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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: September 22, 2012 March 21, 2012
The "about" URI Scheme
draft-ietf-appsawg-about-uri-scheme-04
Abstract
This document specifies the "about" URI scheme, which 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
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provisions of BCP 78 and BCP 79.
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Copyright and License Notice
Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . 2
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
2.3. Encoding Considerations . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
4.1. URI Scheme Registration . . . . . . . . . . . . . . . . . . 4
4.2. A Registry for Registered Tokens . . . . . . . . . . . . . 5
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Normative References . . . . . . . . . . . . . . . . . . . 6
5.2. Informative References . . . . . . . . . . . . . . . . . . 6
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 6
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 formed when applications did not have a
"friendly" user interface, to enable access to the aforementioned
resources by typing URIs into an address bar or similar feature.
They have however become commonplace in modern user applications.
Given their current ubiquity, their absence from the URI scheme
registry and lack of a defining document is conspicuous. Therefore,
this document provides a stable specification for the "about" URI
scheme and registers it with IANA.
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
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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 = *pchar
about-query = "?" query
pchar = <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 to which a particular "about" URI
resolves 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 to
which the URI resolves.
However, it is impossible to specify a binding between all the
possible tokens and the semantics of "about" URIs that would contain
such tokens. Therefore, the resource referenced by the URI is
application-specific, except for those listed below as 'special-
purpose "about" URIs'. Applications MAY use internal redirection to
accomplish this (for instance, the Opera web browser redirects all
"about" URIs except "about:blank" to its internal "opera" URIs).
2.2.1. Special-Purpose "about" URIs
A small, though expandable, range of <about-token>s is reserved for
special purposes ("special-purpose tokens").
A special-purpose URI is an "about" URI that has a special-purpose
token as its <about-token> part. Such URIs MUST be handled in strict
accordance with the rules defined in the special-purpose token
registry (see Section 4.2). The registered entry MAY also define
additional provisions for handling of the <about-query> part. If no
such provisions are defined, the query part has no meaning, and MUST
be ignored.
This document defines one special-purpose token: "blank". The URI
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"about:blank" MUST resolve to a blank page, as seen by the end user.
There is no additional handling of the query component in
"about:blank" URIs.
Additional special-purpose tokens can be defined by by updating the
registry created in Section 4.2. Special-purpose "about" URIs are
intended to be uncommon, and new ones should be defined only when
there is a need to strongly connect a particular <about-token> with a
particular function in all applications.
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, few of those provisions apply to
"about" URI scheme, as they are mainly scoped to schemes used in the
Internet, not internally.
"about" URIs can sometimes refer to a sensitive information, such as
user passwords stored in a cache, or parameters that, if changed,
could affect user's data. The application therefore needs to ensure
that the user's data is secured, and no threats are imposed by
"about" URIs.
4. IANA Considerations
4.1. URI Scheme Registration
IANA is asked to register the "about" URI scheme in the "URI Schemes"
registry defined in Section 5.4 of RFC 4395 [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.
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Security considerations: see Section 3 of RFC xxxx
Contact: IETF Applications Area Directors <app-ads@tools.ietf.org>
Author/Change controller: IESG <iesg@ietf.org> (on behalf of the
IETF)
References: see Section 5 of RFC xxxx
[RFC Editor: Please replace xxxx with assigned RFC number]
4.2. A Registry for Registered Tokens
IANA is asked to set up a new registry entitled "'about' URI Special
Purpose Tokens" following the guidelines below.
The registry entries consist of 3 fields: Special-Purpose Token,
Description and Reference. The Special-Purpose Token field has to
conform to <about-token> production defined in Section 2.1. The
initial registry consists of one entry:
+------------------+------------------------------------+-----------+
| Special-Purpose | Description | Reference |
| Token | | |
+------------------+------------------------------------+-----------+
| blank | Used in "about" URIs to refer to | RFC xxxx |
| | blank page. | |
+------------------+------------------------------------+-----------+
The registration procedures for this registry are "First Come First
Served", described in RFC 5226 [RFC5226], with supporting
documentation meeting the requirements below. The registrant of the
token ought to provide the following registration template, which
will be made available on IANA web site:
o Registered Token: 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, to what resource they
are to resolve.
o Handling query component: Describe any requirements for handling
query components in "about" URIs that contain the registered token.
o Contact/Change controller: An individual or an organization that
(1) should be contacted for more details, and (2) is authorized to
change the registration.
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o Specification. A permanent reference to a specification that can
be used to create a compliant, interoperable implementation of the
registered "about" URI. IANA will consult with the IESG or its
specified delegate if there is doubt about whether the
specification is adequate for this purpose.
The following is a template for "blank" token:
o Registered Token: blank
o Intended usage: The <about:blank> URI must resolve to a blank
page.
o Handling query component: No special provisions.
o Contact/Change controller: IESG <iesg@ietf.org> (on behalf of
IETF).
o Specification: 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.
[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
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Holsten. Additionally, the contributions of Frank Ellermann and
Alexey Melnikov are gratefully acknowledged. Barry Leiba and Murray
Kucherawy deserve a special credit for providing a great amount of
text which has been used in this document.
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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