Subject: Re: Usernames as opaque strings (was Re: Montreal minutes)

From: [email-masked]
Date: Wed, 7 Jul 1999 12:34:15 -0400

John wrote:
>The only problem with opaque strings is that they can't be *completely*
>opaque; you have to define what characters are illegal (so that the 
parser can
>spot the end of the string), and, ideally, include a syntax for 
expressing
>those characters when necessary.  If we use URIs, then we get both of 
these
>for free.

Actually that last part is not true.  Check out RFC 2396 and that is the 
intended meaning of the term 'opaque' in the notes.  For reference check 
out  3. URI Syntactic Components:

      absoluteURI   = scheme ":" ( hier_part | opaque_part )

   URI that are hierarchical in nature use the slash "/" character for
   separating hierarchical components.  For some file systems, a "/"
   character (used to denote the hierarchical structure of a URI) is the
   delimiter used to construct a file name hierarchy, and thus the URI
   path will look similar to a file pathname.  [Snip]

      hier_part     = ( net_path | abs_path ) [ "?" query ]

      net_path      = "//" authority [ abs_path ]

      abs_path      = "/"  path_segments

   URI that do not make use of the slash "/" character for separating
   hierarchical components are considered opaque by the generic URI
   parser.

      opaque_part   = uric_no_slash *uric

      uric_no_slash = unreserved | escaped | ";" | "?" | ":" | "@" |
                      "&" | "=" | "+" | "$" | ","

There was much discussion about putting some convention on the username 
and realm components but thats a slippery slope we didnt want to go down 
in the limitied time there was.  Since not all implementations have 
hierarchical name spaces, we took the KISS approach and called them 
'opqaue' in the spirit that they can be parsed but they are then to be 
treated as just byte sequences to do comparisons agianst for matching...

BTW: no data is every "*completely*" opqaue; you can always parse it but you may not do it properly or be able 
to tell what kind of data it really is...

Bruce
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Bruce Kahn                                INet: [email-masked]
Iris Associates                          Phone: 978.392.5335
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