Internet DRAFT - draft-ietf-appsawg-about-uri-scheme
draft-ietf-appsawg-about-uri-scheme
Applications Area WG (APPSAWG) S. Moonesamy, Ed.
Internet-Draft
Intended Status: Informational
Expires: December 9, 2012 June 7, 2012
The "about" URI Scheme
draft-ietf-appsawg-about-uri-scheme-07
Abstract
This document describes 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.
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the Trust Legal Provisions and are provided without warranty as
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. URI Scheme Specification . . . . . . . . . . . . . . . . . . . 2
2.1. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . . 2
2.2. URI Scheme Semantics . . . . . . . . . . . . . . . . . . . 2
2.2.1. Well-known "about" URIs . . . . . . . . . . . . . . . . 3
2.3. Encoding Considerations . . . . . . . . . . . . . . . . . . 3
3. "about:blank" . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
5.1. URI Scheme Registration . . . . . . . . . . . . . . . . . . 4
5.2. A Registry for Well-known Tokens . . . . . . . . . . . . . 4
5.2.1. Registration procedure . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . . 6
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This document describes the "about" Uniform Resource Identifier (URI)
scheme. The "about" URI scheme is currently widely used by Web
browsers 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).
2. URI Scheme Specification
2.1. URI Scheme Syntax
The "about" URI syntactically conforms to the <about-uri> rule below,
expressed using Augmented Backus-Naur Form (ABNF) [RFC5234]:
about-uri = "about:" about-token [ about-query ] [ about-fragment ]
about-token = *pchar
about-query = "?" query
about-fragment = "#" fragment
pchar = <as specified in RFC 3986, Appendix A>
query = <as specified in RFC 3986, Appendix A>
fragment = <as specified in RFC 3986, Appendix A>
2.2. URI Scheme Semantics
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The resource which a particular "about" URI references is denoted
by <about-token> part of the URI. It is not a hierarchical element
for a naming authority. The <about-query> specifies additional
information about its handling and/or the information that should
be returned by the resource which the URI references.
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 generally
considered as specific to a Web browser implementation.
2.2.1. Well-known "about" URIs
Some <about-token>s have been reserved as the behavior when the
resource is referenced is well-known (Well-known tokens).
A well-known "about" URI is a URI that has a well-known token as
its <about-token> part. It is recommended that such URIs be
handled in accordance with the specification referenced in the
Well-known Tokens registry (see Section 5.2).
Well-known "about" URIs are intended to be registered when there is
a need to codify the behavior of particular <about-token>.
2.3. Encoding Considerations
"about" URIs are subject to encoding rules defined in RFC 3986
[RFC3986].
3. "about:blank"
This document defines one well-known token: "blank". The
"about:blank" URI refers to a resource represented in the browser
by a blank page.
4. Security Considerations
Security considerations for URIs are discussed in Section 7 of RFC
3986 [RFC3986]. However, most of those provisions do not apply to
the "about" URI scheme as they are mainly scoped to schemes used in
the Internet.
"about" URIs can sometimes refer to 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
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by "about" URIs.
5. IANA Considerations
5.1. URI Scheme Registration
The registration of the "about" URI scheme in the "URI Schemes"
registry is requested. The information below is provided according
to the guidelines from 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 that use the scheme: "about" URIs are predominantly
used by Web browsers.
Security considerations: see Section 4 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]
5.2. A Registry for Well-known Tokens
This document creates the '"about" URI Well-known Tokens' registry.
The registry entries consist of three fields: Well-known Token,
Description and Reference. The Well-known Token field has to conform
to <about-token> production defined in Section 2.1. The initial set
of assignments is as follows:
+--------------+------------------------------------+-------------+
| Well-known | Description | Reference |
| Token | | |
+------------------+--------------------------------+-------------+
| blank | The about:blank URI references a | RFC xxxx |
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| | blank page. | |
+--------------+------------------------------------+-------------+
5.2.1. Registration procedure
The registration policy for this registry is "First Come First
Served" as described in RFC 5226 [RFC5226]. The registrant of the
token should provide the information mentioned in the following
registration template:
o Registered Token: The desired Well-known token to be used in
"about" URIs.
o Intended usage: A short description of how "about" URIs with the
registered token is handled including information about the
referenced resource.
o Contact/Change controller: Person (including contact information)
authorized to change this registration.
o Specification: A stable reference to a document which specifies
the registered "about" URI. The question of interoperability does
not arise. The key motivation is to have a reference to a
specification documenting well-known behavior of the "about" URI in
Web browsers. As a rule of thumb if the behavior is common to two
or more Web browser implementations it can be considered as well-
known. An existing assignment may be duplicated if the registered
token is used in more than one Web browser implementation.
The following is a template for the "blank" token:
o Registered Token: blank
o Intended usage: The about:blank URI references a blank page.
o Contact/Change controller: IESG <iesg@ietf.org> (on behalf of
IETF).
o Specification: RFC xxxx. [RFC Editor: Please replace xxxx with
assigned RFC number]
6. References
6.1. Normative References
[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,
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May 2008.
[RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Syntax Specifications: ABNF", STD 68, RFC 5234, January
2008.
6.2. Informative References
[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
Lachlan Hunt and Joseph 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.
Lachlan Hunt and Mykyta Yevstifeyev edited previous versions of this
document. Tim Bray and John Klensin provided suggestions about how
to improve the document.
Authors' Addresses
S. Moonesamy (editor)
76, Ylang Ylang Avenue
Quatre Bornes
Mauritius
EMail: sm+ietf@elandsys.com
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