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Clemm 5 IBM 6 J. Reschke, Ed. 7 greenbytes 8 October 20, 2003 10 WebDAV Redirect Reference Resources 11 draft-ietf-webdav-redirectref-protocol-06 13 Status of this Memo 15 This document is an Internet-Draft and is in full conformance with 16 all provisions of Section 10 of RFC2026. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that other 20 groups may also distribute working documents as Internet-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 http:// 28 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 April 19, 2004. 35 Copyright Notice 37 Copyright (C) The Internet Society (2003). All Rights Reserved. 39 Abstract 41 This specification defines redirect reference resources. A redirect 42 reference resource is a resource whose default response is an HTTP/ 43 1.1 302 (Found) status code, redirecting the client to a different 44 resource, the target resource. A redirect reference makes it 45 possible to access the target resource indirectly, through any URI 46 mapped to the redirect reference resource. There are no integrity 47 guarantees associated with redirect reference resources. 49 Distribution of this document is unlimited. Please send comments to 50 the Distributed Authoring and Versioning (WebDAV) working group at 51 w3c-dist-auth@w3.org [1], which may be joined by sending a message 52 with subject "subscribe" to w3c-dist-auth-request@w3.org [2]. 54 Discussions of the WEBDAV working group are archived at URL: http:// 55 lists.w3.org/Archives/Public/w3c-dist-auth/. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 60 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 7 61 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 8 62 4. Overview of Redirect Reference Resources . . . . . . . . . . 9 63 5. Creating a Redirect Reference Resource . . . . . . . . . . . 10 64 5.1 MKRESOURCE . . . . . . . . . . . . . . . . . . . . . . . . . 10 65 5.2 Example: Creating a Redirect Reference Resource with 66 MKRESOURCE . . . . . . . . . . . . . . . . . . . . . . . . . 11 67 6. Operations on Redirect Reference Resources . . . . . . . . . 13 68 7. Operations on Collections That Contain Redirect Reference 69 Resources . . . . . . . . . . . . . . . . . . . . . . . . . 14 70 7.1 MOVE and DELETE on Collections That Contain Redirect 71 References . . . . . . . . . . . . . . . . . . . . . . . . . 14 72 7.2 LOCK on a Collection That Contains Redirect References . . . 14 73 7.3 Example: PROPFIND on a Collection with Redirect Reference 74 Resources . . . . . . . . . . . . . . . . . . . . . . . . . 15 75 7.4 Example: PROPFIND with Apply-To-Redirect-Ref on a 76 Collection with Redirect Reference Resources . . . . . . . . 16 77 7.5 Example: COPY on a Collection That Contains a Redirect 78 Reference Resource . . . . . . . . . . . . . . . . . . . . . 18 79 7.6 Example: LOCK on a Collection That Contains a Redirect 80 Reference Resource . . . . . . . . . . . . . . . . . . . . . 19 81 8. Operations on Targets of Redirect Reference Resources . . . 22 82 9. Relative URIs in DAV:reftarget . . . . . . . . . . . . . . . 23 83 9.1 Example: Resolving a Relative URI in a Multi-Status 84 Response . . . . . . . . . . . . . . . . . . . . . . . . . . 23 85 10. Redirect References to Collections . . . . . . . . . . . . . 25 86 11. Headers . . . . . . . . . . . . . . . . . . . . . . . . . . 27 87 11.1 Redirect-Ref Response Header . . . . . . . . . . . . . . . . 27 88 11.2 Apply-To-Redirect-Ref Request Header . . . . . . . . . . . . 27 89 12. Properties . . . . . . . . . . . . . . . . . . . . . . . . . 28 90 12.1 reftarget Property . . . . . . . . . . . . . . . . . . . . . 28 91 12.2 location Pseudo-Property . . . . . . . . . . . . . . . . . . 28 92 13. XML Elements . . . . . . . . . . . . . . . . . . . . . . . . 29 93 13.1 redirectref XML Element . . . . . . . . . . . . . . . . . . 29 94 14. Extensions to the DAV:response XML Element for 95 Multi-Status Responses . . . . . . . . . . . . . . . . . . . 30 96 15. Capability Discovery . . . . . . . . . . . . . . . . . . . . 31 97 15.1 Example: Discovery of Support for Redirect Reference 98 Resources . . . . . . . . . . . . . . . . . . . . . . . . . 31 99 16. Security Considerations . . . . . . . . . . . . . . . . . . 32 100 16.1 Privacy Concerns . . . . . . . . . . . . . . . . . . . . . . 32 101 16.2 Redirect Loops . . . . . . . . . . . . . . . . . . . . . . . 32 102 16.3 Redirect Reference Resources and Denial of Service . . . . . 32 103 16.4 Revealing Private Locations . . . . . . . . . . . . . . . . 32 104 17. Internationalization Considerations . . . . . . . . . . . . 34 105 18. IANA Considerations . . . . . . . . . . . . . . . . . . . . 35 106 19. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 36 107 20. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 37 108 Normative References . . . . . . . . . . . . . . . . . . . . 38 109 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 38 110 A. Changes to the WebDAV Document Type Definition . . . . . . . 40 111 B. Change Log (to be removed by RFC Editor before 112 publication) . . . . . . . . . . . . . . . . . . . . . . . . 41 113 B.1 Since draft-ietf-webdav-redirectref-protocol-02 . . . . . . 41 114 B.2 Since draft-ietf-webdav-redirectref-protocol-03 . . . . . . 41 115 B.3 Since draft-ietf-webdav-redirectref-protocol-04 . . . . . . 41 116 B.4 Since draft-ietf-webdav-redirectref-protocol-05 . . . . . . 41 117 C. Resolved issues (to be removed by RFC Editor before 118 publication) . . . . . . . . . . . . . . . . . . . . . . . . 42 119 C.1 lc-60-ex . . . . . . . . . . . . . . . . . . . . . . . . . . 42 120 C.2 lc-06-reftarget-relative . . . . . . . . . . . . . . . . . . 42 121 C.3 lc-71-relative . . . . . . . . . . . . . . . . . . . . . . . 42 122 C.4 9-MKRESOURCE-vs-relative-URI . . . . . . . . . . . . . . . . 43 123 C.5 lc-72-trailingslash . . . . . . . . . . . . . . . . . . . . 43 124 C.6 lc-50-blindredirect . . . . . . . . . . . . . . . . . . . . 43 125 C.7 lc-74-terminology . . . . . . . . . . . . . . . . . . . . . 44 126 C.8 11.2-apply-to-redirect-ref-syntax . . . . . . . . . . . . . 44 127 C.9 15.1-options-response . . . . . . . . . . . . . . . . . . . 44 128 C.10 lc-79-accesscontrol . . . . . . . . . . . . . . . . . . . . 44 129 D. Open issues (to be removed by RFC Editor before 130 publication) . . . . . . . . . . . . . . . . . . . . . . . . 46 131 D.1 lc-85-301 . . . . . . . . . . . . . . . . . . . . . . . . . 46 132 D.2 lc-38-not-hierarchical . . . . . . . . . . . . . . . . . . . 46 133 D.3 lc-36-server . . . . . . . . . . . . . . . . . . . . . . . . 46 134 D.4 lc-33-forwarding . . . . . . . . . . . . . . . . . . . . . . 47 135 D.5 lc-37-integrity . . . . . . . . . . . . . . . . . . . . . . 47 136 D.6 3-terminology-redirectref . . . . . . . . . . . . . . . . . 47 137 D.7 lc-19-direct-ref . . . . . . . . . . . . . . . . . . . . . . 47 138 D.8 lc-41-no-webdav . . . . . . . . . . . . . . . . . . . . . . 48 139 D.9 lc-58-update . . . . . . . . . . . . . . . . . . . . . . . . 48 140 D.10 lc-24-properties . . . . . . . . . . . . . . . . . . . . . . 48 141 D.11 rfc2606-compliance . . . . . . . . . . . . . . . . . . . . . 49 142 D.12 lc-48-s6 . . . . . . . . . . . . . . . . . . . . . . . . . . 49 143 D.13 lc-28-lang . . . . . . . . . . . . . . . . . . . . . . . . . 49 144 D.14 lc-29-lang . . . . . . . . . . . . . . . . . . . . . . . . . 49 145 D.15 lc-44-pseudo . . . . . . . . . . . . . . . . . . . . . . . . 50 146 D.16 lc-61-pseudo . . . . . . . . . . . . . . . . . . . . . . . . 50 147 D.17 lc-62-oldclient . . . . . . . . . . . . . . . . . . . . . . 50 148 D.18 lc-63-move . . . . . . . . . . . . . . . . . . . . . . . . . 51 149 D.19 lc-57-noautoupdate . . . . . . . . . . . . . . . . . . . . . 51 150 D.20 lc-53-s10 . . . . . . . . . . . . . . . . . . . . . . . . . 51 151 D.21 12.1-property-name . . . . . . . . . . . . . . . . . . . . . 52 152 D.22 lc-76-location . . . . . . . . . . . . . . . . . . . . . . . 52 153 D.23 lc-80-i18n . . . . . . . . . . . . . . . . . . . . . . . . . 52 154 D.24 lc-55-iana . . . . . . . . . . . . . . . . . . . . . . . . . 52 155 Intellectual Property and Copyright Statements . . . . . . . 53 157 1. Introduction 159 This is one of a pair of specifications that extend the WebDAV 160 Distributed Authoring Protocol to enable clients to create new access 161 paths to existing resources. This capability is useful for several 162 reasons: 164 URIs of WebDAV-compliant resources are hierarchical and correspond to 165 a hierarchy of collections in resource space. The WebDAV Distributed 166 Authoring Protocol makes it possible to organize these resources into 167 hierarchies, placing them into groupings, known as collections, which 168 are more easily browsed and manipulated than a single flat 169 collection. However, hierarchies require categorization decisions 170 that locate resources at a single location in the hierarchy, a 171 drawback when a resource has multiple valid categories. For example, 172 in a hierarchy of vehicle descriptions containing collections for 173 cars and boats, a description of a combination car/boat vehicle could 174 belong in either collection. Ideally, the description should be 175 accessible from both. Allowing clients to create new URIs that access 176 the existing resource lets them put that resource into multiple 177 collections. 179 Hierarchies also make resource sharing more difficult, since 180 resources that have utility across many collections are still forced 181 into a single collection. For example, the mathematics department at 182 one university might create a collection of information on fractals 183 that contains bindings to some local resources, but also provides 184 access to some resources at other universities. For many reasons, it 185 may be undesirable to make physical copies of the shared resources on 186 the local server: to conserve disk space, to respect copyright 187 constraints, or to make any changes in the shared resources visible 188 automatically. Being able to create new access paths to existing 189 resources in other collections or even on other servers is useful for 190 this sort of case. 192 The redirect reference resources defined here provide a mechanism for 193 creating alternative access paths to existing resources. A redirect 194 reference resource is a resource in one collection whose purpose is 195 to forward requests to another resource (its target), possibly in a 196 different collection. In this way, it allows clients to submit 197 requests to the target resource from another collection. It 198 redirects most requests to the target resource using the HTTP 302 199 (Found) status code, thereby providing a form of mediated access to 200 the target resource. 202 A redirect reference is a resource with properties but no body of its 203 own. Properties of a redirect reference resource can contain such 204 information as who created the reference, when, and why. Since 205 redirect reference resources are implemented using HTTP 302 206 responses, it generally takes two round trips to submit a request to 207 the intended resource. Servers are not required to enforce the 208 integrity of redirect references. Redirect references work equally 209 well for local resources and for resources that reside on a different 210 server from the reference. 212 The remainder of this document is structured as follows: Section 3 213 defines terms that will be used throughout the specification. 214 Section 4 provides an overview of redirect reference resources. 215 Section 5 discusses how to create a redirect reference resource. 216 Section 6 defines the semantics of existing methods when applied to 217 redirect reference resources, and Section 7 discusses their semantics 218 when applied to collections that contain redirect reference 219 resources. Sections 8 through 10 discuss several other issues raised 220 by the existence of redirect reference resources. Sections 11 221 through 14 define the new headers, properties, and XML elements 222 required to support redirect reference resources. Section 15 223 discusses capability discovery. Sections 16 through 18 present the 224 security, internationalization, and IANA concerns raised by this 225 specification. The remaining sections provide a variety of supporting 226 information. 228 2. Notational Conventions 230 Since this document describes a set of extensions to the WebDAV 231 Distributed Authoring Protocol [RFC2518], itself an extension to the 232 HTTP/1.1 protocol, the augmented BNF used here to describe protocol 233 elements is exactly the same as described in Section 2.1 of 234 [RFC2616]. Since this augmented BNF uses the basic production rules 235 provided in Section 2.2 of [RFC2616], these rules apply to this 236 document as well. 238 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 239 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 240 document are to be interpreted as described in [RFC2119]. 242 3. Terminology 244 The terminology used here follows and extends that in the WebDAV 245 Distributed Authoring Protocol specification [RFC2518]. Definitions 246 of the terms resource, Uniform Resource Identifier (URI), and Uniform 247 Resource Locator (URL) are provided in [RFC2396]. 249 Redirect Reference Resource 251 A resource created to redirect all requests made to it, using 302 252 (Found), to a defined target resource. 254 Non-Reference Resource 256 A resource that is not a reference to another resource. 258 Target Resource 260 The resource to which requests are forwarded by a reference 261 resource. A target resource can be anything that can be identified 262 by an absolute URI (see [RFC2396], "absoluteURI"). 264 4. Overview of Redirect Reference Resources 266 For all operations submitted to a redirect reference resource, the 267 default response is a 302 (Found), accompanied by the Redirect-Ref 268 header (defined in Section 11.1 below) and the Location header set to 269 the URI of the target resource. With this information, the client 270 can resubmit the request to the URI of the target resource. 272 A redirect reference resource never automatically forwards requests 273 to its target resource. Redirect resources bring the same benefits as 274 links in HTML documents. They can be created and maintained without 275 the involvement or even knowledge of their target resource. This 276 reduces the cost of linking between resources." 278 If the client is aware that it is operating on a redirect reference 279 resource, it can resolve the reference by retrieving the reference 280 resource's DAV:reftarget property (defined in Section 12.1 below), 281 whose value contains the URI of the target resource. It can then 282 submit requests to the target resource. 284 A redirect reference resource is a new type of resource. To 285 distinguish redirect reference resources from non-reference 286 resources, a new value of the DAV:resourcetype property (defined in 287 [RFC2518]), DAV:redirectref, is defined in Section 13.1 below. 289 Since a redirect reference resource is a resource, methods can be 290 applied to the reference resource as well as to its target resource. 291 The Apply-To-Redirect-Ref request header (defined in Section 11.2 292 below) is provided so that referencing-aware clients can control 293 whether an operation is applied to the redirect reference resource or 294 to its target resource. The Apply-To-Redirect-Ref header can be used 295 with most requests to redirect reference resources. This header is 296 particularly useful with PROPFIND, to retrieve the reference 297 resource's own properties. 299 5. Creating a Redirect Reference Resource 301 The new MKRESOURCE method is used to create new redirect reference 302 resources. In order to create a redirect reference resource using 303 MKRESOURCE, the values of two properties must be set in the body of 304 the MKRESOURCE request. The value of DAV:resourcetype MUST be set to 305 DAV:redirectref, a new value of DAV:resourcetype defined in Section 306 13.1. The value of DAV:reftarget MUST be set to the URI of the target 307 resource. 309 Used in this way, the MKRESOURCE method creates a redirect reference 310 resource whose target is identified by the DAV:reftarget property. 312 5.1 MKRESOURCE 314 The MKRESOURCE method requests the creation of a redirect reference 315 resource and initialization of its properties in one atomic 316 operation. 318 Preconditions: 320 A resource MUST NOT exist at the Request-URI. 322 Request Marshalling: 324 The location of the new resource to be created is specified by the 325 Request-URI. 327 The request body of the MKRESOURCE method MUST consist of the 328 DAV:propertyupdate XML element defined in Section 12.13 of 329 [RFC2518], specifying a DAV:resourcetype of "DAV:redirectref". 331 Postconditions: 333 If the response status code is 201, a new resource exists at the 334 Request-URI. 336 The properties of the new resource are as specified by the 337 DAV:propertyupdate request body, using PROPPATCH semantics. 339 If the response status code is not 201, then a new resource is not 340 created at the Request-URI, and any existing resource at the 341 Request-URI is unaffected. 343 Response Marshalling: 345 Responses from a MKRESOURCE request MUST NOT be cached, as 346 MKRESOURCE has non-idempotent semantics. 348 The following status codes can be expected in responses to 349 MKRESOURCE: 351 201 (Created): The new resource was successfully created. 353 403 (Forbidden): The server does not allow the creation of the 354 requested resource type at the requested location, or the parent 355 collection of the Request-URI exists but cannot accept members. 357 409 (Conflict): A resource cannot be created at the Request-URI 358 because the parent collection for the resource does not exist, or 359 because there is already a resource at that request-URL. 361 423 (Locked): The Request-URI is locked, and the lock token was 362 not passed with the request. 364 507 (Insufficient Storage): The server does not have sufficient 365 space to record the state of the resource. 367 5.2 Example: Creating a Redirect Reference Resource with MKRESOURCE 369 >> Request: 371 MKRESOURCE /~whitehead/dav/spec08.ref HTTP/1.1 372 Host: www.ics.uci.edu 373 Content-Type: text/xml; charset="utf-8" 374 Content-Length: xxx 376 377 378 379 380 381 382 /i-d/draft-webdav-protocol-08.txt 383 384 385 386 388 >> Response: 390 HTTP/1.1 201 Created 392 This request resulted in the creation of a new redirect reference 393 resource at www.ics.uci.edu/~whitehead/dav/spec08.ref, which points 394 to the resource identified by the DAV:reftarget property. In this 395 example, the target resource is identified by the URI http:// 396 www.ics.uci.edu/i-d/draft-webdav-protocol-08.txt. The redirect 397 reference resource's DAV:resourcetype property is set to 398 DAV:redirectref. 400 6. Operations on Redirect Reference Resources 402 Although non-referencing-aware clients cannot create reference 403 resources, they should be able to submit requests through the 404 reference resources created by reference-aware WebDAV clients. They 405 should be able to follow any references to their targets. To make 406 this possible, a server that receives any request made via a redirect 407 reference resource MUST return a 302 (Found) status code, unless the 408 request includes an Apply-To-Redirect-Ref header specifying "T". The 409 client and server MUST follow [RFC2616] Section 10.3.3 "302 Found", 410 but with these additional rules: 412 o The Location response header MUST contain an absolute URI that 413 identifies the target of the reference resource. 415 o The response MUST include the Redirect-Ref header. This header 416 allows reference-aware WebDAV clients to recognize the resource as 417 a reference resource and understand the reason for the 418 redirection. 420 A reference-aware WebDAV client can act on this response in one of 421 two ways. It can, like a non-referencing client, resubmit the 422 request to the URI in the Location header in order to operate on the 423 target resource. Alternatively, it can resubmit the request to the 424 URI of the redirect reference resource with the 425 "Apply-To-Redirect-Ref: T" header in order to operate on the 426 reference resource itself. In this case, the request MUST be applied 427 to the reference resource itself, and a 302 response MUST NOT be 428 returned. 430 A reference-aware client may know before submitting its request that 431 the Request-URI identifies a redirect reference resource. In this 432 case, if the client wants to apply the method to the reference 433 resource, it can save the round trip caused by the 302 response by 434 using an Apply-To-Redirect-Ref header in its initial request to the 435 URI. 437 As redirect references do not have bodies, GET and PUT requests with 438 "Apply-To-Redirect-Ref: T" MUST fail with status 403 (forbidden). 440 7. Operations on Collections That Contain Redirect Reference Resources 442 Consistent with the rules in Section 6, the response for each 443 redirect reference encountered while processing a collection MUST be 444 a 302 (Found) unless a "Apply-To-Redirect-Ref: T" header is included 445 with the request. The overall response will therefore be a 207 446 (Multi-Status). Since a Location header and Redirect-Ref header 447 cannot be returned for each redirect reference encountered, the same 448 information is provided using properties in the response elements for 449 those resources. The DAV:location pseudo-property and the 450 DAV:resourcetype property MUST be included with the 302 status code. 451 This necessitates an extension to the syntax of the DAV:response 452 element that was defined in [RFC2518]. The extension is defined in 453 Section 14 below. 455 It is recommended that future editors of [RFC2518] define the 456 DAV:location pseudo-property in [RFC2518], so that non-referencing 457 clients will also be able to use the response to operate on the 458 target resource. (This will also enable clients to operate on 459 traditional HTTP/1.1 302 responses in Multi-Status responses.) Until 460 then, non-referencing clients will not be able to process 302 461 responses from redirect reference resources encountered while 462 processing a collection. 464 The Apply-To-Redirect-Ref header (defined in Section 11.2) MAY be 465 used with any request on a collection. If present, it will be 466 applied to all redirect reference resources encountered while 467 processing the collection. 469 7.1 MOVE and DELETE on Collections That Contain Redirect References 471 DELETE removes the binding that corresponds to the Request-URI. MOVE 472 removes that binding and creates a new binding to the same resource. 473 In cases where DELETE and MOVE are applied to a collection, these 474 operations affect all the descendents of the collection, but they do 475 so indirectly. There is no need to visit each descendent in order to 476 process the request. Consequently, even if there are redirect 477 reference resources in a tree that is being deleted or moved, there 478 will be no 302 responses from the redirect reference resources. 480 7.2 LOCK on a Collection That Contains Redirect References 482 LOCK poses special problems because it is atomic. An attempt to lock 483 (with Depth: infinity) a collection that contains redirect references 484 will always fail. The Multi-Status response will contain a 302 485 response for each redirect reference. 487 Reference-aware clients can lock the collection by using 488 Apply-To-Redirect-Ref, and, if desired, lock the targets of the 489 redirect references individually. 491 Non-referencing clients must resort to locking each resource 492 individually. 494 7.3 Example: PROPFIND on a Collection with Redirect Reference Resources 496 Suppose a PROPFIND request with Depth: infinity is submitted to the 497 following collection, with the members shown here: 499 http://www.svr.com/MyCollection/ 500 (non-reference resource) diary.html 501 (redirect reference resource) nunavut 503 >> Request: 505 PROPFIND /MyCollection/ HTTP/1.1 506 Host: www.svr.com 507 Depth: infinity 508 Content-Type: text/xml 509 Content-Length: xxxx 511 512 513 514 515 516 517 519 >> Response: 521 HTTP/1.1 207 Multi-Status 522 Content-Type: text/xml 523 Content-Length: xxxx 525 526 527 528 http://www.svr.com/MyCollection/ 529 530 531 532 diary, interests, hobbies 533 534 HTTP/1.1 200 OK 535 537 538 539 http://www.svr.com/MyCollection/diary.html 540 541 542 543 diary, travel, family, history 544 545 HTTP/1.1 200 OK 546 547 548 549 http://www.svr.com/MyCollection/nunavut 550 HTTP/1.1 302 Found 551 552 553 http://www.inac.gc.ca/art/inuit/ 554 555 556 557 558 560 In this example the Depth header is set to infinity, and the 561 Apply-To-Redirect-Ref header is not used. The collection contains 562 one URI that identifies a redirect reference resource. The response 563 element for the redirect reference resource has a status of 302 564 (Found), and includes a DAV:prop element with the DAV:location 565 pseudo-property and the DAV:resourcetype property to allow clients to 566 retrieve the properties of its target resource. (The response 567 element for the redirect reference resource does not include the 568 requested properties. The client can submit another PROPFIND request 569 to the URI in the DAV:location pseudo-property to retrieve those 570 properties.) 572 7.4 Example: PROPFIND with Apply-To-Redirect-Ref on a Collection with 573 Redirect Reference Resources 575 Suppose a PROPFIND request with "Apply-To-Redirect-Ref: T" and Depth: 576 infinity is submitted to the following collection, with the members 577 shown here: 579 /MyCollection/ 580 (non-reference resource) diary.html 581 (redirect reference resource) nunavut 583 >> Request: 585 PROPFIND /MyCollection/ HTTP/1.1 586 Host: example.com 587 Depth: infinity 588 Apply-To-Redirect-Ref: T 589 Content-Type: text/xml 590 Content-Length: xxxx 592 593 594 595 596 597 598 600 >> Response: 602 HTTP/1.1 207 Multi-Status 603 Content-Type: text/xml 604 Content-Length: xxxx 606 607 608 609 /MyCollection/ 610 611 612 613 614 HTTP/1.1 200 OK 615 616 617 618 HTTP/1.1 404 Not Found 619 620 621 622 /MyCollection/diary.html 623 624 625 626 627 HTTP/1.1 200 OK 628 629 630 631 HTTP/1.1 404 Not Found 632 633 634 635 /MyCollection/nunavut 636 637 638 639 640 http://www.inac.gc.ca/art/inuit/ 641 642 643 HTTP/1.1 200 OK 644 645 646 648 Since the "Apply-To-Redirect-Ref: T" header is present, the response 649 shows the properties of the redirect reference resource in the 650 collection rather than reporting a 302 status. 652 7.5 Example: COPY on a Collection That Contains a Redirect Reference 653 Resource 655 Suppose a COPY request is submitted to the following collection, with 656 the members shown: 658 /MyCollection/ 659 (non-reference resource) diary.html 660 (redirect reference resource) nunavut with target 661 /Someplace/nunavut.map 663 >> Request: 665 COPY /MyCollection/ HTTP/1.1 666 Host: www.svr.com 667 Depth: infinity 668 Destination: http://www.svr.com/OtherCollection/ 669 >> Response: 671 HTTP/1.1 207 Multi-Status 672 Content-Type: text/xml; charset="utf-8" 673 Content-Length: xxx 675 676 677 678 http://www.svr.com/MyCollection/nunavut 679 HTTP/1.1 302 Found 680 681 682 http://www.svr.com//Someplace/nunavut.map 683 684 685 686 687 689 In this case, since /MyCollection/nunavut is a redirect reference 690 resource, the COPY operation was only a partial success. The 691 redirect reference resource was not copied, but a 302 response was 692 returned for it. So the resulting collection is as follows: 694 /OtherCollection/ 695 (non-reference resource) diary.html 697 7.6 Example: LOCK on a Collection That Contains a Redirect Reference 698 Resource 700 Suppose a LOCK request is submitted to the following collection, with 701 the members shown: 703 /MyCollection/ 704 (non-reference resource) diary.html 705 (redirect reference resource) nunavut 707 >> Request: 709 LOCK /MyCollection/ HTTP/1.1 710 Host: www.svr.com 711 Content-Type: text/xml 712 Content-Length: nnnn 713 Authorizaton: Digest username="jas", 714 realm=jas@webdav.sb.aol.com, nonce=". . . ", 715 uri="/MyCollection/tuva", 716 response=". . . ", opaque=". . . " 718 719 720 721 722 723 http://www.svr.com/~jas/contact.html 724 725 726 >> Response: 728 HTTP/1.1 207 Multi-Status 729 Content-Type: text/xml 730 Content-Length: nnnn 732 733 734 735 http://www.svr.com/MyCollection/ 736 737 738 HTTP/1.1 424 Failed Dependency 739 740 741 742 http://www.svr.com/MyCollection/diary.html 743 HTTP/1.1 424 Failed Dependency 744 745 746 http://www.svr.com/MyCollection/nunavut 747 HTTP/1.1 302 Found 748 749 750 http://www.inac.gc.ca/art/inuit/ 751 752 753 754 755 757 The server returns a 302 response code for the redirect reference 758 resource in the collection. Consequently, neither the collection nor 759 any of the resources identified by its internal member URIs were 760 locked. A referencing-aware client can submit a separate LOCK request 761 to the URI in the DAV:location pseudo-property returned for the 762 redirect reference resource, and can resubmit the LOCK request with 763 the Apply-To-Redirect-Ref header to the collection. At that point 764 both the reference resource and its target resource will be locked 765 (as well as the collection and all the resources identified by its 766 other members). 768 8. Operations on Targets of Redirect Reference Resources 770 Operations on targets of redirect reference resources have no effect 771 on the reference resource. 773 9. Relative URIs in DAV:reftarget 775 The URI in the href in a DAV:reftarget property MAY be a relative 776 URI. In this case, the base URI to be used for resolving the relative 777 URI to absolute form is the URI used in the HTTP message to identify 778 the redirect reference resource to which the DAV:reftarget property 779 belongs. 781 When DAV:reftarget appears in the context of a Multi-Status response, 782 it is in a DAV:response element that contains a single DAV:href 783 element. The value of this DAV:href element serves as the base URI 784 for resolving a relative URI in DAV:reftarget. The value of DAV:href 785 may itself be relative, in which case it must be resolved first in 786 order to serve as the base URI for the relative URI in DAV:reftarget. 787 If the DAV:href element is relative, its base URI is constructed from 788 the scheme component "http", the value of the Host header in the 789 request, and the request-URI. 791 9.1 Example: Resolving a Relative URI in a Multi-Status Response 793 >> Request: 795 PROPFIND /geog/ HTTP/1.1 796 Host: example.com 797 Apply-To-Redirect-Ref: T 798 Depth: 1 799 Content-Type: text/xml 800 Content-Length: nnn 802 803 804 805 806 807 808 809 >> Response: 811 HTTP/1.1 207 Multi-Status 812 Content-Type: text/xml 813 Content-Length: nnn 815 816 817 818 /geog/ 819 820 821 822 823 HTTP/1.1 200 OK 824 825 826 827 HTTP/1.1 404 Not Found 828 829 830 831 /geog/stats.html 832 833 834 835 836 statistics/population/1997.html 837 838 839 HTTP/1.1 200 OK 840 841 842 844 In this example, the relative URI statistics/population/1997.html is 845 returned as the value of reftarget for the reference resource 846 identified by href /geog/stats.html. The href is itself a relative 847 URI, which resolves to http://example.com/geog/stats.html. This is 848 the base URI for resolving the relative URI in reftarget. The 849 absolute URI of reftarget is http://example.com/geog/statistics/ 850 population/1997.html. 852 10. Redirect References to Collections 854 In a Request-URI /segment1/segment2/segment3, any of the three 855 segments may identify a redirect reference resource. (See [RFC2396], 856 Section 3.3, for definitions of "path" and "segment".) If any 857 segment in a Request- URI identifies a redirect reference resource, 858 the response is a 302. The value of the Location header in the 302 859 response is as follows: 861 The leftmost path segment of the request-URI that identifies a 862 redirect reference resource, together with all path segments and 863 separators to the left of it, is replaced by the value of the 864 redirect reference resource's DAV:reftarget property (resolved to an 865 absolute URI). The remainder of the request-URI is concatenated to 866 this path. 868 Note: If the DAV:reftarget property ends with a "/" and the remainder 869 of the Request-URI is non-empty (and therefore must begin with a "/ 870 "), the final "/" in the DAV:reftarget property is dropped before the 871 remainder of the Request-URI is appended. 873 Consider Request-URI /x/y/z.html. Suppose that /x/ is a redirect 874 reference resource whose target resource is collection /a/, which 875 contains redirect reference resource y whose target resource is 876 collection /b/, which contains redirect reference resource z.html 877 whose target resource is /c/d.html. 879 /x/y/z.html 880 | 881 | /x -> /a 882 | 883 v 884 /a/y/z.html 885 | 886 | /a/y -> /b 887 | 888 v 889 /b/z.html 890 | 891 | /b/z.html -> /c/d.html 892 | 893 v 894 /c/d.html 896 In this case the client must follow up three separate 302 responses 897 before finally reaching the target resource. The server responds to 898 the initial request with a 302 with Location: /a/y/z.html, and the 899 client resubmits the request to /a/y/z.html. The server responds to 900 this request with a 302 with Location: /b/z.html, and the client 901 resubmits the request to /b/z.html. The server responds to this 902 request with a 302 with Location: /c/d.html, and the client resubmits 903 the request to /c/d.html. This final request succeeds. 905 11. Headers 907 11.1 Redirect-Ref Response Header 909 Redirect-Ref = "Redirect-Ref:" (absoluteURI | relativeURI) 910 ; see sections 3 and 5 of [RFC2396] 912 The Redirect-Ref header is used in all 302 responses from redirect 913 reference resources. The value is the (possibly relative) URI of the 914 link target as specified during redirect reference resource creation. 916 11.2 Apply-To-Redirect-Ref Request Header 918 Apply-To-Redirect-Ref = "Apply-To-Redirect-Ref" ":" ("T" | "F") 920 The optional Apply-To-Redirect-Ref header can be used on any request 921 to a redirect reference resource. When it is present and set to "T", 922 the request MUST be applied to the reference resource itself, and a 923 302 response MUST NOT be returned. 925 If the Apply-To-Redirect-Ref header is used on a request to any other 926 sort of resource besides a redirect reference resource, the server 927 MUST ignore it. 929 12. Properties 931 12.1 reftarget Property 933 Name: reftarget 935 Namespace: DAV: 937 Purpose: A property of redirect reference resources that provides an 938 efficient way for clients to discover the URI of the target 939 resource. This is a read-only property after its initial 940 creation. Its value can only be set in a MKRESOURCE request. 942 Value: href containing the URI of the target resource. This value 943 MAY be a relative URI. The reftarget property can occur in the 944 entity bodies of MKRESOURCE requests and of responses to PROPFIND 945 requests. 947 949 12.2 location Pseudo-Property 951 Name: location 953 Namespace: DAV: 955 Purpose: For use with 302 (Found) response codes in Multi-Status 956 responses. It contains the absolute URI of the temporary location 957 of the resource. In the context of redirect reference resources, 958 this value is the absolute URI of the target resource. It is 959 analogous to the Location header in HTTP 302 responses defined in 960 [RFC2616] Section 10.3.3 "302 Found." Including the location 961 pseudo-property in a Multi-Status response requires an extension 962 to the syntax of the DAV:response element defined in [RFC2518], 963 which is defined in Section 14 below. This pseudo-property is not 964 expected to be stored on the reference resource. It is modeled as 965 a property only so that it can be returned inside a DAV:prop 966 element in a Multi-Status response. 968 Value: href containing the absolute URI of the target resource. 970 972 13. XML Elements 974 13.1 redirectref XML Element 976 Name: redirectref 978 Namespace: DAV: 980 Purpose: Used as the value of the DAV:resourcetype property to 981 specify that the resource type is a redirect reference resource. 983 985 14. Extensions to the DAV:response XML Element for Multi-Status 986 Responses 988 As described in Section 7, the DAV:location pseudo-property and the 989 DAV:resourcetype property may be returned in the DAV:response element 990 of a 207 Multi-Status response, to allow clients to resubmit their 991 requests to the target resource of a redirect reference resource. 993 Whenever these properties are included in a Multi-Status response, 994 they are placed in a DAV:prop element associated with the href to 995 which they apply. This structure provides a framework for future 996 extensions by other standards that may need to include additional 997 properties in their responses. 999 Consequently, the definition of the DAV:response XML element changes 1000 to the following: 1002 1005 15. Capability Discovery 1007 Sections 9.1 and 15 of [RFC2518] describe the use of compliance 1008 classes with the DAV header in responses to OPTIONS, to indicate 1009 which parts of the WebDAV Distributed Authoring protocols the 1010 resource supports. This specification defines an OPTIONAL extension 1011 to [RFC2518]. It defines a new compliance class, called 1012 redirectrefs, for use with the DAV header in responses to OPTIONS 1013 requests. If a resource does support redirect references, its 1014 response to an OPTIONS request may indicate that it does, by listing 1015 the new redirectrefs compliance class in the DAV header and by 1016 listing the MKRESOURCE method as one it supports. 1018 When responding to an OPTIONS request, any type of resource can 1019 include redirectrefs in the value of the DAV header. Doing so 1020 indicates that the server permits a redirect reference resource at 1021 the request URI. 1023 15.1 Example: Discovery of Support for Redirect Reference Resources 1025 >> Request: 1027 OPTIONS /somecollection/someresource HTTP/1.1 1028 Host: example.org 1030 >> Response: 1032 HTTP/1.1 200 OK 1033 Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE 1034 Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, MKRESOURCE 1035 DAV: 1, 2, redirectrefs 1037 The DAV header in the response indicates that the resource / 1038 somecollection/someresource is level 1 and level 2 compliant, as 1039 defined in [RFC2518]. In addition, /somecollection/someresource 1040 supports redirect reference resources. The Allow header indicates 1041 that MKRESOURCE requests can be submitted to /somecollection/ 1042 someresource. 1044 16. Security Considerations 1046 This section is provided to make applications that implement this 1047 protocol aware of the security implications of this protocol. 1049 All of the security considerations of HTTP/1.1 and the WebDAV 1050 Distributed Authoring Protocol specification also apply to this 1051 protocol specification. In addition, redirect reference resources 1052 introduce several new security concerns and increase the risk of some 1053 existing threats. These issues are detailed below. 1055 16.1 Privacy Concerns 1057 By creating redirect reference resources on a trusted server, it is 1058 possible for a hostile agent to induce users to send private 1059 information to a target on a different server. This risk is 1060 mitigated somewhat, since clients are required to notify the user of 1061 the redirection for any request other than GET or HEAD. (See 1062 [RFC2616], Section 10.3.3 302 Found.) 1064 16.2 Redirect Loops 1066 Although redirect loops were already possible in HTTP 1.1, the 1067 introduction of the MKRESOURCE method creates a new avenue for 1068 clients to create loops accidentally or maliciously. If the 1069 reference resource and its target are on the same server, the server 1070 may be able to detect MKRESOURCE requests that would create loops. 1071 See also [RFC2616], Section 10.3 "Redirection 3xx." 1073 16.3 Redirect Reference Resources and Denial of Service 1075 Denial of service attacks were already possible by posting URLs that 1076 were intended for limited use at heavily used Web sites. The 1077 introduction of MKRESOURCE creates a new avenue for similar denial of 1078 service attacks. Clients can now create redirect reference resources 1079 at heavily used sites to target locations that were not designed for 1080 heavy usage. 1082 16.4 Revealing Private Locations 1084 There are several ways that redirect reference resources may reveal 1085 information about collection structures. First, the DAV:reftarget 1086 property of every redirect reference resource contains the URI of the 1087 target resource. Anyone who has access to the reference resource can 1088 discover the collection path that leads to the target resource. The 1089 owner of the target resource may have wanted to limit knowledge of 1090 this collection structure. 1092 Sufficiently powerful access control mechanisms can control this risk 1093 to some extent. Property-level access control could prevent users 1094 from examining the DAV:reftarget property. (The Location header 1095 returned in responses to requests on redirect reference resources 1096 reveals the same information, however.) 1098 This risk is no greater than the similar risk posed by HTML links. 1100 17. Internationalization Considerations 1102 This specification follows the practices of [RFC2518] in encoding all 1103 human-readable content using XML [XML] and in the treatment of names. 1104 Consequently, this specification complies with the IETF Character Set 1105 Policy [RFC2277]. 1107 WebDAV applications MUST support the character set tagging, character 1108 set encoding, and the language tagging functionality of the XML 1109 specification. This constraint ensures that the human-readable 1110 content of this specification complies with [RFC2277]. 1112 As in [RFC2518], names in this specification fall into three 1113 categories: names of protocol elements such as methods and headers, 1114 names of XML elements, and names of properties. Naming of protocol 1115 elements follows the precedent of HTTP, using English names encoded 1116 in USASCII for methods and headers. The names of XML elements used 1117 in this specification are English names encoded in UTF-8. 1119 For error reporting, [RFC2518] follows the convention of HTTP/1.1 1120 status codes, including with each status code a short, English 1121 description of the code (e.g., 423 Locked). Internationalized 1122 applications will ignore this message, and display an appropriate 1123 message in the user's language and character set. 1125 This specification introduces no new strings that are displayed to 1126 users as part of normal, error-free operation of the protocol. 1128 For rationales for these decisions and advice for application 1129 implementors, see [RFC2518]. 1131 18. IANA Considerations 1133 All IANA considerations mentioned in [RFC2518] also apply to this 1134 document. 1136 19. Contributors 1138 Many thanks to Jason Crawford, Jim Davis, Chuck Fay and Judith Slein 1139 who can take credit for big parts of the original design of this 1140 specification. 1142 20. Acknowledgements 1144 This document has benefited from thoughtful discussion by Jim Amsden, 1145 Peter Carlson, Steve Carter, Tyson Chihaya, Ken Coar, Ellis Cohen, 1146 Bruce Cragun, Spencer Dawkins, Mark Day, Rajiv Dulepet, David Durand, 1147 Roy Fielding, Yaron Goland, Fred Hitt, Alex Hopmann, James Hunt, 1148 Marcus Jager, Chris Kaler, Manoj Kasichainula, Rohit Khare, Daniel 1149 LaLiberte, Steve Martin, Larry Masinter, Jeff McAffer, Joe Orton, 1150 Surendra Koduru Reddy, Juergen Reuter, Max Rible, Sam Ruby, Bradley 1151 Sergeant, Nick Shelness, John Stracke, John Tigue, John Turner, Kevin 1152 Wiggen, and others. 1154 Normative References 1156 [RFC2277] Alvestrand, H., "IETF Policy on Character Sets and 1157 Languages", BCP 18, RFC 2277, January 1998. 1159 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1160 Requirement Levels", BCP 14, RFC 2119, March 1997. 1162 [RFC2396] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform 1163 Resource Identifiers (URI): Generic Syntax", RFC 2396, 1164 August 1998. 1166 [RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S. and D. 1167 Jensen, "HTTP Extensions for Distributed Authoring -- 1168 WEBDAV", RFC 2518, February 1999. 1170 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 1171 Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext 1172 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 1174 [XML] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler, 1175 "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C 1176 REC-xml, October 2000, . 1179 [1] 1181 [2] 1183 [3] 1186 [4] 1189 [5] 1192 [6] 1195 [7] 1198 [8] 1201 [9] 1204 [10] 1207 [11] 1210 [12] 1213 [13] 1216 [14] 1219 [15] 1222 [16] 1225 [17] 1228 [18] 1231 [19] 1234 [20] 1237 [21] 1240 [22] 1243 [23] 1246 [24] 1249 [25] 1252 [26] 1255 [27] 1258 [28] 1261 [29] 1264 [30] 1267 Authors' Addresses 1269 Jim Whitehead 1270 UC Santa Cruz, Dept. of Computer Science 1271 1156 High Street 1272 Santa Cruz, CA 95064 1273 US 1275 EMail: ejw@cse.ucsc.edu 1277 Geoff Clemm 1278 IBM 1279 20 Maguire Road 1280 Lexington, MA 02421 1281 US 1283 EMail: geoffrey.clemm@us.ibm.com 1285 Julian F. Reschke (editor) 1286 greenbytes GmbH 1287 Salzmannstrasse 152 1288 Muenster, NW 48159 1289 Germany 1291 Phone: +49 251 2807760 1292 Fax: +49 251 2807761 1293 EMail: julian.reschke@greenbytes.de 1294 URI: http://greenbytes.de/tech/webdav/ 1296 Appendix A. Changes to the WebDAV Document Type Definition 1298 1299 1300 Property Elements from Section 12 --> 1301 1302 1303 1304 1307 Appendix B. Change Log (to be removed by RFC Editor before publication) 1309 B.1 Since draft-ietf-webdav-redirectref-protocol-02 1311 Julian Reschke takes editorial role (added to authors list). Cleanup 1312 XML indentation. Start adding all unresolved last call issues. Update 1313 some author's contact information. Update references, split into 1314 "normative" and "informational". Remove non-RFC2616 headers 1315 ("Public") from examples. Fixed width problems in artwork. Start 1316 resolving editorial issues. 1318 B.2 Since draft-ietf-webdav-redirectref-protocol-03 1320 Added Joe Orton and Juergen Reuter to Acknowledgements section. Close 1321 more editorial issues. Remove dependencies on BIND spec. 1323 B.3 Since draft-ietf-webdav-redirectref-protocol-04 1325 More editorial fixes. Clarify that MKRESOURCE can only be used to 1326 create redirect references (switch to new method in a future draft). 1327 Clarify that redirect references do not have bodies. 1329 B.4 Since draft-ietf-webdav-redirectref-protocol-05 1331 Close (accept) issue "lc-79-accesscontrol". Add issue 1332 "rfc2606-compliance". Close issues "lc-50-blindredirect", 1333 "lc-71-relative", "lc-74-terminology". Update contact info for Geoff 1334 Clemm. Moved some of the original authors names to new Contributors 1335 section. Add and close issue "9-MKRESOURCE-vs-relative-URI". Close 1336 issue "lc-72-trailingslash". Close issue "lc-60-ex". Update issue 1337 "lc-85-301" with proposal. Close issue "lc-06-reftarget-relative" 1338 (9-MKRESOURCE-vs-relative-URI was a duplicate of this one). Also 1339 remove section 9.1 (example for MKRESOURCE vs relative URIs). Add 1340 and resolve issue "11.2-apply-to-redirect-ref-syntax" (header now has 1341 values "T" and "F"). Also some cleanup for "rfc2606-compliance". 1342 Typo fixes. Add and resolve "15.1-options-response". 1344 Appendix C. Resolved issues (to be removed by RFC Editor before 1345 publication) 1347 Issues that were either rejected or resolved in this version of this 1348 document. 1350 C.1 lc-60-ex 1352 Type: change 1354 [3] 1356 reuterj@ira.uka.de (2000-02-14): Section 7, para 3: Make it clear 1357 that these are just examples of client behavior, and are not meant to 1358 limit the client's behavior to these options. 1360 Resolution (2003-10-13): Agreed to delete this paragraph. Continue 1361 discussion of what information should be returned with 302 in 1362 multistatus. Just location? Also redirectref? Update: ret gid of 1363 pseudo-property and special response format, define new response 1364 element instead. See ossue lc-61-pseudo. 1366 C.2 lc-06-reftarget-relative 1368 Type: change 1370 [4] 1372 joe@orton.demon.co.uk (2000-01-29): Why does the spec talk about 1373 relative URIs in DAV:reftarget in MKRESOURCE requests? Is the server 1374 required to resolve the relative URI and store it as absolute? Is the 1375 server required to keep DAV:reftarget pointing to the target resource 1376 as the reference / target move, or is DAV:reftarget a dead property? 1378 Resolution (2003-10-13): DAV:reftarget is readonly and present only 1379 on redirect references that are also WebDAV resources. Add a method 1380 for setting the target. Change definition of Redirect-Ref header so 1381 that it has the target as its value (comes back on all 302 1382 responses). Server MUST store the target exactly as it is set. It 1383 MUST NOT resolve relatives to absolutes and MUST NOT update if target 1384 resource moves. See also issue 17, 43, 50, 57 1386 C.3 lc-71-relative 1388 Type: change 1390 [5] 1391 reuterj@ira.uka.de (2000-02-14): Section 9: Base URI should be the 1392 Request-URI or href minus its final segment. 1394 Resolution (2003-10-08): Original WG comment: Fix this. However, this 1395 is just a misunderstanding. The process of resolving a relative URI 1396 against a hierarchical base URI already involves removal of the last 1397 path segment, so the draft is correct here. 1399 C.4 9-MKRESOURCE-vs-relative-URI 1401 Type: change 1403 julian.reschke@greenbytes.de (2003-10-08): Do not say anything about 1404 MKRESOURCE vs relative URIs. The server is supposed to store the 1405 relative URI, thus the issue of resolving the URI does only apply 1406 upon retrieval, not creation. 1408 C.5 lc-72-trailingslash 1410 Type: change 1412 [6] 1414 reuterj@ira.uka.de (2000-02-14): Section 10: Forbid DAV:reftarget 1415 from ending in "/" 1417 julian.reschke@greenbytes.de (): (last call WG response): Make the 1418 note warn about the possibility of two slashes in a row, recommend 1419 against ending target with a slash, since that could result in two 1420 slashes in a row. 1422 Resolution (2003-10-09): It seems that the rule in the 3rd paragraph 1423 already explains how to deal with this situation. No change. 1425 C.6 lc-50-blindredirect 1427 Type: change 1429 [7] 1431 yarong@Exchange.Microsoft.com (2000-02-11): Replace current language 1432 explaining the purpose of the Redirect-Ref header with language that 1433 simply states that it marks blind 302 responses from redirect 1434 resources. (Section 6.3, 11.1) 1436 Resolution (2003-10-02): Section 6.3 was removed in response to issue 1437 48. In 11.1, change the definition of the Redirect-Ref header to have 1438 the value of the target (relative URI) as its value. Then we don't 1439 need a method for retrieving the target's relative URI. Presence of 1440 the Redirect-Ref header lets the client know that the resource 1441 accepts Apply-To-RR header and the new method for updating target. 1442 Reject Yaron's suggested language, but make the above changes. 1444 C.7 lc-74-terminology 1446 Type: change 1448 [8] 1450 reuterj@ira.uka.de (2000-02-14): "plain HTTP/1.1 redirect" - find 1451 some good name for this an use it consistently 1453 Resolution (2003-10-02): Remove the whole sentence. 1455 C.8 11.2-apply-to-redirect-ref-syntax 1457 Type: change 1459 julian.reschke@greenbytes.de (2003-10-17): Many toolkits have 1460 problems sending empty HTTP headers (optimizing them away). 1462 Resolution (2003-10-17): Define values "T" and "F" (similar to WevDAV 1463 Overwrite header). This will also allow clients to express that they 1464 are aware of redirect extensions without also having to apply the 1465 request to the reference resource. 1467 C.9 15.1-options-response 1469 Type: change 1471 julian.reschke@greenbytes.de (2003-10-20): Fix OPTIONS response 1472 ("Public" header mentioned, "Allow" header value line break). Remove 1473 irrelevant response headers. 1475 Resolution (2003-10-20): Fix. 1477 C.10 lc-79-accesscontrol 1479 Type: change 1481 [9] 1483 reuterj@ira.uka.de (2000-02-22): Section 16.4: "In some environments, 1484 the owner of a resource might be able to use access control to 1485 prevent others from creating references to that resource." That would 1486 not be consistent with the concept of redirect references as weak 1487 links (e.g. think of moving a resource to a different locationo that 1488 is already the target of some redirection reference. 1490 Resolution (2003-10-02): Remove the statement. 1492 Appendix D. Open issues (to be removed by RFC Editor before publication) 1494 D.1 lc-85-301 1496 Type: change 1498 ejw@cse.ucsc.edu (2000-01-03): Support creation of other than 302 1499 redirects, especially 301. 1501 julian.reschke@greenbytes.de (2003-10-13): HTTP seems to distinguish 1502 the following use cases: (a) permanent redirect (301), (b) temporary 1503 redirect (302 or 307), (c) redirect to a GET location after POST 1504 (303) and (d) agent-driven negotiation (300). Among these, (a) and 1505 (b) seem to be well understood, so we should support both. (c) 1506 doesn't seem to be applicable. (d) may become interesting when user 1507 agents start supporting it, so the spec should be flexible enough to 1508 support a feature extension for that. For now I propose that the 1509 client is able to specify the redirection type as a resource type, 1510 such as "DAV:permanent-redirect-reference" and 1511 "DAV:temporary-redirect-reference". This spec would only define the 1512 behaviour for these two resource types and would allow future 1513 extensions using new resource types and suggested response codes. 1515 D.2 lc-38-not-hierarchical 1517 Type: change 1519 [10] 1521 yarong@Exchange.Microsoft.com (2000-02-11): Not Hierarchical: The 1522 first sentence of the second paragraph of the introduction of the 1523 redirect spec asserts that the URIs of WebDAV compliant resources 1524 match to collections. The WebDAV standard makes no such requirement. 1525 I therefore move that this sentence be stricken. 1527 Resolution: State the more general HTTP rationale first (alternative 1528 names for the same resource), then introduce the collection hierarchy 1529 rationale, which applies only if you are in a WebDAV-compliant space. 1531 D.3 lc-36-server 1533 Type: change 1535 [11] 1537 yarong@Exchange.Microsoft.com (2000-02-11): Servers: Replace "server" 1538 with "unrelated system" throughout. 1540 Resolution: Try replacing "server" with "host" in some contexts, 1541 rephrasing in passive voice in others. See also issue 40. 1543 D.4 lc-33-forwarding 1545 Type: change 1547 [12] 1549 yarong@Exchange.Microsoft.com (2000-02-11): Forwarding: Replace 1550 "forward" with "redirect" throughout. 1552 Resolution: Use "redirect" for the behavior redirect resources do 1553 exhibit. Use "forward" for the contrasting behavior (passing a method 1554 on to the target with no client action needed). Define these two 1555 terms. See also issue 40. 1557 D.5 lc-37-integrity 1559 Type: change 1561 [13] 1563 yarong@Exchange.Microsoft.com (2000-02-11): Integrity: Intro, para 7 1564 "Servers are not required to enforce the integrity of redirect 1565 references." Integrity is not defined. Replace with something 1566 clearer. 1568 Resolution: Rewrite to say that the server MUST NOT update the target 1569 See also issue 6. 1571 D.6 3-terminology-redirectref 1573 Type: change 1575 [14] 1577 julian.reschke@greenbytes.de (2003-07-27): Consider global rename of 1578 "redirect reference resource" to "redirect resource". 1580 D.7 lc-19-direct-ref 1582 Type: change 1584 [15] 1586 reuterj@ira.uka.de (2000-02-07): Section 4, para 5 and Section 6, 1587 para 3 discussions of the Apply-to-Redirect-Ref header make it sound 1588 as if we are specifying direct reference behavior. 1590 Resolution: Change these passages so that the contrast is between 1591 applying the method to the redirect reference and responding with a 1592 302. 1594 D.8 lc-41-no-webdav 1596 Type: change 1598 [16] 1600 yarong@Exchange.Microsoft.com (2000-02-11): Make redirect references 1601 independent of the rest of WebDAV. The creation method for redirect 1602 references shouldn't require an XML request body. 1604 Resolution: We will make redirect references independent of the rest 1605 of WebDAV. MKREF will not have an XML request body. 1607 D.9 lc-58-update 1609 Type: change 1611 [17] 1613 yarong@Exchange.Microsoft.com (2000-02-11): There needs to be a way 1614 to update the target of a redirect reference. 1616 Resolution: Agreed. See also issues 6, 43. 1618 D.10 lc-24-properties 1620 Type: change 1622 [18] 1624 reuterj@ira.uka.de (2000-02-07): Section 5.1: Replace the sentence 1625 "The properties of the new resource are as specified by the 1626 DAV:propertyupdate request body, using PROPPATCH semantics" with the 1627 following: "The MKRESOURCE request MAY contain a DAV:propertyupdate 1628 request body to initialize resource properties. Herein, the semantics 1629 is the same as when sending a MKRESOURCE request without a request 1630 body, followed by a PROPPATCH with the DAV:propertyupdate request 1631 body." 1633 Resolution: No longer relevant once we switch to MKREF with no 1634 request body. 1636 D.11 rfc2606-compliance 1638 Type: editor 1640 julian.reschke@greenbytes.de (2003-10-02): Ensure that examples use 1641 only sample domains as per RFC2606. 1643 D.12 lc-48-s6 1645 Type: change 1647 [19] 1649 yarong@Exchange.Microsoft.com (2000-02-11): Replace all of section 6 1650 with just this: A redirect resource, upon receiving a request without 1651 an Apply-To-Redirect-Ref header, MUST respond with a 302 (Found) 1652 response. The 302 (Found) response MUST include a location header 1653 identifying the target and a Redirect-Ref header. If a redirect 1654 resource receives a request with an Apply-To-Redirect-Ref header then 1655 the redirect reference resource MUST apply the method to itself 1656 rather than blindly returning a 302 (Found) response. 1658 Resolution: Keep a summary along the lines of Yaron's proposal (don't 1659 use the word "blindly"). Keep the bullets detailing the headers to be 1660 returned. Delete the rest, including the examples. See also issue 28, 1661 29, 30, 31, 32. 1663 D.13 lc-28-lang 1665 Type: edit 1667 [20] 1669 reuterj@ira.uka.de (2000-02-07): Section 6: Get rid of the sentence 1670 "A reference-aware WebDAV client can act on this response in one of 1671 two ways." A client can act on the response in any way it wants. 1673 Resolution: Agreed. See also issue 48. 1675 D.14 lc-29-lang 1677 Type: edit 1679 [21] 1681 reuterj@ira.uka.de (2000-02-07): Section 6, para 4: Obvious, doesn't 1682 need to be stated. Maybe note in an example. 1684 Resolution: Agreed. See also issue 48. 1686 D.15 lc-44-pseudo 1688 Type: change 1690 [22] 1692 yarong@Exchange.Microsoft.com (2000-02-11): Instead of adding an 1693 optional prop XML element to the response element in 207 responses, 1694 define a new location XML element and a new refresource XML element. 1696 Resolution: Agree to define new XML elements that are not 1697 pseudo-properties. Disagreement about whether refresource is needed. 1698 See issue 61. 1700 D.16 lc-61-pseudo 1702 Type: change 1704 [23] 1706 reuterj@ira.uka.de (2000-02-14): Section 7: It doesn't make sense to 1707 ask future editors of RFC 2518 to define DAV:location with the 1708 semantics it has here. RFC 2518 should provide the information in the 1709 Location header somehow in multistatus responses, but not by using 1710 properties. 1712 Resolution: Define an XML element for location that is not a 1713 pseudo-property. We'll keep the recommendation that RFC 2518 add this 1714 for 302 responses. See also issue 44. 1716 D.17 lc-62-oldclient 1718 Type: change 1720 [24] 1722 reuterj@ira.uka.de (2000-02-14): Section 7: It's too strong to claim 1723 that non-referencing clients can't process 302 responses occurring in 1724 Multi-Status responses. They just have an extra round trip for each 1725 302. 1727 Resolution: Remove last sentence of the paragraph that recommends 1728 changes to RFC 2518. 1730 D.18 lc-63-move 1732 Type: change 1734 [25] 1736 reuterj@ira.uka.de (2000-02-14): Section 7.1: Is MOVE atomic from the 1737 perspective of a client? Agrees that there should be no 302s for 1738 member redirect references, but finds the rationale dubious. 1740 Resolution: Remove 7.1. Reword 7.2 to avoid concerns with "poses 1741 special problems" and "due to atomicity". 1743 D.19 lc-57-noautoupdate 1745 Type: change 1747 [26] 1749 yarong@Exchange.Microsoft.com (2000-02-11): Add language to forbid 1750 servers from automatically updating redirect resources when their 1751 targets move. 1753 Resolution: Agreed. See also issue 6. 1755 D.20 lc-53-s10 1757 Type: change 1759 [27] 1761 yarong@Exchange.Microsoft.com (2000-02-11): The behavior described in 1762 this section would have a very serious impact on the efficiency of 1763 mapping Request-URIs to resources in HTTP request processing. Also 1764 specify another type of redirect resource that does not behave as in 1765 section 10, but instead would "expose the behavior we see today in 1766 various HTTP servers that allow their users to create 300 resources." 1767 Be sure we know what behavior will be if the redirect location is not 1768 an HTTP URL, but, say ftp. 1770 Resolution: We won't define 2 sorts of redirect references here. 1771 Servers SHOULD respond with 302 as described here, but if they can't 1772 do that, respond with 404 Not Found. (It's hard to modularize the 1773 behavior specified - it impacts processing Not Found cases of all 1774 methods, so you can't just add it to an HTTP server in a redirect ref 1775 module.) 1777 D.21 12.1-property-name 1779 Type: change 1781 julian.reschke@greenbytes.de (2003-10-06): Sync names for 1782 DAV:reftarget property and "Redirect-Ref" response headers. 1784 D.22 lc-76-location 1786 Type: change 1788 [28] 1790 reuterj@ira.uka.de (2000-02-22): 12.2: Make DAV:location a real 1791 (live) property, get rid of the DAV:reftarget property 1793 D.23 lc-80-i18n 1795 Type: change 1797 [29] 1799 reuterj@ira.uka.de (2000-02-22): Section 17: Could get rid of a lot 1800 of this section, since this protocol extends WebDAV. Just reference 1801 [WebDAV]. 1803 julian.reschke@greenbytes.de (2003-10-02): True, but I note that 1804 other specs have re-stated these considerations as well. Opinions? 1806 D.24 lc-55-iana 1808 Type: change 1810 [30] 1812 yarong@Exchange.Microsoft.com (2000-02-11): Expand the IANA section 1813 to list all methods, headers, XML elements, MIME types, URL schemes, 1814 etc., defined by the spec. 1816 Resolution: Agreed. 1818 Intellectual Property Statement 1820 The IETF takes no position regarding the validity or scope of any 1821 intellectual property or other rights that might be claimed to 1822 pertain to the implementation or use of the technology described in 1823 this document or the extent to which any license under such rights 1824 might or might not be available; neither does it represent that it 1825 has made any effort to identify any such rights. Information on the 1826 IETF's procedures with respect to rights in standards-track and 1827 standards-related documentation can be found in BCP-11. 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