Absolute context is made relative

[whikloj]

I'll say up front that my Json-LD spec fluency is not strong. Anyways...

We are using opaque IRI IDs internally and transforming them to URIs when returned to users to avoid storing hostnames.

It appears like the changes (perhaps in response to #232) is causing us some trouble.

I wrote a small class based on the area of Jena that seemed to be failing.
https://gist.github.com/whikloj/29f61a883dd14cb0cf17e2f292621957

My two tests are as follows.

With regular URI as the it works

> java -jar build/libs/JsonLdTest-1.0-SNAPSHOT-all.jar 'http://fedora/jared' '{ "@context": "https://json-ld.org/contexts/person.jsonld", "@id": "http://dbpedia.org/resource/John_Lennon", "name": "John Lennon", "born": "1940-10-09" }'
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Triples
http://dbpedia.org/resource/John_Lennon @http://schema.org/birthDate "1940-10-09"^^http://www.w3.org/2001/XMLSchema#date
http://dbpedia.org/resource/John_Lennon @http://xmlns.com/foaf/0.1/name "John Lennon"
Quads

With an opaque IRI is does not

> java -jar build/libs/JsonLdTest-1.0-SNAPSHOT-all.jar 'info:fedora/jared' '{ "@context": "https://json-ld.org/contexts/person.jsonld", "@id": "http://dbpedia.org/resource/John_Lennon", "name": "John Lennon", "born": "1940-10-09" }'
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Exception in thread "main" com.github.jsonldjava.core.JsonLdError: loading remote context failed: info:fedora/https://json-ld.org/contexts/person.jsonld
	at com.github.jsonldjava.core.DocumentLoader.loadDocument(DocumentLoader.java:74)
	at com.github.jsonldjava.core.Context.parse(Context.java:199)
	at com.github.jsonldjava.core.Context.parse(Context.java:146)
	at com.github.jsonldjava.core.Context.parse(Context.java:299)
	at com.github.jsonldjava.core.JsonLdApi.expand(JsonLdApi.java:550)
	at com.github.jsonldjava.core.JsonLdApi.expand(JsonLdApi.java:1027)
	at com.github.jsonldjava.core.JsonLdProcessor.expand(JsonLdProcessor.java:139)
	at com.github.jsonldjava.core.JsonLdProcessor.toRDF(JsonLdProcessor.java:528)
	at Tester.parse(Tester.java:85)
	at Tester.main(Tester.java:37)
Caused by: java.net.MalformedURLException: unknown protocol: info
	at java.base/java.net.URL.<init>(URL.java:634)
	at java.base/java.net.URL.<init>(URL.java:523)
	at java.base/java.net.URL.<init>(URL.java:470)
	at com.github.jsonldjava.core.DocumentLoader.loadDocument(DocumentLoader.java:72)
	... 9 more

This might be faulty understanding on our or Apache Jena's side, but it seems like using an IRI does not work as you are only expecting URIs. So I thought I would raise it here first. Thanks

[whikloj]

I still believe this is an issue, but we are switching our processing to using the external URI when parsing the incoming RDF and then translating the subsequent graph. Thanks. fcrepo/fcrepo#1847

[dr0i]

@whikloj thx for reporting this issue. Apologizing for the late response.
It seems indeed a bug, as your using of a base IRI is defined in several documents as:

The base IRI is used to turn relative IRIs into absolute IRIs.

(https://json-ld.org/spec/latest/json-ld-api/#dfn-base-iris)

and

Please note that the @base will be ignored if used in external contexts.

(https://www.w3.org/TR/json-ld11/)

So the remote context you gave (https://json-ld.org/contexts/person.jsonld) should be untouched when defining info:fedora as a base IRI and thus not turning your remote context into info:fedora/https://json-ld.org/contexts/person.jsonld (which obviously cannot be resolved).

[dr0i]

Fix in master. Should come into next release.
Thx @whikloj for reporting.
Closing.