W3C home > Mailing lists > Public > public-linked-json@w3.org > August 2014

Re: Framing by reference/value

From: Dave Longley <dlongley@digitalbazaar.com>
Date: Tue, 12 Aug 2014 22:29:38 -0400
Message-ID: <53EACD92.6040206@digitalbazaar.com>
To: Julian Everett <julianjeverett@yahoo.com>, Markus Lanthaler <markus.lanthaler@gmx.net>, "public-linked-json@w3.org" <public-linked-json@w3.org>
On 08/12/2014 10:42 AM, Julian Everett wrote:
> So I think I now have a working version of the Javascript library with
> the required behaviour (I'm still adding tests for indirect circular
> references via sets, etc - but so far all are passing). Before I
> continue, I just wanted to check my logic with you against the framing
> algorithm http://json-ld.org/spec/latest/json-ld-framing/#framing-algorithm
> What I have done is to remove the whole of 4.4.4, on the basis that if
> you can detect a circular reference and block it prior to injecting it
> then you never need to do a 'Remove Embedded Definition' subsequently.
> I've then added checks for circular reference injection prior to the
> recursive calls at and
> The circular reference check works by traversing back up the chain of
> resource->parent['@id'] links in the 'map of embeds' to ensure that the
> injected resource is not a direct or indirect ancestor of the current
> embed target.
> Any obvious holes in this logic? FYI one thing making feel a bit nervous
> :-) is that I don't entirely get the point of the embed processor option
> (although I can see why it makes sense inside a framing context):
> setting that to false basically means don't frame doesn't it, as the
> only output will be the set of root resource URIs?

It seems ok at first glance, but I'll have to take a closer look when I
can. We definitely want to keep the old behavior around as an option.
Framing is currently being used to filter graphs that will be
digitally-signed, and creating duplicate data (as aggressive embedding
does) is an issue.

The option for setting @embed to false is, as you say, to ensure that
data is not embedded if it's undesirable. Sometimes you just want to get
the link (@id) to some data when you frame, you don't want all of the
node's associated data.

> thanks
> Julian
> ------------------------------------------------------------------------
> *From:* Markus Lanthaler <markus.lanthaler@gmx.net>
> *To:* public-linked-json@w3.org
> *Cc:* 'Julian Everett' <julianjeverett@yahoo.com>; 'Dave Longley'
> <dlongley@digitalbazaar.com>
> *Sent:* Monday, August 11, 2014 4:49 PM
> *Subject:* RE: Framing by reference/value
> On Friday, August 08, 2014 5:35 PM, Dave Longley wrote:
>> On 08/08/2014 06:05 AM, Julian Everett wrote:
>> >> Is such output achievable via framing please, or do I need to add some
>> >> kind of post-framing graph denormalisation step?
>> There have been a number of discussions regarding "aggressive
>> embedding" (or embedding by value as you called it). The details
>> (flags to turn it on/off, dealing with cycles, etc.) haven't been
>> fully worked out and the feature hasn't been implemented in the
>> JavaScript library used on the playground. I think Markus may have
>> implemented something in his PHP processor.
> Yes, my processor [1] supports this (and a couple of other things). There's
> a playground at [2] that you can use to try it without having to install
> anything. The example you posted works exactly as you expected Julian.
> I have found this to be an extremely useful feature and turned it on by
> default (even though that means I fail some of the framing tests we have).
> [1] https://github.com/lanthaler/JsonLD
> [2]
> http://www.markus-lanthaler.com/jsonld/playground/
> --
> Markus Lanthaler
> @markuslanthaler

Dave Longley
Digital Bazaar, Inc.
Received on Wednesday, 13 August 2014 02:30:05 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 16:18:42 UTC