Re: CPIM and URIs

At 11:32 AM 5/24/02 -0400, John D. Ramsdell wrote:
>Graham Klyne <[email protected]> writes:
>
> > I think that is about right, but I also think it doesn't really matter.
> >
> > At the end of the day, an im: URI is just a URI that is used to
> > address an instant inbox.
>
>In seems to me that we must agree on what content is allowed in the
>decoded scheme specific part of an instant inbox URI.  From your
>discussion, it appears that I got the description wrong!  I made the
>assumption that all instant inbox URIs are opaque, but the following
>URI seems legal after all:
>
>         im://mitre.org/[email protected]
>
>since "//mitre.org/ramsdell"@ninebynine.org is a valid email address.

Touche!

Yes, it's a valid email address.  The semantically relevant part, per my 
reading of the specs is //mitre.org/[email protected], so yes that 
would be the logical translation.  Except that RFC2396 reserves "/" at the 
start of a URI for a hierarchical schema (e.g. for the purposes of 
resolving relative URIs), so I'm thinking that that maybe should be 
escaped; e.g.

   im:%2f/mitre.org/[email protected]

but I'm not sure if that's right.

>Let me try this definition instead.
>
>   URI u is an instant inbox URI if and only if all of the following
>   are true:
>
>         * The scheme of u is the string "im".
>
>         * There exists an RFC 2822 email address e such that the
>           decoded scheme specific part of u is identical to e after
>           all invisible characters in e are removed, using the RFC
>           2822 definition of an invisible character.
>
>         * The fragment part of u is absent.

Well, yes, I can't disagree with this (except maybe to deal with leading 
"/" - see above).

But I'm worried that this is making a simple thing complicated, or at least 
difficult to follow for people who aren't familiar with the other related 
specs.  Maybe, instead, we could just define a syntax for an im: URI, and 
leave it at that?

E.g. something like this

[[
    Inboxes are named using URIs with the following ABNF syntax:

        ;; Domain is defined in [RFC2821], either a FQDN or a literal
        inbox       = "im:" local "@" Domain

        local       = address [ "/" subaddress ]

        address     = token

        subaddress  = token

        ;; all non-control characters, excluding "/" and "@" delimiters
        token       = 1*(%x20-2E / %x30-3F / %x41-7E / UTF-8) ;; [RFC2044]

    URI character escaping (%hh) is used as necessary when presenting the
    URI to an environment that expects a US-ASCII URI character sequence
    to be used [RFC2396, section 2.1].
]]

(This was adapted from email addresses, but is not identical to RFC2821/2 
syntax.)

#g

-------------------
Graham Klyne
<[email protected]>



  [reminder: [email protected] for non-technical discussions, please]