You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@marmotta.apache.org by Paul Danckaert <pa...@tacticaledge.us> on 2014/09/23 17:52:47 UTC

LDClient Questions

Hello,

Marmotta looks like a really interesting application, and I'm testing it to get more familiar with it's functions.  One area that looks appealing to me is the LDClient capabilities, and it's ability to allow me to merge other external data into the linked data platform.  As far as I understand it, I should be able to implement my own modules and data providers that would allow me to expose or integrate arbitrary data sources into the system.  I was looking at building a test LDClient that retrieved data from an underlying SQL database, and would this be a reasonable route to take?

Are there limitations on the following of relationships between data elements when some is stored locally in the triple store, and some is provided through the external providers?

Also, are there any tutorials on the implementation or usage of the linked data clients?  

Thanks for all of your help, 

paul

Re: LDClient Questions

Posted by Paul Danckaert <pa...@tacticaledge.us>.
Hello Jakob,

Thanks for the feedback, it's certainly helpful.  I don't think the limitations you mention are too much of a problem, especially given the benefits gained.

When I look at the LDAP provider, I can see the direct retrieval by subject/user, so in this case I wouldn't be able to generate a query to search via some other attribute, is that correct?  So based on that, and the following ldif excerpt:

dn: uid=tester,ou=People,dc=example,dc=com
objectClass: person
objectClass: inetOrgPerson
objectClass: organizationalPerson
objectClass: top
uid: tester
givenname: Bob
cn: Bob Tester
sn: Tester
mail: tester@example.com<ma...@example.com>
ou: Testers
ou: People
uidNumber: 1000
gidNumber: 100

I would be able to do a SPARQL query on the individual's exact account, and would not be able to search on attributes, for example find all users in a particular OU, or search by email address instead of DN.

Is there any mechanism to allow for expanded searching on the remote data, while still allowing it to be transparently resident in the system in a way that LDClient provides?  It seems like the data would need to be actually propagated into the local triple store in order to perform more complex query sorts of operations.

Thanks for the information, and taking the time to help.

paul


On Sep 24, 2014, at 8:24 AM, Jakob Frank <ja...@salzburgresearch.at>> wrote:

Hi Paul,

On 2014-09-23 17:52, Paul Danckaert wrote:
Marmotta looks like a really interesting application, and I'm testing
it to get more familiar with it's functions.  One area that looks
appealing to me is the LDClient capabilities, and it's ability to
allow me to merge other external data into the linked data platform.
As far as I understand it, I should be able to implement my own
modules and data providers that would allow me to expose or integrate
arbitrary data sources into the system.  I was looking at building a
test LDClient that retrieved data from an underlying SQL database,
and would this be a reasonable route to take?
That's exactly what LDClient was meant for

Are there limitations on the following of relationships between data
elements when some is stored locally in the triple store, and some is
provided through the external providers?
In combination with LDCache, triples from LDClient are stored in the
local triple store (in a separated context).

The main limitation here is, that LDClient and LDCache work resource
based. So automatically fetching data for resources will only work for
resources kiwi can identify (e.g. ?s ?p ?o patterns for known ?s).

Also, the native sparql implementation (evaluating SPARQL queries
directly on the database for improved perfomance) will not work in
combination with LDCache, because the native implementation bypasses the
Sesame Stack.

Also, are there any tutorials on the implementation or usage of the
linked data clients?
Best starting point IMHO is the source code one of the ldclient
providers shipped with marmotta, e.g. the ldap provider
(ldclient-provider-ldap)

Best,
Jakob

--
DI Jakob Frank
Knowledge and Media Technologies

Salzburg Research Forschungsgesellschaft mbH
Jakob Haringer-Strasse 5/3 | 5020 Salzburg, Austria
T: +43.662.2288-419 | F: +43.662.2288-222
jakob.frank@salzburgresearch.at<ma...@salzburgresearch.at>
http://www.salzburgresearch.at
http://at.linkedin.com/in/jakobfrank

Re: LDClient Questions

Posted by Jakob Frank <ja...@salzburgresearch.at>.
Hi Paul,

On 2014-09-23 17:52, Paul Danckaert wrote:
> Marmotta looks like a really interesting application, and I'm testing
> it to get more familiar with it's functions.  One area that looks
> appealing to me is the LDClient capabilities, and it's ability to
> allow me to merge other external data into the linked data platform.
> As far as I understand it, I should be able to implement my own
> modules and data providers that would allow me to expose or integrate
> arbitrary data sources into the system.  I was looking at building a
> test LDClient that retrieved data from an underlying SQL database,
> and would this be a reasonable route to take?
That's exactly what LDClient was meant for

> Are there limitations on the following of relationships between data
> elements when some is stored locally in the triple store, and some is
> provided through the external providers?
In combination with LDCache, triples from LDClient are stored in the
local triple store (in a separated context).

The main limitation here is, that LDClient and LDCache work resource
based. So automatically fetching data for resources will only work for
resources kiwi can identify (e.g. ?s ?p ?o patterns for known ?s).

Also, the native sparql implementation (evaluating SPARQL queries
directly on the database for improved perfomance) will not work in
combination with LDCache, because the native implementation bypasses the
Sesame Stack.

> Also, are there any tutorials on the implementation or usage of the
> linked data clients?
Best starting point IMHO is the source code one of the ldclient
providers shipped with marmotta, e.g. the ldap provider
(ldclient-provider-ldap)

Best,
Jakob

-- 
DI Jakob Frank
Knowledge and Media Technologies

Salzburg Research Forschungsgesellschaft mbH
Jakob Haringer-Strasse 5/3 | 5020 Salzburg, Austria
T: +43.662.2288-419 | F: +43.662.2288-222
jakob.frank@salzburgresearch.at
http://www.salzburgresearch.at
http://at.linkedin.com/in/jakobfrank