Network Working Group J. Snell
Internet-Draft June 17, 2007
Intended status: Standards Track
Expires: December 19, 2007
Atom Publishing Protocol Features Extension
draft-snell-atompub-feature-05.txt
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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
collection.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. The 'f:feature' element . . . . . . . . . . . . . . . . . . . 4
3.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5.1. Registry of Atom Publishing Features . . . . . . . . . . . 6
5.1.1. Initial Assignments . . . . . . . . . . . . . . . . . 7
6. Normative References . . . . . . . . . . . . . . . . . . . . . 12
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . . . 14
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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 in an,
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
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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 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 }?,
(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.
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.
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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.
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3.1. Example
The following is an example of a collection supporting one
hypothetical required feature and a number of optional features.
<service
xmlns="http://www.w3.org/2007/app"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:f="http://purl.org/atompub/features/1.0">
<workspace>
<atom:title>My Workspace</atom:title>
<collection href="...">
<atom:title>My Atom Collection</atom:title>
<accept>application/atom+xml;type=entry</accept>
<f:feature
ref="http://www.w3.org/2007/app/drafts" />
<f:feature
ref="http://www.w3.org/2007/app/xhtml-content" />
<f:feature
ref="http://www.w3.org/2007/app/preserve-extensions" />
<f:feature ref="http://purl.org/syndication/thread/1.0" />
<f:feature ref="http://code.google.com/apis/gdata/GoogleLogin"
href="http://code.google.com/apis/gdata/"
label="Google Login" required="yes" />
</collection>
</workspace>
</app:server>
4. 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.
5. IANA Considerations
5.1. 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
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
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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:
5.1.1. Initial Assignments
The Registry of Features initially contains the following
assignments:
5.1.1.1. Drafts - http://www.w3.org/2007/app/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].
5.1.1.2. XHTML Content - http://www.w3.org/2007/app/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.
5.1.1.3. HTML Content - http://www.w3.org/2007/app/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.
5.1.1.4. Text Content - http://www.w3.org/2007/app/text-content
o Ref: http://www.w3.org/2007/app/text-content
o Label: Text Content
o Description: The "Text Content" feature indicates that a server
will accept the use of a plain text value within the atom:content
element.
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5.1.1.5. XML Content - http://www.w3.org/2007/app/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.
5.1.1.6. Binary Content - http://www.w3.org/2007/app/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.
5.1.1.7. Referenced Content - http://www.w3.org/2007/app/src-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.
5.1.1.8. XHTML Title - http://www.w3.org/2007/app/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.
5.1.1.9. HTML Title - http://www.w3.org/2007/app/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.
5.1.1.10. Text Title - http://www.w3.org/2007/app/text-title
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.
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5.1.1.11. XHTML Summary - http://www.w3.org/2007/app/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.
5.1.1.12. HTML Summary - http://www.w3.org/2007/app/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.
5.1.1.13. Text Summary - http://www.w3.org/2007/app/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.
5.1.1.14. Auto Summary - http://www.w3.org/2007/app/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.
5.1.1.15. XHTML Rights - http://www.w3.org/2007/app/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.
5.1.1.16. HTML Rights - http://www.w3.org/2007/app/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.
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5.1.1.17. Text Rights - http://www.w3.org/2007/app/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.
5.1.1.18. Authenticated Author - http://www.w3.org/2007/app/auth-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.
5.1.1.19. Slug - http://www.w3.org/2007/app/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.
5.1.1.20. Multiple Categories -
http://www.w3.org/2007/app/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.
5.1.1.21. Multiple Authors -
http://www.w3.org/2007/app/multiple-authors
o Ref: http://www.w3.org/2007/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.
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5.1.1.22. Multiple Contributors -
http://www.w3.org/2007/app/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.
5.1.1.23. Preserve Infoset -
http://www.w3.org/2007/app/preserve-infoset
Label: Preserve Infoset
Description: The "Preserve Infoset" feature indicates that a server
will preserve the complete XML XML Infoset
[W3C.REC-xml-infoset-20040204] of entries POST or PUT to a
collection.
5.1.1.24. Preserve IDs - http://www.w3.org/2007/app/preserve-id
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.
5.1.1.25. Preserve Dates - http://www.w3.org/2007/app/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.
5.1.1.26. Preserve Extensions -
http://www.w3.org/2007/app/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.
5.1.1.27. Preserve Links - http://www.w3.org/2007/app/preserve-links
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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.
5.1.1.28. Preserve Rights - http://www.w3.org/2007/app/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
[I-D.snell-atompub-feed-license] contained within an entry.
5.1.1.29. Threading - http://purl.org/syndication/thread/1.0
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. Normative References
[I-D.ietf-atompub-protocol]
Hora, B. and J. Gregorio, "The Atom Publishing Protocol",
draft-ietf-atompub-protocol-15 (work in progress),
May 2007.
[I-D.snell-atompub-feed-license]
Snell, J., "Atom License Extension",
draft-snell-atompub-feed-license-11 (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.
[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.
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[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.
[W3C.REC-xml-20040204]
Yergeau, F., Maler, E., Bray, T., Paoli, J., and C.
Sperberg-McQueen, "Extensible Markup Language (XML) 1.0
(Third Edition)", World Wide Web Consortium
FirstEdition REC-xml-20040204, February 2004,
<http://www.w3.org/TR/2004/REC-xml-20040204>.
[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,
<http://www.w3.org/TR/2004/REC-xml-infoset-20040204>.
[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,
<http://www.w3.org/TR/1999/REC-xml-names-19990114>.
[W3C.REC-xmlbase-20010627]
Marsh, J., "XML Base", World Wide Web Consortium
Recommendation REC-xmlbase-20010627, June 2001,
<http://www.w3.org/TR/2001/REC-xmlbase-20010627>.
Appendix A. Acknowledgements
The author acknowledges the feedback from Elias Torres, Robert Yates,
David Johnson, Byrne Reese, Joe Gregorio, Bill de hO`ra and the other
members of the IETF Atom Publishing working group during the
development of this specification.
Author's Address
James M Snell
Phone:
Email: jasnell@gmail.com
URI: http://snellspace.com
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Full Copyright Statement
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contained in BCP 78, and except as set forth therein, the authors
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