[jira] [Commented] (JENA-1378) RDFDataMgr does not perform conneg when reading remote RDF resources

["Andy Seaborne (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-1378?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16102355#comment-16102355 ] 

Andy Seaborne commented on JENA-1378:
-------------------------------------

Yes, but it is a bit more complicated to fix :-)

The HTTP accept header is client settable via {{RDFParserBuilder.httpAccept}} in which case it becomes part of the {{HttpClient}}.

But as I read the code, if {{execHttpGet}} has a non-null accept string (the default should be {{WebContent.defaultRDFAcceptHeader}}), it will override the custom HttpClient default settings which is how the application set header got in.

This works for me:
{noformat}
        Graph g = GraphFactory.createDefaultGraph();
        StreamRDF dest = StreamRDFLib.graph(g);
        RDFParser.create().source("http://purl.org/dc/terms/")
            .httpAccept("text/turtle")
            .parse(dest);
        RDFDataMgr.write(System.out, g, Lang.TTL);
{noformat}

Comment out "httpAccept()" and it fails.


> RDFDataMgr does not perform conneg when reading remote RDF resources
> --------------------------------------------------------------------
>
>                 Key: JENA-1378
>                 URL: https://issues.apache.org/jira/browse/JENA-1378
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: ARQ
>    Affects Versions: Jena 3.4.0
>            Reporter: Aaron Coburn
>
> In the past, I have been able to use RDFDataMgr.read(Graph, String) to fetch vocabularies like so:
> final Graph graph = Factory.createDefaultGraph();
> RDFDataMgr.read(graph, "http://purl.org/dc/terms");
> This no longer works in 3.4.0. The error is:
>      org.apache.jena.riot.RiotException: Failed to determine the content type: (URI=http://purl.org/dc/terms/ : stream=text/html)
> The key thing about these remote resources is that they involve content negotiation in order to get to the RDF serialization; otherwise an HTML page is returned that cannot be parsed by RIOT.
> Adding a Lang attribute to the read() function does not help.
> This appears to be due to the RDFParser library not including an Accept header in the HTTP request to the remote resource: https://git.io/v7sTV
> Perhaps a good solution would be to provide a default accept header ("text/turtle, application/rdf+xml, application/ld+json") or, even better, that accept header could be configurable by a client.
> A work-around for me is to just use the HttpOp.execHttpGet function directly, but it would be nice if this functioned as it once did.



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