White space (was RE: [wss] Proposal for a new attribute of UsernameToken)

["Reid, Irving" <irving.reid@hp.com>]

> From: Eric Gravengaard [mailto:eric@reactivity.com]
> 
> Reading Jerry's email made me think of something that 
> happened at the interop event back in June. How are leading 
> and trailing white space treated in the computation of the 
> digest? It wasn't clear to me that there couldn't be a 
> trailing or leading space in the format of the date in the 
> <wsu:Created> element. If there was would it change the 
> digest or not? If I'm wrong and there are schema rules for 
> not allowing white space then I apologize for wasting the bandwidth.
> 
> -Eric
> 
> Oh and the interop story was that the part about 
> KeyIdentifiers having white space and most of us not trimming it out.


It's this sort of thing that fuels my "trimming white space is a bad idea" rants. I believe that XML DSig made a serious mistake by specifying that KeyIdentifiers could have non-significant white space around them.

XML gives us a way to represent *exactly* the text we intend. Let's use it that way. Besides, unless you have drunk deeply at the well of Unicode, you might not know white space when you see it. Specifying that text inside XML elements can have leading and/or trailing white space trimmed before processing is a recipe for interop failures.

 - irving -