One document matched: draft-snell-atompub-feed-index-06.txt
Differences from draft-snell-atompub-feed-index-05.txt
Network Working Group J. Snell
Internet-Draft February 20, 2006
Expires: August 24, 2006
Feed Rank
draft-snell-atompub-feed-index-06.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 24, 2006.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines a mechanism for numerically ranking entries
within a syndication feed.
Snell Expires August 24, 2006 [Page 1]
Internet-Draft Feed Rank February 2006
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. Ranking Domains and Schemes . . . . . . . . . . . . . . . . . 3
3.1. The 'r:scheme' element . . . . . . . . . . . . . . . . . . 4
3.2. The 'r:rank' element . . . . . . . . . . . . . . . . . . . 5
4. Ranking Domain Scope . . . . . . . . . . . . . . . . . . . . . 5
5. Ranking Domain and Scheme Identifiers . . . . . . . . . . . . 7
6. Processing Rankings . . . . . . . . . . . . . . . . . . . . . 7
7. Default Ranking Scheme . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
Snell Expires August 24, 2006 [Page 2]
Internet-Draft Feed Rank February 2006
1. Introduction
In syndication document formats such as Atom [RFC4287] and RSS, the
order of entries as presented in the list is typically insignificant.
This presents a challenge when the list of entries is intended to
represent an ordered or ranked set. This document specifies a
mechanism that allows feed publishers to establish numeric rankings
for entries within a feed to be used as a means of organizing and
sorting those entries. Although this document refers to Atom
normatively, the mechanism described herein can be used with similar
syndication formats, such as the various flavors of RSS.
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].
In this specification, "entry" refers to an atom:entry element or
similar construct from other syndication formats (e.g., RSS) that are
contained within a feed.
In this specification, "feed" refers to an Atom Feed Document or
similar syndication format (e.g., RSS) that contains a collection of
entries.
In this specification, "head section" refers to the children of a
feed document's document-wide metadata container; e.g., the child
elements of the atom:feed element in an Atom Feed Document or the
children of the RSS 'channel' element.
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;
"r": "http://purl.org/syndication/index/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 term "element,"
it is referring to an Element Information Item in Infoset terms.
3. Ranking Domains and Schemes
A 'Ranking Domain' is a uniquely identifiable logical collection of
entries containing numeric ranking values.
Snell Expires August 24, 2006 [Page 3]
Internet-Draft Feed Rank February 2006
'Ranking Schemes' identify the specific rules for how the numeric
ranking values within a 'Ranking Domain' are to be interpreted.
3.1. The 'r:scheme' element
Ranking Schemes are defined using the r:scheme element.
rankingScheme = element r:scheme {
atomCommonAttributes,
attribute id { IRI }?,
attribute label { text }?,
attribute significance { 'ascending' | 'descending' }?,
attribute precision { nonNegativeInteger }?,
attribute minimum { decimal }?,
attribute maximum { decimal }?
}
o The 'id' attribute provides a universally unique identifier for
the scheme.
o The 'label' attribute specifies a language-sensitive, human
readable label for the scheme.
o The 'significance' attribute indicates how implementations are to
interpret the significance of an entries numeric ranking value. A
value of 'descending' indicates that the significance of the rank
descends as the numeric ranking value increases. A value of
'ascending' indicates that the significance of the rank increases
as the numeric ranking value increases. If not specified, the
significance is considered to be 'ascending'.
o The 'precision' attribute specifies the level of precision to be
applied to the value of the numeric ranking value. The value is
expressed as a non-negative integer. If not specified the value
is considered to be indeterminate (e.g., the number 2.0 is not
distinct from the number 2.00). Ranking schemes that are based on
fractional numeric ranking values SHOULD specify a precision.
o The 'minumum' attribute specifies the lowest possible numeric
ranking value (inclusive). If not specified, the minimum value is
considered to be 0.
o The 'maximum' attribute specifies the highest possible numeric
ranking value (inclusive). If not specified, no maximum value is
considered to apply.
An Atom feed element MAY contain any number of r:scheme elements. A
Feed MUST NOT contain more than one r:scheme element with the same
id.
Snell Expires August 24, 2006 [Page 4]
Internet-Draft Feed Rank February 2006
<feed xmlns="http://www.w3.org/2005/Atom"
xmlns:r="http://purl.org/syndication/index/1.0">
...
<r:scheme
id="tag:example.org,2006:movie_reviews"
xml:lang="en-us"
label="Five Star Reviews"
precision="0"
significance="ascending"
minimum="0"
maximum="5" />
...
</feed>
3.2. The 'r:rank' element
Entries within a feed MAY contain zero or more r:rank elements
specifing a numeric ranking value within a given Ranking Domain. An
entry MUST NOT contain more than one r:rank element with the same
combination of domain and scheme attribute values.
rankingValue = element r:rank {
atomCommonAttributes,
attribute domain {IRI}?,
attribute scheme {IRI}?,
attribute label { text },
(decimal}
}
The 'domain' attribute identifies the Ranking Domain. See "Ranking
Domain Scope" for details.
The 'scheme' attribute identifies the Ranking Scheme. If not
specified, the scheme is assumed to be the Default Ranking Scheme.
The 'label' attribute provides a language-sensitive, human readable
label for the ranking value.
The value of the r:rank is a decimal value conforming to the XML
Schema decimal data type [W3C.REC-xmlschema-2-20041028]. The value
MUST NOT contain any leading or trailing whitespace.
<r:rank
domain="http://example.org/movie_reviews"
scheme="tag:example.com,2006:movie_reviews">3.5</r:rank>
4. Ranking Domain Scope
Ranking Domain's provide a logical mechanism used to associate a
Snell Expires August 24, 2006 [Page 5]
Internet-Draft Feed Rank February 2006
numerically ranked set of resources. Ranking Domains are identified
by IRI's.
Ranking Domains fall into one of three scopes:
o Feed Scope (known as the "Feed Ranking Domain")
o Document Scope (known as the "Document Ranking Domain")
o Domain Scope
Numeric ranking values that do not specify a domain attribute are
associated with the Feed Ranking Domain. The IRI identity of the
Feed Ranking Domain is the same as the containing feed element's
atom:id element.
A numeric ranking associated with the Feed Ranking Domain
<r:rank scheme="tag:example.org,2006:movie_reviews">3.5</r:rank>
The set of entries contained within the Feed Ranking Domain is
limited to the set of entries contained within the Feed.
Numeric rankings that specify a domain equal or equivalent to the
Feed Document's Base URI are associated with the Document Ranking
Domain. The IRI identity of the Document Ranking Domain is the
normalized form of the containing Feed Document's Base URI.
A numeric ranking associated with the Feed Ranking Domain
<r:rank
domain=""
scheme="tag:example.org,2006:movie_reviews">3.5</r:rank>
The set of entries contained within the Document Ranking Domain is
limited to the set entries contained within the Document identified
by the Base URI.
Numeric ranking values that specify any IRI value other than the Base
URI of the containing document are associated with a Domain Scope.
A numeric ranking associated with the Feed Ranking Domain
<r:rank
domain="http://www.example.org/movie_reviews"
scheme="tag:example.org,2006:movie_reviews">3.5</r:rank>
Domain Scoped SHOULD be considered to be open sets consistings of
entries from any number of feeds.
Snell Expires August 24, 2006 [Page 6]
Internet-Draft Feed Rank February 2006
5. Ranking Domain and Scheme Identifiers
The IRI's identifying Ranking Domains and Ranking Schemes are subject
to the same construction and comparison rules as the atom:id element.
Comparison's of domain and scheme identifiers MUST be performed on a
case-sensitive, character-by-character basis solely on the IRI
character strings and MUST NOT rely on dereferencing the IRI's or
URI's mapped from them.
6. Processing Rankings
Processing a Ranking Domain involves the following steps:
Select the Ranking Scheme.
Identify the Ranking Domain
Identify the available set of entries containing numeric ranking
values within the identified Ranking Domain using the selected
Ranking Scheme.
Remove from the set all entries whose rankings fall outside the
minimum and maximum values set by the selected Ranking Scheme.
Sort the remaining set of ranked entries according to the
significance and precision of the numeric ranking as specified by
the Ranking Scheme.
7. Default Ranking Scheme
Feeds MAY contain ranked entries that have no specified scheme.
Software implementations MAY attempt to match such rankings to well-
known schemes associated with the specified domain. For instance, an
online search engine may choose to define a ranking scheme that is
reflective of the relevance of a given result to a search query;
rather than require that a r:scheme element be included in every feed
where the Ranking Scheme may be used, or declared in every 'r:rank'
element, the search engine may separately publish its Ranking Scheme
and associated Ranking Domain.
A hypothetical search engine ranking using well-known scheme
<r:rank domain="http://search.example.org/relevance">5</r:rank>
If a Ranking Scheme cannot be resolved (e.g., no 'scheme' attribute
on the r:rank element, no r:scheme with a matching 'id' attribute can
be found and the domain is not well-known), the Default Ranking
Scheme should be applied.
Snell Expires August 24, 2006 [Page 7]
Internet-Draft Feed Rank February 2006
o label = 'Default Ranking'
o significance = 'ascending'
o precision = unspecified
o minumum = 0
o maximum = unspecified
8. Security Considerations
There are no security considerations introduced by this
specification.
9. IANA Considerations
There are no IANA considerations introduced by this specification.
10. References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4287] Nottingham, M. and R. Sayre, "The Atom Syndication
Format", RFC 4287, December 2005.
[W3C.REC-xml-infoset-20040204]
Tobin, R. and J. Cowan, "XML Information Set (Second
Edition)", W3C REC REC-xml-infoset-20040204,
February 2004.
[W3C.REC-xml-names-19990114]
Hollander, D., Bray, T., and A. Layman, "Namespaces in
XML", W3C REC REC-xml-names-19990114, January 1999.
[W3C.REC-xmlschema-2-20041028]
Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes
Second Edition", W3C REC REC-xmlschema-2-20041028,
October 2004.
Snell Expires August 24, 2006 [Page 8]
Internet-Draft Feed Rank February 2006
Author's Address
James M Snell
Phone:
Email: jasnell@gmail.com
URI: http://snellspace.com
Snell Expires August 24, 2006 [Page 9]
Internet-Draft Feed Rank February 2006
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
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
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
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.
Disclaimer of Validity
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 AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2006). 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.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Snell Expires August 24, 2006 [Page 10]
| PAFTECH AB 2003-2026 | 2026-04-24 04:16:29 |