Proposal (Was: When are and aren't two URLs the same?)

Johannes Ernst at
Mon Apr 24 17:09:38 UTC 2006

On Apr 22, 2006, at 18:41, Martin Atkins wrote:
> * Do the canonicalizations from RFC2616 in order that the URL is
> actually retrievable.

Which canonicalizations are you referring to? Section ...? I can only  
find things that don't seem to deal with URLs.

> * Do a character-by-character string comparison for equality.

This is not currently implemented practice, however. The particular  
problem the (re-)triggered my thinking on this was that certain  
relying party code happened to ask for URL  
(by specifying the port 80 in the HTTP Host header) when I had  
entered at the relying party. Our code did  
exactly what you suggest -- character-by-character string comparison  
-- and said "no identity known by this name".

Now the argument can be made that this trivial transformation --  
dropping redundant port 80 -- should be made by the identity host,  
but unless we all agree what are and aren't allowed, encouraged, ..  
transformations, that way lies interoperability hell. Note that just  
delegating the responsibility to the identity host did not work in  
this case, because the relying party did not pass through the URL  
character by character, considering it to be perfectly within its  
limits to insert port 80 (and not unreasonably so).

It would be fine with me if we agreed on a version of Draft-029 that  
basically just said this "no changes to the identity URL shall be  
made by the relying party for any reason", because I consider it much  
more important to agree on one scheme than that my proposal is  
accepted. On the other hand, that would make the scenario non- 
compliant ... so I still like my algorithm better (and thanks to  
everybody's contributions to make it better than I had proposed it).

Johannes Ernst
NetMesh Inc.

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