Rép. : Marmotta 3.2.1 - Having problem to trigger the LDCache

[Fabian Cretton <Fa...@hevs.ch>]

One more information.
Today I tried from scratch, reinstalling Marmotta, creating the end-point from the load sample.
And then querying "http://dbpedia.org/resource/Europe" with LDPath.
 
LDPath result was: resource http://dbpedia.org/resource/Europe does not exist
 
But I had one error message in the console:

07:38:52.962 ERROR - the HTTP request failed (status: HTTP/1.1 406 Unacceptable)
07:38:52.963 ERROR - HTTP client error while trying to retrieve resource http://dbpedia.org/resource/Europe: the HTTP request failed (status: HTTP/1.1 406 Unacceptable)
 
After that I tried again, but this message didn't come up again.
 
I don't think it comes from some firewall settings we have internally, but I'll check about that.
 
Thank you for any help
Fabian
 
 

>>> "Fabian Cretton" <Fa...@hevs.ch> 08.09.2014 15:50 >>>
Hi,
 
Today I tried without success to setup the LDCache from the Marmotta interface.
 
A first thing is that it is not clearly stated, in my opinion, when the LDCache is triggered.
 
The only further information I found was here:
http://markmail.org/message/m3ft65du5kbuzy5z#query:+page:1+mid:j347sjyegwshvhc7+state:results
and thus I understood that the SPARQL interface don't interact with LDCache, but the LDPath functionality does.
Is there anything else then running a LPath that would trigger the cache ?
 
First of all, I see this error when launching Marmotta 3.2.1, could it be related to my problems ?
INFO: Server startup in 11332 ms
15:25:45.495 WARN  - pattern (C:\marmotta_inst\marmotta-home/resources|http://wh55650:8080/marmotta/resource/|urn:).* is not a valid regular expression; disabling reader/writer filesystem (message was Illegal/unsupported escape sequence near index 4
(C:\marmotta_inst\marmotta-home/resources|http://wh55650:8080/marmotta/resource/|urn:).*    ^)
 
My "ldcache.enabled" parameter is checked.
 
I guess my problem is with setting up the end-point correctly.
 
I first tried the provided sample "load sample -> dbpedia", which gives in the interface:
kind: ld cache
Prefix: http://dbpedia\.org.*
Endpoint: http://dbpedia.org/sparql
 
But a few things are already not clear for me:
* kind: ld cache
When referring to a sparql end-point, shouldn't the kind be "sparkl" ? (I did try changing this, but with no success)
By the way, what is the meaning of the "cache" mode, I can't understand from reading the explanation. Is it a server that servers "linked data" ? if so, what is the difference with "linked data".
* prefix: 
What are the "rules" to define those prefixes ? for instance I see in the example that "." are escaped ?
Defining a prefix as "http://dbpedia\.org ( http://dbpedia/.org ).*" will thus mean that a URI as http://dbpedia.org/resource/Europe is bound to that end-point, right ?
*endpoint:
The explanation says that for a SPARQL end-point, some parameters have to be specified:
"http://sparql.sindice.com/sparql?default-graph-uri=&query={query}&format={contenttype}"
Is this mandatory ? (as the provided sample don't specify them but just specifies "http://dbpedia.org/sparql"), are there default values ?
*mimetype:
Not filled by the sample, are their default values depending on the "mode of operation" ?
 
If it is possible to get a few full examples of those settings, for the different operation modes, it would be very helpful I guess.
 
Than, after trying different configurations, I tried from the LDPath interface to add the URI "http://dbpedia.org/resource/Europe" and the LDPath "rdfs:label :: xsd:string".
When hitting "Test", a message appears next to the button: resource http://dbpedia.org/resource/Europe does not exist.
 
It seems I don't see any corresponding message neither in the console nor in the marmotta-main.log.
 
I tried so many different configurations, on different SPARQL end-point, also trying a "linked data" as DBPedia does provide the content negociation mecanism,  but without success.
 
Finally I tried to run a:

curl http://wh55650:8080/marmotta/cache/live?uri=http://dbpedia.org/resource/Europe
and it did return the rdf/xml file. But what I discovered then is that even without configuring any 'end-point' in Marmotta, this command was succeeding every time, so I think this command is not a sign that my end-point is well configured ? Except maybe if I was dealing with data that are not provided as derefencable "linked data" ?
I also tried on my local version 3.3.0, but with the same results. And also with the same WARNING when starting Marmotta.
Thank you for any help.
Fabian