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Re: JSON-LD onsite examples: are @context values missing a trailing slash?

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Tue, 17 Feb 2015 20:19:15 -0500
Message-ID: <54E3E893.2010706@openlinksw.com>
To: public-vocabs@w3.org
On 2/17/15 6:30 PM, Gregg Kellogg wrote:
>> On Feb 17, 2015, at 1:34 PM, Kingsley Idehen <kidehen@openlinksw.com 
>> <mailto:kidehen@openlinksw.com>> wrote:
>>
>> On 2/17/15 12:53 PM, Gregg Kellogg wrote:
>>>> On Feb 17, 2015, at 8:12 AM, Niklas Lindström <lindstream@gmail.com 
>>>> <mailto:lindstream@gmail.com>> wrote:
>>>>
>>>>
>>>> On Tue, Feb 17, 2015 at 4:20 PM, Jarno van Driel 
>>>> <jarnovandriel@gmail.com <mailto:jarnovandriel@gmail.com>> wrote:
>>>>
>>>>     I noticed that the @context value in the JSON-LD examples on
>>>>     schema.org <http://schema.org/>'s site are noted as:
>>>>
>>>>     "@context": "http://schema.org <http://schema.org/>",
>>>>
>>>>     Where "http://schema.org <http://schema.org/>" doesn't contain
>>>>     a trailing slash.
>>>>
>>>>     Yet when I look at the official specs
>>>>     (http://www.w3.org/TR/json-ld/) I see all values do contain a
>>>>     trailing slash, eg:
>>>>
>>>>     "@context": {
>>>>         "@vocab": "http://schema.org/"
>>>>     }
>>>>
>>>>     Now to me it seems that urls without a trailing slash would
>>>>     resolve in urls like for example schema.orgArticle as opposed
>>>>     to schema.org/Article <http://schema.org/Article>, which makes
>>>>     me wonder whether or not the slash matters for the @context.
>>>>
>>>>     Any thoughts?
>>>>
>>>>
>>>> The difference is that a @context value (if it is a string) 
>>>> represents a URL to a context definition. This is mechanically 
>>>> dereferenced before anything is interpreted. The @vocab value on 
>>>> the other hand, is used syntactically to construct URIs by 
>>>> concatenating it with local terms (as you describe).
>>>
>>> Exactly. Some sites will force a redirect if the URL does not end in 
>>> a "/", but schema.org <http://schema.org/> does not, so in this case 
>>> it doesn't really matter. For other uses, this could result in a 
>>> redirect, but a conforming JSON-LD processor will handle this 
>>> transparently.
>>>
>>> Gregg
>>>
>>
>> Gregg,
>>
>> This heuristic needs some clear emphasis in the JSON-LD specs related 
>> docs, if that isn't the case already.
>>
>> "@context": "http://schema.org <http://schema.org/>" isn't good 
>> practice, having users depend on processors to support such a 
>> heuristic (consistently) will be problematic.
>>
>> Does it really hurt anyone to state:
>>
>> "@context": "http://schema.org <http://schema.org/>/" ?
>
> This isn't a JSON-LD heuristic, but a general web server mechanism to 
> handle ill-formed URLs.

> As it happens, although it's common practice, http://schema.org is not 
> a valid URL, as it doesn't have a path component. However, it's common 
> practice for web servers to handle such URLs by normalizing them, in 
> this case, by adding a trailing '/'. Some servers do this by 
> redirecting the agent to the proper resource, it seems that schema.org 
> <http://schema.org> simply returns the expected resource.
>
> JSON-LD simply follows redirects when requesting resources, as most 
> any other HTTP agent would do (such as a web browser).

The "JSON-LD" mention lead to my JSON-LD spec comment.

>
> Of course, it's always good practice to use well-formed URLs, which 
> means that "@context": "http://schema.org/" is correct, but practice 
> shows that this doesn't end up mattering.

It does matter.

Being precise always trumps being imprecise, in the hope that some 
heuristic is global :)

Kingsley
>
> The JSON-LD API does not call this out specifically, as that's part of 
> HTTP, although there is a brief mention of recording the eventual 
> redirected URL due to redirects [1]. There are numerous tests on 
> handling remote documents that JSON-LD processors must pass to be 
> considered conformant.
>
> [1] 
> http://www.w3.org/TR/json-ld-api/#remote-document-and-context-retrieval
>> -- 
>> Regards,
>>
>> Kingsley Idehen	
>> Founder & CEO
>> OpenLink Software
>> Company Web:http://www.openlinksw.com
>> Personal Weblog 1:http://kidehen.blogspot.com
>> Personal Weblog 2:http://www.openlinksw.com/blog/~kidehen
>> Twitter Profile:https://twitter.com/kidehen
>> Google+ Profile:https://plus.google.com/+KingsleyIdehen/about
>> LinkedIn Profile:http://www.linkedin.com/in/kidehen
>> Personal WebID:http://kingsley.idehen.net/dataspace/person/kidehen#this
>


-- 
Regards,

Kingsley Idehen	
Founder & CEO
OpenLink Software
Company Web: http://www.openlinksw.com
Personal Weblog 1: http://kidehen.blogspot.com
Personal Weblog 2: http://www.openlinksw.com/blog/~kidehen
Twitter Profile: https://twitter.com/kidehen
Google+ Profile: https://plus.google.com/+KingsleyIdehen/about
LinkedIn Profile: http://www.linkedin.com/in/kidehen
Personal WebID: http://kingsley.idehen.net/dataspace/person/kidehen#this




Received on Wednesday, 18 February 2015 01:19:38 UTC

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