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Re: [JSON] Elephant in the room

From: Nathan <nathan@webr3.org>
Date: Wed, 23 Mar 2011 17:16:27 +0000
Message-ID: <4D8A2AEB.9050105@webr3.org>
To: Sandro Hawke <sandro@w3.org>
CC: RDF WG <public-rdf-wg@w3.org>
Sandro Hawke wrote:
> On Wed, 2011-03-23 at 16:22 +0000, Nathan wrote:
>> Just wanted to capture something I don't think I've conveyed until now:
>>
>> Almost every developer I know, from enterprise to bedroom developers, 
>> work primarily with OO oriented languages, or key/value data structures 
>> in functional languages.
>>
>> The primary *huge* issue here, is that most people can't work with 
>> triples and graphs without special tooling. Not to mention that it's 
>> highly unfamiliar to them.
>>
>> Send an object with an id over the wire and people can use it, it's 
>> familiar, they "get it", send them a triple, and they're lost - even if 
>> they grok the graph and triple, they don't have the machinery to handle 
>> it often.
>>
>> This is pretty much the sole reason that every developer I know outside 
>> of the sem web community does not use RDF in any way, even though they 
>> like the concepts and would like "linked data".
> 
> Yes, good to name this elephant, even though I think we're already
> working around it.
> 
> I think of this as a close cousin to the "object-relational impedance
> mismatch"....
> 
> http://en.wikipedia.org/wiki/Object-relational_impedance_mismatch

Ahh yes, I agree :)

> ... and sometimes I just call it that.   Many of the items listed on
> that page don't apply, so many just "impedance mismatch" in the RDF
> context is good enough.  I think I first heard that term applied to this
> problem by Dave Reynolds.
> 
> My sense is that it manifests most clearly in RDF allowing a single
> property of a single item can have multiple values at once.  That's
> nonsense from an OO perspective.   (In RDF we can say the foaf:name
> property of :Sandro has multiple values, simultaneously.  In OO, that's
> nonsense, and instead we would have to say the foaf.name property of
> Sandro has a value which is some sort of collection of other values.)
> 
> (As I recall, Dave Reynolds was also pointing out how different
> rdfs:domain and rdfs:range and rdfs:subClassOf are from what OO folks
> expect.)

Yes, definately, seen that often too, Classes are blueprints in many OO 
languages, then an object is an instance of it, so to have a language 
which is an instance of two classes is confusing for many. Likewise 
multiple inheritance, and another one I hadn't noticed till somebody 
mentioned on sem-web a few weeks (months?) ago -> they thought the 
properties related to a class where the properties which were on every 
instance of that class (as in oo) and this confused them greatly.

> This is part of why I like presenting SPARQL result sets to the json
> folks.  There are no multiple values, and in general I think it's clear
> to say that each object they get is a result from (or a match to) a
> particular query.   They don't need to understand the query itself until
> they are ready to understand the modeling, which is a more advanced step
> that not everyone needs to take.

Great fun watching them then create a table in an rdbms to save the 
results in to query later :p But yes, SPARQL is like a big old shortcut 
for many that saves a lot of confusion and wondering.

Best,

Nathan
Received on Wednesday, 23 March 2011 17:17:27 GMT

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