Network Working Group J. Snell Internet-Draft August 19, 2007 Intended status: Standards Track Expires: February 20, 2008 Atom Publishing Protocol Features Extension draft-snell-atompub-feature-06.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 February 20, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document introduces extensions to the Atom Publishing Protocol service document format for expressing metadata about the behaviors, functions and capabilities supported by an Atom Publishing Protocol collection. Snell Expires February 20, 2008 [Page 1] Internet-Draft APP Features August 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 3. The f:feature element . . . . . . . . . . . . . . . . . . . . 4 3.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. The f:type element . . . . . . . . . . . . . . . . . . . . . . 6 4.1. An example f:feature using the f:type element . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6.1. Registry of Atom Publishing Features . . . . . . . . . . . 7 6.1.1. Initial Assignments . . . . . . . . . . . . . . . . . 8 7. Normative References . . . . . . . . . . . . . . . . . . . . . 13 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 14 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . . . 16 Snell Expires February 20, 2008 [Page 2] Internet-Draft APP Features August 2007 1. Introduction This document introduces extensions for the Atom Publishing Protocol service document format for expressing metadata about the behaviors, functions and capabilities supported by an Atom Publishing Protocol collection. 2. Notational Conventions 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 BCP 14, [RFC2119]. This specification uses XML Namespaces [W3C.REC-xml-names-19990114] to uniquely identify XML element names. It uses the following namespace prefix for the indicated namespace URI; "f": "http://purl.org/atompub/features/1.0" This specification uses terms from the XML Infoset [W3C.REC-xml-infoset-20040204]. However, this specification uses a shorthand; the phrase "Information Item" is omitted when naming Element Information Items. Therefore, when this specification uses the terms "element" and "attribute" it is referring, respectively, to the Element and Attribute Information Items in Infoset terms. This specification uses the terms "atomUri" and "atomCommonAttributes" from the non-normative RELAX NG Compact schema included in [RFC4287]. Where used, these serve the same purpose and have the same meaning as their use in [RFC4287]. Atom allows the use of IRIs [RFC3987]. Every URI [RFC3986] is also an IRI, so a URI may be used wherever below an IRI is named. There are two special considerations: (1) when an IRI that is not also a URI is given for dereferencing, it MUST be mapped to a URI using the steps in Section 3.1 of [RFC3987] and (2) when an IRI is serving as an identifier, it MUST NOT be so mapped. Any element defined by this specification MAY have an xml:base attribute [W3C.REC-xmlbase-20010627]. When xml:base is used, it serves the function described in section 5.1.1 of [RFC3986], establishing the base URI (or IRI) for resolving any relative references found within the effective scope of the xml:base attribute. Any element defined by this specification MAY have an xml:lang attribute, whose content indicates the natural language for the Snell Expires February 20, 2008 [Page 3] Internet-Draft APP Features August 2007 element and its descendents. The language context is only significant for elements and attributes declared to be "Language- Sensitive". Requirements regarding the content and interpretation of xml:lang are specified in XML 1.0 [W3C.REC-xml-20040204], Section 2.12. 3. The f:feature element A feature is an abstract behavior, function and capability supported by an Atom Publishing Protocol collection. Examples of features that might be supported by an Atom publishing server include support for draft entries, scheduled publication of entries, use of a particular set of Atom format extensions, use of a particular authentication scheme, and so on. The f:feature element can be used in an app: collection element to indicate that the collection supports the feature specified and may require that a client wishing to use the endpoint use that feature. Features are identified using permanent, universally unique IRI's. namespace f = "http://purl.org/atompub/features/1.0" feature = element f:feature { atomCommonAttributes, attribute ref { atomUri }, attribute status { 'supported' | 'required' | 'unsupported'}?, attribute href { atomUri }?, attribute label { text }?, (anyElement)* } anyElement = element * - f:* { (attribute * { text } | text | anyElement)* } The ref attribute specifies a globally unique IRI identifying a feature supported by a collection. The value of the ref attribute MUST be compared on a case-sensitive, character-by-character basis. Relative references MUST NOT be used. The status attribute indicates a collections level of support for the identified feature. The value of the attribute can be "supported", "required" or "unsupported". If not specified, the value is assumed to be "supported". Snell Expires February 20, 2008 [Page 4] Internet-Draft APP Features August 2007 o The value "supported" indicates that the server supports the identified feature. Clients MAY utilize the feature when interacting with the collection. o The value "required" indicates that server supports the identified feature. Clients MUST utilize the feature when interacting with the collection. o The value "unsupported" indicates that the server explicitly does not support a feature. Clients SHOULD NOT utilize the feature when interacting with the collection. An optional href attribute MAY be used to specify the URI of a human- readable description of the feature. Relative references MAY be used. The optional label attribute MAY be used to specify a human-readable label for the feature. The value of the label attribute is Language- Sensitive as defined by Section 2 of [RFC4287]. The f:feature element MAY contain child elements and attributes other than those defined in this specification. Such "foreign markup" are considered to be metadata applicable to the feature identified by the f:feature element. Software agents MUST NOT stop processing or signal an error or change their behavior as a result of encountering such foreign markup. An app:collection element MAY contain zero or more f:feature elements but MUST NOT contain more than one with the same ref attribute value. The order in which f:feature elements appear within the app: collection element is insignificant. The f:feature element MAY contain attributes included as part of the atomCommonAttributes production defined by Section 2 of [RFC4287] or any update thereof. When used on an f:feature element, such attributes serve the same purpose described in [RFC4287] or their corresponding specifications. Snell Expires February 20, 2008 [Page 5] Internet-Draft APP Features August 2007 3.1. Example The following is an example of a collection supporting one hypothetical required feature, one unsupported feature, and a number of supported features. My Workspace My Atom Collection application/atom+xml;type=entry 4. The f:type element The content of an f:type element is a media-range as defined in [RFC2616]. The media range specifies a type of content that can be included in an atom:content element or referenced by the atom:content src attribute. type = element f:type { atomCommonAttributes, ( text? ) } Snell Expires February 20, 2008 [Page 6] Internet-Draft APP Features August 2007 The f:type element is similar to the HTTP Accept request-header [RFC2616]. Media type parameters are allowed within f:type, but f:type has no notion of preference - "accept-params" or "q" arguments, as specified in Section 14.1 of [RFC2616] are not significant. White space (as defined in [REC-xml]) around the f:type element's media-range is insignificant and MUST be ignored. Any number of f:type elements MAY appear as children of an f:feature element whose ref attribute identifies the "XML Content", "Binary Content" or "Reference Content" features as defined in Section 6.1.1. When used with these features, the f:type elements specify the range of media types that can be specified in the atom:content elements type attribute. If no f:type element is present, clients SHOULD treat this as equivalent to an f:type element with the content "*/*". The order of f:type elements within a f:feature element is insignificant. 4.1. An example f:feature using the f:type element image/jpg image/png image/gif text/* 5. Security Considerations Specific features supported by a collection may introduce security considerations and concerns beyond those discussed by the Atom Publishing Protocol and Atom Syndication Format specifications. Implementors must refer to the specifications and description of each feature to determine the security considerations relevant to each. 6. IANA Considerations 6.1. Registry of Atom Publishing Features The Registry of Atom Publishing Features is maintained by IANA and contains information about known features that can be supported by Snell Expires February 20, 2008 [Page 7] Internet-Draft APP Features August 2007 Atom Publishing Protocol implementations. New assignments are subject to IESG approval, as outlined in [RFC2434]. Requests should be made by email to IANA, which will then forward the request to the IESG, requesting approval. The request should use the following template: o Ref: (A globally unique IRI identifying the feature) o Label: (A human-readable label for the feature) o Description: (A human-readable description of the feature) o Href: (A URI referencing a document containing a detailed definition of the feature) o Security Considerations: 6.1.1. Initial Assignments The Registry of Features initially contains the following assignments: 6.1.1.1. Drafts o Ref: http://www.w3.org/2007/app/drafts o Label: Drafts o Description: The "Drafts" feature indicates that a collection supports the use of the app:draft control element as defined in section 13.1.1 of [I-D.ietf-atompub-protocol]. 6.1.1.2. XHTML Content o Ref: http://www.w3.org/2007/app/xhtml-content o Label: XHTML Content o Description: The "XHTML Content" feature indicates that a server will accept the use of an XHTML value within the atom:content element. 6.1.1.3. HTML Content o Ref: http://www.w3.org/2007/app/html-content o Label: HTML Content o Description: The "HTML Content" feature indicates that a server will accept the use of an escaped HTML value within the atom: content element. 6.1.1.4. Text Content o Ref: http://www.w3.org/2007/app/text-content o Label: Text Content Snell Expires February 20, 2008 [Page 8] Internet-Draft APP Features August 2007 o Description: The "Text Content" feature indicates that a server will accept the use of a plain text value within the atom:content element. 6.1.1.5. XML Content o Ref: http://www.w3.org/2007/app/xml-content o Label: XML Content o Description: The "XML Content" feature indicates that a server will accept the use of well-formed XML content within the atom: content element. 6.1.1.6. Binary Content o Ref: http://www.w3.org/2007/app/xhtml-content o Label: Binary Content o Description: The "Binary Content" feature indicates that a server will accept Base-64 encoded binary data within the atom:content element. 6.1.1.7. Referenced Content o Ref: http://www.w3.org/2007/app/ref-content o Label: XHTML Content o Description: The "Referenced Content" feature indicates that a server will accept atom:content elements that use the src attribute to reference external content resources. 6.1.1.8. XHTML Title o Ref: http://www.w3.org/2007/app/xhtml-title o Label: XHTML Title o Description: The "XHTML Title" feature indicates that a server will accept the use of an XHTML value within the atom:title element. 6.1.1.9. HTML Title o Ref: http://www.w3.org/2007/app/html-title o Label: HTML Title o Description: The "HTML Content" feature indicates that a server will accept the use of an escaped HTML value within the atom:title element. 6.1.1.10. Text Title Snell Expires February 20, 2008 [Page 9] Internet-Draft APP Features August 2007 o Ref: http://www.w3.org/2007/app/text-title o Label: Text Title o Description: The "Text Content" feature indicates that a server will accept the use of a plain text value within the atom:title element. 6.1.1.11. XHTML Summary o Ref: http://www.w3.org/2007/app/xhtml-summary o Label: XHTML Summary o Description: The "XHTML Summary" feature indicates that a server will accept the use of an XHTML value within the atom:summary element. 6.1.1.12. HTML Summary o Ref: http://www.w3.org/2007/app/html-summary o Label: HTML Summary o Description: The "HTML Summary" feature indicates that a server will accept the use of an escaped HTML value within the atom: summary element. 6.1.1.13. Text Summary o Ref: http://www.w3.org/2007/app/text-summary o Label: Text Summary o Description: The "Text Summary" feature indicates that a server will accept the use of a plain text value within the atom:summary element. 6.1.1.14. Auto Summary o Ref: http://www.w3.org/2007/app/auto-summary o Label: Auto Summary o Description: The "Auto Summary" feature indicates that a server will autogenerate the value of the atom:summary element and will either reject or ignore attempts by the client to modify the value of atom:summary. 6.1.1.15. XHTML Rights o Ref: http://www.w3.org/2007/app/xhtml-rights o Label: XHTML Rights o Description: The "XHTML Rights" feature indicates that a server will accept the use of an XHTML value within the atom:rights element. Snell Expires February 20, 2008 [Page 10] Internet-Draft APP Features August 2007 6.1.1.16. HTML Rights o Ref: http://www.w3.org/2007/app/html-rights o Label: HTML Rights o Description: The "HTML Rights" feature indicates that a server will accept the use of an escaped HTML value within the atom: rights element. 6.1.1.17. Text Rights o Ref: http://www.w3.org/2007/app/text-rights o Label: Text Rights o Description: The "Text Rights" feature indicates that a server will accept the use of a plain text value within the atom:rights element. 6.1.1.18. Authenticated Author o Ref: http://www.w3.org/2007/app/auth-author o Label: Authenticated Author o Description: The "Authenticated Author" feature indicates that a server will use the authenticated identity of the client to determine the values to use within the atom:author element. Attempts by a client to manually set or modify the author information will either be rejected or ignored by the server. 6.1.1.19. Slug o Ref: http://www.w3.org/2007/app/slug o Label: Slug o Description: The "Slug" feature indicates that a server will use the Slug request header defined in section 9.7 of [I-D.ietf-atompub-protocol] to set the URI of newly created resources. 6.1.1.20. Multiple Categories o Ref: http://www.w3.org/2007/app/multiple-categories o Label: Multiple Categories o Description: The "Multiple Categories" feature indicates that a server will accept entries that contain multiple atom:category elements. 6.1.1.21. Multiple Authors o Ref: http://www.w3.org/2007/app/multiple-authors Snell Expires February 20, 2008 [Page 11] Internet-Draft APP Features August 2007 o Label: Multiple Authors o Description: The "Multiple Authors" feature indicates that a server will accept and preserve multiple atom:author elements contained by an entry. 6.1.1.22. Multiple Contributors o Ref: http://www.w3.org/2007/app/contributors o Label: Multiple Contributors o Description: The "Multiple Contributors" feature indicates that a server will accept and preserve atom:contributor elements contained by an entry. 6.1.1.23. Preserve Infoset Label: Preserve Infoset Description: The "Preserve Infoset" feature indicates that a server will preserve the complete XML Infoset [W3C.REC-xml-infoset-20040204] of entries POST or PUT to a collection. 6.1.1.24. Preserve IDs o Ref: http://www.w3.org/2007/app/preserve-id o Label: Preserve IDs o Description: The "Preserve IDs" feature indicates that a server will preserve the value of atom:id elements as provided by a client. 6.1.1.25. Preserve Dates o Ref: http://www.w3.org/2007/app/preserve-updated o Label: Preserve Dates o Description: The "Preserve Dates" feature indicates that a server will preserve the value of the atom:updated and atom:published elements as provided by a client. 6.1.1.26. Preserve Extensions o Ref: http://www.w3.org/2007/app/preserve-extensions o Label: Preserve Extensions o Description: The "Preserve Extensions" feature indicates that a server will preserve unknown foreign markup contained within an entry. Snell Expires February 20, 2008 [Page 12] Internet-Draft APP Features August 2007 6.1.1.27. Preserve Links o Ref: http://www.w3.org/2007/app/preserve-links o Label: Preserve Links o Description: The "Preserve Links" feature indicates that a server will preserve all atom:link elements contained within an entry. 6.1.1.28. Preserve Rights o Ref: http://www.w3.org/2007/app/preserve-rights o Label: Preserve Rights o Description: The "Preserve Rights" feature indicates that a server will preserve all atom:rights elements and License Links [RFC4946] contained within an entry. 6.1.1.29. Threading o Ref: http://purl.org/syndication/thread/1.0 o Label: Threading o Description: The Feed Thread feature indicates that the APP server accepts entries that contain the in-reply-to element as defined by [RFC4685]. 6.1.1.30. Scheduled Publishing o Ref: http://www.w3.org/2007/app/scheduled-publishing o Label: Scheduled Publishing o Description: The "Scheduled Publishing" feature indicates that a collection allows clients to set the value of an entries atom: published element to some future point in time after which the entry will be made publicly visible. Prior to that time, the entry will be considered to be in a draft state and SHOULD contain an app:draft control element with a value of "yes". 7. Normative References [I-D.ietf-atompub-protocol] Hora, B. and J. Gregorio, "The Atom Publishing Protocol", draft-ietf-atompub-protocol-17 (work in progress), July 2007. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Snell Expires February 20, 2008 [Page 13] Internet-Draft APP Features August 2007 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource Identifiers (IRIs)", RFC 3987, January 2005. [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom Syndication Format", RFC 4287, December 2005. [RFC4685] Snell, J., "Atom Threading Extensions", RFC 4685, September 2006. [RFC4946] Snell, J., "Atom License Extension", RFC 4946, July 2007. [W3C.REC-xml-20040204] Maler, E., Sperberg-McQueen, C., Paoli, J., Yergeau, F., and T. Bray, "Extensible Markup Language (XML) 1.0 (Third Edition)", World Wide Web Consortium FirstEdition REC-xml- 20040204, February 2004, . [W3C.REC-xml-infoset-20040204] Tobin, R. and J. Cowan, "XML Information Set (Second Edition)", World Wide Web Consortium Recommendation REC- xml-infoset-20040204, February 2004, . [W3C.REC-xml-names-19990114] Hollander, D., Bray, T., and A. Layman, "Namespaces in XML", World Wide Web Consortium FirstEdition REC-xml- names-19990114, January 1999, . [W3C.REC-xmlbase-20010627] Marsh, J., "XML Base", World Wide Web Consortium Recommendation REC-xmlbase-20010627, June 2001, . Appendix A. Acknowledgements The author acknowledges the feedback from the other members of the IETF Atom Publishing working group during the development of this Snell Expires February 20, 2008 [Page 14] Internet-Draft APP Features August 2007 specification. Author's Address James M Snell Phone: Email: jasnell@gmail.com URI: http://snellspace.com Snell Expires February 20, 2008 [Page 15] Internet-Draft APP Features August 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 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The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Snell Expires February 20, 2008 [Page 16]