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Re: issue 85 - range unit extensions

From: Jamie Lokier <jamie@shareable.org>
Date: Tue, 2 Sep 2008 07:56:17 +0100
To: Robert Brewer <fumanchu@aminus.org>
Cc: Kris Zyp <kris@sitepen.com>, Yves Lafon <ylafon@w3.org>, Julian Reschke <julian.reschke@gmx.de>, ietf-http-wg@w3.org
Message-ID: <20080902065617.GC1327@shareable.org>

Robert Brewer wrote:
> But a cache holding valid JSON items-ranges:
> 
>    "aaa" "bbb" "ccc"
> 
> ...that wished to return them combined in a single response would have
> to join them with a comma and envelop them in brackets to be valid JSON:
> '["aaa", "bbb", "ccc"]'.

Not just merging rules, but also splitting rules.  A cache which
already has items 0-100 and a strong Etag, and is asked for 50-200,
could convert the request to 50-200 with a conditional request.

For this, the cache needs to know how to merge and how to split the
entity syntax.

> There may be other media types that follow those same rules, but off the
> cuff it seems pretty media-type-specific (unless we abandon the hope
> that caches could do that recombination). It's certainly *not*
> vendor-specific--there's no need to call them 'Dojo-items' or
> 'com.dojo.items'. One possibility would be to leave the range
> declaration media-type-neutral ('items') and to add range-recombination
> rules to the media-type itself, so that RFC 4627 (application/json)
> would eventually grow a paragraph on its rules for items-ranges.

My concern was the combination of media-type
"application/x-javascript" (or even "text/plain") and the "items"
range is not specific enough to apply the JSON combination rules.

That's what I was getting at by dojo-items.

If it's only used with the "application/json" media-type, and it can
define that "items" always refers to _array_ items (i.e. numbered) and
the JSON _top-level_ object is an array, then I have no such concern.

I'm a bit surprised that the top-level object in a JSON request would
be an array, though.  For round-trip minimisation in AJAX applications
isn't it usual to send a bit of auxiliary metadata, or a few objects
together, and therefore the top-level JSON object tends to be an
object (i.e. several named data items) with one of its members being
an array, rather than the top-level object being an array itself?

This was also what I was getting at by dojo-items, since I imagined
the merging/splitting rules would tend to apply to a sub-object rather
than the top-level object.

-- Jamie
Received on Tuesday, 2 September 2008 06:57:00 GMT

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