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Versions: (draft-holsten-about-uri-scheme) 00 01 02 03 04 05 06 07 RFC 6694

Applications Area WG (APPSAWG)                              L. Hunt, Ed.
Internet-Draft                                      Opera Software, ASA.
Intended Status: Standards Track                     M. Yevstifeyev, Ed.
Expires: April 19, 2012                                 October 17, 2011

                         The 'about' URI Scheme
                 draft-ietf-appsawg-about-uri-scheme-00

Abstract

   This document defines the 'about' URI scheme, that is widely used by
   Web browsers and some other applications to designate access to their
   internal resources, such as settings, application information, hidden
   built-in functionality, and so on.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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Copyright and License Notice

   Copyright (c) 2011 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
   (http://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



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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  2
     1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. URI Scheme Specification  . . . . . . . . . . . . . . . . . . .  3
     2.1. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . .  3
     2.2. URI Scheme Semantics  . . . . . . . . . . . . . . . . . . .  3
       2.2.1. Special-Purpose 'about' URIs  . . . . . . . . . . . . .  3
       2.2.2. Unrecognized 'about' URIs . . . . . . . . . . . . . . .  4
     2.3. Encoding Considerations . . . . . . . . . . . . . . . . . .  4
   3. Security Considerations . . . . . . . . . . . . . . . . . . . .  4
   4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  5
     4.1. URI Scheme Registration . . . . . . . . . . . . . . . . . .  5
     4.2. A Registry for SPTs . . . . . . . . . . . . . . . . . . . .  5
   5. References  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     5.1. Normative References  . . . . . . . . . . . . . . . . . . .  6
     5.2. Informative References  . . . . . . . . . . . . . . . . . .  7
   Appendix A.  Acknowledgments . . . . . . . . . . . . . . . . . . .  7
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  7

1. Introduction

   This document specifies the 'about' Uniform Resource Identifier (URI)
   scheme, that is currently widely used by Web browsers and some other
   applications to designate access to their internal resources, such as
   settings, application information, so called "Easter eggs" (i.e.
   hidden feature or joke in an application), and so on.

   The concept of 'about' URIs has been formed at the times when the
   applications did not have the "friendly" user interface, in order to
   provide an access to the aforementioned resources via typing the URIs
   in the address bar.  Even though the user interface of current
   Internet-targeted software effectively rescinds the issue, and
   'about' URIs can be thought to be a rudimentary phenomenon, they are
   still supported by a variety of Web browsers and are not going to
   cease to exist.

   As use of 'about' URIs has been quiet long-lasting, and the URIs have
   been used without any proper registration and absent any proper
   specification, the necessity for the the latter two actions arises.
   The purpose of this document is to provide a stable specification for
   'about' URI scheme and correspondingly register it in the IANA
   registry.  Along, several provisions for handling the 'about' URIs
   are set.




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   Please consult RFC 3986 [RFC3986] for definition of generic URIs
   syntax and RFC 4395 [RFC4395] for description of registration process
   for new URI schemes.

1.1. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2. URI Scheme Specification

2.1. URI Scheme Syntax

   The 'about' URI MUST syntactically conform to the <about-uri> rule
   below, expressed using Augmented Backus-Naur Form (ABNF) [RFC5234]:

     about-uri   = "about:" about-token [ about-query ]
     about-token = segment
     about-query = "?" query
     segment     = <as specified in RFC 3986, Appendix A>
     query       = <as specified in RFC 3986, Appendix A>

   In terms of RFC 3986, <about-token> part corresponds to <hier-part>,
   and <about-query> to the query component of URI.

2.2. URI Scheme Semantics

   Generally speaking, the resource a particular 'about' URI resolves to
   is denoted by <about-token> part of the URI, and <about-query>
   specifies additional information concerning its handling and/or the
   information that should be returned in the resource a URI is resolved
   to.

   However, it is impossible to specify binding between all the possible
   tokens and the semantics of 'about' URIs that would contain such
   tokens.  Therefore any application MAY resolve an 'about' URI to any
   desired resource, and MAY redirect such URIs.  Several exceptions are
   defined, though; they are named "special-purpose 'about' URIs" and
   MUST be handled in strict accordance with provisions set in Section
   2.2.1.

2.2.1. Special-Purpose 'about' URIs

   A small, though expandable, range of <about-token>s are reserved for
   use in special-purpose 'about' URIs, abbreviated "SPU" (special-
   purpose URI).  Such tokens are named "special-purpose 'about' URI
   tokens", and abbreviated "SPT" (special-purpose token).



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   An SPU is an 'about' URI containing one of the registered SPTs as the
   <about-token> part.  An SPU MUST be handled in strict accordance with
   the rules defined for SPT contained therein.  The SPT specification
   MAY define additional provisions on handling of <about-query> part in
   the corresponding SPU; by default, it MUST be ignored for the purpose
   of handling SPU.

   SPU MAY be defined to be unresolvable.  This means that an
   application MUST NOT resolve it in some particular resource.  Such
   SPUs may be used as placeholders, or in some other way.

   One pre-defined SPT is specified: the "blank" SPT.  The URI
   <about:blank> MUST resolve to a blank page; this page need not
   necessarily contain no data, it should rather represent blank page.
   There is no additional handling of query component in <about:blank>
   URIs: both <about:blank> and <about:blank?foo> shall resolve into the
   blank page.

   Additional SPTs may be defined via adding the entry in the registry
   created by this document.  Please note that defining an SPT should
   only be used as a last resort approach, when a strict limitation on
   handling 'about' URI with such SPT is necessary.

2.2.2. Unrecognized 'about' URIs

   Naturally, an application will support only a particular range of
   'about' URIs; also, some applications will support 'about' URIs that
   are not supported by an other one.  This document specifies the rules
   for handling unrecognized 'about' URIs.

   An unrecognized 'about' URIs as a URI that may not be recognized by
   an application.  (Correspondingly, such categorization is per-
   application, not per-fact.)  An unrecognized 'about' URI SHOULD be
   handled as the <about:blank> URI, although other behavior is
   possible.

2.3. Encoding Considerations

   'about' URIs are subject to encoding rules defined in RFC 3986
   [RFC3986].  'about' IRIs [RFC3987] are not permitted.

3. Security Considerations

   Generic security considerations for URIs are discussed in Section 7
   of RFC 3986 [RFC3986].  However, many of those provisions hardly
   apply to 'about' URI scheme, as they are mainly scoped to schemes
   used in the Internet, not internally.




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   'about' URIs may sometimes refer to a sensitive information, such as
   user passwords stored in a cache, or parameter that, if changed, may
   affect user's data.  The application should therefore ensure that
   user's data is in the safety, and no threats are imposed by 'about'
   URIs.

4. IANA Considerations

4.1. URI Scheme Registration

   IANA is asked to update the register the 'about' URI scheme using the
   following template, per [RFC4395]:

     URI scheme name: about

     Status: Permanent

     URI scheme syntax: see Section 2.1 of RFC xxxx

     URI scheme semantics: see Section 2.2 of RFC xxxx

     URI scheme encoding considerations: see Section 2.3 of RFC xxxx

     Applications/protocols that use the scheme: 'about' URIs are
     predominantly used by Web browsers, although they may be used by
     other applications.

     Security considerations: see Section 3 of RFC xxxx

     Contact: IESG <iesg@ietf.org>

     Author/Change controller: IETF <ietf@ietf.org>

     References: see Section 5 of RFC xxxx

   [RFC Editor: Please replace xxxx with assigned RFC number]

4.2. A Registry for SPTs

   IANA is asked to set up a new registry entitled "'about' URIs SPTs"
   following the guidelines below.

   The registry entries consist of 3 fields: SPT, Description and
   Reference.  The SPT field MUST conform to <about-token> production
   defined in Section 2.1.  The initial registry contents consist of one
   entry:





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   +----------+----------------------------------------+-----------+
   | SPT      | Description                            | Reference |
   +----------+----------------------------------------+-----------+
   | blank    | Used in 'about' URIs referring to a    | RFC xxxx  |
   |          | blank page.                            |           |
   +----------+----------------------------------------+-----------+

   The registration policy for new entries is "Specification Required",
   as defined in RFC 5226 [RFC5226].  Additionally, the following
   template MUST be provided by the registrant:

   o SPT:  The desired special-purpose token to be used in 'about' URIs.

   o Intended usage:  A short description of how 'about' URIs with the
     registered token must be handled; especially, what they must be
     resolved to, if resolvable.

   o Resolvable:  "Yes" if resolvable (i.e. can be resolved to a
     particular resource) or "No" if unresolvable (see Section 2.2.1).

   o Handling query component:  It should be mentioned whether there are
     some provisions on handling query components in the 'about' URIs
     with the registered token.

   o Contact/Change controller:  An individual or an organization which
     (1) should be contacted for more details, and (2) is authorized to
     change the registration.

   o Published specifications:  A reference to the published
     specification for the registered token.

   The following is a template for "blank" SPT:

   o SPT:  blank
   o Intended usage:  The <about:blank> URI must resolve to a blank
     page.
   o Resolvable:  Yes.
   o Handling query component:  No special provisions.
   o Contact/Change controller:  IESG <iesg@ietf.org> (on behalf of
     IETF).
   o Published specifications:  This document.

5. References

5.1. Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.



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   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC5234]  Crocker, D., Ed., and P. Overell, "Augmented BNF for
              Syntax Specifications: ABNF", STD 68, RFC 5234, January
              2008.

5.2. Informative References

   [RFC3987]  Duerst, M. and M. Suignard, "Internationalized Resource
              Identifiers (IRIs)", RFC 3987, January 2005.

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 35,
              RFC 4395, February 2006.

Appendix A.  Acknowledgments

   This document has been formed from the draft initially authored by,
   additionally to Lachlan Hunt, the editor of the current one, Joseph
   Holsten.  Additionally, the contributions of <TBD> are gratefully
   acknowledged.

Authors' Addresses

   Lachlan Hunt (editor)
   Opera Software, ASA.

   EMail: lachlan.hunt@lachy.id.au
   URI:   http://lachy.id.au/


   Mykyta Yevstifeyev (editor)
   8 Kuzovkov St., Apt. 25
   Kotovsk
   Ukraine

   EMail: evnikita2@gmail.com








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