Network Working Group J. Holsten Internet-Draft Intended status: Informational L. Hunt Expires: November 9, 2009 Opera Software, ASA. May 8, 2009 The 'about' URI scheme draft-holsten-about-uri-scheme-01 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 other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on November 9, 2009. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Abstract This document specifies the URI (Uniform Resource Identifier) scheme "about". About URIs are designed to be an internal, application- Holsten & Hunt Expires November 9, 2009 [Page 1] Internet-Draft The 'about' URI scheme May 2009 level identifier. Unlike many other URI schemes, the resolution of, and resources represented by, about URIs are left entirely to each individual application. 1. Editorial Note (To be removed by RFC Editor) Discussion of this draft should take place on the URI Review mailing list (uri-review@ietf.org). 2. Introduction An about URI is designed to be used internally by applications for almost any desired purpose. Such URIs have commonly been used by web browsers for providing access to built-in functionality, such as application information, preferences, settings, or "easter eggs". While any number of existing schemes could be used to identify such resources, about URIs have become the de facto standard. Browsers already use the about scheme. The about:blank (Section 4.1) URI is ubiquitous, and some browsers also provide other resources with the about scheme, including those in Section 4.2. 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 [RFC2119]. 3. URI Syntax The general syntax of a about URI, in ABNF [RFC5234] is: abouturi = "about:" segment [ "?" query ] [ "#" fragment ] where "segment", "query", and "fragment" are imported from [RFC3986]. In the interests of tractability to humans, about URIs SHOULD NOT be minted with percent-encoded parts. However, the about URI syntax does allow percent-encoded characters in the "pchar" elements defined in [RFC3986]. No relative URI syntax is defined. 4. Resolving About URIs In general, applications are free to resolve any about URI to any resource, either internal or external, or redirect to an alternative URI, with about:blank being the only exception. As about URIs are designed to be internal to each application, there Holsten & Hunt Expires November 9, 2009 [Page 2] Internet-Draft The 'about' URI scheme May 2009 is no expectation of any URI, except about:blank, returning the same resource among different applications. However, it is worth noting that some conventions have arisen for providing particular functionality via common about URIs. Because about URIs identify application specific information, applications SHOULD NOT need to retrieve remote information for such a resource. The about:blank URI is the only about URI reserved by this specification. 4.1. about:blank Applications resolving this URI MUST return an empty resource, with the media type "text/html" and the character encoding "UTF-8". 4.2. Examples The following examples illustrate some known URIs supported by existing applications. They are not guaranteed to be resolvable by every application. about:config Commonly provides access to application preferences and settings about:cache Commonly provides access to information about resources stored in the browsers cache. about:plugins Commonly provides access to information about installed plugins about:mozilla An easter egg supported by Mozilla showing a passage from the fictional Book of Mozilla Applications are also permitted to redirect such URIs. For example, Opera redirects all about: URIs, with the exception of about:blank, to the equivalent URI using their internal opera: scheme. e.g. about: config redirects to opera:config. This is not an exhaustive list. Many more are supported by numerous applications. For more examples, consult Wikipedia's entry on the "about: URI Scheme" [wikiabout]. 5. Security Considerations About URIs SHOULD NOT cause the application to modify any data. Applications SHOULD NOT use about URIs to access or erase files or Holsten & Hunt Expires November 9, 2009 [Page 3] Internet-Draft The 'about' URI scheme May 2009 other sensitive information. About URIs MAY identify resources which show sensitive information. Applications SHOULD ensure appropriate restrictions are in place to protect such information from access or modification by untrusted sources. The HTML representation of the URI about:blank MUST use the origin and the effective script origin as defined by HTML5 Section 5.4 Origin [W3C.WD-html5]. The origin of the about:blank Document is set when the Document is created. If the new browsing context has a creator browsing context, then the origin of the about:blank Document is the origin of the creator Document. Otherwise, the origin of the about:blank Document is a globally unique identifier assigned when the new browsing context is created. 6. IANA Considerations This specification requests the IANA permanently register the about URI scheme as specified in this document and summarized in the following template, per [RFC4395]: URI scheme name: about Status: Provisional URI scheme syntax: See Section 3 URI scheme semantics: See Section 2 Encoding considerations: Percent-encoding is allowed in 'segment' components (see Section 3) Intended usage: See Section 2 Applications and/or protocols that use this URI scheme name: Any applications that use URIs as identifiers for private resources, such as web browsers. Interoperability considerations: Applications are only required to support about:blank, and may choose to interpret other about URIs differently. Security considerations: See Section 5 Holsten & Hunt Expires November 9, 2009 [Page 4] Internet-Draft The 'about' URI scheme May 2009 Relevant publications: None Contact: Joseph Holsten (joseph@josephholsten.com) Author/Change controller: Joseph Holsten 7. Acknowledgements This document was made possible thanks to the input of Henri Sivonen, Ian Hickson and Larry Masinter. 8. References 8.1. Normative References [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [W3C.WD-html5] Hickson, I. and D. Hyatt, "HTML 5", World Wide Web Consortium TR html5, February 2009, . 8.2. Informative References [RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and Registration Procedures for New URI Schemes", BCP 35, RFC 4395, February 2006. [wikiabout] Wikipedia, The Free Encyclopedia, "About: URI scheme", March 2009. Authors' Addresses Joseph Anthony Pasquale Holsten EMail: joseph@josephholsten.com URI: http://josephholsten.com Holsten & Hunt Expires November 9, 2009 [Page 5] Internet-Draft The 'about' URI scheme May 2009 Lachlan Hunt Opera Software, ASA. EMail: lachlan.hunt@lachy.id.au URI: http://lachy.id.au/ Holsten & Hunt Expires November 9, 2009 [Page 6]