
> worlds, I want to try it :)
> Please note that I'm not personally interested in the semantic web or the
> RDF artificial intelligence koolaid. I'm interested in the graph model with
> a great appreciation for free standards and simplicity. If RDF* can make
> the design of graphs simpler (ie. richer structures, fewer hacks and
> workarounds) then it's definitely something that I will use.
> Another issue for me with property graphs, but I would like to hear your
> feedback on this, is that properties are indexed globally and it's my
> understanding that they only accept one data type (eg. Integer). So I'm not
> sure how indexing work over there from a storage point of view. I think
> they would require me to define 2 properties instead of one or some kind of
> namespace, let's say "ns1_age" and "ns2_age" where one property takes
> Integer and the other one String for example. Which, at the end of the day,
> is the same thing as using RDF prefixes.
>
Re: Does Jena support RDF*?
Posted by Andy Seaborne <an...@apache.org>.
On 13/12/2020 19:34, Laura Morales wrote:
>> What's your interest in RDF*?
...
> Another issue for me with property graphs, but I would like to hear your feedback on this, is that properties are indexed globally and it's my understanding that they only accept one data type (eg. Integer). So I'm not sure how indexing work over there from a storage point of view. I think they would require me to define 2 properties instead of one or some kind of namespace, let's say "ns1_age" and "ns2_age" where one property takes Integer and the other one String for example. Which, at the end of the day, is the same thing as using RDF prefixes.
The two styles of graphs - labelled property graphs (LPG) and RDF - have
different heritages and usage and it shows.
The RDF ecosystem is about modelling, mergeable data, variety and scale
in a web style - i.e. distributed and multi-publisher with a strong
emphasis of being able to exchange data without messing up. So, for
example, data format standards matter a lot and system support and
fidelity of implementation for formats is very high. Users go "this
data does not work on that system" and submit bug reports - in LPG,
no-one is surprised if data doesn't transfer without preparation.
LPG comes from data analytics, data ingestion and ETL. There isn't a
shared data model and LPG systems have differences. The idea of smushing
data from different places together just isn't on their list of primary
use cases.
Andy
Re: Does Jena support RDF*?
Posted by Laura Morales <la...@mail.com>.
> What's your interest in RDF*?
There seems to have been this endless debate about triplestores vs property graphs since as far as I can remember. This new standard apparently promises to be the best of both world by supporting RDF plus what they call "richer types" (aka nodes, vertexes). "Richer" compared to the extremely atomic level of triples. So my interest is mostly to try it and see how it compares. Also from a storage point of view since everything that I've read claims that property graphs are faster to traverse because their storage is not "index-based" like triples. I've personally tried to use a couple of property graphs databases but I keep going back to triplestores for the only reason that they use more standardized technology. Every property graph instead seems to have its own way of doing things; I couldn't even find a standardized format for exporting/importing graphs or a standardized query language (although there are some efforts toward one called GQL). So if RDF* can combine the best parts of both worlds, I want to try it :)
Please note that I'm not personally interested in the semantic web or the RDF artificial intelligence koolaid. I'm interested in the graph model with a great appreciation for free standards and simplicity. If RDF* can make the design of graphs simpler (ie. richer structures, fewer hacks and workarounds) then it's definitely something that I will use.
Another issue for me with property graphs, but I would like to hear your feedback on this, is that properties are indexed globally and it's my understanding that they only accept one data type (eg. Integer). So I'm not sure how indexing work over there from a storage point of view. I think they would require me to define 2 properties instead of one or some kind of namespace, let's say "ns1_age" and "ns2_age" where one property takes Integer and the other one String for example. Which, at the end of the day, is the same thing as using RDF prefixes.
Re: Does Jena support RDF*?
Posted by Andy Seaborne <an...@apache.org>.
On 13/12/2020 17:05, Laura Morales wrote:
> I've only recently discovered the existence of RDF* and Turtle*. Looks like they were introduced around 2019. Does Jena have support for these in the current release?
>
https://jena.apache.org/documentation/rdfstar/index.html
As RDF* is currently an active area of community-standardisation,
details may change.
https://issues.apache.org/jira/browse/JENA-2015
(the new annotation syntax)
which I have done but not PR'ed yet
What's your interest in RDF*?
Andy