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Re: Renditions/Reviews/Thumbnails in WebDAV

From: Werner Donné <werner.donne@re.be>
Date: Wed, 27 May 2009 09:20:28 +0200
To: Julian Reschke <julian.reschke@gmx.de>
Message-Id: <0ABE4CE3-BB9E-4A81-94EF-E492F3FA62E7@re.be>
Cc: WebDAV <w3c-dist-auth@w3.org>
Hi,

I would not limit preview-sets to images. Any type of document can  
have a
preview thumbnail (cfr. Coverflow on Mac OS X).

When retrieving preview-set in expand-property, into what the URLs in
preview-set would expand?

There should be a property to represent an embedded form of a  
thumbnail, i.e.
one that also contains an element with the base64-encoded binary  
stream of
the thumbnail. This way the contents of a folder, thumbnails included,  
could
be retrieved with a single round-trip, which is much more efficient on  
the
server-side. Such a property would be available directly in the PROPFIND
method.

Best regards,

Werner.

On 26 May 2009, at 20:48, Julian Reschke wrote:

> Hi,
>
> the CMIS TC is currently discussing how to expose thumbnails in  
> their API. While listening to that discussion, I realized it would  
> be trivial in WebDAV, based on link-typed properties and the  
> DAV:expand-property REPORT.
>
> So, the use case is: retrieve contents of a folder, and for each  
> image in the folder, retrieve URLs + metadata for thumbnail images.
>
> Solution:
>
> 1) New property x:preview-set, containing a set of DAV:href elements  
> referencing HTTP resources representing the preview (thumbnail)  
> resources.
>
> 2) The DAV:expand-property (<http://greenbytes.de/tech/webdav/rfc3253.html#rfc.section.3.8 
> >) already allows getting the contents of a collection, while also  
> expanding link-type properties.
>
> Such as:
>
> REPORT / HTTP/1.1
> Host: www.webdav.org
> Depth: 1
> Content-Type: text/xml; charset="utf-8"
> Content-Length: xxxx
>
> <D:expand-property xmlns:D="DAV:">
> <D:property name="preview-set" namespace="extension-URI">
> </D:property>
> </D:expand-property>
>
> Note that this REPORT will also allow retrieving properties of the  
> link targets, such as the thumbnail's dimensions.
>
> BR, Julian

--
Werner Donné  --  Re                                     http://www.pincette.biz
Engelbeekstraat 8                                               http://www.re.be
BE-3300 Tienen
tel: (+32) 486 425803	e-mail: werner.donne@re.be
Received on Wednesday, 27 May 2009 07:21:11 GMT

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