Network Working Group J. Snell Internet-Draft March 19, 2007 Intended status: Standards Track Expires: September 20, 2007 Atom Publishing Protocol Features Extension draft-snell-atompub-feature-02.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 September 20, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document introduces extensions to the Atom Publishing Protocol introspection format for expressing metadata about the behaviors, functions and capabilities supported by an Atom Publishing Protocol server implementation. Snell Expires September 20, 2007 [Page 1] Internet-Draft APP Features March 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 3. Feature Introspection and the 'f:feature' element . . . . . . 3 3.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Publishing Controls and the 'f:control' element . . . . . . . 5 4.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6.1. Registry of Features and Controls . . . . . . . . . . . . 8 6.1.1. Initial Assignments . . . . . . . . . . . . . . . . . 8 7. Normative References . . . . . . . . . . . . . . . . . . . . . 15 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . . . 17 Snell Expires September 20, 2007 [Page 2] Internet-Draft APP Features March 2007 1. Introduction This document introduces extensions for the Atom Publishing Protocol introspection format for expressing metadata about the behaviors, functions and capabilities supported by an Atom Publishing Protocol server implementation. 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. 3. Feature Introspection and the 'f:feature' element A feature is an abstract behavior, function and capability supported by an Atom Publishing Protocol server. Examples of features that might be supported by an APP 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 presence of a f:feature element in an app:collection element is an indication 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. feature = element f:feature { atomCommonAttributes, attribute ref { atomUri }, attribute required { 'yes' | 'no' }?, attribute href { atomURI }?, attribute label { text }?, (extensionElement*) Snell Expires September 20, 2007 [Page 3] Internet-Draft APP Features March 2007 } The "ref" attribute specifies an 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. A 'required' attribute value of "yes" indicates that clients MUST utilize the identified feature when interacting with the collection. A server MAY reject requests from clients that do not support or use the feature. If not specified, the value is assumed to be "no". 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 appears is insignificant. Snell Expires September 20, 2007 [Page 4] Internet-Draft APP Features March 2007 3.1. Example The following is an example of a collection supporting one required and one optional feature. ... 4. Publishing Controls and the 'f:control' element Publishing Controls are a mechanism provided by the Atom Publishing Protocol to embed metadata within atom:entry elements designed to influence the way a server processes the entry. The app:control element is provided as a convenient container for this metadata within an atom:entry. The Atom Publishing Protocol does not define a mechanism by which clients can discover which publishing controls a server supports. The presence of a f:control element in an app:collection element is an indication that the collection supports the control and may require that a client wishing to use the endpoint use that control. Controls are identified using permanent, universally unique IRI's. control = element f:control { atomCommonAttributes, attribute ref { atomUri }, attribute required { 'yes' | 'no' }?, attribute href { atomURI }?, attribute label { text }?, (extensionElement*) } Snell Expires September 20, 2007 [Page 5] Internet-Draft APP Features March 2007 The "ref" attribute specifies an globally unique IRI identifying a control 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. A 'required' attribute value of "yes" indicates that clients MUST utilize the identified control when interacting with the collection. A server MAY reject requests from clients that do not support or use the control. If not specified, the value is assumed to be "no". An optional 'href' attribute MAY be used to specify the URI of a human-readable description of the control. Relative references MAY be used. The optional 'label' attribute MAY be used to specify a human- readable label for the control. The value of the 'label' attribute is Language-Sensitive as defined by Section 2 of [RFC4287]. The f:control 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 control identified by the f:control 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:control elements but MUST NOT contain more than one with the same ref attribute value. The order in which f:control elements appear is insignificant. Snell Expires September 20, 2007 [Page 6] Internet-Draft APP Features March 2007 4.1. Example The following is an example of a collection supporting one required and one optional control. ... markdown wiki line-breaks An example atom:entry using the listed controls could appear as: ... yes markdown line-breaks ... 5. Security Considerations Specific features and controls 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 and control to determine the security considerations relevant to each. Snell Expires September 20, 2007 [Page 7] Internet-Draft APP Features March 2007 6. IANA Considerations 6.1. Registry of Features and Controls The Registry of Features and Controls is maintained by IANA and contains information about known features and controls that can be supported by 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 Type: ("Control" or "Feature") o Ref: (A globally unique IRI identifying the control or feature) o Label: (A human-readable label for the feature) o Description: o Href: (A URI referencing a document containing a detailed definition of the control or feature) o Security Considerations: 6.1.1. Initial Assignments The Registry of Features and Controls initially contains the following assignments: 6.1.1.1. Drafts - http://purl.org/atom/app#drafts o Type: Feature o Ref: http://purl.org/atom/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]. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.2. Preserve Entries - http://purl.org/atom/app#preserve-entry o Type: Feature o Ref: http://purl.org/atom/app#preserve-entry o Label: Preserve Entries o Description: The "Preserve Entries" feature indicates that a server will preserve the semantic content of entries POST and PUT to the collection without modification. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt Snell Expires September 20, 2007 [Page 8] Internet-Draft APP Features March 2007 o Security Considerations: 6.1.1.3. Preserve IDs - http://purl.org/atom/app#preserve-id o Type: Feature o Ref: http://purl.org/atom/app#preserve-id o Label: Preserve IDs o Description: The "Preserve IDs" feature indicates that a server will preserve the atom:id of entries POSTed to a collection. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.4. XHTML Content - http://purl.org/atom/app#xhtml-content o Type: Feature o Ref: http://purl.org/atom/app#xhtml-content o Label: XHTML Content o Description: The "XHTML Content" feature indicates that a server will accept XHTML within the atom:content element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.5. HTML Content - http://purl.org/atom/app#html-content o Type: Feature o Ref: http://purl.org/atom/app#html-content o Label: HTML Content o Description: The "HTML Content" feature indicates that a server will accept escaped HTML within the atom:content element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.6. Text Content - http://purl.org/atom/app#text-content o Type: Feature o Ref: http://purl.org/atom/app#text-content o Label: Text Content o Description: The "Text Content" feature indicates that a server will accept plain text within the atom:content element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: Snell Expires September 20, 2007 [Page 9] Internet-Draft APP Features March 2007 6.1.1.7. Binary Content - http://purl.org/atom/app#binary-content o Type: Feature o Ref: http://purl.org/atom/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. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.8. Referenced Content - http://purl.org/atom/app#ref-content o Type: Feature o Ref: http://purl.org/atom/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. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.9. XHTML Title - http://purl.org/atom/app#xhtml-title o Type: Feature o Ref: http://purl.org/atom/app#xhtml-title o Label: XHTML Title o Description: The "XHTML Title" feature indicates that a server will accept XHTML within the atom:title element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.10. HTML Title - http://purl.org/atom/app#html-title o Type: Feature o Ref: http://purl.org/atom/app#html-title o Label: HTML Title o Description: The "HTML Content" feature indicates that a server will accept escaped HTML within the atom:title element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: Snell Expires September 20, 2007 [Page 10] Internet-Draft APP Features March 2007 6.1.1.11. Text Title - http://purl.org/atom/app#text-title o Type: Feature o Ref: http://purl.org/atom/app#text-title o Label: Text Title o Description: The "Text Content" feature indicates that a server will accept plain text within the atom:title element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.12. XHTML Summary - http://purl.org/atom/app#xhtml-summary o Type: Feature o Ref: http://purl.org/atom/app#xhtml-summary o Label: XHTML Summary o Description: The "XHTML Summary" feature indicates that a server will accept XHTML within the atom:summary element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.13. HTML Summary - http://purl.org/atom/app#html-summary o Type: Feature o Ref: http://purl.org/atom/app#html-summary o Label: HTML Summary o Description: The "HTML Summary" feature indicates that a server will accept escaped HTML within the atom:summary element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.14. Text Summary - http://purl.org/atom/app#text-summary o Type: Feature o Ref: http://purl.org/atom/app#text-summary o Label: Text Summary o Description: The "Text Summary" feature indicates that a server will accept plain text within the atom:summary element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.15. Auto Summary - http://purl.org/atom/app#auto-summary Snell Expires September 20, 2007 [Page 11] Internet-Draft APP Features March 2007 o Type: Feature o Ref: http://purl.org/atom/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. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.16. XHTML Rights - http://purl.org/atom/app#xhtml-rights o Type: Feature o Ref: http://purl.org/atom/app#xhtml-rights o Label: XHTML Rights o Description: The "XHTML Rights" feature indicates that a server will accept XHTML within the atom:rights element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.17. HTML Rights - http://purl.org/atom/app#html-rights o Type: Feature o Ref: http://purl.org/atom/app#html-rights o Label: HTML Rights o Description: The "HTML Rights" feature indicates that a server will accept escaped HTML within the atom:rights element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.18. Text Rights - http://purl.org/atom/app#text-rights o Type: Feature o Ref: http://purl.org/atom/app#text-rights o Label: Text Rights o Description: The "Text Rights" feature indicates that a server will accept plain text within the atom:rights element. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.19. Authenticated Author - http://purl.org/atom/app#auth-author Snell Expires September 20, 2007 [Page 12] Internet-Draft APP Features March 2007 o Type: Feature o Ref: http://purl.org/atom/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. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.20. Preserve Updated - http://purl.org/atom/app#preserve-updated o Type: Feature o Ref: http://purl.org/atom/app#preserve-updated o Label: Preserve Updated o Description: The "Preserve Updated" feature indicates that a server will preserve the value of the atom:updated element provided by a client. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.21. Preserve Extensions - http://purl.org/atom/app#preserve-extensions o Type: Feature o Ref: http://purl.org/atom/app#preserve-extensions o Label: Preserve Extensions o Description: The "Preserve Extensions" feature indicates that a server will preserve arbitrary unknown foreign markup contained within an entry. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.22. Preserve Links - http://purl.org/atom/app#preserve-links o Type: Feature o Ref: http://purl.org/atom/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. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt Snell Expires September 20, 2007 [Page 13] Internet-Draft APP Features March 2007 o Security Considerations: 6.1.1.23. Slug - http://purl.org/atom/app#slug o Type: Feature o Ref: http://purl.org/atom/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. o Security Considerations: 6.1.1.24. Multiple Categories - http://purl.org/atom/app#multiple-categories o Type: Feature o Ref: http://purl.org/atom/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. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.25. Contributors - http://purl.org/atom/app#contributors o Type: Feature o Ref: http://purl.org/atom/app#contributors o Label: Contributors o Description: The "Contributors" feature indicates that a server will accept and preserve atom:contributor elements contained by an entry. o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 6.1.1.26. Multiple Authors - http://purl.org/atom/app#multiple-authors o Type: Feature o Ref: http://purl.org/atom/app#multiple-authors 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. Snell Expires September 20, 2007 [Page 14] Internet-Draft APP Features March 2007 o Href: http://www.ietf.org/internet-drafts/ draft-ietf-atompub-protocol-14.txt o Security Considerations: 7. Normative References [I-D.ietf-atompub-protocol] Hora, B. and J. Gregorio, "The Atom Publishing Protocol", draft-ietf-atompub-protocol-14 (work in progress), March 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. [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom Syndication Format", RFC 4287, December 2005. [W3C.REC-xml-infoset-20040204] Cowan, J. and R. Tobin, "XML Information Set (Second Edition)", World Wide Web Consortium Recommendation REC- xml-infoset-20040204, February 2004, . [W3C.REC-xml-names-19990114] Layman, A., Hollander, D., and T. Bray, "Namespaces in XML", World Wide Web Consortium FirstEdition REC-xml- names-19990114, January 1999, . Appendix A. Acknowledgements The author acknowledges the feedback from Elias Torres, Robert Yates, David Johnson, Byrne Reese, Joe Gregorio and the other members of the IETF Atom Publishing working group during the development of this specification. Snell Expires September 20, 2007 [Page 15] Internet-Draft APP Features March 2007 Author's Address James M Snell Phone: Email: jasnell@gmail.com URI: http://snellspace.com Snell Expires September 20, 2007 [Page 16] Internet-Draft APP Features March 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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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 September 20, 2007 [Page 17]