Hi Andy,
Thank for your comments! I can understand your idea of A/ B/ C/. But
there'a problem in practice.
In brief:
For A/, at the server side, always call
QueryExecutionBase::execConstructDataset()
For B/, the problem is, there're overlaps between DEF.rdfOffer and
DEF.quadsOffer, e.g. TriX, TriXxml and JSONLD.
For C/, e.g. if the Accept lang is JSONLD, which should be written out
by RDFDataMgr, model or dataset? Note that, the server side doesn't
know which it's called from the client side,
QueryEngineHTTP::exeConstructTriples() or exeConstructQuads().
Also at the client side, if
QueryEngineHTTP::exeConstructTriples()/exeConstructQuads() gets the
content type of, e.g. JSONLD, it doesn't know whether it is a model or
dataset.
So, that's why I introduce the DEF.pureRdfOffer to distinguish the
triple format that is not a quad format. In my way, both the sever
side and the client side separate model and dataset. It's kind of ugly
in code. Any more suggestion?
regards,
Qihong
On Mon, Aug 17, 2015 at 10:49 PM, Andy Seaborne <a...@apache.org> wrote:
> Thanks for the clarification. I had made a combined version to start
> testing and hopefully it's a close approximation of the intended
> deliverables.
>
> [ Ying - how's your testing going? ]
>
> A few things about the pull requests so far:
>
> 0/ More tests in TestQuery in Fuseki:
>
> For example, this should show up:
>
> 1/ QueryEngineHttp.execConstructDataset is not implemented.
>
>
> 2/ SPARQL_Query:
>
> This line
>
> if ( ! rdfMediaType.getType().equals("*") ) {
>
> means that only "Accept: *" will trigger dataset results.
>
> then in ResponseDataset
>
> MediaType i = ConNeg.chooseContentType(request, DEF.quadsOffer,
> DEF.acceptNQuads) ;
>
> will always choose TriG because the accept is "*" ("output=" works but that
> is overriding content negotiation).
>
> There is no way to ask for a specific syntax (n-quads, trig, JSON-LD) using
> "Accept:"
>
> e.g. "Accept: application/n-quads"
>
>
> 3/ ResponseDataset is copy of ResponseModel yet the only differences (after
> reformatting) are different data values and
>
> < RDFDataMgr.write(out, dataset, lang) ;
> ---
> > RDFDataMgr.write(out, model, lang) ;
>
> It is not good to have copied code because it makes maintenance harder.
>
>
>
> (2) and (3) can be addressed by
>
> A/ SPARQL_Query:
>
> For CONSTRUCT, always work in datasets; execConstructDataset().
> No need for mention of Models. if it's a triples CONSTRUCT, treating as a
> dataset will simply put the results in to the default graph.
>
> QueryExecutionBase::execConstructQuads
>
> Following on from that, treating datasets as a natural extension of models.
> There is no need to test for extended syntax. If it's strict SPARQL 1.1, a
> dataset will just have only a default graph.
>
>
> B/ Content negotiate for a combined DEF.rdfOffer+DEF.quadsOffer (I don't
> underatand DEF.pureRdfOffer -- N-triples is a standard).
>
> C/ If it's a triple format (test the Lang),
>
> RDFDataMgr.write(out, dataset.getDefaultModel(), lang) ;
> otherwise:
> RDFDataMgr.write(out, dataset, lang) ;
>
>
> Andy
