So - no one else on the users list wishes to add anything? - 2 of 2 people seem to think predetermined queries are a necessary function - any thoughts on whether this might end up as a Marmotta capability (module) , or at a minimum as a Use Case for Marmotta that should be articulated?
Should I take this to the dev list to see if any of the developer's have thought about this - or are you all represented here? Cheers Rob Atkinson On Wed, 17 Feb 2016 at 20:41 Rob Atkinson <r...@metalinkage.com.au> wrote: > > Actually - thats pretty much what I want - its the ad-hoc part of the LDA > API I eschewed - I really cant see how a user can form a meaningful ad-hoc > query (and this applies to SPARQL, SQL, WSDL and OGC spatial Web services) > without something providing metadata about what the information model is, > and how its populated. > > Parameterised queries (where annotations can be provided for the > parameters) seems to be a basic requirement and quite simple to build and > use - hence my probing here to see if its already in Marmotta (but not > immediately visible) - or in some roadmap or available third-party > extension. > > Rob > > On Wed, 17 Feb 2016 at 17:13 Robson, Alan <alan.rob...@viasat.com> wrote: > >> I meant to build a query by fetching a query template from LDP and >> enriching it with arguments from the GET parameters in the web service >> request. That process would involve just the little application I wrote >> accessing marmotta’s existing LDP API. >> >> What I put together is not a marmotta module and I don’t think it >> addresses your desire for a general purpose query API (in fact, it >> deliberately does not support ad-hoc queries, just pre-approved ones) >> >> >> >> Cheers >> >> >> >> Alan >> >> >> >> *From:* Rob Atkinson [mailto:r...@metalinkage.com.au] >> *Sent:* Tuesday, February 16, 2016 10:04 PM >> >> >> *To:* users@marmotta.apache.org >> *Subject:* Re: Support for RDF-shapes, Linked data API >> >> >> >> Do you mean 'to build a query if that functionality was available in a >> marmotta module'? Or am i missing something :-) >> >> >> >> On Wed, 17 Feb 2016 4:09 pm Robson, Alan <alan.rob...@viasat.com> wrote: >> >> Maybe the linked data caching feature of Marmotta will provide the >> federation necessary. >> >> Or perhaps one could use a single instance of marmotta to build a query >> and then send the query to a federation of endpoints using fed-x: >> http://www2.informatik.uni-freiburg.de/~mschmidt/docs/iswc11_fedx.pdf >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www2.informatik.uni-2Dfreiburg.de_-7Emschmidt_docs_iswc11-5Ffedx.pdf&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=R2jBNjzFDI8TFOPKdpk4qyIsnkrpWIAGHVAlc04_fWs&s=_eoMKuRMARivxGSiF3L2jFqO7rI6qOyU20s1Ozl8Pog&e=> >> >> >> >> >> >> Alan >> >> >> >> *From:* Rob Atkinson [mailto:r...@metalinkage.com.au] >> *Sent:* Tuesday, February 16, 2016 8:51 PM >> *To:* users@marmotta.apache.org >> *Subject:* Re: Support for RDF-shapes, Linked data API >> >> >> >> Thanks Alan >> >> >> >> this is indeed the sort of functionality I'm looking for. >> >> I have been using a subset of the functionality of the LinkedDataAPI - >> for which implementations exist (ELDA, Puelia) - against Sesame and >> Triplify backends. >> >> >> >> https://code.google.com/archive/p/linked-data-api/wikis/Specification.wiki >> <https://urldefense.proofpoint.com/v2/url?u=https-3A__code.google.com_archive_p_linked-2Ddata-2Dapi_wikis_Specification.wiki&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=YcjMBFlQEV1Twmm2_suPJX4D_RGWXZsWPCg8XTyQFW0&s=GMD14ltrtdU51q-8_cOeSZrcfTssDPt6nSulAGDzX5E&e=> >> >> >> >> LDA works nicely enough, modulo a few things >> >> >> >> There are a few issues with this: >> >> 1) it would be nice if the LDA spec was supported by a SDO >> >> 2) implementation was supported by a larger developer community >> >> 3) and it didnt mean a whole set of additional dependency wrangling for >> system requirements, imported components and licences - all of which would >> be solved if the equivalent functionality was in Marmotta :-) >> >> 4) it supported CONSTRUCT queries to transform statements inject default >> and calculated values into the result. >> >> 5) it supported querying over blank nodes (which we find all the time >> when there is an OWL model as part of the graph - and OWL is really useful >> for many things) >> >> 6) LDA itself could be factored into core and extensions >> >> >> >> Given Marmotta's modular architecture - a module with this functionality >> seems a fairly good fit. >> >> >> >> The main hurdle I see is that Marmotta is keen to bind to a single >> repository - whereas I specifically want to combine data from triple-stores >> and existing RDBMS environments. Decoupling APIs against separate SPARQL >> endpoints works fine for this. IMHO If the Marmotta build configured APIs >> by default against its configured SPARQL endpoint, but allowed additional >> APIs to be configured against alternative SPARQL endpoints then all would >> be bliss. >> >> >> >> Rob >> >> >> >> >> >> >> >> >> >> >> >> On Wed, 17 Feb 2016 at 13:33 Robson, Alan <alan.rob...@viasat.com> wrote: >> >> This may be way off base… >> >> >> >> I wrote a small java EE application that accepts a get request with >> parameters, it then searches for an RDF record in LDP that matches the name >> of the query, validates the parameters according to the instructions it >> finds in the RDF, formulates a SPARQL query then returns the results/errors. >> >> >> >> Here’s an example record representing an allowable query – I just made up >> the vocabulary… >> >> >> >> *@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema# >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.w3.org_2000_01_rdf-2Dschema-23&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=YcjMBFlQEV1Twmm2_suPJX4D_RGWXZsWPCg8XTyQFW0&s=PCyJ1Crd5ubX_3ZtYBPfC50412u_Qxn3e5VRbx6im9Y&e=>> >> .* >> >> *@prefix foaf: <http://xmlns.com/foaf/0.1/ >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__xmlns.com_foaf_0.1_&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=YcjMBFlQEV1Twmm2_suPJX4D_RGWXZsWPCg8XTyQFW0&s=kUU78ZVQ1QGo56Zx8Sp60brKF7U58hCnnxlaGMGbP9Q&e=>> >> .* >> >> *@prefix dlq: <http://unfortunate.name/2015/query# >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__unfortunate.name_2015_query-23&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=YcjMBFlQEV1Twmm2_suPJX4D_RGWXZsWPCg8XTyQFW0&s=FSy2Ot3Aks_NIVKd3OGX308BMB2XQuqArOiA1pv9RfU&e=>> >> .* >> >> >> >> *<> a dlq:sparqlQuery;* >> >> * rdfs:label "Returns a list of names of individuals who have attained >> the age of majority and hence are considered to be adults.";* >> >> * dlq:param [ dlq:paramName "majority"; dlq:dataType dlq:unsignedInt; >> dlq:maxValue "150"; dlq:defaultValue "18"; rdfs:label "age of majority" ];* >> >> * dlq:sparql "PREFIX foaf: <http://xmlns.com/foaf/0.1/ >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__xmlns.com_foaf_0.1_&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=YcjMBFlQEV1Twmm2_suPJX4D_RGWXZsWPCg8XTyQFW0&s=kUU78ZVQ1QGo56Zx8Sp60brKF7U58hCnnxlaGMGbP9Q&e=>> >> SELECT ?name WHERE {?i a foaf:Person . ?i foaf:name ?name . ?i foaf:age >> ?age . FILTER (?age >= majority)}"; .* >> >> >> >> I post the above ttl file to marmotta so that it can be found via LDP at: >> >> >> * http://ldp:8080/marmotta/ldp/QUERIES/findAdults >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__ldp-3A8080_marmotta_ldp_QUERIES_findAdults&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=R2jBNjzFDI8TFOPKdpk4qyIsnkrpWIAGHVAlc04_fWs&s=jr00Vl2x2DHWDYKUBdlNXM02wQ62ZoSTXx555YomGwQ&e=>* >> >> >> >> My SPARQL proxy sits on tomcat alongside marmotta and when it gets a >> query like: >> >> >> >> http://ldp:8080/proxy/Services/findAdults?majority=21 >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__ldp-3A8080_proxy_Services_findAdults-3Fmajority-3D21&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=YcjMBFlQEV1Twmm2_suPJX4D_RGWXZsWPCg8XTyQFW0&s=RnFLwo-2Gev42YD9-eJzs98OeUealDGZG2cH0uw5400&e=> >> >> >> >> It looks up the above record in LDP by appending findAdults to the path, >> then it validates the “majority” parameter and builds a SPARQL query, >> substituting in the parameter where it is named then executes it and >> returns the result (or of course an error message if anything is out of >> kilter) >> >> >> >> I also went ahead and added a few dummy records with people of various >> ages so that the SPARQL query had something to work with. >> >> >> >> Right now it only supports simple validations like integer ranges, but it >> could be extended to other types. >> >> >> >> I built it because while don’t mind users having SPARQL access in my dev >> environment, I want only canned queries in my production environment >> because I have seen how unfettered queries can bog down other databases. I >> was not so worried about security as performance. >> >> >> >> The only interfaces between marmotta and the query proxy are marmotta’s >> standard REST APIs, so the proxy need not be hosted on the same machine as >> marmotta. >> >> >> >> Is this along the lines of what you wanted ? >> >> >> >> Alan >> >> *From:* Rob Atkinson [mailto:r...@metalinkage.com.au] >> *Sent:* Monday, February 15, 2016 4:55 AM >> *To:* users@marmotta.apache.org >> *Subject:* Support for RDF-shapes, Linked data API >> >> >> >> Hi >> >> >> >> I am looking at linked data applications to add value to data exposed via >> Web Services, to add the missing semantics about the exposed content needed >> to actually discover and use those services. >> >> i need to be able to traverse graphs composed of things like VoiD, >> RDF-Datacube etc. >> >> The RDF-shapes scope covers this, and there are some elements of Marmotta >> such as LDPath that are relevant. I've previously built the functionality I >> needed using the LinkedDataAPI ( >> https://github.com/UKGovLD/linked-data-api >> <https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_UKGovLD_linked-2Ddata-2Dapi&d=BQMFaQ&c=jcv3orpCsv7C4ly8-ubDob57ycZ4jvhoYZNDBA06fPk&r=xN9AnMDZvO_QvUZQZcoply6WFqSJuNcpv-dDu2fA4Ac&m=sJnASXMUIR0ucnEHlcG3kM1GZ5TFHlhGyAhkYT45qfY&s=StoV4m3FfnN5m7Y1JgL1aSFxde0mEhsWqxXB6i_H-FA&e=> >> ). >> >> Is there anything in Marmotta to support parameterised SPARQL queries >> accessed via URL based APIs, and building a response by traversing paths >> from the query results? (i've looked but not found anything - any pointers >> to descriptions of the marnotta core would be helpful!) >> >> >> >> Regards >> >> Rob Atkinson >> >>
