Well-Known Uniform Resource Identifiers (URIs)
RFC 8615

Document Type RFC - Proposed Standard (May 2019; No errata)
Obsoletes RFC 5785
Was draft-nottingham-rfc5785bis (individual in art area)
Last updated 2019-05-20
Stream IETF
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Reviews
Stream WG state (None)
Document shepherd Martin Thomson
Shepherd write-up Show (last changed 2018-09-05)
IESG IESG state RFC 8615 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Alexey Melnikov
Send notices to Martin Thomson <martin.thomson@gmail.com>
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                     M. Nottingham
Request for Comments: 8615                                      May 2019
Obsoletes: 5785
Updates: 7230, 7595
Category: Standards Track
ISSN: 2070-1721

             Well-Known Uniform Resource Identifiers (URIs)

Abstract

   This memo defines a path prefix for "well-known locations",
   "/.well-known/", in selected Uniform Resource Identifier (URI)
   schemes.

   In doing so, it obsoletes RFC 5785 and updates the URI schemes
   defined in RFC 7230 to reserve that space.  It also updates RFC 7595
   to track URI schemes that support well-known URIs in their registry.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8615.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Nottingham                   Standards Track                    [Page 1]
RFC 8615                     Well-Known URIs                    May 2019

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   3
   3.  Well-Known URIs . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Registering Well-Known URIs . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
     4.1.  Protecting Well-Known Resources . . . . . . . . . . . . .   6
     4.2.  Interaction with Web Browsing . . . . . . . . . . . . . .   6
     4.3.  Scoping Applications  . . . . . . . . . . . . . . . . . .   7
     4.4.  Hidden Capabilities . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  The Well-Known URI Registry . . . . . . . . . . . . . . .   8
     5.2.  The Uniform Resource Identifier (URI) Schemes Registry  .   9
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  Frequently Asked Questions . . . . . . . . . . . . .  12
   Appendix B.  Changes from RFC 5785  . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Some applications on the Web require the discovery of information
   about an origin [RFC6454] (sometimes called "site-wide metadata")
   before making a request.  For example, the Robots Exclusion Protocol
   (http://www.robotstxt.org) specifies a way for automated processes to
   obtain permission to access resources; likewise, the Platform for
   Privacy Preferences [P3P] tells user agents how to discover privacy
   policy before interacting with an origin server.

   While there are several ways to access per-resource metadata (e.g.,
   HTTP header fields, PROPFIND in Web Distributed Authoring and
   Versioning (WebDAV) [RFC4918]), the perceived overhead (either in
   terms of client-perceived latency and/or deployment difficulties)
   associated with them often precludes their use in these scenarios.

   At the same time, it has become more popular to use HTTP as a
   substrate for non-Web protocols.  Sometimes, such protocols need a
   way to locate one or more resources on a given host.

   When this happens, one solution is to designate a "well-known
   location" for data or services related to the origin overall, so that
   it can be easily located.  However, this approach has the drawback of
   risking collisions, both with other such designated "well-known
   locations" and with resources that the origin has created (or wishes
   to create).  Furthermore, defining well-known locations usurps the
   origin's control over its own URI space [RFC7320].

Nottingham                   Standards Track                    [Page 2]
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