W3C home > Mailing lists > Public > public-linked-json@w3.org > October 2011

Re: Distinguishing a context document from an instance document

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Sat, 01 Oct 2011 15:34:52 -0400
Message-ID: <4E876B5C.7040801@digitalbazaar.com>
To: public-linked-json@w3.org
On 09/28/2011 06:31 AM, Markus Lanthaler wrote:
> What's the currenty way to distuingish a context document from an instance
> document?

There is none because a use case has not been presented where it is 
necessary to differentiate. I do agree that it may be cleaner if one 
could differentiate, but I don't know what new application this would 
enable for JSON-LD.

> There are a couple of options to solve this issue (ISSUE-30)
>
> - create a new MIME type

-1

I like this one the least, it's a bit heavy weight and would require us 
to create a new MIME type and file extension for JSON-LD documents.

> - use the form MIME type parameter, i.e., form=context

-0.5

I like this better, but it would still be difficult for a Web Server to 
decide what it is serving without looking in the file. The easiest thing 
for a web server is to have a file extension, which would make 
registering a MIME type a better solution, albeit, overkill.

> - include @context also in pure context documents

+0.5

I think this is the best solution. However, what important use case is 
this a solution to?

> Using a MIME type (parameter) for this is problematic for client-side
> JavaScript implementations. Including @context also in context documents
> seems to be a straightforward and simple way to do it. The only issue then
> is to ensure that there isn't any data in a context document - but I'm not
> even sure if we need to do that.

I wouldn't expect data in context documents to be a bad thing, 
necessarily. You could have triples that describe the context document 
as data. The processing rules for "@context" could specify that the only 
thing read from the remote document is the "@context" key. However, 
applications could still read the document in its entirety to find out 
more about each item in the context.

> Perhaps we also just say it's not important to be able to distinguish it
> because a client has to know what it requests!?

Perhaps a good compromise is to require that JSON-LD Context documents 
are valid JSON-LD documents. That is, "@context" is required... and if 
it has any triples, those triples could describe the context document.

This wouldn't complicate implementations that much, and wouldn't require 
a new MIME type and file extension. I don't feel very strongly about 
this... but if we want this feature, this may be the way to go. Thoughts?

-- manu

-- 
Manu Sporny (skype: msporny, twitter: manusporny)
Founder/CEO - Digital Bazaar, Inc.
blog: Standardizing Payment Links - Why Online Tipping has Failed
http://manu.sporny.org/2011/payment-links/
Received on Saturday, 1 October 2011 19:35:28 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:25:35 GMT