idnits 2.17.1
draft-snell-atompub-feed-expires-05.txt:
Checking boilerplate required by RFC 5378 and the IETF Trust (see
https://trustee.ietf.org/license-info):
----------------------------------------------------------------------------
** It looks like you're using RFC 3978 boilerplate. You should update this
to the boilerplate described in the IETF Trust License Policy document
(see https://trustee.ietf.org/license-info), which is required now.
-- Found old boilerplate from RFC 3978, Section 5.1 on line 15.
-- Found old boilerplate from RFC 3978, Section 5.5 on line 321.
-- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 298.
-- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 305.
-- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 311.
** This document has an original RFC 3978 Section 5.4 Copyright Line,
instead of the newer IETF Trust Copyright according to RFC 4748.
** This document has an original RFC 3978 Section 5.5 Disclaimer, instead
of the newer disclaimer which includes the IETF Trust according to RFC
4748.
Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt:
----------------------------------------------------------------------------
== No 'Intended status' indicated for this document; assuming Proposed
Standard
Checking nits according to https://www.ietf.org/id-info/checklist :
----------------------------------------------------------------------------
** The document seems to lack separate sections for Informative/Normative
References. All references will be assumed normative when checking for
downward references.
Miscellaneous warnings:
----------------------------------------------------------------------------
== The copyright year in the RFC 3978 Section 5.4 Copyright Line does not
match the current year
-- The document seems to lack a disclaimer for pre-RFC5378 work, but may
have content which was first submitted before 10 November 2008. If you
have contacted all the original authors and they are all willing to grant
the BCP78 rights to the IETF Trust, then this is fine, and you can ignore
this comment. If not, you may need to add the pre-RFC5378 disclaimer.
(See the Legal Provisions document at
https://trustee.ietf.org/license-info for more information.)
-- The document date (September 2005) is 6798 days in the past. Is this
intentional?
Checking references for intended status: Proposed Standard
----------------------------------------------------------------------------
(See RFCs 3967 and 4897 for information about using normative references
to lower-maturity documents in RFCs)
== Unused Reference: 'I-D.ietf-atompub-format' is defined on line 251, but
no explicit reference was found in the text
Summary: 4 errors (**), 0 flaws (~~), 3 warnings (==), 7 comments (--).
Run idnits with the --verbose option for more detailed information about
the items above.
--------------------------------------------------------------------------------
2 Network Working Group J. Snell
3 Internet-Draft September 2005
4 Expires: March 5, 2006
6 Atom Metadata Expiration: Specifying Expiration Timestamps for Atom
7 Feed and Entry metadata
8 draft-snell-atompub-feed-expires-05.txt
10 Status of this Memo
12 By submitting this Internet-Draft, each author represents that any
13 applicable patent or other IPR claims of which he or she is aware
14 have been or will be disclosed, and any of which he or she becomes
15 aware will be disclosed, in accordance with Section 6 of BCP 79.
17 Internet-Drafts are working documents of the Internet Engineering
18 Task Force (IETF), its areas, and its working groups. Note that
19 other groups may also distribute working documents as Internet-
20 Drafts.
22 Internet-Drafts are draft documents valid for a maximum of six months
23 and may be updated, replaced, or obsoleted by other documents at any
24 time. It is inappropriate to use Internet-Drafts as reference
25 material or to cite them other than as "work in progress."
27 The list of current Internet-Drafts can be accessed at
28 http://www.ietf.org/ietf/1id-abstracts.txt.
30 The list of Internet-Draft Shadow Directories can be accessed at
31 http://www.ietf.org/shadow.html.
33 This Internet-Draft will expire on March 5, 2006.
35 Copyright Notice
37 Copyright (C) The Internet Society (2005).
39 Abstract
41 This memo presents a mechanism that allows feed publishers to express
42 maximum age and expiration properties for information content within
43 an Atom entry.
45 Table of Contents
47 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
48 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
49 3. The 'expires' extension element . . . . . . . . . . . . . . . 4
50 4. The 'max-age' extension element . . . . . . . . . . . . . . . 5
51 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
52 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
53 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
54 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7
55 A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
56 Intellectual Property and Copyright Statements . . . . . . . . 8
58 1. Introduction
60 This document specifies a mechanism that allows the expression of
61 expiration timestamps and maximum age properties for information
62 content within the Atom Syndication Format ([I-D.ietf-atompub-
63 format]). The mechanism defines two mutually exclusive extension
64 elements that may be used to specify either an exact instant that the
65 information content of an atom:entry expires, or a maximum age from
66 the moment specified by an entries atom:updated element.
68 When an atom:feed, atom:entry or atom:source contains an 'expires' or
69 'max-age' extension element, the information content of the contained
70 element is considered to be 'time constrained'. Time constrainted
71 information content is considered to be either 'active' or 'expired'.
72 The default state is 'active'. When the age (calculated in
73 miliseconds from the moment specified by the atom:published or atom:
74 updated elements) exceeds the value specified by the 'max-age'
75 extension, or when the moment specified by the 'expires' extension
76 elements passes, the state of the time constrained information
77 content MUST be considered to be 'expired' and no longer valid. It
78 is strongly recommended that implementations either discard 'expired'
79 information content or otherwise warn users that the information
80 content has expired.
82 The mechanism defined herein MUST NOT be used to support the caching
83 of Atom documents and MUST NOT be used to schedule when a client
84 should revisit/refresh local copies of Atom documents. Specifically,
85 the 'expires' and 'max-age' extension elements are relevant only to
86 the informational content within an atom:entry and are not adequate
87 mechanism for determining the freshness of a cached copy of the
88 document in which the elements appear.
90 The presence of an 'expires' or 'max-age' extension within an atom:
91 feed or atom:source element is relevant only to the informational
92 content of the containing element and not to any associated atom:
93 entry elements.
95 Section 6.3 of the Atom Format specification indicates that Atom
96 processors that encounter unknown extensions MUST ignore those
97 extensions without altering their behavior. Because of this
98 requirement, there can be no assumption that a particular software
99 implementation will support the extensions defined herein.
101 2. Notational Conventions
103 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
104 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
105 document are to be interpreted as described in BCP 14, [RFC2119], as
106 scoped to those conformance targets.
108 In this specification, "entry" refers to an atom:entry element.
110 In this specification, "feed" refers to an Atom Feed Document.
112 In this specification, "head section" refers to the children of a
113 feed's document-wide metadata container; e.g., the child elements of
114 the atom:feed element in an Atom Feed Document.
116 In this specification, the term "extension element" refers to a
117 structured extension element as described in [I-D.ietf-atompub-
118 format].
120 In this specification, the term "information content" refers to the
121 collection of metadata relevant to an atom:entry element.
123 This specification uses XML Namespaces [W3C.REC-xml-names-19990114]
124 to uniquely identify XML element names. It uses the following
125 namespace prefix for the indicated namespace URI;
127 {Ed. Note: this namespace MUST be changed to a proper IETF namespace
128 scheme prior to publication}
129 "age": "http://purl.org/atompub/age/1.0"
131 This specification uses terms from the XML Infoset [W3C.REC-xml-
132 infoset-20040204]. However, this specification uses a shorthand; the
133 phrase "Information Item" is omitted when naming Element Information
134 Items. Therefore, when this specification uses the term "element,"
135 it is referring to an Element Information Item in Infoset terms.
137 This specification defines the notion of a Non-Negative Integer
138 Construct whose value MUST conform to the canonical representation of
139 the "nonNegativeInteger" construction defined by [W3C.REC-xmlschema-
140 2-20041028]. The value of the Non-Negative Integer Construct MUST
141 NOT contain any leading or trailing whitespace.
142 nonNegativeIntegerConstruct =
143 atomCommonAttributes,
144 xsd:nonNegativeInteger
146 Example Non-Negative Integer Constructs
147 0
148 1000000
150 3. The 'expires' extension element
152 The 'expires' extension element conforms to the Atom Date Construct
153 and is used to indicate a precise moment in time after which the
154 information content of the containing element MUST be considered to
155 have "expired".
156 expiresElement = element age:expires { atomDateConstruct }
158 o atom:entry elements MAY contain exactly one 'expires' extension
159 element.
160 o atom:feed elements MAY contain exactly one 'expires' extension
161 element.
162 o atom:source elements MAY contain exactly one 'expires' extension
163 element.
164 o An atom:entry that contains an 'expires' extension element MUST
165 NOT contain a 'max-age' extension element.
166 o An atom:feed that contains an 'expires' extension element MUST NOT
167 contain a 'max-age' extension element.
168 o An atom:source that contains an 'expires' extension element MUST
169 NOT contain a 'max-age' extension element.
170 o The value of the 'expires' extension element MUST NOT specify a
171 date and time earlier than the moment specified by the atom:
172 updated element or the atom:published element (if present). If an
173 'expires' element does specify a date and time earlier than either
174 the atom:updated or atom:published elements, the 'expires' element
175 MUST be ignored.
177 For example
178
180 http://www.example.com/myfeed
181 My Example Feed
182 2005-07-28T12:00:00Z
183
184 James
185
186 tag:entries.com,2005:1
187 An entry with an expiration timestamp
188
189 2005-07-28T12:00:00Z
190 2005-12-12T12:00:00Z
191 An entry with an expiration
192
193
195 4. The 'max-age' extension element
197 The 'max-age' extension element is used to indicate a maximum age of
198 the information content in miliseconds from the moment specified by
199 the atom:published element (if present) or the atom:updated element
200 after which the information content MUST be considered to have
201 "expires". The value is specified as a non-negative integer
202 conforming to the nonNegativeIntegerConstruct.
203 maxageElement = element age:max-age { nonNegativeIntegerConstruct }
205 o atom:entry elements MAY contain exactly one 'max-age' extension
206 element.
207 o atom:feed elements MAY contain exactly one 'max-age' extension
208 element.
209 o atom:source elements MAY contain exactly one 'max-age' extension
210 element.
211 o An atom:entry that contains a 'max-age' extension element MUST NOT
212 contain an 'expires' extension element.
213 o An atom:feed that contains a 'max-age' extension element MUST NOT
214 contain an 'expires' extension element.
215 o An atom:source that contains a 'max-age' extension element MUST
216 NOT contain an 'expires' extension element.
218 For example
219
221 http://www.example.com/myfeed
222 My Example Feed
223 2005-07-28T12:00:00Z
224
225 James
226
227 tag:entries.com,2005:1
228 An entry with a maximum age of 20 seconds
229
230 2005-07-28T12:00:00Z
231 20000
232 expire after a mere 20 seconds
233
234
236 5. Security Considerations
238 It is possible for malicious intermediaries to alter the expiration
239 metadata in an Atom document. This risk can be mitigated by
240 digitally signing the elements in which the 'expires' or 'max-age'
241 extension elements appear. It is strongly recommended that
242 implementations discard expired information content or otherwise warn
243 users that the information content has expired.
245 6. IANA Considerations
247 There are no IANA considerations introduced by this specification.
249 7. References
251 [I-D.ietf-atompub-format]
252 Sayre, R. and M. Nottingham, "The Atom Syndication
253 Format", draft-ietf-atompub-format-11 (work in progress),
254 August 2005.
256 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
257 Requirement Levels", BCP 14, RFC 2119, March 1997.
259 [W3C.REC-xml-infoset-20040204]
260 Tobin, R. and J. Cowan, "XML Information Set (Second
261 Edition)", W3C REC REC-xml-infoset-20040204,
262 February 2004.
264 [W3C.REC-xml-names-19990114]
265 Hollander, D., Bray, T., and A. Layman, "Namespaces in
266 XML", W3C REC REC-xml-names-19990114, January 1999.
268 [W3C.REC-xmlschema-2-20041028]
269 Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes
270 Second Edition", W3C REC REC-xmlschema-2-20041028,
271 October 2004.
273 Author's Address
275 James M Snell
277 Phone:
278 Email: jasnell@gmail.com
279 URI: http://snellspace.com
281 Appendix A. Acknowledgements
283 The author gratefully acknowledges the feedback from Eric Scheid,
284 Walter Underwood, Henry Story, Tim Bray, Mark Nottingham, Robert
285 Sayrer, James Holderness, Phil Ringnalda, Antone Roundy and the other
286 members of Atom Publishing Format and Protocol working group during
287 the development of this specification.
289 Intellectual Property Statement
291 The IETF takes no position regarding the validity or scope of any
292 Intellectual Property Rights or other rights that might be claimed to
293 pertain to the implementation or use of the technology described in
294 this document or the extent to which any license under such rights
295 might or might not be available; nor does it represent that it has
296 made any independent effort to identify any such rights. Information
297 on the procedures with respect to rights in RFC documents can be
298 found in BCP 78 and BCP 79.
300 Copies of IPR disclosures made to the IETF Secretariat and any
301 assurances of licenses to be made available, or the result of an
302 attempt made to obtain a general license or permission for the use of
303 such proprietary rights by implementers or users of this
304 specification can be obtained from the IETF on-line IPR repository at
305 http://www.ietf.org/ipr.
307 The IETF invites any interested party to bring to its attention any
308 copyrights, patents or patent applications, or other proprietary
309 rights that may cover technology that may be required to implement
310 this standard. Please address the information to the IETF at
311 ietf-ipr@ietf.org.
313 Disclaimer of Validity
315 This document and the information contained herein are provided on an
316 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
317 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
318 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
319 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
320 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
321 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
323 Copyright Statement
325 Copyright (C) The Internet Society (2005). This document is subject
326 to the rights, licenses and restrictions contained in BCP 78, and
327 except as set forth therein, the authors retain all their rights.
329 Acknowledgment
331 Funding for the RFC Editor function is currently provided by the
332 Internet Society.