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Posted to issues@jena.apache.org by GitBox <gi...@apache.org> on 2022/04/09 20:48:38 UTC
[GitHub] [jena] fatzh opened a new issue, #1254: json-ld serialisation and URIs/predicate overlapping
fatzh opened a new issue, #1254:
URL: https://github.com/apache/jena/issues/1254
First off, thanks for the great software, we use it a lot and it's brilliant ;)
I stumbled upon something today while trying to parse a json-ld response from Jena/Fuseki. I have a test store with a few books, their URIs look like this: `<http://onbetween.ch/3ms/cms#book_1>`.
If there's a custom predicate `<http://onbetween.ch/3ms/cms#book>`, there's an overlap with the book URIs and the JSON-LD serialisation is no longer valid :-/ as I get book URIs like this: `book:_1`.
Here's the very simple CONSTRUCT query that I send to Fuseki (version 4.4.0):
```
In [67]: response = requests.post('http://localhost:3030/threems_example', data={'query': """
...: PREFIX cms: <http://onbetween.ch/3ms/cms#>
...:
...: CONSTRUCT {
...: ?a cms:book ?c
...: }
...: FROM <http://example/cmstest_data>
...: WHERE {
...: ?a a cms:Collection.
...: VALUES ?a { cms:collection_1 }.
...: ?c a cms:Book.
...: }
...: """})
In [68]: print(response.content.decode())
@prefix schema: <http://schema.org/> .
@prefix threems: <http://onbetween.ch/3ms/core#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix cms: <http://onbetween.ch/3ms/cms#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix cmsapi: <http://onbetween.ch/3ms/cmsapi#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix cmsui: <http://onbetween.ch/3ms/cmsui#> .
@prefix dc: <http://purl.org/dc/elements/1.1/> .
cms:collection_1 cms:book cms:book_B , cms:book_C , cms:book_2 , cms:book_1 , cms:book_A .
```
Which is correct, got a simple collection with 5 books.
Now if I request JSON-LD form Fuseki (just adding headers `Accept: application/ld+json` to the query)
```
In [73]: response = requests.post('http://localhost:3030/threems_example', data={'query': """
...: PREFIX cms: <http://onbetween.ch/3ms/cms#>
...:
...: CONSTRUCT {
...: ?a cms:book ?c
...: }
...: FROM <http://example/cmstest_data>
...: WHERE {
...: ?a a cms:Collection.
...: VALUES ?a { cms:collection_1 }.
...: ?c a cms:Book.
...: }
...: """}, headers={'Accept': 'application/ld+json'})
In [74]: print(response.content.decode())
{
"@id" : "cms:collection_1",
"book" : [ "book:_B", "book:_C", "book:_2", "book:_1", "book:_A" ],
"@context" : {
"book" : {
"@id" : "http://onbetween.ch/3ms/cms#book",
"@type" : "@id"
},
"schema" : "http://schema.org/",
"threems" : "http://onbetween.ch/3ms/core#",
"owl" : "http://www.w3.org/2002/07/owl#",
"cms" : "http://onbetween.ch/3ms/cms#",
"xsd" : "http://www.w3.org/2001/XMLSchema#",
"skos" : "http://www.w3.org/2004/02/skos/core#",
"rdfs" : "http://www.w3.org/2000/01/rdf-schema#",
"cmsapi" : "http://onbetween.ch/3ms/cmsapi#",
"xml" : "http://www.w3.org/XML/1998/namespace",
"rdf" : "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
"cmsui" : "http://onbetween.ch/3ms/cmsui#",
"dc" : "http://purl.org/dc/elements/1.1/"
}
}
```
Fuseki serializes the books like this:
` "book" : [ "book:_B", "book:_C", "book:_2", "book:_1", "book:_A" ],`
I wasn't sure if that's actually correct json-ld serialisation, but trying on the json-ld playground [here](https://tinyurl.com/y8jlny9t) I get this interpretation:
```
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <book:_1> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <book:_2> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <book:_A> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <book:_B> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <book:_C> .
```
Which is incorrect. Should be:
```
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <http://onbetween.ch/3ms/cms#book_1> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <http://onbetween.ch/3ms/cms#book_2> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <http://onbetween.ch/3ms/cms#book_A> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <http://onbetween.ch/3ms/cms#book_B> .
<http://onbetween.ch/3ms/cms#collection_1> <http://onbetween.ch/3ms/cms#book> <http://onbetween.ch/3ms/cms#book_C> .
```
It's a bit of an edge case, but actually for us this may happen when working with organisation specific ontologies.
I'm more of a python dev nowadays but if I can help let me know. If you can confirm it's a bug, I can also look into it, but I'm actually not 100% sure if that's not a JSON-LD spec issue.
Also if the predicate serialisation would be using the prefixes, i.e. `cms:book`, this wouldn't happen, we would have `cms:book_1`, something like:
```
{
"@id": "cms:collection_1",
"cms:book": [
"cms:book_B",
"cms:book_C",
"cms:book_2",
"cms:book_1",
"cms:book_A"
],
"@context": {
"cms:book": {
"@id": "http://onbetween.ch/3ms/cms#book",
"@type": "@id"
},
"schema": "http://schema.org/",
"threems": "http://onbetween.ch/3ms/core#",
"owl": "http://www.w3.org/2002/07/owl#",
"cms": "http://onbetween.ch/3ms/cms#",
"xsd": "http://www.w3.org/2001/XMLSchema#",
"skos": "http://www.w3.org/2004/02/skos/core#",
"rdfs": "http://www.w3.org/2000/01/rdf-schema#",
"cmsapi": "http://onbetween.ch/3ms/cmsapi#",
"xml": "http://www.w3.org/XML/1998/namespace",
"rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
"cmsui": "http://onbetween.ch/3ms/cmsui#",
"dc": "http://purl.org/dc/elements/1.1/"
}
}
```
What do you think ?
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[GitHub] [jena] afs commented on issue #1254: json-ld serialisation and URIs/predicate overlapping
Posted by GitBox <gi...@apache.org>.
afs commented on issue #1254:
URL: https://github.com/apache/jena/issues/1254#issuecomment-1102192335
@gkellogg -- thanks for the details.
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[GitHub] [jena] afs commented on issue #1254: json-ld serialisation and URIs/predicate overlapping
Posted by GitBox <gi...@apache.org>.
afs commented on issue #1254:
URL: https://github.com/apache/jena/issues/1254#issuecomment-1101575333
@gkellogg -- Hi Gregg, the 1.0 and 1.1 playgrounds confirm this difference in behaviour for the "book:YYY".
If you have a moment, could you point to which of items in https://www.w3.org/TR/json-ld11/#changes-from-10 is causing this?
Simplified version:
```json
{
"@id" : "http://example/collection",
"http://example/p" : [ "book:ZZZ" ],
"book" : [ "book:YYY" ],
"@context" : {
"book" : {
"@id" : "http://onbetween.ch/3ms/cms#",
"@type" : "@id"
}
}
}
```
gives 1.0 playground:
```nt
<http://example/collection> <http://example/p> "book:ZZZ" .
<http://example/collection> <http://onbetween.ch/3ms/cms#> <http://onbetween.ch/3ms/cms#YYY> .
```
or 1.1 playground:
```nt
<http://example/collection> <http://example/p> "book:ZZZ" .
<http://example/collection> <http://onbetween.ch/3ms/cms#> <book:YYY> .
```
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[GitHub] [jena] afs commented on issue #1254: json-ld serialisation and URIs/predicate overlapping
Posted by GitBox <gi...@apache.org>.
afs commented on issue #1254:
URL: https://github.com/apache/jena/issues/1254#issuecomment-1100612572
Hi @fatzh,
Jena uses [jsonld-java](https://github.com/jsonld-java/jsonld-java) for reading JSON-LD 1.0 and uses [titanium-json-ld](https://github.com/filip26/titanium-json-ld) to parse JSON-LD 1.1.
Jena uses jsonld-java for writing JSON-LD (so JSON-LD 1.0). Note - your data does not have "@ version" (space added to not name a GH user!)
When I parse the `[ "book:_B", "book:_C", "book:_2", "book:_1", "book:_A" ]` I get different RDF between JSON-LD 1.0 and 1.1 across json-ld-java and titanium. Same for the JSON-LD playground does the same for JSON-LD 1.0 vs 1.1.
See a users@jena thread:
https://lists.apache.org/thread/zl0c6jgxnc9ckmc5pvhcoy72ypyr41fp
Suggestion - could you add a prefix to the data for `book:`? The writer tries to use the prefixes to build the context.
It looks like a difference between JSON-LD 1.0 and 1.1.
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[GitHub] [jena] fatzh commented on issue #1254: json-ld serialisation and URIs/predicate overlapping
Posted by GitBox <gi...@apache.org>.
fatzh commented on issue #1254:
URL: https://github.com/apache/jena/issues/1254#issuecomment-1100751582
hi @afs ! thanks, indeed it seems ok when parsing with `@version: 1.0`. I guess at some point jsonld-java will support 1.1, they seem to be on it.
> Note - your data does not have "@ version"
the data is what I get back from Jena, I guess I can live with it for now, but good to know.
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[GitHub] [jena] fatzh closed issue #1254: json-ld serialisation and URIs/predicate overlapping
Posted by GitBox <gi...@apache.org>.
fatzh closed issue #1254: json-ld serialisation and URIs/predicate overlapping
URL: https://github.com/apache/jena/issues/1254
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[GitHub] [jena] gkellogg commented on issue #1254: json-ld serialisation and URIs/predicate overlapping
Posted by GitBox <gi...@apache.org>.
gkellogg commented on issue #1254:
URL: https://github.com/apache/jena/issues/1254#issuecomment-1101793606
Yes, this was intentional, as terms were used too liberally as prefixes, which caused unintended consequences. The note in the [Changes since 1.0 Recommendation of 16 January 2014](https://www.w3.org/TR/json-ld11-api/#changes-since-1-0-recommendation-of-16-january-2014) says the following:
> In JSON-LD 1.1, terms will be used as [compact IRI](https://www.w3.org/TR/json-ld11/#dfn-compact-iri) prefixes when compacting only if a [simple term definition](https://www.w3.org/TR/json-ld11/#dfn-simple-term-definition) is used where the value ends with a URI [gen-delim](https://tools.ietf.org/html/rfc3986#section-2.2) character, or if their [expanded term definition](https://www.w3.org/TR/json-ld11/#dfn-expanded-term-definition) contains an @prefix [entry](https://infra.spec.whatwg.org/#map-entry) with the value true. The 1.0 algorithm has been updated to only consider terms that map to a value that ends with a URI [gen-delim](https://tools.ietf.org/html/rfc3986#section-2.2) character.
The operative step is Step 10 in the [Create Term Definition Algorithm](https://www.w3.org/TR/json-ld11-api/#algorithm-0)
> Create a new [term definition](https://www.w3.org/TR/json-ld11/#dfn-term-definition), definition, initializing [prefix flag](https://www.w3.org/TR/json-ld11-api/#dfn-prefix-flag) to false, [protected](https://www.w3.org/TR/json-ld11-api/#dfn-protected) to protected, and [reverse property](https://www.w3.org/TR/json-ld11-api/#dfn-reverse-property) to false.
And step 14.2.5:
> If term contains neither a colon (:) nor a slash (/), simple term is true, and if the [IRI](https://tools.ietf.org/html/rfc3987#section-2) mapping of definition is either an IRI ending with a [gen-delim](https://tools.ietf.org/html/rfc3986#section-2.2) character, or a [blank node identifier](https://www.w3.org/TR/rdf11-concepts/#dfn-blank-node-identifier), set the [prefix flag](https://www.w3.org/TR/json-ld11-api/#dfn-prefix-flag) in definition to true.
The operative bit is that this is not a _simple term_.
This can be changed by adding `"@prefix": true` to the term definition ([playground link](https://json-ld.org/playground/#startTab=tab-nquads&json-ld=%7B%22%40id%22%3A%22http%3A%2F%2Fexample%2Fcollection%22%2C%22http%3A%2F%2Fexample%2Fp%22%3A%5B%22book%3AZZZ%22%5D%2C%22book%22%3A%5B%22book%3AYYY%22%5D%2C%22%40context%22%3A%7B%22book%22%3A%7B%22%40id%22%3A%22http%3A%2F%2Fonbetween.ch%2F3ms%2Fcms%23%22%2C%22%40type%22%3A%22%40id%22%2C%22%40prefix%22%3Atrue%7D%7D%7D)):
```json
{
"@id" : "http://example/collection",
"http://example/p" : [ "book:ZZZ" ],
"book" : [ "book:YYY" ],
"@context" : {
"book" : {
"@id" : "http://onbetween.ch/3ms/cms#",
"@type" : "@id",
"@prefix": true
}
}
}
```
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