Re: [Uri-review] Request for review of "ab:" URI scheme

[Graham Klyne <[e-mail]>]

(For the avoidance of doubt, these comments are made with my URI scheme reviewer 
hat OFF.)

I am reminded of recent discussions about the jms: scheme, and how appropriate 
it is to mint a new URI scheme for accessing information for which there is no 
specific access protocol.  The fundamental problem is "The use and deployment of 
new URI schemes in the Internet infrastructure is costly;" 
(http://tools.ietf.org/html/rfc439) and "New URI schemes SHOULD have clear 
utility to the broad Internet community, beyond that available with already 
registered URI schemes." (ibid).

As I recall, the jms: scheme was allowed because there was a significant body of 
usage in code, if not on the wire.  Similarly, the recently discussed about: 
scheme was looked upon favourably because it was essentially codifying what 
browsers have been doing since the very early days.

In this case, I see no evidence of prior use to be accommodated, nor do I see 
any *technical* reason why an existing scheme cannot be used.  As I read your 
document, the only *required* value is ab:default - everything else is 
implementation dependent.  My suggestion would be to use instead 
"http://ietf.org/sieve/addrbook#default" (and, as a bonus, create a web page at 
that address explaining what it means).  The other values can be arbitrary URIs 
chosen by implementers.  if there is a future need for additional interoperable 
values, the above pattern is easily extended.  (My use of "#default" rather than 
"/default" is to sidestep an obscure issue of web architecture, but either could 
be used.)

Some folks are uncomfortable with http: URIs that represent not just web pages, 
but using http: URIs in this way is now a widely established practice in web 
data cicrles.  If you really don't like the http: approach, other possibilities 
might be a urn namespace - there's already a URN namespace for protocol 
parameters (http://tools.ietf.org/html/rfc3553), so one might end up with 
something like "urn:ietf:params:sieve:default".

In summary, in this case, I don't think the case has been made that a new URI 
scheme is justified.

#g
--


Barry Leiba wrote:
> In the Sieve working group, draft-ietf-sieve-external-lists defines an
> address-book URI scheme, "ab:".  See the draft, here:
> http://tools.ietf.org/html/draft-ietf-sieve-external-lists
> 
> We would like to get uri-review comments on the proposed scheme.
> There's a reference to the scheme in section 2.5, it's used in the
> examples in section 2.8.1 and at the end of the Security
> Considerations (section 3), and it's defined and registered in section
> 4.3.
> 
> Thanks in advance for reviews and comments.
> 
> Barry
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