Re: How much can RDF graph scale

[Andrii Berezovskyi]

https://www.w3.org/wiki/LargeTripleStores

And in production, Wikidata has scaled to 13B+ triples so far using Blazegraph 
that is public to the world: https://scholia.toolforge.org/statistics

Sadly, http://sparqles.ai.wu.ac.at/ is down but it had a list of smaller 
endpoints you could check for examples of what dataset sizes you can host 
publicly with a good uptime. You can excavate some of its data on 
https://web.archive.org/web/*/http://sparqles.ai.wu.ac.at//* (use text/html 
MIME filter).

I think http://lod-a-lot.lod.labs.vu.nl/ shut down its SPARQL endpoint in 
favour of an TPF interface but it had 
20B+ triples AFAIK queryable over SPARQL at some point of time.

/Andrew

Re: How much can RDF graph scale

[Andy Seaborne]

On 20/12/2021 13:37, emri mbiemri wrote:

Dear all,

I am using RDF graphs for persisting my domain information, I am interested
to know if there is any study or experiment conducted so far that measures
the scalability of an RDF graph? I want to know if I can say that my
repository scales since it is RDF-based and why?  I have converted and
persisted so far about 1k models, it works well, but does it scale when I
have to cope with millions of models?

Thanks a lot.



https://www.w3.org/wiki/LargeTripleStores

Andy

Re: fuseki and tomcat 10

[Andy Seaborne]

https://tomcat.apache.org/migration-10.html

"""
There is a significant breaking change between Tomcat 9.0.x and Tomcat 
10.0.x. The Java package used by the specification APIs has changed from 
javax... to jakarta It will be necessary to recompile web 
applications against the new APIs.

"""

You might try the conversion tool:
https://tomcat.apache.org/download-migration.cgi

and let us know what happens.

Andy


On 20/12/2021 14:10, Pietro Liuzzo wrote:

Dear all,

sorry to bother,
I have tried to install the newly released Fuseki 4.3.2 under tomcat 10.0.14 on 
Ubuntu 18 and I am having not little truble. If anyone could point me in the 
right direction I would very much appreciate.

I have followed these steps 
, which 
usually work nice and easy.

the entire tomcat installation is owned by a user tomcat and a group tomcat, 
but since on that I am also having issues here is what I get running tomcat 10 
as root.

sparql --version
Jena:   VERSION: 4.3.2
Jena:   BUILD_DATE: 2021-12-17T18:56:02Z

tells me that the path is ok, or at least so I believe.

I changed owner and allowed r and x on fuseki.war in the distribution and moved 
it to webapps.

/etc/fuseki, where my data is, is owned by tomcat:tomcat.

I start tomcat and logs are clean, no warning of sort, but instead of the 
fuseki I am returned a 404 with the message
The requested resource [/fuseki/] is not available

The origin server did not find a current representation for the target resource 
or is not willing to disclose that one exists.

It used to work so nicely, and now I have the impression I have been changing 
quotes, commas, lines for four days without being able to replicate the nice 
setup for this to run.

Any suggestion will be greatly appreciated.

all best
Pietro

Re: fuseki and tomcat 10

[Pietro Liuzzo]

I guess you solved my problem! Thanks a lot! I did not check because that
is what brew got for me and i trusted that, wrongly.

Andrii Berezovskyi  schrieb am Mo., 20. Dez. 2021, 15:15:

> Hello Pietro,
>
> I am sorry for asking, but before going further: why are you running
> Tomcat 10, especially on Ubuntu 18.04? Ubuntu 18.04 and 20.04 seem to only
> support Tomcat 9 officially:
> https://packages.ubuntu.com/search?suite=default=all=any=tomcat=names.
> I think (official) Tomcat 10 support may come in the next LTS, 22.04.
>
> /Andrew
>
> On 2021-12-20, at 15:10, Pietro Liuzzo  pietro.liu...@gmail.com>> wrote:
>
> Dear all,
>
> sorry to bother,
> I have tried to install the newly released Fuseki 4.3.2 under tomcat
> 10.0.14 on Ubuntu 18 and I am having not little truble. If anyone could
> point me in the right direction I would very much appreciate.
>
> I have followed these steps <
> https://jena.apache.org/documentation/fuseki2/fuseki-quick-start.html>,
> which usually work nice and easy.
>
> the entire tomcat installation is owned by a user tomcat and a group
> tomcat, but since on that I am also having issues here is what I get
> running tomcat 10 as root.
>
> sparql --version
> Jena:   VERSION: 4.3.2
> Jena:   BUILD_DATE: 2021-12-17T18:56:02Z
>
> tells me that the path is ok, or at least so I believe.
>
> I changed owner and allowed r and x on fuseki.war in the distribution and
> moved it to webapps.
>
> /etc/fuseki, where my data is, is owned by tomcat:tomcat.
>
> I start tomcat and logs are clean, no warning of sort, but instead of the
> fuseki I am returned a 404 with the message
> The requested resource [/fuseki/] is not available
>
> The origin server did not find a current representation for the target
> resource or is not willing to disclose that one exists.
>
> It used to work so nicely, and now I have the impression I have been
> changing quotes, commas, lines for four days without being able to
> replicate the nice setup for this to run.
>
> Any suggestion will be greatly appreciated.
>
> all best
> Pietro
>
>
>

Re: fuseki and tomcat 10

[Andrii Berezovskyi]

Hello Pietro,

I am sorry for asking, but before going further: why are you running Tomcat 10, 
especially on Ubuntu 18.04? Ubuntu 18.04 and 20.04 seem to only support Tomcat 
9 officially: 
https://packages.ubuntu.com/search?suite=default=all=any=tomcat=names.
 I think (official) Tomcat 10 support may come in the next LTS, 22.04.

/Andrew

On 2021-12-20, at 15:10, Pietro Liuzzo 
mailto:pietro.liu...@gmail.com>> wrote:

Dear all,

sorry to bother,
I have tried to install the newly released Fuseki 4.3.2 under tomcat 10.0.14 on 
Ubuntu 18 and I am having not little truble. If anyone could point me in the 
right direction I would very much appreciate.

I have followed these steps 
, which 
usually work nice and easy.

the entire tomcat installation is owned by a user tomcat and a group tomcat, 
but since on that I am also having issues here is what I get running tomcat 10 
as root.

sparql --version
Jena:   VERSION: 4.3.2
Jena:   BUILD_DATE: 2021-12-17T18:56:02Z

tells me that the path is ok, or at least so I believe.

I changed owner and allowed r and x on fuseki.war in the distribution and moved 
it to webapps.

/etc/fuseki, where my data is, is owned by tomcat:tomcat.

I start tomcat and logs are clean, no warning of sort, but instead of the 
fuseki I am returned a 404 with the message
The requested resource [/fuseki/] is not available

The origin server did not find a current representation for the target resource 
or is not willing to disclose that one exists.

It used to work so nicely, and now I have the impression I have been changing 
quotes, commas, lines for four days without being able to replicate the nice 
setup for this to run.

Any suggestion will be greatly appreciated.

all best
Pietro

fuseki and tomcat 10

[Pietro Liuzzo]

Dear all,

sorry to bother,
I have tried to install the newly released Fuseki 4.3.2 under tomcat 10.0.14 on 
Ubuntu 18 and I am having not little truble. If anyone could point me in the 
right direction I would very much appreciate.

I have followed these steps 
, which 
usually work nice and easy.

the entire tomcat installation is owned by a user tomcat and a group tomcat, 
but since on that I am also having issues here is what I get running tomcat 10 
as root. 

sparql --version
Jena:   VERSION: 4.3.2
Jena:   BUILD_DATE: 2021-12-17T18:56:02Z

tells me that the path is ok, or at least so I believe.

I changed owner and allowed r and x on fuseki.war in the distribution and moved 
it to webapps.

/etc/fuseki, where my data is, is owned by tomcat:tomcat.

I start tomcat and logs are clean, no warning of sort, but instead of the 
fuseki I am returned a 404 with the message
The requested resource [/fuseki/] is not available

The origin server did not find a current representation for the target resource 
or is not willing to disclose that one exists. 

It used to work so nicely, and now I have the impression I have been changing 
quotes, commas, lines for four days without being able to replicate the nice 
setup for this to run.

Any suggestion will be greatly appreciated.

all best
Pietro

Re: Read-only wrapper for Jena Model

[Martynas Jusevičius]

Thanks Andy.

I want to resolve imports and run inferences and then wrap it to make it
immutable so it can be passed around but not modified. The getOntology()
method is being used so OntModel is preferred to plain Model.

On Mon, 20 Dec 2021 at 13.55, Andy Seaborne  wrote:

>
>
> On 18/12/2021 22:00, Martynas Jusevičius wrote:
> > Andy,
> >
> > A follow-up question: how would you create an immutable OntModel?
> >
> >  OntModel ontModel = ModelFactory.createOntologyModel(ontModelSpec,
> modelRO);
> >
> > Would the ontModel still be mutable?
>
> Don't know.
>
> And what do you want with regards to imports?
> Won't it depend on the OntModelSpec and any inference?
>
> You could always have a read-only wrapper implementation of interface
> OntModel.
>
>  Andy
>
> >
> > On Sat, Aug 28, 2021 at 3:43 PM Andy Seaborne  wrote:
> >>
> >>
> >>
> >> On 27/08/2021 12:23, Zak Mc Kracken wrote:
> >>> Hi all,
> >>>
> >>> I have a little RDF file (describing a dataset metadata), which I want
> >>> to read in an helper class and return as a read-only view on the file.
> >>> The reason to return it as read-only is that I also keep a simple cache
> >>> of uri/Object, which is a simplified view of RDF resources in the file,
> >>> so a modifiable Model would make it impossible to keep the two aligned.
> >>>
> >>> That said, I wonder if there is some read-only wrapper for the Jena's
> >>> Model interface, something similar to Collections.unmodifiableXXX(),
> >>> which of course, would be based on the decorator pattern, with
> >>> delegation to a base Model for most of the interface methods, except
> >>> interceptors for addXXX(), which would throw
> >>> UnsupportedOperationException. Would be easy to implement it, but I
> >>> don't like to reinvent wheels, if something like that already exists.
> >>
> >> Apparently there isn't one. Not sure why not.
> >>
> >> There is a read-only graph (and a read-only DatasetGraph) so one way to
> >> create a read-only model is:
> >>
> >>   Model model = ModelFactory.createDefaultModel();
> >>   Graph graphRO = new GraphReadOnly(model.getGraph());
> >>   Model modelRO = ModelFactory.createModelForGraph(graphRO);
> >>
> >> Graph is a narrower interface do catching things here is less code.  In
> >> fact, GraphBase is read-only unless add/delete(Triple) are overwritten.
> >>
> >>   Andy
> >>>
> >>> Thanks,
> >>> Marco.
> >>>
> >>>
>

How much can RDF graph scale

[emri mbiemri]

Dear all,

I am using RDF graphs for persisting my domain information, I am interested
to know if there is any study or experiment conducted so far that measures
the scalability of an RDF graph? I want to know if I can say that my
repository scales since it is RDF-based and why?  I have converted and
persisted so far about 1k models, it works well, but does it scale when I
have to cope with millions of models?

Thanks a lot.

Re: Read-only wrapper for Jena Model

[Andy Seaborne]

On 18/12/2021 22:00, Martynas Jusevičius wrote:

Andy,

A follow-up question: how would you create an immutable OntModel?

 OntModel ontModel = ModelFactory.createOntologyModel(ontModelSpec, 
modelRO);

Would the ontModel still be mutable?


Don't know.

And what do you want with regards to imports?
Won't it depend on the OntModelSpec and any inference?

You could always have a read-only wrapper implementation of interface 
OntModel.


Andy



On Sat, Aug 28, 2021 at 3:43 PM Andy Seaborne  wrote:




On 27/08/2021 12:23, Zak Mc Kracken wrote:

Hi all,

I have a little RDF file (describing a dataset metadata), which I want
to read in an helper class and return as a read-only view on the file.
The reason to return it as read-only is that I also keep a simple cache
of uri/Object, which is a simplified view of RDF resources in the file,
so a modifiable Model would make it impossible to keep the two aligned.

That said, I wonder if there is some read-only wrapper for the Jena's
Model interface, something similar to Collections.unmodifiableXXX(),
which of course, would be based on the decorator pattern, with
delegation to a base Model for most of the interface methods, except
interceptors for addXXX(), which would throw
UnsupportedOperationException. Would be easy to implement it, but I
don't like to reinvent wheels, if something like that already exists.


Apparently there isn't one. Not sure why not.

There is a read-only graph (and a read-only DatasetGraph) so one way to
create a read-only model is:

  Model model = ModelFactory.createDefaultModel();
  Graph graphRO = new GraphReadOnly(model.getGraph());
  Model modelRO = ModelFactory.createModelForGraph(graphRO);

Graph is a narrower interface do catching things here is less code.  In
fact, GraphBase is read-only unless add/delete(Triple) are overwritten.

  Andy


Thanks,
Marco.

Re: Convert JSON to RDF with Jena

[Martynas Jusevičius]

https://github.com/AtomGraph/JSON2RDF

On Mon, 20 Dec 2021 at 12.29, emri mbiemri 
wrote:

> Hello all,
>
> I would like to ask if there is any method to directly convert the below
> JSON file to an RDF graph? If so then how can I do it?
>
>
> https://github.com/iliriani/iliriangit/blob/master/CustomerForm.form%20(1).xml
>

Re: Convert JSON to RDF with Jena

[Andrii Berezovskyi]

Hello,

See https://rml.io/docs/rml/tutorials/json/. Not a direct method though.

/Andrew

On 2021-12-20, at 12:29, emri mbiemri 
mailto:emrimbiemri8...@gmail.com>> wrote:

Hello all,

I would like to ask if there is any method to directly convert the below
JSON file to an RDF graph? If so then how can I do it?

https://github.com/iliriani/iliriangit/blob/master/CustomerForm.form%20(1).xml

Convert JSON to RDF with Jena

[emri mbiemri]

Hello all,

I would like to ask if there is any method to directly convert the below
JSON file to an RDF graph? If so then how can I do it?

https://github.com/iliriani/iliriangit/blob/master/CustomerForm.form%20(1).xml