At 05:13 AM 12/20/2004, Marc Cromme wrote:
>Does anybody had problems with SRU/GET yet?
>Problems which will corrected using SRU/POST?
On 15 December I posted concerns about Geospatial searches.
As you might guess, geospatial queries often involve looking
for overlap of areas. These are typically represented by
a chain of lat/long coordinates. Most natural boundaries
require a _lot_ of such coordinates (and most political
boundaries follow natural boundaries as well). Another
issue I noted is that SRW/SRU uses URI's for schemas, so
the overall URL length has to incude the embedded URI's.
I've seen assertions that POST must be used wherever the
form data has non-ASCII characters. I gather this means
we will need HTTP POST for any SRU that includes characters
from languages using character sets other than Latin-1.
In a bit of poking around the Web, I find that the WAP
folks advice that URL's ought to be limited to 128
characters. Awahile ago I saw Matthew's Z39.50 interface
over WAP, so I guess SRU over WAP is not unimaginable.
I've also seen cool work by Rondon Andrade in Brazil using
SVG (Scalable Vector Graphics). To put an SRU URL into
the embed tag for an SVG object, the limit is 256 characters.
BTW, it may be that the oft-cited limit of 1024 charcaters
for URLs comes from HTML. Apparently, <A> anchors in HTML
have a length limit determined by the SGML declaration for
HTML, wherein the number of characters which can appear in
a single attribute value literal is limited to 1024.
(There is a nice discussion of considerations for choosing
between GET and POST, last modified 2003-09-28, available
at http://www.cs.tut.fi/~jkorpela/forms/methods.html )