Re: [wellknown-uri-review] A .well-known registration for review: ni

[Eran Hammer <[e-mail]>]

I am writing this in my capacity as the registry's Designated Expert.

This will be an informal review as I have not received a proper review request using the template and email format specified in RFC 5785.

I have read through the document and have some concerns about its use of the Well-Known URI registry. When the registry was created, it was explicitly designed not to form a large namespace or allow the creation of resource trees within in. Section 1.1 is pretty explicit about this:

---
1.1.  Appropriate Use of Well-Known URIs

   There are a number of possible ways that applications could use Well-
   known URIs.  However, in keeping with the Architecture of the World-
   Wide Web [W3C.REC-webarch-20041215], well-known URIs are not intended
   for general information retrieval or establishment of large URI
   namespaces on the Web.  Rather, they are designed to facilitate
   discovery of information on a site when it isn't practical to use
   other mechanisms; for example, when discovering policy that needs to
   be evaluated before a resource is accessed, or when using multiple
   round-trips is judged detrimental to performance.

   As such, the well-known URI space was created with the expectation
   that it will be used to make site-wide policy information and other
   metadata available directly (if sufficiently concise), or provide
   references to other URIs that provide such metadata.
---

I do not believe that this draft utilizes the registry in the way it was designed. In fact, it is set to accomplish the exact opposite, where an unlimited number of resources may be made available within the well-known namespace.

An easy solution would be to create a single well-known resource that will always redirect using an HTTP 3xx response to the actual, non-well-known, URI prefix to be used by the rest of the scheme. This is the approach taken by CalDAV and CardDAV well-known resources defined in [1], after a similar discussion.

Another solution is to use the host-meta well-known document [2] by including a property or link record to the actual prefix, or alternatively, using a URI template to allow more flexibility in the design of such URIs (if that is desired).

Of course, the two proposed solutions add another round trip to the request, at least for the initial one - something the document authors will need to consider in their design and use cases.

EH

[1] http://tools.ietf.org/html/draft-daboo-srv-caldav-10
[2] http://tools.ietf.org/html/rfc6415



> -----Original Message-----
> From: [e-mail] [mailto:wellknown-uri-
> [e-mail]] On Behalf Of Stephen Farrell
> Sent: Monday, April 30, 2012 9:00 AM
> Cc: Alexey Melnikov; Barry Leiba; [e-mail];
> [e-mail]
> Subject: [wellknown-uri-review] A .well-known registration for review
> 
> 
> Hi,
> 
> We have a draft [1] that requests a registration of a .well-known URI.
> 
> The core WG are likely to want to use these we think and possibly decade,
> but they're intended to be generally useful as well.
> 
> Barry Leiba is planning to AD sponsor this and Alexey Melnikov will be
> shepherding so if you can cc them as well as the authors on any questions or
> comments that'd be good.
> 
> I hope the plan is to IETF LC this soon, once this review and the uri
> registrations review are done.
> 
> Thanks,
> Stephen.
> 
> [1] http://tools.ietf.org/html/draft-farrell-decade-ni-05
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