[Ietf-message-headers] Packaging, was: provisional registration: packaged content over http (5 headers)

Julian Reschke <julian.reschke@gmx.de> Tue, 17 January 2012 09:05 UTC

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Date: Tue, 17 Jan 2012 10:05:25 +0100
From: Julian Reschke <julian.reschke@gmx.de>
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To: Graham Klyne <GK-lists@ninebynine.org>
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Subject: [Ietf-message-headers] Packaging, was: provisional registration: packaged content over http (5 headers)
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On 2012-01-17 09:44, Graham Klyne wrote:
> ...
> [[
> The Packaging header applies to resources delivered over HTTP which are
> comprised of component resources, and is for uniquely identifying these
> well structured packaged objects in a similar way that Content-Type does
> for MIME formats.
> ]]
>
> I think this would be a good opportunity to canvas for information about
> whether any other projects are addressing similar issues w.r.t.
> conveying information about packaging or composite object formats in
> HTTP. I'm pretty sure this isn't a one-off problem.

+1

> Packaging doesn't really fall into the role of a content-type, as it
> doesn't say anything about the nature of purpose of the packaged
> content. But it also is not really a content transfer encoding, as it
> may convey application-relevant metadata in addition to simply encoding
> content for transfer.
>
> The nearest I can think of that has been addressed in the IETF is the
> MHTML work from some years ago, which uses multipart/related structures
> to bundle up the content of a web page
> (http://tools.ietf.org/html/rfc2557). But that doesn't really work in
> this case, as SWORD and related applications are already using a number
> of alternative formats that don't easily map into a multipart/related or
> similar MIME encapsulation structure.
>
> [[
> The Packaging request header SHOULD be used by the client during HTTP
> POST to give information to the server about the packaging format used
> to construct the content being POSTed or PUT. Servers SHOULD use this

POST *and* PUT?

> information to unpack the supplied content into its component parts. If
> the server does not understand the package format it MUST either store
> the content as delivered without unpacking or respond with 415
> (Unsupported Media Type).
> ]]

No. 415 is for unsupported media types.

> It is not clear from this text that the SHOULD here applies to
> implementations of SWORD. For the header specification document, I think
> it would be better to avoid such normative claims about its use, which
> might be read as claiming that any HTTP client SHOULD use the header.
> e.g. just say "The Packaging request header may be used by a client ..."

 From the description in the spec it's not clear to me at all how this 
is supposed to work, and why it is needed in addition to the 
Content-Type. I'm sure there's a reason, but it really would be good to 
add more explanations.

Best regards, Julian