Re: Example code

[John A. Fereira]

When developing a UI with a SQL database, if the developer is using an MVC 
pattern, they’re not sending SQL statements to the server and iterating over 
the result set.  Instead, they’re making a request to the server such as 
“getPersonList” and the business logic on the server side is constructing the 
query to the database,  maps the result set to a list of objects (which might 
be in JSON) , and returning those objects to the UI for display.  That really 
isn’t any different when an application has a triple store on the back end 
except that the business logic is running SPARQL (or accessing the data model 
directly) instead of SQL.

With that in mind,  there is a robust example page here 
(http://jena.apache.org/tutorials/rdf_api.html) which provides examples for how 
to read  or write RDF (and much more).  When reading RDF, instead of writing 
the results to standard out, transforming them to objects, then sending them to 
a UI is no different from how one might do it with  a SQL database on the back 
end. 



On 3/20/18, 7:11 AM, "David Moss"  wrote:



On 19/3/18, 9:59 pm, "Laura Morales"  wrote:

>TBH I think you're writing to the wrong mailing list. You should write 
to the  mailing list, and ask them to provide example 
code to use the UI with a Fuseki>backend instead of MySQL.

The UI people would, quite rightly, point to any number of examples of 
people using SQL or other custom means of getting information into their 
components.
Then they would tell me to go to the mailing list for the exotic framework 
I'm interested on promoting and ask the users to contribute some example code.

Which is what I have done.
The answer seems to be that there isn't any. I can live with that. If I 
find the time I'll write some.
Then the people in this group can laugh at my efforts and write better 
examples!

DM

Sent: Monday, March 19, 2018 at 12:33 PM
From: "David Moss" 
To: users@jena.apache.org
Subject: Re: Example code

On 19/3/18, 5:39 pm, "Lorenz Buehmann" 
 wrote:

>Well, isn't that the task of the UI logic? You get JSON-LD and now you
>can visualize it. I don't really see the problem here?

Therein lies the problem. I'm sure _you_ know how to do it.
How does someone without experience in integrating Jena with UI know 
how to do it?

>dataset -> query -> data -> visualization (table, graph, etc.)

Those are indeed a set of steps. Do you have an example of how to do 
that in java code and load the result into a combobox for selection in a UI?

>Why should this be an example on the Apache Jena documentation?

It shouldn't. It should be stored separately from the Apache Jena 
documentation.
The Javadoc is for how Jena works internally and how to maintain Jena 
itself.
I'm talking about examples to help people use Jena in the kind of 
applications people want to use.

One of the dilemmas I have regarding Jena is how to store query results 
locally.
I could use Jena to query an endpoint, iterate through the ResultSet 
and build POJOs or Tables.
Or is it better to keep the results in a Model and query that again to 
build UI components?
Or maybe I should ditch the fancy Jena objects and just get a result as 
a JSON object and work with that?

These are all possibilities, but how is it actually being done in real 
projects? Where are the examples?

A reply like "dataset -> query -> data -> visualization (table, graph, 
etc.)" is very glib, but it doesn't actually have anything in the way of 
example code that can be used by people new to Jena in their own real-world 
programs. That is what I see as missing.


DM












On 19.03.2018 08:31, David Moss wrote:
> That is certainly a way to get data from a SPARQL endpoint to display 
in a terminal window.
> It does not store it locally or put it into a user-friendly GUI 
control however.
> Looks like I might have to roll my own and face the music publicly if 
I'm doing it wrong.
>
> I think real-world examples of how to use Jena in a user friendly 
program are essential to advancing the semantic web.
> Thanks for considering my question.
>
> DM
>
> On 19/3/18, 4:19 pm, "Laura Morales"  wrote:
>
> As far as I know the only way to query a Jena remotely is via HTTP. 
So, install Fuseki and then send a traditional HTTP GET/POST request to it with 
two parameters, "query" and "format". For example
>
> 

Re: Splitting data into graphs vs datasets

[Martynas Jusevičius]

Provenance. With named graphs, it's easier to track where data came from:
who imported it, when etc.
You can also have meta-graphs about other graphs.

Also editing and updating data. You can load named graph contents (of
smallish size) in an editor, make changes and then store a new version in
the same graph. You probably would not want to do this with a large default
graph.

On Tue, Mar 20, 2018 at 1:16 PM, Mikael Pesonen 
wrote:

>
> Hi,
>
> I'm using Fuseki GSP, and so far have put all data into one default
> dataset and using graphs to split it.
>
> If I'm right there would be benefits using more than one dataset
> - better performance - each query is done inside a dataset so less data =
> faster query
> - protection of data - can't "accidentaly" query data from other datasets
> Downsides:
> - combining data from various datasets is heavier task
>
> Is this correct? Any other things that should be considered?
>
> Thank you
>
> --
> Lingsoft - 30 years of Leading Language Management
>
> www.lingsoft.fi
>
> Speech Applications - Language Management - Translation - Reader's and
> Writer's Tools - Text Tools - E-books and M-books
>
> Mikael Pesonen
> System Engineer
>
> e-mail: mikael.peso...@lingsoft.fi
> Tel. +358 2 279 3300
>
> Time zone: GMT+2
>
> Helsinki Office
> Eteläranta 10
> 
> FI-00130 Helsinki
> FINLAND
>
> Turku Office
> Kauppiaskatu 5 A
> 
> FI-20100 Turku
> FINLAND
>
>

Splitting data into graphs vs datasets

[Mikael Pesonen]

Hi,

I'm using Fuseki GSP, and so far have put all data into one default 
dataset and using graphs to split it.


If I'm right there would be benefits using more than one dataset
- better performance - each query is done inside a dataset so less data 
= faster query

- protection of data - can't "accidentaly" query data from other datasets
Downsides:
- combining data from various datasets is heavier task

Is this correct? Any other things that should be considered?

Thank you

--
Lingsoft - 30 years of Leading Language Management

www.lingsoft.fi

Speech Applications - Language Management - Translation - Reader's and Writer's 
Tools - Text Tools - E-books and M-books

Mikael Pesonen
System Engineer

e-mail: mikael.peso...@lingsoft.fi
Tel. +358 2 279 3300

Time zone: GMT+2

Helsinki Office
Eteläranta 10
FI-00130 Helsinki
FINLAND

Turku Office
Kauppiaskatu 5 A
FI-20100 Turku
FINLAND

Re: Example code

[Martynas Jusevičius]

David,

the actual UI rendering is done not by Java but by XSLT stylesheets that
render RDF/XML:
https://github.com/AtomGraph/Web-Client/blob/master/src/main/webapp/static/com/atomgraph/client/xsl/bootstrap/2.3.2/layout.xsl

The stylesheet is invoked by the ModelXSLTWriter provider I mentioned
earlier.

On Tue, Mar 20, 2018 at 12:22 PM, David Moss  wrote:

>
>
> On 19/3/18, 9:40 pm, "Martynas Jusevičius" 
> wrote:
>
> David,
>
> >I gave you links but I take you haven't looked. The Web-Client project
>> specifically renders RDF as HTML. The crucial class is this:
>> https://github.com/AtomGraph/Web-Client/blob/master/src/
> main/java/com/atomgraph/client/writer/ModelXSLTWriter.java
>
> Actually, I have looked. The code you mentioned is over 400 lines long and
> I can't see a UI component in it.
> I have to admire your self-documenting coding style, but it is not the
> easy to follow example I was looking for.
>
>> If you are looking to write generic software, you definitely want to
> render
>>Model and not ResultSet. With ResultSet you only get a plain old table,
>> with all the graph relationships stripped away.
>
> I've suspected as much. By iterating over ResultSet I may as well use a
> relational database instead of a semantic model.
> It is frustrating! I know intuitively using a semantic model is richer but
> without examples I'm reinventing a wheel that took teams of smarter people
> than me years to invent the first time.
>
> >It also helps to think about the UI as a function of the data. HTML
> webpage
> >is just one more transformation applied to the Linked Data RDF
> description.
>
> Again, easy to say. Probably easy for YOU to do. Bet where are the easy to
> follow example code in small enough bites for the beginner to follow?
>
> I'm pretty much resigned to there not being any. I will try to write some.
>
> DM
>
>
>
> On Mon, Mar 19, 2018 at 12:33 PM, David Moss 
> wrote:
>
> >
> >
> > On 19/3/18, 5:39 pm, "Lorenz Buehmann"  > leipzig.de> wrote:
> >
> > >Well, isn't that the task of the UI logic? You get JSON-LD and
> now you
> > >can visualize it. I don't really see the problem here?
> >
> > Therein lies the problem. I'm sure _you_ know how to do it.
> > How does someone without experience in integrating Jena with UI know
> how
> > to do it?
> >
> > >dataset -> query -> data -> visualization (table, graph, etc.)
> >
> > Those are indeed a set of steps. Do you have an example of how to do
> that
> > in java code and load the result into a combobox for selection in a
> UI?
> >
> > >Why should this be an example on the Apache Jena documentation?
> >
> > It shouldn't. It should be stored separately from the Apache Jena
> > documentation.
> > The Javadoc is for how Jena works internally and how to maintain Jena
> > itself.
> > I'm talking about examples to help people use Jena in the kind of
> > applications people want to use.
> >
> > One of the dilemmas I have regarding Jena is how to store query
> results
> > locally.
> > I could use Jena to query an endpoint, iterate through the ResultSet
> and
> > build POJOs or Tables.
> > Or is it better to keep the results in a Model and query that again
> to
> > build UI components?
> > Or maybe I should ditch the fancy Jena objects and just get a result
> as a
> > JSON object and work with that?
> >
> > These are all possibilities, but how is it actually being done in
> real
> > projects? Where are the examples?
> >
> > A reply like "dataset -> query -> data -> visualization (table,
> graph,
> > etc.)"  is very glib, but it doesn't actually have anything in the
> way of
> > example code that can be used by people new to Jena in their own
> real-world
> > programs. That is what I see as missing.
> >
> >
> > DM
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > On 19.03.2018 08:31, David Moss wrote:
> > > That is certainly a way to get data from a SPARQL endpoint to
> > display in a terminal window.
> > > It does not store it locally or put it into a user-friendly GUI
> > control however.
> > > Looks like I might have to roll my own and face the music
> publicly
> > if I'm doing it wrong.
> > >
> > > I think real-world examples of how to use Jena in a user
> friendly
> > program are essential to advancing the semantic web.
> > > Thanks for considering my question.
> > >
> > > DM
> > >
> > > On 19/3/18, 4:19 pm, "Laura Morales" 
> wrote:
> > >
> > > As far as I know the only way to query a Jena remotely is
> via
> > HTTP. So, install Fuseki 

Re: Example code

[David Moss]

On 19/3/18, 9:40 pm, "Martynas Jusevičius"  wrote:

David,

>I gave you links but I take you haven't looked. The Web-Client project
   > specifically renders RDF as HTML. The crucial class is this:
   > 
https://github.com/AtomGraph/Web-Client/blob/master/src/main/java/com/atomgraph/client/writer/ModelXSLTWriter.java

Actually, I have looked. The code you mentioned is over 400 lines long and I 
can't see a UI component in it.
I have to admire your self-documenting coding style, but it is not the easy to 
follow example I was looking for.

   > If you are looking to write generic software, you definitely want to render
   >Model and not ResultSet. With ResultSet you only get a plain old table,
   > with all the graph relationships stripped away.

I've suspected as much. By iterating over ResultSet I may as well use a 
relational database instead of a semantic model.
It is frustrating! I know intuitively using a semantic model is richer but 
without examples I'm reinventing a wheel that took teams of smarter people than 
me years to invent the first time.

>It also helps to think about the UI as a function of the data. HTML webpage
>is just one more transformation applied to the Linked Data RDF description.

Again, easy to say. Probably easy for YOU to do. Bet where are the easy to 
follow example code in small enough bites for the beginner to follow?

I'm pretty much resigned to there not being any. I will try to write some.

DM



On Mon, Mar 19, 2018 at 12:33 PM, David Moss  wrote:

>
>
> On 19/3/18, 5:39 pm, "Lorenz Buehmann"  leipzig.de> wrote:
>
> >Well, isn't that the task of the UI logic? You get JSON-LD and now 
you
> >can visualize it. I don't really see the problem here?
>
> Therein lies the problem. I'm sure _you_ know how to do it.
> How does someone without experience in integrating Jena with UI know how
> to do it?
>
> >dataset -> query -> data -> visualization (table, graph, etc.)
>
> Those are indeed a set of steps. Do you have an example of how to do that
> in java code and load the result into a combobox for selection in a UI?
>
> >Why should this be an example on the Apache Jena documentation?
>
> It shouldn't. It should be stored separately from the Apache Jena
> documentation.
> The Javadoc is for how Jena works internally and how to maintain Jena
> itself.
> I'm talking about examples to help people use Jena in the kind of
> applications people want to use.
>
> One of the dilemmas I have regarding Jena is how to store query results
> locally.
> I could use Jena to query an endpoint, iterate through the ResultSet and
> build POJOs or Tables.
> Or is it better to keep the results in a Model and query that again to
> build UI components?
> Or maybe I should ditch the fancy Jena objects and just get a result as a
> JSON object and work with that?
>
> These are all possibilities, but how is it actually being done in real
> projects? Where are the examples?
>
> A reply like "dataset -> query -> data -> visualization (table, graph,
> etc.)"  is very glib, but it doesn't actually have anything in the way of
> example code that can be used by people new to Jena in their own 
real-world
> programs. That is what I see as missing.
>
>
> DM
>
>
>
>
>
>
>
>
>
>
>
>
> On 19.03.2018 08:31, David Moss wrote:
> > That is certainly a way to get data from a SPARQL endpoint to
> display in a terminal window.
> > It does not store it locally or put it into a user-friendly GUI
> control however.
> > Looks like I might have to roll my own and face the music publicly
> if I'm doing it wrong.
> >
> > I think real-world examples of how to use Jena in a user friendly
> program are essential to advancing the semantic web.
> > Thanks for considering my question.
> >
> > DM
> >
> > On 19/3/18, 4:19 pm, "Laura Morales"  wrote:
> >
> > As far as I know the only way to query a Jena remotely is via
> HTTP. So, install Fuseki and then send a traditional HTTP GET/POST request
> to it with two parameters, "query" and "format". For example
> >
> > $ curl --data "format=json=..." http://your-endpoint.org
> >
> >
> >
> > Sent: Sunday, March 18, 2018 at 11:26 PM
> > From: "David Moss" 
> > To: users@jena.apache.org
> > Subject: Re: Example code
> >
> > On 18/3/18, 6:24 pm, "Laura Morales"  wrote:
> >
> > >> For example, when using data from a SPARQL 

Re: Example code

[David Moss]

On 19/3/18, 9:59 pm, "Laura Morales"  wrote:

>TBH I think you're writing to the wrong mailing list. You should write to 
the  mailing list, and ask them to provide example 
code to use the UI with a Fuseki>backend instead of MySQL.

The UI people would, quite rightly, point to any number of examples of people 
using SQL or other custom means of getting information into their components.
Then they would tell me to go to the mailing list for the exotic framework I'm 
interested on promoting and ask the users to contribute some example code.

Which is what I have done.
The answer seems to be that there isn't any. I can live with that. If I find 
the time I'll write some.
Then the people in this group can laugh at my efforts and write better examples!

DM

Sent: Monday, March 19, 2018 at 12:33 PM
From: "David Moss" 
To: users@jena.apache.org
Subject: Re: Example code

On 19/3/18, 5:39 pm, "Lorenz Buehmann" 
 wrote:

>Well, isn't that the task of the UI logic? You get JSON-LD and now you
>can visualize it. I don't really see the problem here?

Therein lies the problem. I'm sure _you_ know how to do it.
How does someone without experience in integrating Jena with UI know how to 
do it?

>dataset -> query -> data -> visualization (table, graph, etc.)

Those are indeed a set of steps. Do you have an example of how to do that 
in java code and load the result into a combobox for selection in a UI?

>Why should this be an example on the Apache Jena documentation?

It shouldn't. It should be stored separately from the Apache Jena 
documentation.
The Javadoc is for how Jena works internally and how to maintain Jena 
itself.
I'm talking about examples to help people use Jena in the kind of 
applications people want to use.

One of the dilemmas I have regarding Jena is how to store query results 
locally.
I could use Jena to query an endpoint, iterate through the ResultSet and 
build POJOs or Tables.
Or is it better to keep the results in a Model and query that again to 
build UI components?
Or maybe I should ditch the fancy Jena objects and just get a result as a 
JSON object and work with that?

These are all possibilities, but how is it actually being done in real 
projects? Where are the examples?

A reply like "dataset -> query -> data -> visualization (table, graph, 
etc.)" is very glib, but it doesn't actually have anything in the way of 
example code that can be used by people new to Jena in their own real-world 
programs. That is what I see as missing.


DM












On 19.03.2018 08:31, David Moss wrote:
> That is certainly a way to get data from a SPARQL endpoint to display in 
a terminal window.
> It does not store it locally or put it into a user-friendly GUI control 
however.
> Looks like I might have to roll my own and face the music publicly if I'm 
doing it wrong.
>
> I think real-world examples of how to use Jena in a user friendly program 
are essential to advancing the semantic web.
> Thanks for considering my question.
>
> DM
>
> On 19/3/18, 4:19 pm, "Laura Morales"  wrote:
>
> As far as I know the only way to query a Jena remotely is via HTTP. So, 
install Fuseki and then send a traditional HTTP GET/POST request to it with two 
parameters, "query" and "format". For example
>
> $ curl --data "format=json=..." http://your-endpoint.org
>
>
>
> Sent: Sunday, March 18, 2018 at 11:26 PM
> From: "David Moss" 
> To: users@jena.apache.org
> Subject: Re: Example code
>
> On 18/3/18, 6:24 pm, "Laura Morales"  wrote:
>
> >> For example, when using data from a SPARQL endpoint, what is the 
accepted
> >> way to retrieve it, store it locally and make it available through user
> >> interface controls?
>
> >Make a query that returns a jsonld document.
>
> How? Do you have some example code showing how this query is retrieved, 
dealt with locally and made available to an end user through a GUI control?
> What I am looking for here is a bridge between what experts glean from 
reading Javadoc and what ordinary people need to use Jena within a GUI based 
application.
>
> I see this kind of example as the missing link that prevents anyone other 
than expert using Jena.
> So long as easy to follow examples of how to get from an rdf triplestore 
to information displayed on a screen in a standard GUI way are missing, Jena 
will remain a plaything for expert enthusiasts.
>
> DM
>
>
>
>
>
>
>
>
>
>
>
>
>