Network Working Group J. Snell
Internet-Draft June 8, 2009
Updates: 4287 (if approved)
Intended status: Informational
Expires: December 10, 2009
The Atom "deleted-entry" Element
draft-snell-atompub-tombstones-06.txt
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Abstract
This specification adds mechanisms to the Atom Syndication Format
which Atom Feed publishers can use to explicitly identify Atom
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entries that have been removed from an Atom feed.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. The at:deleted-entry element . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
This specification adds a new element to the Atom Syndication Format
[RFC4287] that can be used to explicitly indicate that specific
entries have been removed from a feed.
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;
"at": "http://purl.org/atompub/tombstones/1.0"
3. The at:deleted-entry element
The at:deleted-entry element MAY appear as a child of atom:feed to
represent an Atom Entry that has been removed from a feed.
deletedEntry = element at:deleted-entry {
atomCommonAttributes,
attribute ref { atomUri },
attribute when { atomDateConstruct },
( element at:by { atomPersonConstruct}?,
& element at:comment {atomTextConstruct}?,
& extensionElement* )
}
The at:deleted-entry element MUST contain a ref attribute whose value
specifies the value of the atom:id of the entry that has been
removed.
The at:deleted-entry element MUST contain a when attribute whose
value is an [RFC3339] "date-time" specifying the instant the entry
was removed from the feed. An uppercase "T" character MUST be used
to separate date and time, and an uppercase "Z" character MUST be
present in the absence of a numeric time zone offset
The at:deleted-entry element MAY contain one at:by element used to
identify the entity that removed the entry from the feed. The at:by
element is an Atom Person Construct as defined by Section 3.2 of
[RFC4287].
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The at:deleted-entry element MAY contain one at:comment element whose
value provides additional, language-sensitive information about the
deletion operation. The atom:comment element is an Atom Text
Construct as defined by Section 3.1 of [RFC4287].
An Atom feed MAY contain any number of at:deleted-entry elements, but
MUST NOT contain more than one with the same combination of ref and
when attribute values.
...
John Doe
jdoe@example.org
Removed comment spam
...
An Atom feed MAY contain atom:entry elements and at:deleted-entry
elements sharing the same atom:id value. Atom processors SHOULD
ignore any at:deleted-entry elements sharing an atom:id value with an
atom:entry whose atom:updated element specifies a date and time more
recent than the at:deleted-entry element's when value.
Elements and attributes from other XML vocabularies MAY be used
within an at:deleted-entry element following the same model defined
by Section 6 of [RFC4287]. Processors encountering such markup MUST
NOT stop processing or signal an error. It might be the case that
the Processor is able to process the foreign markup correctly and
does so. When unknown markup is encountered as a child of at:
deleted-entry, Processors MAY bypass the markup and any textual
content and MUST NOT change their behavior as a result of the
markup's presence.
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4. Security Considerations
As specified in [RFC4287], Atom processors should be aware of the
potential for spoofing attacks where an attacker publishes atom:entry
or atom:deleted-entry elements using the same atom:id values as
entries from other Atom feeds. An attacker may attempt to trick an
application into believing that a given entry has either been removed
from or added to a feed. To mitigate this issue, Atom processors are
advised to ignore atom:deleted-entry elements referencing entries
that have not previously appeared within the containing Feed document
and should take steps to verify the origin of the Atom feed before
considering the entries to be removed.
5. IANA Considerations
No IANA actions are required by this document.
6. Acknowledgements
The author gratefully acknowledges the feedback from the members of
the Atom Publishing Format and Protocol working group during the
development of this specification.
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the
Internet: Timestamps", RFC 3339, July 2002.
[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
Syndication Format", RFC 4287, December 2005.
[W3C.REC-xml-names-19990114]
Bray, T., Hollander, D., and A. Layman, "Namespaces in
XML", World Wide Web Consortium FirstEdition REC-xml-
names-19990114, January 1999,
.
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Author's Address
James M Snell
Phone:
Email: jasnell@us.ibm.com
URI: http://ibm.com
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