[uf-new] Re: hAudio rel-enclosure & linking issues

Andy Mabbett andy at pigsonthewing.org.uk
Fri Jan 11 13:00:05 PST 2008

In message <1200070018.3565.26.camel at localhost.localdomain>, Martin
McEvoy <martin at weborganics.co.uk> writes

>> It would also seem to be inadvisable to use rel="enclosure" for links to
>> off-site files.
>Please can you explain a little further why you have an issue with

If I set an agent to cache:


which linked to:



I would expect it to cache the former, but not the latter; any more than
I would expect the agent, set to cache:


to cache all the myriad pages linked to from there.

>It seems sound enough to me :) I have found more often than not that a
>purchased audio track is rarely downloaded from the website you
>actually buy the track from.

If site "A" acts as an agent for site "B", you would not expect a cached
version of "A" to include all of the content from "B". The content is
not "cacheable", and thus outside the scope of rel-enclosure.

Not least if "A" is McEvoy's hobby pages and "B" is MegaCorp Records!

>rel="encloseure" simply means that the hyperlink destination is
>something that can be downloaded or cached?

No; as I indicated previously:

        By adding rel="enclosure" to a hyperlink, a page indicates that
        the destination of that hyperlink is intended to be downloaded
        and cached.

I take that to mean that the "enclosure" is an intrinsic part of the
document represented by the page; you would expect to find them

Otherwise, why not mark up every href as an enclosure?

I think we need three classes; say:

   *    download

        for direct links to .mp3 or .wav files, etc.

   *    stream

        for direct links to .ram files, etc.

   *    source

        for links to .html files, etc., which link in turn to one of the

In the use case:

        User issues instruction to a user-agent to "scan pages until you
        find one which discusses Beethoven's 'Clair de Lune', then find
        me a downloadable version so I can put it on my pocket device".

the agent should ignore the second type, and use the first or third to
find an mp3 or wav.

If rel-license becomes part of hAudio (a no-brainer, surely?), along
with  "type", then the use case could include "find me a
freely-downloadable mp3 version..."

Andy Mabbett

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