At Tue, 18 Nov 2008 06:13:46 -0500,
Ed Summers <[log in to unmask]> wrote:
> Thanks for bringing this up Erik. It really does seem to be
> preferable to me to treat these tiles as web resources in their own
> right, and to avoid treating them like resources that need to be
> routed to with OpenURL. It is also seems preferable to leverage
> RESTful practices like using the Accept header.
>
> I wonder if it would improve downstream cache-ability to push parts of
> the query string into the path of the URL, for example:
>
>   http://an.example.org/ds/CB_TM_QQ432/4/0/899/1210/657/1106
>
> Which could be documented with a URI template [1]:
>
>   http://an.example.org/ds/{id}/{level}/{rotate}/{y}/{x}/{height}/{width}
>
> I guess I ought to read the paper (and refresh my knowledge of http
> caching) to see if portions of the URI would need to be optional, and
> what that would mean.
>
> Still, sure is nice to see this sort of open source work going on
> around jpeg2000. My nagging complaint about jpeg2000 as a technology
> is the somewhat limited options it presents tool wise ... and djatoka
> is certainly movement in the right direction.

It might improve cache-ability: my understanding (not checking sources
here) is that many caches do not cache GETs to URIs with query parts,
although it is allowed. However: query parameter order does matter, so
an explicitly ordered URI template could certainly prevent the problem
of:

http://example.org/?a=1&b=2

being considered a different resource than:

http://example.org/?b=2&a=1

If you read rest-discuss, there have been discussions of image
manipulation with URI query parameters/paths.

<http://article.gmane.org/gmane.comp.web.services.rest/6699>
<http://article.gmane.org/gmane.comp.web.services.rest/8167>

There seem to be advantages to both methods (query parameters/paths).

There is the further possibility of using path parameters [1], which
seems a pretty natural fit, but not widely used:

http://an.example.org/ds/{id};level={level};rotate={rotate};y={y};x={x};height={height};width={width}

Additionally, I think that reading about how Amazon does (mostly) the
same thing would be useful:

<http://www.aaugh.com/imageabuse.html>

I think that the library community could contribute to possible work
in standardizing, to some extent, image manipulation with URIs; but I
do feel that using OpenURL will slow or prevent uptake.

best,
Erik Hetzner

1. http://www.w3.org/DesignIssues/Axioms.html#matrix



;; Erik Hetzner, California Digital Library
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