Re: Checking equality of graphs serialized in JSON-LD and Turtle

On 19 October 2014 18:25, Kingsley Idehen <kidehen@openlinksw.com> wrote:

>  On 10/19/14 5:22 AM, ☮ elf Pavlik ☮ wrote:
>
>  On 10/19/2014 09:50 AM, Melvin Carvalho wrote:
>
>  > > > On 18 October 2014 23:03, ☮ elf Pavlik ☮ <perpetual-tripper@wwelves.org> <mailto:perpetual-tripper@wwelves.org> <perpetual-tripper@wwelves.org>> wrote:> >     On 10/18/2014 11:59 AM, bergi wrote:>     > Am 17.10.2014 um 15:35 schrieb ☮ elf Pavlik ☮:>     >> Howdy,>     >>>     >> I work on automated tests for examples in draft of>     ActivityStreams 2.0>     >> spec[1]>     >>>     >> So far I use jsonld.js to get N-Quads from JSON-LD examples in spec +>     >> latest context document. For now I modified those N-Quads by hand to>     >> make it more human readable Turtle so we can review and define>     expected>     >> RDF as fixtures.>     >>>     >> I still don't have clear strategy how to compare graphs serialized in>     >> both JSON-LD and Turtle. I plan to use N3.js to parse turtle, also in>     >> LevelGraph extensions[2][3] we already have code which converts both>     >> serializations to array of plain triples for persisting them. It may>     >> require some carefulness with blank nodes...>     >>>     >> I remember us having conversation about common js format which we>     could>     >> use as common base for converting all the other serializations. I>     think>     >> we considered expanded JSON-LD as main candidate.>     >>>     >> Any recommendations for quick way of comparing, for now just>     equality,>     >> graphs serialized in JSON-LD and Turtle?>     >>     > I have created the module rdf-test-utils[1] for my RDF-Ext>     tests[2]. The>     > module contains a compareGraph method to compare two RDF-Interfaces>     > graph objects. The jsonld.normalize function is used to generate>     > canonical N-Triples. You could use the RDF-Ext parsers to get>     > RDF-Interfaces graph objects. Internal RDF-Ext also uses the>     JSON-LD and>     > N3.js library.>     neat! it almost solved my task, but then **blank node identifiers** jumped>     at me and after normalizing graphs it compared '' with '' returning>     true :D>     https://github.com/bergos/rdf-ext/issues/3> > > Dont use bnodes, you are violating axiom 0 of the web (among others!),> anything of significance should be given a URI.
>
>  Melvin, IMO **sometimes** they do make sense, still all the time
> triggering debates:
> * http://lists.w3.org/Archives/Public/semantic-web/2014Sep/0101.html
> * http://lists.w3.org/Archives/Public/semantic-web/2014Sep/0106.html
> * http://manu.sporny.org/2013/rdf-identifiers/#comment-3369
>
> Anyways, once we patch RDF-Ext I can compare equality of graphs with
> blank nodes and normalized to JSON-LD, this way I address current state
> of things :)
>
> * http://www.w3.org/2001/sw/wiki/How_to_diff_RDF#Some_Related_Papers
> * http://www.w3.org/DesignIssues/Diff
>
>
>
> Yes, blank nodes (indefinite pronouns [1]) are useful. The key is to use
> them where useful.
>

I didnt not say they were useless.  I said dont use them.

On reflection bnodes have caused more harm than good, imho.  One of the
(many) reasons that we have two identity groups at the W3C was that bblfish
insisted on including bnodes in WebID (indeed, his profile contains one),
and Manu said that would mean you could not supply the key material for
unexpected reuse, e.g. for signing.  The outcome makes both groups much
more likely to fail.   So these decisions have consequences.

This isnt really a debate, the term "axiom" means not up for discussion.

>
>
> They are not implicitly bad.
>
> A Language without pronouns is limited, at best.
>
> [1] https://www.englishclub.com/grammar/pronouns-indefinite.htm .
>
> --
> Regards,
>
> Kingsley Idehen 
> Founder & CEO
> OpenLink Software
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>