idnits 2.17.1 draft-snell-atompub-feed-expires-00.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 317. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 294. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 301. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 307. ** 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 (August 16, 2005) is 6827 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 248, 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 August 16, 2005 4 Expires: February 17, 2006 6 Atom Entry Expiration: Specifying Expiration Timestamps for Atom Entry 7 metadata 8 draft-snell-atompub-feed-expires-00.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 February 17, 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 entry contains an 'expires' or 'max-age' extension element, 69 the information content of that entry is considered to be 'time 70 constrained'. Time constrainted information content is considered to 71 be either 'active' or 'expired'. The default state is 'active'. 72 When the age (calculated in miliseconds from the moment specified by 73 the atom:updated element) exceeds the value specified by the 'max- 74 age' extension, or when the moment specified by the 'expires' 75 extension elements passes, the state of the time constrained 76 information content MUST be considered to be 'expired' and no longer 77 valid. It is strongly recommended that implementations either 78 discard 'expired' entries or otherwise warn users that the 79 information content of the entry has expired. 81 The mechanism defined herein MUST NOT be used mechanism to support 82 caching of Atom documents and MUST NOT be used to schedule when a 83 client should revisit/refresh local copies of Atom documents. 84 Specifically, the 'expires' and 'max-age' extension elements are 85 relevant only to the informational content within an atom:entry and 86 are not relevant to the Atom Feed and Entry Documents in which they 87 happen to appear. 89 2. Notational Conventions 91 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 92 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 93 document are to be interpreted as described in BCP 14, [RFC2119], as 94 scoped to those conformance targets. 96 In this specification, "entry" refers to an atom:entry element. 98 In this specification, "feed" refers to an Atom Feed Document. 100 In this specification, "head section" refers to the children of a 101 feed's document-wide metadata container; e.g., the child elements of 102 the atom:feed element in an Atom Feed Document. 104 In this specification, the term "extension element" refers to a 105 structured extension element as described in [I-D.ietf-atompub- 106 format]. 108 In this specification, the term "information content" refers to the 109 collection of metadata relevant to an atom:entry element. 111 This specification uses XML Namespaces [W3C.REC-xml-names-19990114] 112 to uniquely identify XML element names. It uses the following 113 namespace prefix for the indicated namespace URI; 114 "age": "http://purl.org/syndication/age/1.0" 116 This specification uses terms from the XML Infoset [W3C.REC-xml- 117 infoset-20040204]. However, this specification uses a shorthand; the 118 phrase "Information Item" is omitted when naming Element Information 119 Items. Therefore, when this specification uses the term "element," 120 it is referring to an Element Information Item in Infoset terms. 122 This specification defines the notion of a Non-Negative Integer 123 Construct whose value MUST conform to the canonical representation of 124 the "nonNegativeInteger" construction defined by [W3C.REC-xmlschema- 125 2-20041028]. The value of the Non-Negative Integer Construct MUST 126 NOT contain any leading or trailing whitespace. 127 nonNegativeIntegerConstruct = 128 atomCommonAttributes, 129 xsd:nonNegativeInteger 131 Example Non-Negative Integer Constructs 132 0 133 1000000 135 3. The 'expires' extension element 137 The 'expires' extension element conforms to the Atom Date Construct 138 and is used to indicate a precise moment in time (inclusive) when the 139 information content of an entry expires. 140 expiresElement = element age:expires { atomDateConstruct } 142 o atom:entry elements MAY contain exactly one 'expires' extension 143 element. 144 o atom:feed elements MAY contain exactly one 'expires' extension 145 element. 146 o atom:source elements MAY contain exactly one 'expires' extension 147 element. 148 o If an atom:entry element does not contain an 'expires' extension 149 element, the 'expires' extension element of the contained atom: 150 source is considered to apply 151 o In an Atom Feed Document, if an atom:entry element or a contained 152 atom:source element do not contain an 'expires' extension element, 153 the 'expires' extension element in the feed head section are 154 considered to apply. 155 o An atom:entry that contains an 'expires' extension element MUST 156 NOT contain a 'max-age' extension element. 157 o An atom:source that contains an 'expires' extension element MUST 158 NOT contain a 'max-age' extension element. 159 o An atom:feed that contains an 'expires' extension element MUST NOT 160 contain a 'max-age' extension element. 162 For example 163 165 http://www.example.com/myfeed 166 My Example Feed 167 2005-07-28T12:00:00Z 168 169 James 170 171 tag:entries.com,2005:1 172 An entry with an expiration timestamp 173 174 2005-12-12T12:00:00Z 175 An entry with an expiration 176 177 179 While the 'expires' element MAY appear as a child of the atom:feed 180 and atom:source elements, it's effect is constrained to the 181 information content of atom:entry elements. 183 4. The 'max-age' extension element 185 The 'max-age' extension element is used to indicate the maximum age 186 of the information content in miliseconds from the moment specified 187 by the atom:updated element. The value is specified as a non- 188 negative integer conforming to the nonNegativeIntegerConstruct. 189 maxAgeElement = element age:max-age { nonNegativeIntegerConstruct } 191 o atom:entry elements MAY contain exactly one 'max-age' extension 192 element. 193 o atom:feed elements MAY contain exactly one 'max-age' extension 194 element. 195 o atom:source elements MAY contain exactly one 'max-age' extension 196 element. 197 o If an atom:entry element does not contain an 'max-age' extension 198 element, the 'max-age' extension element of the contained atom: 199 source is considered to apply 201 o In an Atom Feed Document, if an atom:entry element or a contained 202 atom:source element do not contain an 'max-age' extension element, 203 the 'max-age' extension element in the feed head section are 204 considered to apply. 205 o An atom:entry that contains an 'max-age' extension element MUST 206 NOT contain a 'expires' extension element. 207 o An atom:source that contains an 'max-age' extension element MUST 208 NOT contain a 'expires' extension element. 209 o An atom:feed that contains an 'max-age' extension element MUST NOT 210 contain a 'expires' extension element. 212 For example 213 215 http://www.example.com/myfeed 216 My Example Feed 217 2005-07-28T12:00:00Z 218 219 James 220 221 tag:entries.com,2005:1 222 An entry with a maximum age of 20 seconds 223 224 20000 225 expire after a mere 20 seconds 226 227 229 While the 'max-age' element MAY appear as a child of the atom:feed 230 and atom:source elements, it's effect is constrained to the 231 information content of atom:entry elements. 233 5. Security Considerations 235 It is possible for malicious intermediaries to alter the expiration 236 metadata for an entry. This risk can be mitigated by digitally 237 signing the atom:feed or atom:entry in which the 'expires' or 'max- 238 age' extension elements appear. It is strongly recommended that 239 implementations discard expired atom:entry elements or otherwise warn 240 users that the atom:entry has expired. 242 6. IANA Considerations 244 There are no IANA considerations introduced by this specification. 246 7. References 248 [I-D.ietf-atompub-format] 249 Sayre, R. and M. Nottingham, "The Atom Syndication 250 Format", draft-ietf-atompub-format-11 (work in progress), 251 August 2005. 253 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 254 Requirement Levels", BCP 14, RFC 2119, March 1997. 256 [W3C.REC-xml-infoset-20040204] 257 Tobin, R. and J. Cowan, "XML Information Set (Second 258 Edition)", W3C REC REC-xml-infoset-20040204, 259 February 2004. 261 [W3C.REC-xml-names-19990114] 262 Hollander, D., Bray, T., and A. Layman, "Namespaces in 263 XML", W3C REC REC-xml-names-19990114, January 1999. 265 [W3C.REC-xmlschema-2-20041028] 266 Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes 267 Second Edition", W3C REC REC-xmlschema-2-20041028, 268 October 2004. 270 Author's Address 272 James M Snell 274 Phone: 275 Email: jasnell@gmail.com 276 URI: http://snellspace.com 278 Appendix A. Acknowledgements 280 The author gratefully acknowledges the feedback from Eric Scheid, 281 Walter Underwood, Henry Story and the other members of Atom 282 Publishing Format and Protocol working group during the development 283 of this specification. 285 Intellectual Property Statement 287 The IETF takes no position regarding the validity or scope of any 288 Intellectual Property Rights or other rights that might be claimed to 289 pertain to the implementation or use of the technology described in 290 this document or the extent to which any license under such rights 291 might or might not be available; nor does it represent that it has 292 made any independent effort to identify any such rights. Information 293 on the procedures with respect to rights in RFC documents can be 294 found in BCP 78 and BCP 79. 296 Copies of IPR disclosures made to the IETF Secretariat and any 297 assurances of licenses to be made available, or the result of an 298 attempt made to obtain a general license or permission for the use of 299 such proprietary rights by implementers or users of this 300 specification can be obtained from the IETF on-line IPR repository at 301 http://www.ietf.org/ipr. 303 The IETF invites any interested party to bring to its attention any 304 copyrights, patents or patent applications, or other proprietary 305 rights that may cover technology that may be required to implement 306 this standard. Please address the information to the IETF at 307 ietf-ipr@ietf.org. 309 Disclaimer of Validity 311 This document and the information contained herein are provided on an 312 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 313 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 314 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 315 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 316 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 317 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 319 Copyright Statement 321 Copyright (C) The Internet Society (2005). This document is subject 322 to the rights, licenses and restrictions contained in BCP 78, and 323 except as set forth therein, the authors retain all their rights. 325 Acknowledgment 327 Funding for the RFC Editor function is currently provided by the 328 Internet Society.