Network Working Group J. Snell
Internet-Draft September 10, 2007
Intended status: Standards Track
Expires: March 13, 2008
Atom Publishing Protocol Features Extension
draft-snell-atompub-feature-09.txt
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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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. The f:feature element . . . . . . . . . . . . . . . . . . . . 4
3.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2. Contradictory Features . . . . . . . . . . . . . . . . . . 7
4. The f:type element . . . . . . . . . . . . . . . . . . . . . . 8
4.1. An example f:feature using the f:type element . . . . . . 9
5. Digitally Signing Service Documents . . . . . . . . . . . . . 9
6. The "http://purl.org/atompub/features/1.0" Namespace . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8.1. Registry of Atom Publishing Features . . . . . . . . . . . 10
8.1.1. Initial Assignments . . . . . . . . . . . . . . . . . 11
9. Normative References . . . . . . . . . . . . . . . . . . . . . 24
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 25
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 25
Intellectual Property and Copyright Statements . . . . . . . . . . 27
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1. Introduction
This document introduces extensions for the Atom Publishing Protocol
service document [I-D.ietf-atompub-protocol] 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-20060816]
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
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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-20060816], 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 declare that a collection supports the feature
specified and may require that a client use that feature when
interacting with the endpoint. 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' | 'preferred' |
'required' | 'unsupported'}?,
attribute href { atomUri }?,
attribute label { text }?,
(anyElement)*
}
anyElement = element * - f:feature {
(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 collection's level of support for
the identified feature. The value of the attribute can be
"supported", "preferred", "required" or "unsupported". If not
specified, the value is assumed to be "supported". If any value
other than those listed in this specification is specified, the
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attribute MUST be interpreted as being "supported".
Support attribute values are case-insenstive.
o The value "supported" indicates that the server supports the
identified feature. Clients MAY utilize the feature when
interacting with the collection. If the client does not support
or recognize a "supported" feature, the client can safely ignore
it.
o The value "preferred" indicates that the server prefers the use of
the identified feature over other contradictory features or over
not using the feature at all. The "preferred" support level is
applicable to any feature the "supported" level can be applied to.
Clients SHOULD utilize the feature when interacting with the
collection.
o The value "required" indicates that server supports the identified
feature and requires that clients utilize it when interacting with
a collection. A client that does not support or understand a
required feature SHOULD NOT attempt to interact 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.
Some features supported by a collection might not require that the
client take any specific action when interacting with the server.
For such features, the "required" and "preferred" support levels
SHOULD be considered to be synonymous with "supported".
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 any number of child elements and
attributes from any XML namespace, with the exception of the
f:feature element itself. Such markup is 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 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.
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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.
It is important to point out that implementors who add "required"
features to existing collections can cause existing client
applications to fail and can limit the ability of client applications
to evolve independently of a specific server implementation. A
better strategy would be to indicate that new features are
"preferred". Doing so can allow existing clients to continue to
function while communicating the servers preference that new clients
utilize the new feature.
Server implementors also need to remember that, as an extension to
the Service Document syntax, not all Atom Publishing Protocol client
applications will recognize and support the use of the f:feature
element. Such clients will be incapable of determining which
features are supported, preferred, or required.
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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.
<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"
support="preferred" />
<f:feature
ref="http://www.w3.org/2007/app/html-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://www.w3.org/2007/app/binary-content"
status="unsupported" />
<f:feature
ref="http://code.google.com/apis/gdata/GoogleLogin"
href="http://code.google.com/apis/gdata/"
label="Google Login" status="required" />
</collection>
</workspace>
</service>
3.2. Contradictory Features
Some combinations of features can be contradictory when the support
level of one or more of those features is "required" and the others
are "supported" or "preferred". For instance, a collection that
specifies that XHTML values in the atom:title is required and that
HTML in an atom:title is supported is contradictory. Such
contradictions can cause problems for clients that are attempting to
select an appropriate collection based on the support level of
various features. A service document MUST NOT specify contradictory
features. If a client determines that the features specified in a
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service document are contradictory, the client SHOULD proceed as if
the support level for each of those features is "supported".
When multiple, potentially contradictory features are specified such
that the support level for one is marked as "preferred" and the
others are "supported", clients SHOULD use the "preferred" feature.
If more than one potentially contradictory feature is marked as
"preferred", the client SHOULD proceed as if the support level for
each of those features is "supported".
4. The f:type element
The content of an f:type element is a media-range as defined in
[RFC2616].
type =
element f:type {
atomCommonAttributes,
( text? )
}
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 [W3C.REC-xml-20060816]) 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. When used with features whose ref attributes identify the
"XML Content", "Binary Content" or "Reference Content" features as
defined in Section 6.1.1, the f:type elements specify the set of
media types that can be specified in the atom:content elements type
attribute and thereby the type of content that be included within or
referenced by the atom:content. If no f:type elements are specified
for these features, 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.
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4.1. An example f:feature using the f:type element
<f:feature
ref="http://www.w3.org/2007/app/binary-content">
<f:type>image/jpg</f:type>
<f:type>image/png</f:type>
<f:type>image/gif</f:type>
<f:type>text/*</f:type>
</f:feature>
5. Digitally Signing Service Documents
Because the mechanisms defined in this specification can be used to
compel client applications to implement certain behaviors when
interacting with a collection, implementors who specify required
features are encouraged to sign Service Documents containing the
features extension using an Enveloped Signature, as described by XML-
Signature and Syntax Processing [W3C.REC-xmldsig-core-20020212].
Processors of Service Documents MUST NOT reject signed documents
because they are not capable of verifying it; they MUST continue
processing and MAY inform the user of their failure to validate the
signature. In other words, the presence of an element with the
namespace URI "http://www.w3.org/2000/09/xmldsig#" and a local name
of "Signature" as a child of the document element MUST NOT cause a
Processor to fail merely because of its presence.
Section 6.5.1 of [W3C.REC-xmldsig-core-20020212] requires support for
Canonical XML [W3C.REC-xml-c14n-20010315]. However, many
implementers do not use it because signed XML documents enclosed in
other XML documents have their signatures broken. Thus, Processors
that verify signed Service Documents MUST be able to canonicalize
with the exclusive XML canonicalization method identified by the URI
"http://www.w3.org/2001/10/xml-exc-c14n#", as specified in Exclusive
XML Canonicalization [W3C.REC-xml-exc-c14n-20020718].
Section 4.4.2 of [W3C.REC-xmldsig-core-20020212] requires support for
DSA signatures and recommends support for RSA signatures. However,
because of the much greater popularity in the market of RSA versus
DSA, Processors that verify signed Atom Service Documents MUST be
able to verify RSA signatures, but do not need be able to verify DSA
signatures. Due to security issues that can arise if the keying
material for message authentication code (MAC) authentication is not
handled properly, Service Documents SHOULD NOT use MACs for
signatures.
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6. The "http://purl.org/atompub/features/1.0" Namespace
The "http://purl.org/atompub/features/1.0" XML namespace is reserved
for future forward-compatible revisions of this specification.
Future updates to this document can add new elements and attributes
to the namespace. Software written to conform to this version of the
specification will not be able to process such markup correctly and,
in fact, will not be able to distinguish it from markup error.
Processors that encounter such markup MUST NOT stop processing or
signal an error. It might be the case that the Processor is able to
handle such markup correctly, and does so. Otherwise, processors MAY
bypass the markup and MUST NOT change their behavior as a result of
the markups presence.
7. 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.
Service documents can be signed using [W3C.REC-xmldsig-core-20020212]
and are subject to the security considerations implied by its use.
Digital signatures provide authentication, message integrity, and
non-repudiation with proof of origin.
8. IANA Considerations
8.1. 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
template:
o Ref: (A globally unique IRI identifying the feature)
o Label: (A human-readable label for the feature)
o Support Levels: (A description of the relevant support levels for
the feature)
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o Contradictory Features: (A listing of features that are
contradictory to this feature when one or more are marked as
"required")
o Href: (A URI referencing a document containing a detailed
definition of the feature)
o Security Considerations:
8.1.1. Initial Assignments
The Registry of Features initially contains the following
assignments:
8.1.1.1. Drafts
o Ref: http://www.w3.org/2007/app/drafts
o Label: Drafts
o Support Levels:
* "supported" indicates that the collection accepts entries that
contain the app:draft control element.
* "required" indicates that the collection requires all entries
to contain the app:draft control element.
* "unsupported" indicates that the collection does not accept
entries that use the app:draft control element or that the
server will ignore the element if present.
o Contradictory Features: none
8.1.1.2. XHTML Content
o Ref: http://www.w3.org/2007/app/xhtml-content
o Label: XHTML Content
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide XHTML in the atom:content element.
* "required" indicates that the collection requires all entries
to provide XHTML in the atom:content element.
* "unsupported" indicates that the collection does not accept
entries that provide XHTML in the atom:content element.
o Contradictory Features: http://www.w3.org/2007/app/html-content,
http://www.w3.org/2007/app/text-content,
http://www.w3.org/2007/app/xml-content,
http://www.w3.org/2007/app/binary-content,
http://www.w3.org/2007/app/ref-content
8.1.1.3. HTML Content
o Ref: http://www.w3.org/2007/app/html-content
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o Label: HTML Content
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide HTML in the atom:content element.
* "required" indicates that the collection requires all entries
to provide HTML in the atom:content element.
* "unsupported" indicates that the collection does not accept
entries that provide HTML in the atom:content element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-content,
http://www.w3.org/2007/app/text-content,
http://www.w3.org/2007/app/xml-content,
http://www.w3.org/2007/app/binary-content,
http://www.w3.org/2007/app/ref-content
8.1.1.4. Text Content
o Ref: http://www.w3.org/2007/app/text-content
o Label: Text Content
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide plain text in the atom:content element.
* "required" indicates that the collection requires all entries
to provide plain text in the atom:content element.
* "unsupported" indicates that the collection does not accept
entries that provide plain text in the atom:content element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-content,
http://www.w3.org/2007/app/html-content,
http://www.w3.org/2007/app/xml-content,
http://www.w3.org/2007/app/binary-content,
http://www.w3.org/2007/app/ref-content
8.1.1.5. XML Content
o Ref: http://www.w3.org/2007/app/xml-content
o Label: XML Content
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide well-formed XML in the atom:content element.
* "required" indicates that the collection requires all entries
to provide well-formed XML in the atom:content element.
* "unsupported" indicates that the collection does not accept
entries that provide XML in the atom:content element. The MIME
media type of acceptable XML formats is specified using one or
more f:type elements within the f:feature.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-content,
http://www.w3.org/2007/app/html-content,
http://www.w3.org/2007/app/text-content,
http://www.w3.org/2007/app/binary-content,
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http://www.w3.org/2007/app/ref-content
8.1.1.6. Binary Content
o Ref: http://www.w3.org/2007/app/binary-content
o Label: Binary Content
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide binary content in the atom:content element.
* "required" indicates that the collection requires all entries
to provide binary content in the atom:content element.
* "unsupported" indicates that the collection does not accept
entries that provide binary content in the atom:content
element. The MIME media type of acceptable binary formats is
specified using one or more f:type elements within the
f:feature.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-content,
http://www.w3.org/2007/app/html-content,
http://www.w3.org/2007/app/text-content,
http://www.w3.org/2007/app/xml-content,
http://www.w3.org/2007/app/ref-content
8.1.1.7. Referenced Content
o Ref: http://www.w3.org/2007/app/ref-content
o Label: XHTML Content
o Support Levels:
* "supported" indicates that the collection accepts entries that
use the atom:content src attribute to reference external
content.
* "required" indicates that the collection requires all entries
to use the atom:content src attribute to reference external
content.
* "unsupported" indicates that the collection does not accept
entries that use the atom:content src attribute. The MIME
media type of acceptable referenced resources is specified
using one or more f:type elements within the f:feature.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-content,
http://www.w3.org/2007/app/html-content,
http://www.w3.org/2007/app/text-content,
http://www.w3.org/2007/app/xml-content,
http://www.w3.org/2007/app/binary-content
8.1.1.8. XHTML Title
o Ref: http://www.w3.org/2007/app/xhtml-title
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o Label: XHTML Title
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide XHTML in the atom:title element.
* "required" indicates that the collectionrequires all entries to
provide XHTML in the atom:title element.
* "unsupported" indicates that the collection does not accept
entries that provide XHTML in the atom:title element.
o Contradictory Features: http://www.w3.org/2007/app/html-title,
http://www.w3.org/2007/app/text-title
8.1.1.9. HTML Title
o Ref: http://www.w3.org/2007/app/html-title
o Label: HTML Title
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide HTML in the atom:title element.
* "required" indicates that the collection requires all entries
to provide HTML in the atom:title element.
* "unsupported" indicates that the collection does not accept
entries that provide HTML in the atom:title element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-title,
http://www.w3.org/2007/app/text-title
8.1.1.10. Text Title
o Ref: http://www.w3.org/2007/app/text-title
o Label: Text Title
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide plain text in the atom:title element.
* "required" indicates that the collection requires all entries
to provide plain text in the atom:title element.
* "unsupported" indicates that the collection does not accept
entries that provide plain text in the atom:title element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-title,
http://www.w3.org/2007/app/html-title
8.1.1.11. Summary
o Ref: http://www.w3.org/2007/app/summary
o Label: Summary
o Support Levels:
* "supported" indicates that the server will allow the use of the
atom:summary element to provide a summary or excerpt that is
independent of the atom:content.
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* "required" indicates that the server requires the presence of
an atom:summary element to provide a summary or excerpt that is
independent of the atom:content.
* "unsupported" indicates that the server does not support the
use of the atom:summary element to provide a summary or excerpt
independent of the atom:content. When an atom:summary is
provided by a client, the server will either reject the request
or ignore the element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary,
http://www.w3.org/2007/app/html-summary,
http://www.w3.org/2007/app/text-summary
8.1.1.12. Auto Summary
o Ref: http://www.w3.org/2007/app/auto-summary
o Label: Auto Summary
o Support Levels:
* "supported" indicates that the server will automatically
generate an atom:summary element if the entry provided by the
client does not already contain one.
* For this feature,"required" and "preferred" are synonymous with
"supported".
* "unsupported" indicates that the server will not automatically
generate an atom:summary element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary,
http://www.w3.org/2007/app/html-summary,
http://www.w3.org/2007/app/text-summary
8.1.1.13. XHTML Summary
o Ref: http://www.w3.org/2007/app/xhtml-summary
o Label: XHTML Summary
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide XHTML in the atom:summary element.
* "required" indicates that the collection requires all entries
to provide XHTML in the atom:summary element.
* "unsupported" indicates that the collection does not accept
entries that provide XHTML in the atom:summary element.
o Contradictory Features: http://www.w3.org/2007/app/html-summary,
http://www.w3.org/2007/app/text-summary
8.1.1.14. HTML Summary
o Ref: http://www.w3.org/2007/app/html-summary
o Label: HTML Summary
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o Support Levels:
* "supported" indicates that the collection accepts entries that
provide HTML in the atom:summary element.
* "required" indicates that the collection requires all entries
to provide HTML in the atom:summary element.
* "unsupported" indicates that the collection does not accept
entries that provide HTML in the atom:summary element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary,
http://www.w3.org/2007/app/text-summary
8.1.1.15. Text Summary
o Ref: http://www.w3.org/2007/app/text-summary
o Label: Text Summary
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide plain text in the atom:summary element.
* "required" indicates that the collection requires all entries
to provide plain text in the atom:summary element.
* "unsupported" indicates that the collection does not accept
entries that provide plain text in the atom:summary element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary,
http://www.w3.org/2007/app/html-summary
8.1.1.16. XHTML Rights
o Ref: http://www.w3.org/2007/app/xhtml-rights
o Label: XHTML Rights
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide XHTML in the atom:rights element.
* "required" indicates that the collection requires all entries
to provide XHTML in the atom:rights element.
* "unsupported" indicates that the collection does not accept
entries that provide XHTML in the atom:rights element.
o Contradictory Features: http://www.w3.org/2007/app/html-rights,
http://www.w3.org/2007/app/text-rights
8.1.1.17. HTML Rights
o Ref: http://www.w3.org/2007/app/html-rights
o Label: HTML Rights
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide HTML in the atom:rights element.
* "required" indicates that the collection requires all entries
to provide HTML in the atom:rights element.
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* "unsupported" indicates that the collection does not accept
entries that provide HTML in the atom:rights element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-rights,
http://www.w3.org/2007/app/text-rights
8.1.1.18. Text Rights
o Ref: http://www.w3.org/2007/app/text-rights
o Label: Text Rights
o Support Levels:
* "supported" indicates that the collection accepts entries that
provide plain text in the atom:rights element.
* "required" indicates that the collection requires all entries
to provide plain text in the atom:rights element.
* "unsupported" indicates that the collection does not accept
entries that provide plain text in the atom:rights element.
o Contradictory Features: http://www.w3.org/2007/app/xhtml-rights,
http://www.w3.org/2007/app/html-rights
8.1.1.19. Authenticated Author
o Ref: http://www.w3.org/2007/app/auth-author
o Label: Authenticated Author
o Support Levels:
* "supported" indicates that the server will automatically
generate the atom:author element based on the client's
authenticated identity.
* For this feature,"required" and "preferred" are synonymous with
"supported".
* "unsupported" indicates that the server will not automatically
generate the atom:author for an entry based on the client's
authenticated identity.
o Contradictory Features:
http://www.w3.org/2007/app/multiple-authors,
http://www.w3.org/2007/app/person-email,
http://www.w3.org/2007/app/person-uri
8.1.1.20. Slug
o Ref: http://www.w3.org/2007/app/slug
o Label: Slug
o Support Levels:
* "supported" indicates that the collection accepts the use of
the Slug header in POST requests.
* "required" indicates that the collection requires that the Slug
header be used for all POST requests.
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* "unsupported" indicates that the collection will not accept the
use of the Slug header in POST requests or that the header will
be ignored.
o Contradictory Features: none
8.1.1.21. Multiple Categories
o Ref: http://www.w3.org/2007/app/multiple-categories
o Label: Multiple Categories
o Support Levels:
* "supported" indicates that the collection accepts the use of
multiple atom:category elements within an entry.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection will not accept
entries with multiple atom:category elements or that that
additional atom:category elements will be ignored.
o Contradictory Features: none
8.1.1.22. Multiple Authors
o Ref: http://www.w3.org/2007/app/multiple-authors
o Label: Multiple Authors
o Support Levels:
* "supported" indicates that the collection accepts the use of
multiple atom:author elements within an entry.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection will not accept
entries with multiple atom:author elements or that the
additional atom:author elements will be ignored.
o Contradictory Features: http://www.w3.org/2007/app/auth-author
8.1.1.23. Multiple Contributors
o Ref: http://www.w3.org/2007/app/contributors
o Label: Multiple Contributors
o Support Levels:
* "supported" indicates that the collection accepts the use of
multiple atom:contributor elements within an entry.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection will not accept
entries with multiple atom:contributor elements or that the
additional atom:contributor elements will be ignored.
o Contradictory Features: none
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8.1.1.24. Preserve Infoset
o Ref: http://www.w3.org/2007/app/preserve-infoset
o Label: Preserve Infoset
o Support Levels:
* "supported" indicates that the collection will store entries in
such a way as to preserve the complete XML infoset of the entry
document.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection may not preserve
the complete XML infoset of the entry when storing.
o Contradictory Features: none
8.1.1.25. Preserve IDs
o Ref: http://www.w3.org/2007/app/preserve-id
o Label: Preserve IDs
o Support Levels:
* "supported" indicates that the collection will preserve the
value of the atom:id element as provided by the client.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection may not preserve
the value of the atom:id element as provided by the client
(e.g. the server will generate it's own value for the atom:id
element.
o Contradictory Features: none
8.1.1.26. Preserve Dates
o Ref: http://www.w3.org/2007/app/preserve-dates
o Label: Preserve Dates
o Support Levels:
* "supported" indicates that the collection will preserve the
value of all date elements as provided by the client.
* For this feature,"required" and "preferred" are synonymous with
"supported".
* "unsupported" indicates that the collection may not preserve
the value of date elements as provided by the client (e.g. the
server will generate it's own value for the date elements.
o Contradictory Features: none
8.1.1.27. Preserve Title
o Ref: http://www.w3.org/2007/app/preserve-title
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o Label: Preserve Title
o Support Levels:
* "supported" indicates that the collection will preserve the
value of the atom:title element as provided by the client.
* For this feature,"required" and "preferred" are synonymous with
"supported".
* "unsupported" indicates that the collection may not preserve
the value of the atom:title as provided by the client (e.g. the
server will generate it's own value for the atom:title element.
o Contradictory Features: none
8.1.1.28. Preserve Extensions
o Ref: http://www.w3.org/2007/app/preserve-extensions
o Label: Preserve Extensions
o Support Levels:
* "supported" indicates that the collection will preserve all
extensions contained within an entry.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection may not preserve
all extensions contained within an entry, however some
extensions may be preserved.
o Contradictory Features: none
8.1.1.29. Preserve Links
o Ref: http://www.w3.org/2007/app/preserve-links
o Label: Preserve Links
o Support Levels:
* "supported" indicates that the collection will preserve all
atom:link elements contained within an entry.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection may not preserve
all atom:links contained within an entry, however some atom:
link elements may be preserved.
o Contradictory Features: none
8.1.1.30. Preserve Rights
o Ref: http://www.w3.org/2007/app/preserve-rights
o Label: Preserve Rights
o Support Levels:
* "supported" indicates that the collection will preserve the
value of the atom:rights element as well as all License Links
[RFC4946] contained within an entry.
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* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection may not preserve
the value of the atom:rights element or all License Links
[RFC4946], however, some rights information may be preserved.
o Contradictory Features: none
8.1.1.31. Threading
o Ref: http://purl.org/syndication/thread/1.0
o Label: Threading
o Support Levels:
* "supported" indicates that the collection accepts entries that
contain the in-reply-to element as defined by [RFC4685].
* "required" indicates that the collection requires that all
entries contain an in-reply-to element.
* "unsupported" indicates that the collection will not accept
entries containing the in-reply-to element or that the element
will be ignored if present.
o Contradictory Features: none
8.1.1.32. Scheduled Publishing
o Ref: http://www.w3.org/2007/app/scheduled-publishing
o Label: Scheduled Publishing
o Support Levels:
* "supported" indicates that the collection allows clients to
specify a future instant in time for the atom:published element
when the entry should be made publicly available.
* "required" indicates that the collection requires clients to
specify a future instant in time for the atom:published
element.
* "unsupported" indicates that the collection will not allow
clients to specify a future instance in time for the atom:
published element.
o Contradictory Features: none
8.1.1.33. Signed Entries
o Ref: http://www.w3.org/2007/app/signed-entries
o Label: Signed Entries
o Support Levels:
* "supported" indicates that the collection may reject entries
that do not contain a valid XML Signature as specified in
section 5.1 of [RFC4287].
* "required" indicates that the collection requires that all
entries contain a valid XML Signature as specified in section
5.1 of [RFC4287].
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* "unsupported" indicates that the collection will ignore XML
Signatures contained in an entry.
o Contradictory Features: none
8.1.1.34. Person Email
o Ref: http://www.w3.org/2007/app/person-email
o Label: Person Email
o Support Levels:
* "supported" indicates that the collection may reject entries
whose atom:author and atom:contributor elements do not contain
a non-empty atom:email element.
* "required" indicates that the collection requires that all
atom:author and atom:contributor elements in an entry contain a
non-empty atom:email element..
* "unsupported" indicates that the collection will reject or
ignore the atom:email element in all atom:author and atom:
contributor elements contained in an entry.
o Contradictory Features: http://www.w3.org/2007/app/auth-author
8.1.1.35. Person URI
o Ref: http://www.w3.org/2007/app/person-uri
o Label: Person URI
o Support Levels:
* "supported" indicates that the collection may reject entries
whose atom:author and atom:contributor elements do not contain
a non-empty atom:uri element.
* "required" indicates that the collection requires that all
atom:author and atom:contributor elements in an entry contain a
non-empty atom:uri element..
* "unsupported" indicates that the collection will reject or
ignore the atom:uri element in all atom:author and atom:
contributor elements contained in an entry.
o Contradictory Features: http://www.w3.org/2007/app/auth-author
8.1.1.36. Publish Email
o Ref: http://www.w3.org/2007/app/publish-email
o Label: Publish Email
o Support Levels:
* "supported" indicates that the collection will include the
value of atom:email elements in public, non-editable
representations of an entry.
* For this feature, "required" and "preferred" are synonymous
with "supported".
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* "unsupported" indicates that the collection will not include
the value of atom:email elements in public, non-editable
representations of an entry.
o Contradictory Features: none
8.1.1.37. Publish URI
o Ref: http://www.w3.org/2007/app/publish-uri
o Label: Publish URI
o Support Levels:
* "supported" indicates that the collection will include the
value of atom:uri elements in public, non-editable
representations of an entry.
* For this feature, "required" and "preferred" are synonymous
with "supported".
* "unsupported" indicates that the collection will not include
the value of atom:uri elements in public, non-editable
representations of an entry.
o Contradictory Features: none
8.1.1.38. XML Language
o Ref: http://www.w3.org/2007/app/xml-lang
o Label: XML Language
o Support Levels:
* "supported" indicates that the collection will accept and
preserve the value of xml:lang attributes used on an atom:entry
element.
* "required" indicates that the collection may reject atom:entry
elements that do not contain an xml:lang attribute.
* "unsupported" indicates that the collection will ignore the
xml:lang attribute.
o Contradictory Features: none
8.1.1.39. Conditional Modification
o Ref: http://www.w3.org/2007/app/conditional
o Label: Conditional Modification
o Support Levels:
* "supported" indicates that the collection provides an Entity
Tag or Last Modified timestamp for member resources and
supports the use of the HTTP If-Match, If-None-Match, If-
Modified-Since or If-Unmodified-Since request headers.
* "supported" indicates that the collection provides an Entity
Tag or Last Modified timestamp for member resources and
requires the use of the HTTP If-Match, If-None-Match, If-
Modified-Since or If-Unmodified-Since request headers.
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* "unsupported" indicates that the collection either does not
provide an Entity Tag or Last Modified timestamps for member
resources or does not otherwise support the use of the HTTP If-
Match, If-None-Match, If-Modified-Since and If-Unmodified-Since
request headers.
o Contradictory Features: none
9. 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.
[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-20060816]
Paoli, J., Sperberg-McQueen, C., Yergeau, F., Maler, E.,
and T. Bray, "Extensible Markup Language (XML) 1.0 (Fourth
Edition)", World Wide Web Consortium Recommendation REC-
xml-20060816, August 2006,
<http://www.w3.org/TR/2006/REC-xml-20060816>.
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[W3C.REC-xml-c14n-20010315]
Boyer, J., "Canonical XML Version 1.0", World Wide Web
Consortium Recommendation REC-xml-c14n-20010315,
March 2001,
<http://www.w3.org/TR/2001/REC-xml-c14n-20010315>.
[W3C.REC-xml-exc-c14n-20020718]
Boyer, J., 3rd, D., and J. Reagle, "Exclusive XML
Canonicalization Version 1.0", World Wide Web Consortium
Recommendation REC-xml-exc-c14n-20020718, July 2002,
<http://www.w3.org/TR/2002/REC-xml-exc-c14n-20020718>.
[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-20060816]
Layman, A., Hollander, D., Bray, T., and R. Tobin,
"Namespaces in XML 1.0 (Second Edition)", World Wide Web
Consortium Recommendation REC-xml-names-20060816,
August 2006,
<http://www.w3.org/TR/2006/REC-xml-names-20060816>.
[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>.
[W3C.REC-xmldsig-core-20020212]
Eastlake, D., Solo, D., and J. Reagle, "XML-Signature
Syntax and Processing", World Wide Web Consortium
Recommendation REC-xmldsig-core-20020212, February 2002,
<http://www.w3.org/TR/2002/REC-xmldsig-core-20020212>.
Appendix A. Acknowledgements
The author acknowledges the feedback from the other members of the
IETF Atom Publishing working group during the development of this
specification.
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Author's Address
James M Snell
Phone:
Email: jasnell@gmail.com
URI: http://snellspace.com
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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
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Intellectual Property Rights or other rights that might be claimed to
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this document or the extent to which any license under such rights
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made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
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Funding for the RFC Editor function is provided by the IETF
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Snell Expires March 13, 2008 [Page 27]
