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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Snell 3 Internet-Draft September 10, 2007 4 Intended status: Standards Track 5 Expires: March 13, 2008 7 Atom Publishing Protocol Features Extension 8 draft-snell-atompub-feature-09.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 13, 2008. 35 Copyright Notice 37 Copyright (C) The IETF Trust (2007). 39 Abstract 41 This document introduces extensions to the Atom Publishing Protocol 42 service document format for expressing metadata about the behaviors, 43 functions and capabilities supported by an Atom Publishing Protocol 44 collection. 46 Table of Contents 48 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 49 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 50 3. The f:feature element . . . . . . . . . . . . . . . . . . . . 4 51 3.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 7 52 3.2. Contradictory Features . . . . . . . . . . . . . . . . . . 7 53 4. The f:type element . . . . . . . . . . . . . . . . . . . . . . 8 54 4.1. An example f:feature using the f:type element . . . . . . 9 55 5. Digitally Signing Service Documents . . . . . . . . . . . . . 9 56 6. The "http://purl.org/atompub/features/1.0" Namespace . . . . . 10 57 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 58 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 59 8.1. Registry of Atom Publishing Features . . . . . . . . . . . 10 60 8.1.1. Initial Assignments . . . . . . . . . . . . . . . . . 11 61 9. Normative References . . . . . . . . . . . . . . . . . . . . . 24 62 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 25 63 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 25 64 Intellectual Property and Copyright Statements . . . . . . . . . . 27 66 1. Introduction 68 This document introduces extensions for the Atom Publishing Protocol 69 service document [I-D.ietf-atompub-protocol] format for expressing 70 metadata about the behaviors, functions and capabilities supported by 71 an Atom Publishing Protocol collection. 73 2. Notational Conventions 75 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 76 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 77 document are to be interpreted as described in BCP 14, [RFC2119]. 79 This specification uses XML Namespaces [W3C.REC-xml-names-20060816] 80 to uniquely identify XML element names. It uses the following 81 namespace prefix for the indicated namespace URI; 83 "f": "http://purl.org/atompub/features/1.0" 85 This specification uses terms from the XML Infoset 86 [W3C.REC-xml-infoset-20040204]. However, this specification uses a 87 shorthand; the phrase "Information Item" is omitted when naming 88 Element Information Items. Therefore, when this specification uses 89 the terms "element" and "attribute" it is referring, respectively, to 90 the Element and Attribute Information Items in Infoset terms. 92 This specification uses the terms "atomUri" and 93 "atomCommonAttributes" from the non-normative RELAX NG Compact schema 94 included in [RFC4287]. Where used, these serve the same purpose and 95 have the same meaning as their use in [RFC4287]. 97 Atom allows the use of IRIs [RFC3987]. Every URI [RFC3986] is also 98 an IRI, so a URI may be used wherever below an IRI is named. There 99 are two special considerations: (1) when an IRI that is not also a 100 URI is given for dereferencing, it MUST be mapped to a URI using the 101 steps in Section 3.1 of [RFC3987] and (2) when an IRI is serving as 102 an identifier, it MUST NOT be so mapped. 104 Any element defined by this specification MAY have an xml:base 105 attribute [W3C.REC-xmlbase-20010627]. When xml:base is used, it 106 serves the function described in section 5.1.1 of [RFC3986], 107 establishing the base URI (or IRI) for resolving any relative 108 references found within the effective scope of the xml:base 109 attribute. 111 Any element defined by this specification MAY have an xml:lang 112 attribute, whose content indicates the natural language for the 113 element and its descendents. The language context is only 114 significant for elements and attributes declared to be "Language- 115 Sensitive". Requirements regarding the content and interpretation of 116 xml:lang are specified in XML 1.0 [W3C.REC-xml-20060816], Section 117 2.12. 119 3. The f:feature element 121 A feature is an abstract behavior, function and capability supported 122 by an Atom Publishing Protocol collection. Examples of features that 123 might be supported by an Atom publishing server include support for 124 draft entries, scheduled publication of entries, use of a particular 125 set of Atom format extensions, use of a particular authentication 126 scheme, and so on. The f:feature element can be used in an app: 127 collection element to declare that a collection supports the feature 128 specified and may require that a client use that feature when 129 interacting with the endpoint. Features are identified using 130 permanent, universally unique IRI's. 132 namespace f = "http://purl.org/atompub/features/1.0" 134 feature = element f:feature { 135 atomCommonAttributes, 136 attribute ref { atomUri }, 137 attribute status { 'supported' | 'preferred' | 138 'required' | 'unsupported'}?, 139 attribute href { atomUri }?, 140 attribute label { text }?, 141 (anyElement)* 142 } 144 anyElement = element * - f:feature { 145 (attribute * { text } 146 | text 147 | anyElement)* 148 } 150 The ref attribute specifies a globally unique IRI identifying a 151 feature supported by a collection. The value of the ref attribute 152 MUST be compared on a case-sensitive, character-by-character basis. 153 Relative references MUST NOT be used. 155 The status attribute indicates a collection's level of support for 156 the identified feature. The value of the attribute can be 157 "supported", "preferred", "required" or "unsupported". If not 158 specified, the value is assumed to be "supported". If any value 159 other than those listed in this specification is specified, the 160 attribute MUST be interpreted as being "supported". 162 Support attribute values are case-insenstive. 164 o The value "supported" indicates that the server supports the 165 identified feature. Clients MAY utilize the feature when 166 interacting with the collection. If the client does not support 167 or recognize a "supported" feature, the client can safely ignore 168 it. 169 o The value "preferred" indicates that the server prefers the use of 170 the identified feature over other contradictory features or over 171 not using the feature at all. The "preferred" support level is 172 applicable to any feature the "supported" level can be applied to. 173 Clients SHOULD utilize the feature when interacting with the 174 collection. 175 o The value "required" indicates that server supports the identified 176 feature and requires that clients utilize it when interacting with 177 a collection. A client that does not support or understand a 178 required feature SHOULD NOT attempt to interact with the 179 collection. 180 o The value "unsupported" indicates that the server explicitly does 181 not support a feature. Clients SHOULD NOT utilize the feature 182 when interacting with the collection. 184 Some features supported by a collection might not require that the 185 client take any specific action when interacting with the server. 186 For such features, the "required" and "preferred" support levels 187 SHOULD be considered to be synonymous with "supported". 189 An optional href attribute MAY be used to specify the URI of a human- 190 readable description of the feature. Relative references MAY be 191 used. 193 The optional label attribute MAY be used to specify a human-readable 194 label for the feature. The value of the label attribute is Language- 195 Sensitive as defined by Section 2 of [RFC4287]. 197 The f:feature element MAY contain any number of child elements and 198 attributes from any XML namespace, with the exception of the 199 f:feature element itself. Such markup is considered to be metadata 200 applicable to the feature identified by the f:feature element. 201 Software agents MUST NOT stop processing or signal an error or change 202 their behavior as a result of encountering such markup. 204 An app:collection element MAY contain zero or more f:feature elements 205 but MUST NOT contain more than one with the same ref attribute value. 206 The order in which f:feature elements appear within the app: 207 collection element is insignificant. 209 The f:feature element MAY contain attributes included as part of the 210 atomCommonAttributes production defined by Section 2 of [RFC4287] or 211 any update thereof. When used on an f:feature element, such 212 attributes serve the same purpose described in [RFC4287] or their 213 corresponding specifications. 215 It is important to point out that implementors who add "required" 216 features to existing collections can cause existing client 217 applications to fail and can limit the ability of client applications 218 to evolve independently of a specific server implementation. A 219 better strategy would be to indicate that new features are 220 "preferred". Doing so can allow existing clients to continue to 221 function while communicating the servers preference that new clients 222 utilize the new feature. 224 Server implementors also need to remember that, as an extension to 225 the Service Document syntax, not all Atom Publishing Protocol client 226 applications will recognize and support the use of the f:feature 227 element. Such clients will be incapable of determining which 228 features are supported, preferred, or required. 230 3.1. Example 232 The following is an example of a collection supporting one 233 hypothetical required feature, one unsupported feature, and a number 234 of supported features. 236 240 241 My Workspace 242 243 My Atom Collection 244 application/atom+xml;type=entry 245 247 250 252 254 256 259 263 264 265 267 3.2. Contradictory Features 269 Some combinations of features can be contradictory when the support 270 level of one or more of those features is "required" and the others 271 are "supported" or "preferred". For instance, a collection that 272 specifies that XHTML values in the atom:title is required and that 273 HTML in an atom:title is supported is contradictory. Such 274 contradictions can cause problems for clients that are attempting to 275 select an appropriate collection based on the support level of 276 various features. A service document MUST NOT specify contradictory 277 features. If a client determines that the features specified in a 278 service document are contradictory, the client SHOULD proceed as if 279 the support level for each of those features is "supported". 281 When multiple, potentially contradictory features are specified such 282 that the support level for one is marked as "preferred" and the 283 others are "supported", clients SHOULD use the "preferred" feature. 284 If more than one potentially contradictory feature is marked as 285 "preferred", the client SHOULD proceed as if the support level for 286 each of those features is "supported". 288 4. The f:type element 290 The content of an f:type element is a media-range as defined in 291 [RFC2616]. 293 type = 294 element f:type { 295 atomCommonAttributes, 296 ( text? ) 297 } 299 Media type parameters are allowed within f:type, but f:type has no 300 notion of preference - "accept-params" or "q" arguments, as specified 301 in Section 14.1 of [RFC2616] are not significant. 303 White space (as defined in [W3C.REC-xml-20060816]) around the f:type 304 element's media-range is insignificant and MUST be ignored. 306 Any number of f:type elements MAY appear as children of an f:feature 307 element. When used with features whose ref attributes identify the 308 "XML Content", "Binary Content" or "Reference Content" features as 309 defined in Section 6.1.1, the f:type elements specify the set of 310 media types that can be specified in the atom:content elements type 311 attribute and thereby the type of content that be included within or 312 referenced by the atom:content. If no f:type elements are specified 313 for these features, clients SHOULD treat this as equivalent to an 314 f:type element with the content "*/*". 316 The order of f:type elements within a f:feature element is 317 insignificant. 319 4.1. An example f:feature using the f:type element 321 323 image/jpg 324 image/png 325 image/gif 326 text/* 327 329 5. Digitally Signing Service Documents 331 Because the mechanisms defined in this specification can be used to 332 compel client applications to implement certain behaviors when 333 interacting with a collection, implementors who specify required 334 features are encouraged to sign Service Documents containing the 335 features extension using an Enveloped Signature, as described by XML- 336 Signature and Syntax Processing [W3C.REC-xmldsig-core-20020212]. 338 Processors of Service Documents MUST NOT reject signed documents 339 because they are not capable of verifying it; they MUST continue 340 processing and MAY inform the user of their failure to validate the 341 signature. In other words, the presence of an element with the 342 namespace URI "http://www.w3.org/2000/09/xmldsig#" and a local name 343 of "Signature" as a child of the document element MUST NOT cause a 344 Processor to fail merely because of its presence. 346 Section 6.5.1 of [W3C.REC-xmldsig-core-20020212] requires support for 347 Canonical XML [W3C.REC-xml-c14n-20010315]. However, many 348 implementers do not use it because signed XML documents enclosed in 349 other XML documents have their signatures broken. Thus, Processors 350 that verify signed Service Documents MUST be able to canonicalize 351 with the exclusive XML canonicalization method identified by the URI 352 "http://www.w3.org/2001/10/xml-exc-c14n#", as specified in Exclusive 353 XML Canonicalization [W3C.REC-xml-exc-c14n-20020718]. 355 Section 4.4.2 of [W3C.REC-xmldsig-core-20020212] requires support for 356 DSA signatures and recommends support for RSA signatures. However, 357 because of the much greater popularity in the market of RSA versus 358 DSA, Processors that verify signed Atom Service Documents MUST be 359 able to verify RSA signatures, but do not need be able to verify DSA 360 signatures. Due to security issues that can arise if the keying 361 material for message authentication code (MAC) authentication is not 362 handled properly, Service Documents SHOULD NOT use MACs for 363 signatures. 365 6. The "http://purl.org/atompub/features/1.0" Namespace 367 The "http://purl.org/atompub/features/1.0" XML namespace is reserved 368 for future forward-compatible revisions of this specification. 369 Future updates to this document can add new elements and attributes 370 to the namespace. Software written to conform to this version of the 371 specification will not be able to process such markup correctly and, 372 in fact, will not be able to distinguish it from markup error. 374 Processors that encounter such markup MUST NOT stop processing or 375 signal an error. It might be the case that the Processor is able to 376 handle such markup correctly, and does so. Otherwise, processors MAY 377 bypass the markup and MUST NOT change their behavior as a result of 378 the markups presence. 380 7. Security Considerations 382 Specific features supported by a collection may introduce security 383 considerations and concerns beyond those discussed by the Atom 384 Publishing Protocol and Atom Syndication Format specifications. 385 Implementors must refer to the specifications and description of each 386 feature to determine the security considerations relevant to each. 388 Service documents can be signed using [W3C.REC-xmldsig-core-20020212] 389 and are subject to the security considerations implied by its use. 391 Digital signatures provide authentication, message integrity, and 392 non-repudiation with proof of origin. 394 8. IANA Considerations 396 8.1. Registry of Atom Publishing Features 398 The Registry of Atom Publishing Features is maintained by IANA and 399 contains information about known features that can be supported by 400 Atom Publishing Protocol implementations. New assignments are 401 subject to IESG approval, as outlined in [RFC2434]. Requests should 402 be made by email to IANA, which will then forward the request to the 403 IESG, requesting approval. The request should use the following 404 template: 406 o Ref: (A globally unique IRI identifying the feature) 407 o Label: (A human-readable label for the feature) 408 o Support Levels: (A description of the relevant support levels for 409 the feature) 411 o Contradictory Features: (A listing of features that are 412 contradictory to this feature when one or more are marked as 413 "required") 414 o Href: (A URI referencing a document containing a detailed 415 definition of the feature) 416 o Security Considerations: 418 8.1.1. Initial Assignments 420 The Registry of Features initially contains the following 421 assignments: 423 8.1.1.1. Drafts 425 o Ref: http://www.w3.org/2007/app/drafts 426 o Label: Drafts 427 o Support Levels: 428 * "supported" indicates that the collection accepts entries that 429 contain the app:draft control element. 430 * "required" indicates that the collection requires all entries 431 to contain the app:draft control element. 432 * "unsupported" indicates that the collection does not accept 433 entries that use the app:draft control element or that the 434 server will ignore the element if present. 435 o Contradictory Features: none 437 8.1.1.2. XHTML Content 439 o Ref: http://www.w3.org/2007/app/xhtml-content 440 o Label: XHTML Content 441 o Support Levels: 442 * "supported" indicates that the collection accepts entries that 443 provide XHTML in the atom:content element. 444 * "required" indicates that the collection requires all entries 445 to provide XHTML in the atom:content element. 446 * "unsupported" indicates that the collection does not accept 447 entries that provide XHTML in the atom:content element. 448 o Contradictory Features: http://www.w3.org/2007/app/html-content, 449 http://www.w3.org/2007/app/text-content, 450 http://www.w3.org/2007/app/xml-content, 451 http://www.w3.org/2007/app/binary-content, 452 http://www.w3.org/2007/app/ref-content 454 8.1.1.3. HTML Content 456 o Ref: http://www.w3.org/2007/app/html-content 457 o Label: HTML Content 458 o Support Levels: 459 * "supported" indicates that the collection accepts entries that 460 provide HTML in the atom:content element. 461 * "required" indicates that the collection requires all entries 462 to provide HTML in the atom:content element. 463 * "unsupported" indicates that the collection does not accept 464 entries that provide HTML in the atom:content element. 465 o Contradictory Features: http://www.w3.org/2007/app/xhtml-content, 466 http://www.w3.org/2007/app/text-content, 467 http://www.w3.org/2007/app/xml-content, 468 http://www.w3.org/2007/app/binary-content, 469 http://www.w3.org/2007/app/ref-content 471 8.1.1.4. Text Content 473 o Ref: http://www.w3.org/2007/app/text-content 474 o Label: Text Content 475 o Support Levels: 476 * "supported" indicates that the collection accepts entries that 477 provide plain text in the atom:content element. 478 * "required" indicates that the collection requires all entries 479 to provide plain text in the atom:content element. 480 * "unsupported" indicates that the collection does not accept 481 entries that provide plain text in the atom:content element. 482 o Contradictory Features: http://www.w3.org/2007/app/xhtml-content, 483 http://www.w3.org/2007/app/html-content, 484 http://www.w3.org/2007/app/xml-content, 485 http://www.w3.org/2007/app/binary-content, 486 http://www.w3.org/2007/app/ref-content 488 8.1.1.5. XML Content 490 o Ref: http://www.w3.org/2007/app/xml-content 491 o Label: XML Content 492 o Support Levels: 493 * "supported" indicates that the collection accepts entries that 494 provide well-formed XML in the atom:content element. 495 * "required" indicates that the collection requires all entries 496 to provide well-formed XML in the atom:content element. 497 * "unsupported" indicates that the collection does not accept 498 entries that provide XML in the atom:content element. The MIME 499 media type of acceptable XML formats is specified using one or 500 more f:type elements within the f:feature. 501 o Contradictory Features: http://www.w3.org/2007/app/xhtml-content, 502 http://www.w3.org/2007/app/html-content, 503 http://www.w3.org/2007/app/text-content, 504 http://www.w3.org/2007/app/binary-content, 505 http://www.w3.org/2007/app/ref-content 507 8.1.1.6. Binary Content 509 o Ref: http://www.w3.org/2007/app/binary-content 510 o Label: Binary Content 511 o Support Levels: 512 * "supported" indicates that the collection accepts entries that 513 provide binary content in the atom:content element. 514 * "required" indicates that the collection requires all entries 515 to provide binary content in the atom:content element. 516 * "unsupported" indicates that the collection does not accept 517 entries that provide binary content in the atom:content 518 element. The MIME media type of acceptable binary formats is 519 specified using one or more f:type elements within the 520 f:feature. 521 o Contradictory Features: http://www.w3.org/2007/app/xhtml-content, 522 http://www.w3.org/2007/app/html-content, 523 http://www.w3.org/2007/app/text-content, 524 http://www.w3.org/2007/app/xml-content, 525 http://www.w3.org/2007/app/ref-content 527 8.1.1.7. Referenced Content 529 o Ref: http://www.w3.org/2007/app/ref-content 530 o Label: XHTML Content 531 o Support Levels: 532 * "supported" indicates that the collection accepts entries that 533 use the atom:content src attribute to reference external 534 content. 535 * "required" indicates that the collection requires all entries 536 to use the atom:content src attribute to reference external 537 content. 538 * "unsupported" indicates that the collection does not accept 539 entries that use the atom:content src attribute. The MIME 540 media type of acceptable referenced resources is specified 541 using one or more f:type elements within the f:feature. 542 o Contradictory Features: http://www.w3.org/2007/app/xhtml-content, 543 http://www.w3.org/2007/app/html-content, 544 http://www.w3.org/2007/app/text-content, 545 http://www.w3.org/2007/app/xml-content, 546 http://www.w3.org/2007/app/binary-content 548 8.1.1.8. XHTML Title 550 o Ref: http://www.w3.org/2007/app/xhtml-title 551 o Label: XHTML Title 552 o Support Levels: 553 * "supported" indicates that the collection accepts entries that 554 provide XHTML in the atom:title element. 555 * "required" indicates that the collectionrequires all entries to 556 provide XHTML in the atom:title element. 557 * "unsupported" indicates that the collection does not accept 558 entries that provide XHTML in the atom:title element. 559 o Contradictory Features: http://www.w3.org/2007/app/html-title, 560 http://www.w3.org/2007/app/text-title 562 8.1.1.9. HTML Title 564 o Ref: http://www.w3.org/2007/app/html-title 565 o Label: HTML Title 566 o Support Levels: 567 * "supported" indicates that the collection accepts entries that 568 provide HTML in the atom:title element. 569 * "required" indicates that the collection requires all entries 570 to provide HTML in the atom:title element. 571 * "unsupported" indicates that the collection does not accept 572 entries that provide HTML in the atom:title element. 573 o Contradictory Features: http://www.w3.org/2007/app/xhtml-title, 574 http://www.w3.org/2007/app/text-title 576 8.1.1.10. Text Title 578 o Ref: http://www.w3.org/2007/app/text-title 579 o Label: Text Title 580 o Support Levels: 581 * "supported" indicates that the collection accepts entries that 582 provide plain text in the atom:title element. 583 * "required" indicates that the collection requires all entries 584 to provide plain text in the atom:title element. 585 * "unsupported" indicates that the collection does not accept 586 entries that provide plain text in the atom:title element. 587 o Contradictory Features: http://www.w3.org/2007/app/xhtml-title, 588 http://www.w3.org/2007/app/html-title 590 8.1.1.11. Summary 592 o Ref: http://www.w3.org/2007/app/summary 593 o Label: Summary 594 o Support Levels: 595 * "supported" indicates that the server will allow the use of the 596 atom:summary element to provide a summary or excerpt that is 597 independent of the atom:content. 599 * "required" indicates that the server requires the presence of 600 an atom:summary element to provide a summary or excerpt that is 601 independent of the atom:content. 602 * "unsupported" indicates that the server does not support the 603 use of the atom:summary element to provide a summary or excerpt 604 independent of the atom:content. When an atom:summary is 605 provided by a client, the server will either reject the request 606 or ignore the element. 607 o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary, 608 http://www.w3.org/2007/app/html-summary, 609 http://www.w3.org/2007/app/text-summary 611 8.1.1.12. Auto Summary 613 o Ref: http://www.w3.org/2007/app/auto-summary 614 o Label: Auto Summary 615 o Support Levels: 616 * "supported" indicates that the server will automatically 617 generate an atom:summary element if the entry provided by the 618 client does not already contain one. 619 * For this feature,"required" and "preferred" are synonymous with 620 "supported". 621 * "unsupported" indicates that the server will not automatically 622 generate an atom:summary element. 623 o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary, 624 http://www.w3.org/2007/app/html-summary, 625 http://www.w3.org/2007/app/text-summary 627 8.1.1.13. XHTML Summary 629 o Ref: http://www.w3.org/2007/app/xhtml-summary 630 o Label: XHTML Summary 631 o Support Levels: 632 * "supported" indicates that the collection accepts entries that 633 provide XHTML in the atom:summary element. 634 * "required" indicates that the collection requires all entries 635 to provide XHTML in the atom:summary element. 636 * "unsupported" indicates that the collection does not accept 637 entries that provide XHTML in the atom:summary element. 638 o Contradictory Features: http://www.w3.org/2007/app/html-summary, 639 http://www.w3.org/2007/app/text-summary 641 8.1.1.14. HTML Summary 643 o Ref: http://www.w3.org/2007/app/html-summary 644 o Label: HTML Summary 645 o Support Levels: 646 * "supported" indicates that the collection accepts entries that 647 provide HTML in the atom:summary element. 648 * "required" indicates that the collection requires all entries 649 to provide HTML in the atom:summary element. 650 * "unsupported" indicates that the collection does not accept 651 entries that provide HTML in the atom:summary element. 652 o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary, 653 http://www.w3.org/2007/app/text-summary 655 8.1.1.15. Text Summary 657 o Ref: http://www.w3.org/2007/app/text-summary 658 o Label: Text Summary 659 o Support Levels: 660 * "supported" indicates that the collection accepts entries that 661 provide plain text in the atom:summary element. 662 * "required" indicates that the collection requires all entries 663 to provide plain text in the atom:summary element. 664 * "unsupported" indicates that the collection does not accept 665 entries that provide plain text in the atom:summary element. 666 o Contradictory Features: http://www.w3.org/2007/app/xhtml-summary, 667 http://www.w3.org/2007/app/html-summary 669 8.1.1.16. XHTML Rights 671 o Ref: http://www.w3.org/2007/app/xhtml-rights 672 o Label: XHTML Rights 673 o Support Levels: 674 * "supported" indicates that the collection accepts entries that 675 provide XHTML in the atom:rights element. 676 * "required" indicates that the collection requires all entries 677 to provide XHTML in the atom:rights element. 678 * "unsupported" indicates that the collection does not accept 679 entries that provide XHTML in the atom:rights element. 680 o Contradictory Features: http://www.w3.org/2007/app/html-rights, 681 http://www.w3.org/2007/app/text-rights 683 8.1.1.17. HTML Rights 685 o Ref: http://www.w3.org/2007/app/html-rights 686 o Label: HTML Rights 687 o Support Levels: 688 * "supported" indicates that the collection accepts entries that 689 provide HTML in the atom:rights element. 690 * "required" indicates that the collection requires all entries 691 to provide HTML in the atom:rights element. 693 * "unsupported" indicates that the collection does not accept 694 entries that provide HTML in the atom:rights element. 695 o Contradictory Features: http://www.w3.org/2007/app/xhtml-rights, 696 http://www.w3.org/2007/app/text-rights 698 8.1.1.18. Text Rights 700 o Ref: http://www.w3.org/2007/app/text-rights 701 o Label: Text Rights 702 o Support Levels: 703 * "supported" indicates that the collection accepts entries that 704 provide plain text in the atom:rights element. 705 * "required" indicates that the collection requires all entries 706 to provide plain text in the atom:rights element. 707 * "unsupported" indicates that the collection does not accept 708 entries that provide plain text in the atom:rights element. 709 o Contradictory Features: http://www.w3.org/2007/app/xhtml-rights, 710 http://www.w3.org/2007/app/html-rights 712 8.1.1.19. Authenticated Author 714 o Ref: http://www.w3.org/2007/app/auth-author 715 o Label: Authenticated Author 716 o Support Levels: 717 * "supported" indicates that the server will automatically 718 generate the atom:author element based on the client's 719 authenticated identity. 720 * For this feature,"required" and "preferred" are synonymous with 721 "supported". 722 * "unsupported" indicates that the server will not automatically 723 generate the atom:author for an entry based on the client's 724 authenticated identity. 725 o Contradictory Features: 726 http://www.w3.org/2007/app/multiple-authors, 727 http://www.w3.org/2007/app/person-email, 728 http://www.w3.org/2007/app/person-uri 730 8.1.1.20. Slug 732 o Ref: http://www.w3.org/2007/app/slug 733 o Label: Slug 734 o Support Levels: 735 * "supported" indicates that the collection accepts the use of 736 the Slug header in POST requests. 737 * "required" indicates that the collection requires that the Slug 738 header be used for all POST requests. 740 * "unsupported" indicates that the collection will not accept the 741 use of the Slug header in POST requests or that the header will 742 be ignored. 743 o Contradictory Features: none 745 8.1.1.21. Multiple Categories 747 o Ref: http://www.w3.org/2007/app/multiple-categories 748 o Label: Multiple Categories 749 o Support Levels: 750 * "supported" indicates that the collection accepts the use of 751 multiple atom:category elements within an entry. 752 * For this feature, "required" and "preferred" are synonymous 753 with "supported". 754 * "unsupported" indicates that the collection will not accept 755 entries with multiple atom:category elements or that that 756 additional atom:category elements will be ignored. 757 o Contradictory Features: none 759 8.1.1.22. Multiple Authors 761 o Ref: http://www.w3.org/2007/app/multiple-authors 762 o Label: Multiple Authors 763 o Support Levels: 764 * "supported" indicates that the collection accepts the use of 765 multiple atom:author elements within an entry. 766 * For this feature, "required" and "preferred" are synonymous 767 with "supported". 768 * "unsupported" indicates that the collection will not accept 769 entries with multiple atom:author elements or that the 770 additional atom:author elements will be ignored. 771 o Contradictory Features: http://www.w3.org/2007/app/auth-author 773 8.1.1.23. Multiple Contributors 775 o Ref: http://www.w3.org/2007/app/contributors 776 o Label: Multiple Contributors 777 o Support Levels: 778 * "supported" indicates that the collection accepts the use of 779 multiple atom:contributor elements within an entry. 780 * For this feature, "required" and "preferred" are synonymous 781 with "supported". 782 * "unsupported" indicates that the collection will not accept 783 entries with multiple atom:contributor elements or that the 784 additional atom:contributor elements will be ignored. 785 o Contradictory Features: none 787 8.1.1.24. Preserve Infoset 789 o Ref: http://www.w3.org/2007/app/preserve-infoset 790 o Label: Preserve Infoset 791 o Support Levels: 792 * "supported" indicates that the collection will store entries in 793 such a way as to preserve the complete XML infoset of the entry 794 document. 795 * For this feature, "required" and "preferred" are synonymous 796 with "supported". 797 * "unsupported" indicates that the collection may not preserve 798 the complete XML infoset of the entry when storing. 799 o Contradictory Features: none 801 8.1.1.25. Preserve IDs 803 o Ref: http://www.w3.org/2007/app/preserve-id 804 o Label: Preserve IDs 805 o Support Levels: 806 * "supported" indicates that the collection will preserve the 807 value of the atom:id element as provided by the client. 808 * For this feature, "required" and "preferred" are synonymous 809 with "supported". 810 * "unsupported" indicates that the collection may not preserve 811 the value of the atom:id element as provided by the client 812 (e.g. the server will generate it's own value for the atom:id 813 element. 814 o Contradictory Features: none 816 8.1.1.26. Preserve Dates 818 o Ref: http://www.w3.org/2007/app/preserve-dates 819 o Label: Preserve Dates 820 o Support Levels: 821 * "supported" indicates that the collection will preserve the 822 value of all date elements as provided by the client. 823 * For this feature,"required" and "preferred" are synonymous with 824 "supported". 825 * "unsupported" indicates that the collection may not preserve 826 the value of date elements as provided by the client (e.g. the 827 server will generate it's own value for the date elements. 828 o Contradictory Features: none 830 8.1.1.27. Preserve Title 832 o Ref: http://www.w3.org/2007/app/preserve-title 833 o Label: Preserve Title 834 o Support Levels: 835 * "supported" indicates that the collection will preserve the 836 value of the atom:title element as provided by the client. 837 * For this feature,"required" and "preferred" are synonymous with 838 "supported". 839 * "unsupported" indicates that the collection may not preserve 840 the value of the atom:title as provided by the client (e.g. the 841 server will generate it's own value for the atom:title element. 842 o Contradictory Features: none 844 8.1.1.28. Preserve Extensions 846 o Ref: http://www.w3.org/2007/app/preserve-extensions 847 o Label: Preserve Extensions 848 o Support Levels: 849 * "supported" indicates that the collection will preserve all 850 extensions contained within an entry. 851 * For this feature, "required" and "preferred" are synonymous 852 with "supported". 853 * "unsupported" indicates that the collection may not preserve 854 all extensions contained within an entry, however some 855 extensions may be preserved. 856 o Contradictory Features: none 858 8.1.1.29. Preserve Links 860 o Ref: http://www.w3.org/2007/app/preserve-links 861 o Label: Preserve Links 862 o Support Levels: 863 * "supported" indicates that the collection will preserve all 864 atom:link elements contained within an entry. 865 * For this feature, "required" and "preferred" are synonymous 866 with "supported". 867 * "unsupported" indicates that the collection may not preserve 868 all atom:links contained within an entry, however some atom: 869 link elements may be preserved. 870 o Contradictory Features: none 872 8.1.1.30. Preserve Rights 874 o Ref: http://www.w3.org/2007/app/preserve-rights 875 o Label: Preserve Rights 876 o Support Levels: 877 * "supported" indicates that the collection will preserve the 878 value of the atom:rights element as well as all License Links 879 [RFC4946] contained within an entry. 881 * For this feature, "required" and "preferred" are synonymous 882 with "supported". 883 * "unsupported" indicates that the collection may not preserve 884 the value of the atom:rights element or all License Links 885 [RFC4946], however, some rights information may be preserved. 886 o Contradictory Features: none 888 8.1.1.31. Threading 890 o Ref: http://purl.org/syndication/thread/1.0 891 o Label: Threading 892 o Support Levels: 893 * "supported" indicates that the collection accepts entries that 894 contain the in-reply-to element as defined by [RFC4685]. 895 * "required" indicates that the collection requires that all 896 entries contain an in-reply-to element. 897 * "unsupported" indicates that the collection will not accept 898 entries containing the in-reply-to element or that the element 899 will be ignored if present. 900 o Contradictory Features: none 902 8.1.1.32. Scheduled Publishing 904 o Ref: http://www.w3.org/2007/app/scheduled-publishing 905 o Label: Scheduled Publishing 906 o Support Levels: 907 * "supported" indicates that the collection allows clients to 908 specify a future instant in time for the atom:published element 909 when the entry should be made publicly available. 910 * "required" indicates that the collection requires clients to 911 specify a future instant in time for the atom:published 912 element. 913 * "unsupported" indicates that the collection will not allow 914 clients to specify a future instance in time for the atom: 915 published element. 916 o Contradictory Features: none 918 8.1.1.33. Signed Entries 920 o Ref: http://www.w3.org/2007/app/signed-entries 921 o Label: Signed Entries 922 o Support Levels: 923 * "supported" indicates that the collection may reject entries 924 that do not contain a valid XML Signature as specified in 925 section 5.1 of [RFC4287]. 926 * "required" indicates that the collection requires that all 927 entries contain a valid XML Signature as specified in section 928 5.1 of [RFC4287]. 930 * "unsupported" indicates that the collection will ignore XML 931 Signatures contained in an entry. 932 o Contradictory Features: none 934 8.1.1.34. Person Email 936 o Ref: http://www.w3.org/2007/app/person-email 937 o Label: Person Email 938 o Support Levels: 939 * "supported" indicates that the collection may reject entries 940 whose atom:author and atom:contributor elements do not contain 941 a non-empty atom:email element. 942 * "required" indicates that the collection requires that all 943 atom:author and atom:contributor elements in an entry contain a 944 non-empty atom:email element.. 945 * "unsupported" indicates that the collection will reject or 946 ignore the atom:email element in all atom:author and atom: 947 contributor elements contained in an entry. 948 o Contradictory Features: http://www.w3.org/2007/app/auth-author 950 8.1.1.35. Person URI 952 o Ref: http://www.w3.org/2007/app/person-uri 953 o Label: Person URI 954 o Support Levels: 955 * "supported" indicates that the collection may reject entries 956 whose atom:author and atom:contributor elements do not contain 957 a non-empty atom:uri element. 958 * "required" indicates that the collection requires that all 959 atom:author and atom:contributor elements in an entry contain a 960 non-empty atom:uri element.. 961 * "unsupported" indicates that the collection will reject or 962 ignore the atom:uri element in all atom:author and atom: 963 contributor elements contained in an entry. 964 o Contradictory Features: http://www.w3.org/2007/app/auth-author 966 8.1.1.36. Publish Email 968 o Ref: http://www.w3.org/2007/app/publish-email 969 o Label: Publish Email 970 o Support Levels: 971 * "supported" indicates that the collection will include the 972 value of atom:email elements in public, non-editable 973 representations of an entry. 974 * For this feature, "required" and "preferred" are synonymous 975 with "supported". 977 * "unsupported" indicates that the collection will not include 978 the value of atom:email elements in public, non-editable 979 representations of an entry. 980 o Contradictory Features: none 982 8.1.1.37. Publish URI 984 o Ref: http://www.w3.org/2007/app/publish-uri 985 o Label: Publish URI 986 o Support Levels: 987 * "supported" indicates that the collection will include the 988 value of atom:uri elements in public, non-editable 989 representations of an entry. 990 * For this feature, "required" and "preferred" are synonymous 991 with "supported". 992 * "unsupported" indicates that the collection will not include 993 the value of atom:uri elements in public, non-editable 994 representations of an entry. 995 o Contradictory Features: none 997 8.1.1.38. XML Language 999 o Ref: http://www.w3.org/2007/app/xml-lang 1000 o Label: XML Language 1001 o Support Levels: 1002 * "supported" indicates that the collection will accept and 1003 preserve the value of xml:lang attributes used on an atom:entry 1004 element. 1005 * "required" indicates that the collection may reject atom:entry 1006 elements that do not contain an xml:lang attribute. 1007 * "unsupported" indicates that the collection will ignore the 1008 xml:lang attribute. 1009 o Contradictory Features: none 1011 8.1.1.39. Conditional Modification 1013 o Ref: http://www.w3.org/2007/app/conditional 1014 o Label: Conditional Modification 1015 o Support Levels: 1016 * "supported" indicates that the collection provides an Entity 1017 Tag or Last Modified timestamp for member resources and 1018 supports the use of the HTTP If-Match, If-None-Match, If- 1019 Modified-Since or If-Unmodified-Since request headers. 1020 * "supported" indicates that the collection provides an Entity 1021 Tag or Last Modified timestamp for member resources and 1022 requires the use of the HTTP If-Match, If-None-Match, If- 1023 Modified-Since or If-Unmodified-Since request headers. 1025 * "unsupported" indicates that the collection either does not 1026 provide an Entity Tag or Last Modified timestamps for member 1027 resources or does not otherwise support the use of the HTTP If- 1028 Match, If-None-Match, If-Modified-Since and If-Unmodified-Since 1029 request headers. 1030 o Contradictory Features: none 1032 9. Normative References 1034 [I-D.ietf-atompub-protocol] 1035 Hora, B. and J. Gregorio, "The Atom Publishing Protocol", 1036 draft-ietf-atompub-protocol-17 (work in progress), 1037 July 2007. 1039 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1040 Requirement Levels", BCP 14, RFC 2119, March 1997. 1042 [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1043 IANA Considerations Section in RFCs", BCP 26, RFC 2434, 1044 October 1998. 1046 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 1047 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 1048 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 1050 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1051 Resource Identifier (URI): Generic Syntax", STD 66, 1052 RFC 3986, January 2005. 1054 [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource 1055 Identifiers (IRIs)", RFC 3987, January 2005. 1057 [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom 1058 Syndication Format", RFC 4287, December 2005. 1060 [RFC4685] Snell, J., "Atom Threading Extensions", RFC 4685, 1061 September 2006. 1063 [RFC4946] Snell, J., "Atom License Extension", RFC 4946, July 2007. 1065 [W3C.REC-xml-20060816] 1066 Paoli, J., Sperberg-McQueen, C., Yergeau, F., Maler, E., 1067 and T. Bray, "Extensible Markup Language (XML) 1.0 (Fourth 1068 Edition)", World Wide Web Consortium Recommendation REC- 1069 xml-20060816, August 2006, 1070 . 1072 [W3C.REC-xml-c14n-20010315] 1073 Boyer, J., "Canonical XML Version 1.0", World Wide Web 1074 Consortium Recommendation REC-xml-c14n-20010315, 1075 March 2001, 1076 . 1078 [W3C.REC-xml-exc-c14n-20020718] 1079 Boyer, J., 3rd, D., and J. Reagle, "Exclusive XML 1080 Canonicalization Version 1.0", World Wide Web Consortium 1081 Recommendation REC-xml-exc-c14n-20020718, July 2002, 1082 . 1084 [W3C.REC-xml-infoset-20040204] 1085 Tobin, R. and J. Cowan, "XML Information Set (Second 1086 Edition)", World Wide Web Consortium Recommendation REC- 1087 xml-infoset-20040204, February 2004, 1088 . 1090 [W3C.REC-xml-names-20060816] 1091 Layman, A., Hollander, D., Bray, T., and R. Tobin, 1092 "Namespaces in XML 1.0 (Second Edition)", World Wide Web 1093 Consortium Recommendation REC-xml-names-20060816, 1094 August 2006, 1095 . 1097 [W3C.REC-xmlbase-20010627] 1098 Marsh, J., "XML Base", World Wide Web Consortium 1099 Recommendation REC-xmlbase-20010627, June 2001, 1100 . 1102 [W3C.REC-xmldsig-core-20020212] 1103 Eastlake, D., Solo, D., and J. Reagle, "XML-Signature 1104 Syntax and Processing", World Wide Web Consortium 1105 Recommendation REC-xmldsig-core-20020212, February 2002, 1106 . 1108 Appendix A. Acknowledgements 1110 The author acknowledges the feedback from the other members of the 1111 IETF Atom Publishing working group during the development of this 1112 specification. 1114 Author's Address 1116 James M Snell 1118 Phone: 1119 Email: jasnell@gmail.com 1120 URI: http://snellspace.com 1122 Full Copyright Statement 1124 Copyright (C) The IETF Trust (2007). 1126 This document is subject to the rights, licenses and restrictions 1127 contained in BCP 78, and except as set forth therein, the authors 1128 retain all their rights. 1130 This document and the information contained herein are provided on an 1131 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 1132 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 1133 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 1134 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 1135 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 1136 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1138 Intellectual Property 1140 The IETF takes no position regarding the validity or scope of any 1141 Intellectual Property Rights or other rights that might be claimed to 1142 pertain to the implementation or use of the technology described in 1143 this document or the extent to which any license under such rights 1144 might or might not be available; nor does it represent that it has 1145 made any independent effort to identify any such rights. Information 1146 on the procedures with respect to rights in RFC documents can be 1147 found in BCP 78 and BCP 79. 1149 Copies of IPR disclosures made to the IETF Secretariat and any 1150 assurances of licenses to be made available, or the result of an 1151 attempt made to obtain a general license or permission for the use of 1152 such proprietary rights by implementers or users of this 1153 specification can be obtained from the IETF on-line IPR repository at 1154 http://www.ietf.org/ipr. 1156 The IETF invites any interested party to bring to its attention any 1157 copyrights, patents or patent applications, or other proprietary 1158 rights that may cover technology that may be required to implement 1159 this standard. Please address the information to the IETF at 1160 ietf-ipr@ietf.org. 1162 Acknowledgment 1164 Funding for the RFC Editor function is provided by the IETF 1165 Administrative Support Activity (IASA).