idnits 2.17.1 draft-ietf-webdav-bind-16.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 20. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 1832. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 1839. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 1845. ** The document seems to lack an RFC 3978 Section 5.5 (updated by RFC 4748) Disclaimer -- however, there's a paragraph with a matching beginning. Boilerplate error? Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- ** Missing revision: the document name given in the document, 'draft-ietf-webdav-rfc2518bis', does not give the document revision number ~~ Missing draftname component: the document name given in the document, 'draft-ietf-webdav-rfc2518bis', does not seem to contain all the document name components required ('draft' prefix, document source, document name, and revision) -- see https://www.ietf.org/id-info/guidelines#naming for more information. == Mismatching filename: the document gives the document name as 'draft-ietf-webdav-rfc2518bis', but the file name used is 'draft-ietf-webdav-bind-16' Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust Copyright Line does not match the current year == Line 542 has weird spacing: '...| x.gif y.g...' == Line 564 has weird spacing: '...| x.gif y.g...' == Line 770 has weird spacing: '...| x.gif y.g...' -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (January 5, 2007) is 6321 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 2616 (Obsoleted by RFC 7230, RFC 7231, RFC 7232, RFC 7233, RFC 7234, RFC 7235) -- Possible downref: Non-RFC (?) normative reference: ref. 'XML' Summary: 4 errors (**), 1 flaw (~~), 5 warnings (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group G. Clemm 3 Internet-Draft IBM 4 Updates: J. Crawford 5 draft-ietf-webdav-rfc2518bis IBM Research 6 (if approved) J. Reschke, Ed. 7 Intended status: Standards Track greenbytes 8 Expires: July 9, 2007 J. Whitehead 9 U.C. Santa Cruz 10 January 5, 2007 12 Binding Extensions to Web Distributed Authoring and Versioning (WebDAV) 13 draft-ietf-webdav-bind-16 15 Status of this Memo 17 By submitting this Internet-Draft, each author represents that any 18 applicable patent or other IPR claims of which he or she is aware 19 have been or will be disclosed, and any of which he or she becomes 20 aware will be disclosed, in accordance with Section 6 of BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF), its areas, and its working groups. Note that 24 other groups may also distribute working documents as Internet- 25 Drafts. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 The list of current Internet-Drafts can be accessed at 33 http://www.ietf.org/ietf/1id-abstracts.txt. 35 The list of Internet-Draft Shadow Directories can be accessed at 36 http://www.ietf.org/shadow.html. 38 This Internet-Draft will expire on July 9, 2007. 40 Copyright Notice 42 Copyright (C) The IETF Trust (2007). 44 Abstract 46 This specification defines bindings, and the BIND method for creating 47 multiple bindings to the same resource. Creating a new binding to a 48 resource causes at least one new URI to be mapped to that resource. 50 Servers are required to insure the integrity of any bindings that 51 they allow to be created. 53 Editorial Note (To be removed by RFC Editor before publication) 55 Please send comments to the Distributed Authoring and Versioning 56 (WebDAV) working group at , which may be 57 joined by sending a message with subject "subscribe" to 58 . Discussions of the WEBDAV 59 working group are archived at 60 . 62 lists 63 all registered issues since draft 02. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 68 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 69 1.2. Method Preconditions and Postconditions . . . . . . . . . 6 70 2. Overview of Bindings . . . . . . . . . . . . . . . . . . . . . 6 71 2.1. Bindings to Collections . . . . . . . . . . . . . . . . . 7 72 2.1.1. Bind loops . . . . . . . . . . . . . . . . . . . . . . 8 73 2.2. URI Mappings Created by a new Binding . . . . . . . . . . 8 74 2.3. COPY and Bindings . . . . . . . . . . . . . . . . . . . . 9 75 2.3.1. Example: COPY with 'Depth: infinity' in presence 76 of bind loops . . . . . . . . . . . . . . . . . . . . 11 77 2.3.2. Example: COPY with 'Depth: infinity' with multiple 78 bindings to a leaf resource . . . . . . . . . . . . . 13 79 2.4. DELETE and Bindings . . . . . . . . . . . . . . . . . . . 14 80 2.5. MOVE and Bindings . . . . . . . . . . . . . . . . . . . . 14 81 2.6. PROPFIND and Bindings . . . . . . . . . . . . . . . . . . 15 82 2.7. Determining Whether Two Bindings Are to the Same 83 Resource . . . . . . . . . . . . . . . . . . . . . . . . . 15 84 2.8. Discovering the Bindings to a Resource . . . . . . . . . . 16 85 3. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . 16 86 3.1. DAV:resource-id Property . . . . . . . . . . . . . . . . . 17 87 3.2. DAV:parent-set Property . . . . . . . . . . . . . . . . . 17 88 3.2.1. Example for DAV:parent-set property . . . . . . . . . 17 89 4. BIND Method . . . . . . . . . . . . . . . . . . . . . . . . . 18 90 4.1. Example: BIND . . . . . . . . . . . . . . . . . . . . . . 21 91 5. UNBIND Method . . . . . . . . . . . . . . . . . . . . . . . . 21 92 5.1. Example: UNBIND . . . . . . . . . . . . . . . . . . . . . 23 93 6. REBIND Method . . . . . . . . . . . . . . . . . . . . . . . . 23 94 6.1. Example: REBIND . . . . . . . . . . . . . . . . . . . . . 25 95 6.2. Example: REBIND in presence of locks and bind loops . . . 26 96 7. Additional Status Codes . . . . . . . . . . . . . . . . . . . 28 97 7.1. 208 Already Reported . . . . . . . . . . . . . . . . . . . 28 98 7.1.1. Example: PROPFIND by bind-aware client . . . . . . . . 29 99 7.1.2. Example: PROPFIND by non-bind-aware client . . . . . . 31 100 7.2. 506 Loop Detected . . . . . . . . . . . . . . . . . . . . 31 101 8. Capability discovery . . . . . . . . . . . . . . . . . . . . . 31 102 8.1. OPTIONS method . . . . . . . . . . . . . . . . . . . . . . 31 103 8.2. 'DAV' request header . . . . . . . . . . . . . . . . . . . 31 104 9. Relationship to WebDAV Access Control Protocol . . . . . . . . 32 105 10. Security Considerations . . . . . . . . . . . . . . . . . . . 32 106 10.1. Privacy Concerns . . . . . . . . . . . . . . . . . . . . . 32 107 10.2. Bind Loops . . . . . . . . . . . . . . . . . . . . . . . . 32 108 10.3. Bindings, and Denial of Service . . . . . . . . . . . . . 32 109 10.4. Private Locations May Be Revealed . . . . . . . . . . . . 33 110 10.5. DAV:parent-set and Denial of Service . . . . . . . . . . . 33 111 11. Internationalization Considerations . . . . . . . . . . . . . 33 112 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 113 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 33 114 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 34 115 14.1. Normative References . . . . . . . . . . . . . . . . . . . 34 116 14.2. Informative References . . . . . . . . . . . . . . . . . . 34 117 Appendix A. Clarification to RFC2518bis' Usage of the term 118 'lock root' . . . . . . . . . . . . . . . . . . . . . 34 119 Appendix B. Change Log (to be removed by RFC Editor before 120 publication) . . . . . . . . . . . . . . . . . . . . 35 121 B.1. Since draft-ietf-webdav-bind-02 . . . . . . . . . . . . . 35 122 B.2. Since draft-ietf-webdav-bind-03 . . . . . . . . . . . . . 35 123 B.3. Since draft-ietf-webdav-bind-04 . . . . . . . . . . . . . 35 124 B.4. Since draft-ietf-webdav-bind-05 . . . . . . . . . . . . . 36 125 B.5. Since draft-ietf-webdav-bind-06 . . . . . . . . . . . . . 36 126 B.6. Since draft-ietf-webdav-bind-07 . . . . . . . . . . . . . 36 127 B.7. Since draft-ietf-webdav-bind-08 . . . . . . . . . . . . . 36 128 B.8. Since draft-ietf-webdav-bind-09 . . . . . . . . . . . . . 36 129 B.9. Since draft-ietf-webdav-bind-10 . . . . . . . . . . . . . 36 130 B.10. Since draft-ietf-webdav-bind-11 . . . . . . . . . . . . . 37 131 B.11. Since draft-ietf-webdav-bind-12 . . . . . . . . . . . . . 37 132 B.12. Since draft-ietf-webdav-bind-13 . . . . . . . . . . . . . 37 133 B.13. Since draft-ietf-webdav-bind-14 . . . . . . . . . . . . . 37 134 B.14. Since draft-ietf-webdav-bind-15 . . . . . . . . . . . . . 38 135 Appendix C. Resolved issues (to be removed by RFC Editor 136 before publication) . . . . . . . . . . . . . . . . . 38 137 C.1. rfc2518bis-lock-root . . . . . . . . . . . . . . . . . . . 38 138 Appendix D. Open issues (to be removed by RFC Editor prior to 139 publication) . . . . . . . . . . . . . . . . . . . . 38 140 D.1. edit . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 141 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 142 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 40 143 Intellectual Property and Copyright Statements . . . . . . . . . . 42 145 1. Introduction 147 This specification extends the WebDAV Distributed Authoring Protocol 148 ([draft-ietf-webdav-rfc2518bis]) to enable clients to create new 149 access paths to existing resources. This capability is useful for 150 several reasons: 152 URIs of WebDAV-compliant resources are hierarchical and correspond to 153 a hierarchy of collections in resource space. The WebDAV Distributed 154 Authoring Protocol makes it possible to organize these resources into 155 hierarchies, placing them into groupings, known as collections, which 156 are more easily browsed and manipulated than a single flat 157 collection. However, hierarchies require categorization decisions 158 that locate resources at a single location in the hierarchy, a 159 drawback when a resource has multiple valid categories. For example, 160 in a hierarchy of vehicle descriptions containing collections for 161 cars and boats, a description of a combination car/boat vehicle could 162 belong in either collection. Ideally, the description should be 163 accessible from both. Allowing clients to create new URIs that 164 access the existing resource lets them put that resource into 165 multiple collections. 167 Hierarchies also make resource sharing more difficult, since 168 resources that have utility across many collections are still forced 169 into a single collection. For example, the mathematics department at 170 one university might create a collection of information on fractals 171 that contains bindings to some local resources, but also provides 172 access to some resources at other universities. For many reasons, it 173 may be undesirable to make physical copies of the shared resources on 174 the local server: to conserve disk space, to respect copyright 175 constraints, or to make any changes in the shared resources visible 176 automatically. Being able to create new access paths to existing 177 resources in other collections or even on other servers is useful for 178 this sort of case. 180 The BIND method defined here provides a mechanism for allowing 181 clients to create alternative access paths to existing WebDAV 182 resources. HTTP [RFC2616] and WebDAV [draft-ietf-webdav-rfc2518bis] 183 methods are able to work because there are mappings between URIs and 184 resources. A method is addressed to a URI, and the server follows 185 the mapping from that URI to a resource, applying the method to that 186 resource. Multiple URIs may be mapped to the same resource, but 187 until now there has been no way for clients to create additional URIs 188 mapped to existing resources. 190 BIND lets clients associate a new URI with an existing WebDAV 191 resource, and this URI can then be used to submit requests to the 192 resource. Since URIs of WebDAV resources are hierarchical, and 193 correspond to a hierarchy of collections in resource space, the BIND 194 method also has the effect of adding the resource to a collection. 195 As new URIs are associated with the resource, it appears in 196 additional collections. 198 A BIND request does not create a new resource, but simply makes 199 available a new URI for submitting requests to an existing resource. 200 The new URI is indistinguishable from any other URI when submitting a 201 request to a resource. Only one round trip is needed to submit a 202 request to the intended target. Servers are required to enforce the 203 integrity of the relationships between the new URIs and the resources 204 associated with them. Consequently, it may be very costly for 205 servers to support BIND requests that cross server boundaries. 207 This specification is organized as follows. Section 1.1 defines 208 terminology used in the rest of the specification, while Section 2 209 overviews bindings. Section 3 defines the new properties needed to 210 support multiple bindings to the same resource. Section 4 specifies 211 the BIND method, used to create multiple bindings to the same 212 resource. Section 5 specifies the UNBIND method, used to remove a 213 binding to a resource. Section 6 specifies the REBIND method, used 214 to move a binding to another collection. 216 1.1. Terminology 218 The terminology used here follows and extends that in the WebDAV 219 Distributed Authoring Protocol specification 220 [draft-ietf-webdav-rfc2518bis]. 222 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 223 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 224 document are to be interpreted as described in [RFC2119]. 226 This document uses XML DTD fragments ([XML]) as a notational 227 convention, using the rules defined in Section 17 of 228 [draft-ietf-webdav-rfc2518bis]. 230 URI Mapping 232 A relation between an absolute URI and a resource. For an 233 absolute URI U and the resource it identifies R, the URI mapping 234 can be thought of as (U => R). Since a resource can represent 235 items that are not network retrievable, as well as those that are, 236 it is possible for a resource to have zero, one, or many URI 237 mappings. Mapping a resource to an "http" scheme URI makes it 238 possible to submit HTTP protocol requests to the resource using 239 the URI. 241 Path Segment 243 Informally, the characters found between slashes ("/") in a URI. 244 Formally, as defined in Section 3.3 of [RFC3986]. 246 Binding 248 A relation between a single path segment (in a collection) and a 249 resource. A binding is part of the state of a collection. If two 250 different collections contain a binding between the same path 251 segment and the same resource, these are two distinct bindings. 252 So for a collection C, a path segment S, and a resource R, the 253 binding can be thought of as C:(S -> R). Bindings create URI 254 mappings, and hence allow requests to be sent to a single resource 255 from multiple locations in a URI namespace. For example, given a 256 collection C (accessible through the URI 257 http://www.example.com/CollX), a path segment S (equal to 258 "foo.html"), and a resource R, then creating the binding C: (S -> 259 R) makes it possible to use the URI 260 http://www.example.com/CollX/foo.html to access R. 262 Collection 264 A resource that contains, as part of its state, a set of bindings 265 that identify internal member resources. 267 Internal Member URI 269 The URI that identifies an internal member of a collection, and 270 that consists of the URI for the collection, followed by a slash 271 character ('/'), followed by the path segment of the binding for 272 that internal member. 274 1.2. Method Preconditions and Postconditions 276 See Section 16 of [draft-ietf-webdav-rfc2518bis] for the definitions 277 of "precondition" and "postcondition". 279 2. Overview of Bindings 281 Bindings are part of the state of a collection. They define the 282 internal members of the collection, and the names of those internal 283 members. 285 Bindings are added and removed by a variety of existing HTTP methods. 286 A method that creates a new resource, such as PUT, COPY, and MKCOL, 287 adds a binding. A method that deletes a resource, such as DELETE, 288 removes a binding. A method that moves a resource (e.g. MOVE) both 289 adds a binding (in the destination collection) and removes a binding 290 (in the source collection). The BIND method introduced here provides 291 a mechanism for adding a second binding to an existing resource. 292 There is no difference between an initial binding added by PUT, COPY, 293 or MKCOL, and additional bindings added with BIND. 295 It would be very undesirable if one binding could be destroyed as a 296 side effect of operating on the resource through a different binding. 297 In particular, the removal of one binding to a resource (e.g. with a 298 DELETE or a MOVE) MUST NOT disrupt another binding to that resource, 299 e.g. by turning that binding into a dangling path segment. The 300 server MUST NOT reclaim system resources after removing one binding, 301 while other bindings to the resource remain. In other words, the 302 server MUST maintain the integrity of a binding. It is permissible, 303 however, for future method definitions (e.g., a DESTROY method) to 304 have semantics that explicitly remove all bindings and/or immediately 305 reclaim system resources. 307 2.1. Bindings to Collections 309 Creating a new binding to a collection makes each resource associated 310 with a binding in that collection accessible via a new URI, and thus 311 creates new URI mappings to those resources but no new bindings. 313 For example, suppose a new binding CollY is created for collection C1 314 in the figure below. It immediately becomes possible to access 315 resource R1 using the URI /CollY/x.gif and to access resource R2 316 using the URI /CollY/y.jpg, but no new bindings for these child 317 resources were created. This is because bindings are part of the 318 state of a collection, and associate a URI that is relative to that 319 collection with its target resource. No change to the bindings in 320 Collection C1 is needed to make its children accessible using /CollY/ 321 x.gif and /CollY/y.jpg. 323 +-------------------------+ 324 | Root Collection | 325 | bindings: | 326 | CollX CollY | 327 +-------------------------+ 328 | / 329 | / 330 | / 331 +------------------+ 332 | Collection C1 | 333 | bindings: | 334 | x.gif y.jpg | 335 +------------------+ 336 | \ 337 | \ 338 | \ 339 +-------------+ +-------------+ 340 | Resource R1 | | Resource R2 | 341 +-------------+ +-------------+ 343 2.1.1. Bind loops 345 Bindings to collections can result in loops, which servers MUST 346 detect when processing "Depth: infinity" requests. It is sometimes 347 possible to complete an operation in spite of the presence of a loop. 348 For instance, a PROPFIND can still succeed if the server uses the new 349 status code 208 (Already Reported) defined in Section 7.1. 351 However, the 506 (Loop Detected) status code is defined in 352 Section 7.2 for use in contexts where an operation is terminated 353 because a loop was encountered. 355 2.2. URI Mappings Created by a new Binding 357 Suppose a binding from "Binding-Name" to resource R is to be added to 358 a collection, C. Then if C-MAP is the set of URIs that were mapped to 359 C before the BIND request, then for each URI "C-URI" in C-MAP, the 360 URI "C-URI/Binding-Name" is mapped to resource R following the BIND 361 request. 363 For example, if a binding from "foo.html" to R is added to a 364 collection C, and if the following URIs are mapped to C: 366 http://www.example.com/A/1/ 367 http://example.com/A/one/ 368 then the following new mappings to R are introduced: 370 http://www.example.com/A/1/foo.html 371 http://example.com/A/one/foo.html 373 Note that if R is a collection, additional URI mappings are created 374 to the descendents of R. Also, note that if a binding is made in 375 collection C to C itself (or to a parent of C), an infinite number of 376 mappings are introduced. 378 For example, if a binding from "myself" to C is then added to C, the 379 following infinite number of additional mappings to C are introduced: 381 http://www.example.com/A/1/myself 382 http://www.example.com/A/1/myself/myself 383 ... 385 and the following infinite number of additional mappings to R are 386 introduced: 388 http://www.example.com/A/1/myself/foo.html 389 http://www.example.com/A/1/myself/myself/foo.html 390 ... 392 2.3. COPY and Bindings 394 As defined in Section 9.8 of [draft-ietf-webdav-rfc2518bis], COPY 395 causes the resource identified by the Request-URI to be duplicated, 396 and makes the new resource accessible using the URI specified in the 397 Destination header. Upon successful completion of a COPY, a new 398 binding is created between the last path segment of the Destination 399 header, and the destination resource. The new binding is added to 400 its parent collection, identified by the Destination header minus its 401 final segment. 403 The following figure shows an example: Suppose that a COPY is issued 404 to URI-3 for resource R (which is also mapped to URI-1 and URI-2), 405 with the Destination header set to URI-X. After successful 406 completion of the COPY operation, resource R is duplicated to create 407 resource R', and a new binding has been created which creates at 408 least the URI mapping between URI-X and the new resource (although 409 other URI mappings may also have been created). 411 URI-1 URI-2 URI-3 URI-X 412 | | | | 413 | | | <---- URI Mappings ----> | 414 | | | | 415 +---------------------+ +------------------------+ 416 | Resource R | | Resource R' | 417 +---------------------+ +------------------------+ 419 It might be thought that a COPY request with "Depth: 0" on a 420 collection would duplicate its bindings, since bindings are part of 421 the collection's state. This is not the case, however. The 422 definition of Depth in [draft-ietf-webdav-rfc2518bis] makes it clear 423 that a "Depth: 0" request does not apply to a collection's members. 424 Consequently, a COPY with "Depth: 0" does not duplicate the bindings 425 contained by the collection. 427 If a COPY request causes an existing resource to be updated, the 428 bindings to that resource MUST be unaffected by the COPY request. 429 Using the preceding example, suppose that a COPY request is issued to 430 URI-X for resource R', with the Destination header set to URI-2. The 431 content and dead properties of resource R would be updated to be a 432 copy of those of resource R', but the mappings from URI-1, URI-2, and 433 URI-3 to resource R remain unaffected. If because of multiple 434 bindings to a resource, more than one source resource updates a 435 single destination resource, the order of the updates is server 436 defined. 438 If a COPY request would cause a new resource to be created as a copy 439 of an existing resource, and that COPY request has already created a 440 copy of that existing resource, the COPY request instead creates 441 another binding to the previous copy, instead of creating a new 442 resource. 444 2.3.1. Example: COPY with 'Depth: infinity' in presence of bind loops 446 As an example of how COPY with Depth infinity would work in the 447 presence of bindings, consider the following collection: 449 +------------------+ 450 | Root Collection | 451 | bindings: | 452 | CollX | 453 +------------------+ 454 | 455 | 456 +-------------------------------+ 457 | Collection C1 |<-------+ 458 | bindings: | | 459 | x.gif CollY | | 460 +-------------------------------+ | 461 | \ (creates loop) | 462 | \ | 463 +-------------+ +------------------+ | 464 | Resource R1 | | Collection C2 | | 465 +-------------+ | bindings: | | 466 | y.gif CollZ | | 467 +------------------+ | 468 | | | 469 | +--------+ 470 | 471 +-------------+ 472 | Resource R2 | 473 +-------------+ 475 If a COPY with Depth infinity is submitted to /CollX, with 476 destination of /CollA, the outcome of the copy operation is: 478 +------------------+ 479 | Root Collection | 480 | bindings: | 481 | CollX CollA | 482 +------------------+ 483 | | 484 | +---------------------------+ 485 | | 486 +-------------------+ | 487 | Collection C1 |<------------------+ | 488 | bindings: | | | 489 | x.gif CollY | | | 490 +-------------------+ | | 491 | \ (creates loop) | | 492 | \ | | 493 +-------------+ +-----------------+ | | 494 | Resource R1 | | Collection C2 | | | 495 +-------------+ | bindings: | | | 496 | y.gif CollZ | | | 497 +-----------------+ | | 498 | | | | 499 | +-------+ | 500 | | 501 +-------------+ | 502 | Resource R2 | | 503 +-------------+ | 504 | 505 +-------------------------------+ 506 | 507 +-------------------+ 508 | Collection C3 |<------------------+ 509 | bindings: | | 510 | x.gif CollY | | 511 +-------------------+ | 512 | \ (creates loop) | 513 | \ | 514 +-------------+ +-----------------+ | 515 | Resource R3 | | Collection C4 | | 516 +-------------+ | bindings: | | 517 | y.gif CollZ | | 518 +-----------------+ | 519 | | | 520 | +-------+ 521 | 522 +-------------+ 523 | Resource R4 | 524 +-------------+ 526 2.3.2. Example: COPY with 'Depth: infinity' with multiple bindings to a 527 leaf resource 529 Given the following collection hierarchy: 531 +------------------+ 532 | Root Collection | 533 | bindings: | 534 | CollX | 535 +------------------+ 536 | 537 | 538 | 539 +----------------+ 540 | Collection C1 | 541 | bindings: | 542 | x.gif y.gif | 543 +----------------+ 544 | | 545 | | 546 +-------------+ 547 | Resource R1 | 548 +-------------+ 550 A COPY of /CollX with Depth infinity to /CollY results in the 551 following collection hierarchy: 553 +------------------+ 554 | Root Collection | 555 | bindings: | 556 | CollX CollY | 557 +------------------+ 558 | \ 559 | \ 560 | \ 561 +----------------+ +-----------------+ 562 | Collection C1 | | Collection C2 | 563 | bindings: | | bindings: | 564 | x.gif y.gif | | x.gif y.gif | 565 +----------------+ +-----------------+ 566 | | | | 567 | | | | 568 +-------------+ +-------------+ 569 | Resource R1 | | Resource R2 | 570 +-------------+ +-------------+ 572 2.4. DELETE and Bindings 574 When there are multiple bindings to a resource, a DELETE applied to 575 that resource MUST NOT remove any bindings to that resource other 576 than the one identified by the Request-URI. For example, suppose the 577 collection identified by the URI "/a" has a binding named "x" to a 578 resource R, and another collection identified by "/b" has a binding 579 named "y" to the same resource R. Then a DELETE applied to "/a/x" 580 removes the binding named "x" from "/a" but MUST NOT remove the 581 binding named "y" from "/b" (i.e. after the DELETE, "/y/b" continues 582 to identify the resource R). 584 When DELETE is applied to a collection, it MUST NOT modify the 585 membership of any other collection that is not itself a member of the 586 collection being deleted. For example, if both "/a/.../x" and 587 "/b/.../y" identify the same collection, C, then applying DELETE to 588 "/a" must not delete an internal member from C or from any other 589 collection that is a member of C, because that would modify the 590 membership of "/b". 592 If a collection supports the UNBIND method (see Section 5), a DELETE 593 of an internal member of a collection MAY be implemented as an UNBIND 594 request. In this case, applying DELETE to a Request-URI has the 595 effect of removing the binding identified by the final segment of the 596 Request-URI from the collection identified by the Request-URI minus 597 its final segment. Although [draft-ietf-webdav-rfc2518bis] allows a 598 DELETE to be a non-atomic operation, when the DELETE operation is 599 implemented as an UNBIND, the operation is atomic. In particular, a 600 DELETE on a hierarchy of resources is simply the removal of a binding 601 to the collection identified by the Request-URI. 603 2.5. MOVE and Bindings 605 When MOVE is applied to a resource, the other bindings to that 606 resource MUST be unaffected, and if the resource being moved is a 607 collection, the bindings to any members of that collection MUST be 608 unaffected. Also, if MOVE is used with Overwrite:T to delete an 609 existing resource, the constraints specified for DELETE apply. 611 If the destination collection of a MOVE request supports the REBIND 612 method (see Section 6), a MOVE of a resource into that collection MAY 613 be implemented as a REBIND request. Although 614 [draft-ietf-webdav-rfc2518bis] allows a MOVE to be a non-atomic 615 operation, when the MOVE operation is implemented as a REBIND, the 616 operation is atomic. In particular, applying a MOVE to a Request-URI 617 and a Destination URI has the effect of removing a binding to a 618 resource (at the Request-URI), and creating a new binding to that 619 resource (at the Destination URI). Even when the Request-URI 620 identifies a collection, the MOVE operation involves only removing 621 one binding to that collection and adding another. 623 As an example, suppose that a MOVE is issued to URI-3 for resource R 624 below (which is also mapped to URI-1 and URI-2), with the Destination 625 header set to URI-X. After successful completion of the MOVE 626 operation, a new binding has been created which creates the URI 627 mapping between URI-X and resource R. The binding corresponding to 628 the final segment of URI-3 has been removed, which also causes the 629 URI mapping between URI-3 and R to be removed. If resource R were a 630 collection, old URI-3 based mappings to members of R would have been 631 removed, and new URI-X based mappings to members of R would have been 632 created. 634 >> Before Request: 636 URI-1 URI-2 URI-3 637 | | | 638 | | | <---- URI Mappings 639 | | | 640 +---------------------+ 641 | Resource R | 642 +---------------------+ 644 >> After Request: 646 URI-1 URI-2 URI-X 647 | | | 648 | | | <---- URI Mappings 649 | | | 650 +---------------------+ 651 | Resource R | 652 +---------------------+ 654 2.6. PROPFIND and Bindings 656 Consistent with [draft-ietf-webdav-rfc2518bis], the value of a dead 657 property MUST be independent of the number of bindings to its host 658 resource or of the path submitted to PROPFIND. On the other hand, 659 the behaviour for each live property depends on its individual 660 definition (for example, see [RFC3744], Section 5, paragraph 2). 662 2.7. Determining Whether Two Bindings Are to the Same Resource 664 It is useful to have some way of determining whether two bindings are 665 to the same resource. Two resources might have identical contents 666 and properties, but not be the same resource (e.g. an update to one 667 resource does not affect the other resource). 669 The REQUIRED DAV:resource-id property defined in Section 3.1 is a 670 resource identifier, which MUST be unique across all resources for 671 all time. If the values of DAV:resource-id returned by PROPFIND 672 requests through two bindings are identical character by character, 673 the client can be assured that the two bindings are to the same 674 resource. 676 The DAV:resource-id property is created, and its value assigned, when 677 the resource is created. The value of DAV:resource-id MUST NOT be 678 changed. Even after the resource is no longer accessible through any 679 URI, that value MUST NOT be reassigned to another resource's DAV: 680 resource-id property. 682 Any method that creates a new resource MUST assign a new, unique 683 value to its DAV:resource-id property. For example, a PUT applied to 684 a null resource, COPY (when not overwriting an existing target) and 685 CHECKIN (see [RFC3253], Section 4.4) must assign a new, unique value 686 to the DAV:resource-id property of the new resource they create. 688 On the other hand, any method that affects an existing resource must 689 not change the value of its DAV:resource-id property. Specifically, 690 a PUT or a COPY that updates an existing resource must not change the 691 value of its DAV:resource-id property. A REBIND, since it does not 692 create a new resource, but only changes the location of an existing 693 resource, must not change the value of the DAV:resource-id property. 695 2.8. Discovering the Bindings to a Resource 697 An OPTIONAL DAV:parent-set property on a resource provides a list of 698 the bindings that associate a collection and a URI segment with that 699 resource. If the DAV:parent-set property exists on a given resource, 700 it MUST contain a complete list of all bindings to that resource that 701 the client is authorized to see. When deciding whether to support 702 the DAV:parent-set property, server implementers / administrators 703 should balance the benefits it provides against the cost of 704 maintaining the property and the security risks enumerated in 705 Sections 10.4 and 10.5. 707 3. Properties 709 The bind feature introduces the properties defined below. 711 A DAV:allprop PROPFIND request SHOULD NOT return any of the 712 properties defined by this document. This allows a binding server to 713 perform efficiently when a naive client, which does not understand 714 the cost of asking a server to compute all possible live properties, 715 issues a DAV:allprop PROPFIND request. 717 3.1. DAV:resource-id Property 719 The DAV:resource-id property is a REQUIRED property that enables 720 clients to determine whether two bindings are to the same resource. 721 The value of DAV:resource-id is a URI, and may use any registered URI 722 scheme that guarantees the uniqueness of the value across all 723 resources for all time (e.g. the urn:uuid: URN namespace defined in 724 [RFC4122] or the opaquelocktoken: URI scheme defined in 725 [draft-ietf-webdav-rfc2518bis]). 727 729 3.2. DAV:parent-set Property 731 The DAV:parent-set property is an OPTIONAL property that enables 732 clients to discover what collections contain a binding to this 733 resource (i.e. what collections have that resource as an internal 734 member). It contains an of href/segment pair for each collection 735 that has a binding to the resource. The href identifies the 736 collection, and the segment identifies the binding name of that 737 resource in that collection. 739 A given collection MUST appear only once in the DAV:parent-set for 740 any given binding, even if there are multiple URI mappings to that 741 collection. 743 744 745 746 749 3.2.1. Example for DAV:parent-set property 751 For example, if collection C1 is mapped to both /CollX and /CollY, 752 and C1 contains a binding named "x.gif" to a resource R1, then either 753 [/CollX, x.gif] or [/CollY, x.gif] can appear in the DAV:parent-set 754 of R1, but not both. But if C1 also had a binding named "y.gif" to 755 R1, then there would be two entries for C1 in the DAV:binding-set of 756 R1 (i.e. both [/CollX, x.gif] and [/CollX, y.gif] or, alternatively, 757 both [/CollY, x.gif] and [/CollY, y.gif]). 759 +-------------------------+ 760 | Root Collection | 761 | bindings: | 762 | CollX CollY | 763 +-------------------------+ 764 | / 765 | / 766 | / 767 +-----------------+ 768 | Collection C1 | 769 | bindings: | 770 | x.gif y.gif | 771 +-----------------+ 772 | | 773 | | 774 | | 775 +--------------+ 776 | Resource R1 | 777 +--------------+ 779 In this case, one possible value for DAV:parent-set property on 780 "/CollX/x.gif" would be: 782 783 784 /CollX 785 x.gif 786 787 788 /CollX 789 y.gif 790 791 793 4. BIND Method 795 The BIND method modifies the collection identified by the Request- 796 URI, by adding a new binding from the segment specified in the BIND 797 body to the resource identified in the BIND body. 799 If a server cannot guarantee the integrity of the binding, the BIND 800 request MUST fail. Note that it is especially difficult to maintain 801 the integrity of cross-server bindings. Unless the server where the 802 resource resides knows about all bindings on all servers to that 803 resource, it may unwittingly destroy the resource or make it 804 inaccessible without notifying another server that manages a binding 805 to the resource. For example, if server A permits creation of a 806 binding to a resource on server B, server A must notify server B 807 about its binding and must have an agreement with B that B will not 808 destroy the resource while A's binding exists. Otherwise server B 809 may receive a DELETE request that it thinks removes the last binding 810 to the resource and destroy the resource while A's binding still 811 exists. The precondition DAV:cross-server-binding is defined below 812 for cases where servers fail cross-server BIND requests because they 813 cannot guarantee the integrity of cross-server bindings. 815 By default, if there already is a binding for the specified segment 816 in the collection, the new binding replaces the existing binding. 817 This default binding replacement behavior can be overridden using the 818 Overwrite header defined in Section 10.6 of 819 [draft-ietf-webdav-rfc2518bis]. 821 If a BIND request fails, the server state preceding the request MUST 822 be restored. This method is unsafe and idempotent (see [RFC2616], 823 Section 9.1). 825 Marshalling: 827 The request MAY include an Overwrite header. 829 The request body MUST be a DAV:bind XML element. 831 833 If the request succeeds, the server MUST return 201 (Created) when 834 a new binding was created and 200 (OK) when an existing binding 835 was replaced. 837 If a response body for a successful request is included, it MUST 838 be a DAV:bind-response XML element. Note that this document does 839 not define any elements for the BIND response body, but the DAV: 840 bind-response element is defined to ensure interoperability 841 between future extensions that do define elements for the BIND 842 response body. 844 846 Preconditions: 848 (DAV:bind-into-collection): The Request-URI MUST identify a 849 collection. 851 (DAV:bind-source-exists): The DAV:href element MUST identify a 852 resource. 854 (DAV:binding-allowed): The resource identified by the DAV:href 855 supports multiple bindings to it. 857 (DAV:cross-server-binding): If the resource identified by the DAV: 858 href element in the request body is on another server from the 859 collection identified by the Request-URI, the server MUST support 860 cross-server bindings. 862 (DAV:name-allowed): The name specified by the DAV:segment is 863 available for use as a new binding name. 865 (DAV:can-overwrite): If the collection already contains a binding 866 with the specified path segment, and if an Overwrite header is 867 included, the value of the Overwrite header MUST be "T". 869 (DAV:cycle-allowed): If the DAV:href element identifies a 870 collection, and if the Request-URI identifies a collection that is 871 a member of that collection, the server MUST support cycles in the 872 URI namespace. 874 (DAV:locked-update-allowed): If the collection identified by the 875 Request-URI is write-locked, then the appropriate token MUST be 876 specified in an If request header. 878 (DAV:locked-overwrite-allowed): If the collection already contains 879 a binding with the specified path segment, and if that binding is 880 protected by a write-lock, then the appropriate token MUST be 881 specified in an If request header. 883 Postconditions: 885 (DAV:new-binding): The collection MUST have a binding that maps 886 the segment specified in the DAV:segment element in the request 887 body, to the resource identified by the DAV:href element in the 888 request body. 890 4.1. Example: BIND 892 >> Request: 894 BIND /CollY HTTP/1.1 895 Host: www.example.com 896 Content-Type: application/xml; charset="utf-8" 897 Content-Length: xxx 899 900 901 bar.html 902 http://www.example.com/CollX/foo.html 903 905 >> Response: 907 HTTP/1.1 201 Created 909 The server added a new binding to the collection, 910 "http://www.example.com/CollY", associating "bar.html" with the 911 resource identified by the URI 912 "http://www.example.com/CollX/foo.html". Clients can now use the URI 913 "http://www.example.com/CollY/bar.html" to submit requests to that 914 resource. 916 5. UNBIND Method 918 The UNBIND method modifies the collection identified by the Request- 919 URI, by removing the binding identified by the segment specified in 920 the UNBIND body. 922 Once a resource is unreachable by any URI mapping, the server MAY 923 reclaim system resources associated with that resource. If UNBIND 924 removes a binding to a resource, but there remain URI mappings to 925 that resource, the server MUST NOT reclaim system resources 926 associated with the resource. 928 If an UNBIND request fails, the server state preceding the request 929 MUST be restored. This method is unsafe and idempotent (see 930 [RFC2616], Section 9.1). 932 Marshalling: 934 The request body MUST be a DAV:unbind XML element. 936 937 If the request succeeds, the server MUST return 200 (OK) when the 938 binding was successfully deleted. 940 If a response body for a successful request is included, it MUST 941 be a DAV:unbind-response XML element. Note that this document 942 does not define any elements for the UNBIND response body, but the 943 DAV:unbind-response element is defined to ensure interoperability 944 between future extensions that do define elements for the UNBIND 945 response body. 947 949 Preconditions: 951 (DAV:unbind-from-collection): The Request-URI MUST identify a 952 collection. 954 (DAV:unbind-source-exists): The DAV:segment element MUST identify 955 a binding in the collection identified by the Request-URI. 957 (DAV:locked-update-allowed): If the collection identified by the 958 Request-URI is write-locked, then the appropriate token MUST be 959 specified in the request. 961 (DAV:protected-url-deletion-allowed): If the binding identified by 962 the segment is protected by a write-lock, then the appropriate 963 token MUST be specified in the request. 965 Postconditions: 967 (DAV:binding-deleted): The collection MUST NOT have a binding for 968 the segment specified in the DAV:segment element in the request 969 body. 971 (DAV:lock-deleted): If the internal member URI of the binding 972 specified by the Request-URI and the DAV:segment element in the 973 request body was protected by a write-lock at the time of the 974 request, that write-lock must have been deleted by the request. 976 5.1. Example: UNBIND 978 >> Request: 980 UNBIND /CollX HTTP/1.1 981 Host: www.example.com 982 Content-Type: application/xml; charset="utf-8" 983 Content-Length: xxx 985 986 987 foo.html 988 990 >> Response: 992 HTTP/1.1 200 OK 994 The server removed the binding named "foo.html" from the collection, 995 "http://www.example.com/CollX". A request to the resource named 996 "http://www.example.com/CollX/foo.html" will return a 404 (Not Found) 997 response. 999 6. REBIND Method 1001 The REBIND method removes a binding to a resource from a collection, 1002 and adds a binding to that resource into the collection identified by 1003 the Request-URI. The request body specifies the binding to be added 1004 (segment) and the old binding to be removed (href). It is 1005 effectively an atomic form of a MOVE request, and MUST be treated the 1006 same way as MOVE for the purpose of determining access permissions. 1008 If a REBIND request fails, the server state preceding the request 1009 MUST be restored. This method is unsafe and idempotent (see 1010 [RFC2616], Section 9.1). 1012 Marshalling: 1014 The request MAY include an Overwrite header. 1016 The request body MUST be a DAV:rebind XML element. 1018 1020 If the request succeeds, the server MUST return 201 (Created) when 1021 a new binding was created and 200 (OK) when an existing binding 1022 was replaced. 1024 If a response body for a successful request is included, it MUST 1025 be a DAV:rebind-response XML element. Note that this document 1026 does not define any elements for the REBIND response body, but the 1027 DAV:rebind-response element is defined to ensure interoperability 1028 between future extensions that do define elements for the REBIND 1029 response body. 1031 1033 Preconditions: 1035 (DAV:rebind-into-collection): The Request-URI MUST identify a 1036 collection. 1038 (DAV:rebind-source-exists): The DAV:href element MUST identify a 1039 resource. 1041 (DAV:cross-server-binding): If the resource identified by the DAV: 1042 href element in the request body is on another server from the 1043 collection identified by the Request-URI, the server MUST support 1044 cross-server bindings. 1046 (DAV:name-allowed): The name specified by the DAV:segment is 1047 available for use as a new binding name. 1049 (DAV:can-overwrite): If the collection already contains a binding 1050 with the specified path segment, and if an Overwrite header is 1051 included, the value of the Overwrite header MUST be "T". 1053 (DAV:cycle-allowed): If the DAV:href element identifies a 1054 collection, and if the Request-URI identifies a collection that is 1055 a member of that collection, the server MUST support cycles in the 1056 URI namespace. 1058 (DAV:locked-update-allowed): If the collection identified by the 1059 Request-URI is write-locked, then the appropriate token MUST be 1060 specified in the request. 1062 (DAV:protected-url-modification-allowed): If the collection 1063 identified by the Request-URI already contains a binding with the 1064 specified path segment, and if that binding is protected by a 1065 write-lock, then the appropriate token MUST be specified in the 1066 request. 1068 (DAV:locked-source-collection-update-allowed): If the collection 1069 identified by the parent collection prefix of the DAV:href URI is 1070 write-locked, then the appropriate token MUST be specified in the 1071 request. 1073 (DAV:protected-source-url-deletion-allowed): If the DAV:href URI 1074 is protected by a write lock, then the appropriate token MUST be 1075 specified in the request. 1077 Postconditions: 1079 (DAV:new-binding): The collection MUST have a binding that maps 1080 the segment specified in the DAV:segment element in the request 1081 body, to the resource that was identified by the DAV:href element 1082 in the request body. 1084 (DAV:binding-deleted): The URL specified in the DAV:href element 1085 in the request body MUST NOT be mapped to a resource. 1087 (DAV:lock-deleted): If the URL specified in the DAV:href element 1088 in the request body was protected by a write-lock at the time of 1089 the request, that write-lock must have been deleted by the 1090 request. 1092 6.1. Example: REBIND 1094 >> Request: 1096 REBIND /CollX HTTP/1.1 1097 Host: www.example.com 1098 Content-Type: application/xml; charset="utf-8" 1099 Content-Length: xxx 1101 1102 1103 foo.html 1104 http://www.example.com/CollY/bar.html 1105 1107 >> Response: 1109 HTTP/1.1 200 OK 1111 The server added a new binding to the collection, 1112 "http://www.example.com/CollX", associating "foo.html" with the 1113 resource identified by the URI 1114 "http://www.example.com/CollY/bar.html", and removes the binding 1115 named "bar.html" from the collection identified by the URI 1116 "http://www.example.com/CollY". Clients can now use the URI 1117 "http://www.example.com/CollX/foo.html" to submit requests to that 1118 resource, and requests on the URI 1119 "http://www.example.com/CollY/bar.html" will fail with a 404 (Not 1120 Found) response. 1122 6.2. Example: REBIND in presence of locks and bind loops 1124 To illustrate the effects of locks and bind loops on a REBIND 1125 operation, consider the following collection: 1127 +------------------+ 1128 | Root Collection | 1129 | bindings: | 1130 | CollW | 1131 +------------------+ 1132 | 1133 | 1134 | 1135 +-------------------------------+ 1136 | Collection C1 |<--------+ 1137 | LOCKED infinity | | 1138 | (lock token L1) | | 1139 | bindings: | | 1140 | CollX CollY | | 1141 +-------------------------------+ | 1142 | | | 1143 | | (creates loop) | 1144 | | | 1145 +-----------------+ +------------------+ | 1146 | Collection C2 | | Collection C3 | | 1147 | (inherit lock) | | (inherit lock) | | 1148 | (lock token L1) | | (lock token L1) | | 1149 | bindings: | | bindings: | | 1150 | {none} | | y.gif CollZ | | 1151 +-----------------+ +------------------+ | 1152 | | | 1153 | +-----+ 1154 | 1155 +---------------------------+ 1156 | Resource R2 | 1157 | (lock inherited from C1) | 1158 | (lock token L1) | 1159 +---------------------------+ 1161 (where L1 is "opaquelocktoken:f92d4fae-7012-11ab-a765-00c0ca1f6bf9"). 1163 Note that the binding between CollZ and C1 creates a loop in the 1164 containment hierarchy. Servers are not required to support such 1165 loops, though the server in this example does. 1167 The REBIND request below will remove the segment "CollZ" from C3 and 1168 add a new binding from "CollA" to the collection C2. 1170 REBIND /CollW/CollX HTTP/1.1 1171 Host: www.example.com 1172 If: () 1173 Content-Type: application/xml; charset="utf-8" 1174 Content-Length: xxx 1176 1177 1178 CollA 1179 /CollW/CollY/CollZ 1180 1181 The outcome of the REBIND operation is: 1183 +------------------+ 1184 | Root Collection | 1185 | bindings: | 1186 | CollW | 1187 +------------------+ 1188 | 1189 | 1190 | 1191 +-------------------------------+ 1192 | Collection C1 | 1193 | LOCKED infinity | 1194 | (lock token L1) | 1195 | bindings: | 1196 | CollX CollY | 1197 +-------------------------------+ 1198 | ^ | 1199 | | | 1200 +-----------------+ | +------------------+ 1201 | Collection C2 | | | Collection C3 | 1202 |(inherited lock) | | | (inherited lock) | 1203 |(lock token L1) | | | (lock token L1) | 1204 | bindings: | | | bindings: | 1205 | CollA | | | y.gif | 1206 +-----------------+ | +------------------+ 1207 | | | 1208 +---------------+ | 1209 (creates loop) | 1210 +---------------------------+ 1211 | Resource R2 | 1212 | (inherited lock from C1) | 1213 | (lock token L1) | 1214 +---------------------------+ 1216 7. Additional Status Codes 1218 7.1. 208 Already Reported 1220 The 208 (Already Reported) status code can be used inside a DAV: 1221 propstat response element to avoid enumerating the internal members 1222 of multiple bindings to the same collection repeatedly. For each 1223 binding to a collection inside the request's scope, only one will be 1224 reported with a 200 status, while subsequent DAV:response elements 1225 for all other bindings will use the 208 status, and no DAV:response 1226 elements for their descendants are included. 1228 Note that the 208 status will only occur for "Depth: infinity" 1229 requests, and that it is of particular importance when the multiple 1230 collection bindings cause a bind loop as discussed in Section 2.2. 1232 A client can request the DAV:resource-id property in a PROPFIND 1233 request to guarantee that they can accurately reconstruct the binding 1234 structure of a collection with multiple bindings to a single 1235 resource. 1237 For backward compatibility with clients not aware of the 208 status 1238 code appearing in multistatus response bodies, it SHOULD NOT be used 1239 unless the client has signalled support for this specification using 1240 the "DAV" request header (see Section 8.2). Instead, a 506 status 1241 should be returned when a binding loop is discovered. This allows 1242 the server to return the 506 as the top level return status, if it 1243 discovers it before it started the response, or in the middle of a 1244 multistatus, if it discovers it in the middle of streaming out a 1245 multistatus response. 1247 7.1.1. Example: PROPFIND by bind-aware client 1249 For example, consider a PROPFIND request on /Coll (bound to 1250 collection C), where the members of /Coll are /Coll/Foo (bound to 1251 resource R) and /Coll/Bar (bound to collection C). 1253 >> Request: 1255 PROPFIND /Coll/ HTTP/1.1 1256 Host: www.example.com 1257 Depth: infinity 1258 DAV: bind 1259 Content-Type: application/xml; charset="utf-8" 1260 Content-Length: xxx 1262 1263 1264 1265 1266 1267 1268 1270 >> Response: 1272 HTTP/1.1 207 Multi-Status 1273 Content-Type: application/xml; charset="utf-8" 1274 Content-Length: xxx 1276 1277 1278 1279 http://www.example.com/Coll/ 1280 1281 1282 Loop Demo 1283 1284 urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf8 1286 1287 1288 HTTP/1.1 200 OK 1289 1290 1291 1292 http://www.example.com/Coll/Foo 1293 1294 1295 Bird Inventory 1296 1297 urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf9 1299 1300 1301 HTTP/1.1 200 OK 1302 1303 1304 1305 http://www.example.com/Coll/Bar 1306 1307 1308 Loop Demo 1309 1310 urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf8 1312 1313 1314 HTTP/1.1 208 Already Reported 1315 1316 1317 1319 7.1.2. Example: PROPFIND by non-bind-aware client 1321 In this example, the client isn't aware of the 208 status code 1322 introduced by this specification. As the "Depth: infinity" PROPFIND 1323 request would cause a loop condition, the whole request is rejected 1324 with a 506 status. 1326 >> Request: 1328 PROPFIND /Coll/ HTTP/1.1 1329 Host: www.example.com 1330 Depth: infinity 1331 Content-Type: application/xml; charset="utf-8" 1332 Content-Length: xxx 1334 1335 1336 1337 1339 >> Response: 1341 HTTP/1.1 506 Loop Detected 1343 7.2. 506 Loop Detected 1345 The 506 (Loop Detected) status code indicates that the server 1346 terminated an operation because it encountered an infinite loop while 1347 processing a request with "Depth: infinity". This status indicates 1348 that the entire operation failed. 1350 8. Capability discovery 1352 8.1. OPTIONS method 1354 If the server supports bindings, it MUST return the compliance class 1355 name "bind" as a field in the "DAV" response header (see 1356 [draft-ietf-webdav-rfc2518bis], Section 10.1) from an OPTIONS request 1357 on any resource implemented by that server. A value of "bind" in the 1358 "DAV" header MUST indicate that the server supports all MUST level 1359 requirements and REQUIRED features specified in this document. 1361 8.2. 'DAV' request header 1363 Clients SHOULD signal support for all MUST level requirements and 1364 REQUIRED features by submitting a "DAV" request header containing the 1365 compliance class name "bind". In particular, the client MUST 1366 understand the 208 status code defined in Section 7.1. 1368 9. Relationship to WebDAV Access Control Protocol 1370 BIND and REBIND behave the same as MOVE with respect to the DAV:acl 1371 property (see [RFC3744], Section 7.3). 1373 10. Security Considerations 1375 This section is provided to make WebDAV implementors aware of the 1376 security implications of this protocol. 1378 All of the security considerations of HTTP/1.1 and the WebDAV 1379 Distributed Authoring Protocol specification also apply to this 1380 protocol specification. In addition, bindings introduce several new 1381 security concerns and increase the risk of some existing threats. 1382 These issues are detailed below. 1384 10.1. Privacy Concerns 1386 In a context where cross-server bindings are supported, creating 1387 bindings on a trusted server may make it possible for a hostile agent 1388 to induce users to send private information to a target on a 1389 different server. 1391 10.2. Bind Loops 1393 Although bind loops were already possible in HTTP 1.1, the 1394 introduction of the BIND method creates a new avenue for clients to 1395 create loops accidentally or maliciously. If the binding and its 1396 target are on the same server, the server may be able to detect BIND 1397 requests that would create loops. Servers are required to detect 1398 loops that are caused by bindings to collections during the 1399 processing of any requests with "Depth: infinity". 1401 10.3. Bindings, and Denial of Service 1403 Denial of service attacks were already possible by posting URIs that 1404 were intended for limited use at heavily used Web sites. The 1405 introduction of BIND creates a new avenue for similar denial of 1406 service attacks. If cross-server bindings are supported, clients can 1407 now create bindings at heavily used sites to target locations that 1408 were not designed for heavy usage. 1410 10.4. Private Locations May Be Revealed 1412 If the DAV:parent-set property is maintained on a resource, the 1413 owners of the bindings risk revealing private locations. The 1414 directory structures where bindings are located are available to 1415 anyone who has access to the DAV:parent-set property on the resource. 1416 Moving a binding may reveal its new location to anyone with access to 1417 DAV:parent-set on its resource. 1419 10.5. DAV:parent-set and Denial of Service 1421 If the server maintains the DAV:parent-set property in response to 1422 bindings created in other administrative domains, it is exposed to 1423 hostile attempts to make it devote resources to adding bindings to 1424 the list. 1426 11. Internationalization Considerations 1428 All internationalization considerations mentioned in 1429 [draft-ietf-webdav-rfc2518bis] also apply to this document. 1431 12. IANA Considerations 1433 There are no IANA considerations related to this specification. 1435 13. Acknowledgements 1437 This document is the collaborative product of the authors and Tyson 1438 Chihaya, Jim Davis, Chuck Fay and Judith Slein. This draft has 1439 benefited from thoughtful discussion by Jim Amsden, Peter Carlson, 1440 Steve Carter, Ken Coar, Ellis Cohen, Dan Connolly, Bruce Cragun, 1441 Spencer Dawkins, Mark Day, Rajiv Dulepet, David Durand, Lisa 1442 Dusseault, Stefan Eissing, Roy Fielding, Yaron Goland, Joe 1443 Hildebrand, Fred Hitt, Alex Hopmann, James Hunt, Marcus Jager, Chris 1444 Kaler, Manoj Kasichainula, Rohit Khare, Brian Korver, Daniel 1445 LaLiberte, Steve Martin, Larry Masinter, Jeff McAffer, Surendra 1446 Koduru Reddy, Max Rible, Sam Ruby, Bradley Sergeant, Nick Shelness, 1447 John Stracke, John Tigue, John Turner, Kevin Wiggen, and other 1448 members of the WebDAV working group. 1450 14. References 1451 14.1. Normative References 1453 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1454 Requirement Levels", BCP 14, RFC 2119, March 1997. 1456 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 1457 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 1458 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 1460 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1461 Resource Identifier (URI): Generic Syntax", STD 66, 1462 RFC 3986, January 2005. 1464 [XML] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and 1465 F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fourth 1466 Edition)", W3C REC-xml-20060816, August 2006, 1467 . 1469 [draft-ietf-webdav-rfc2518bis] 1470 Dusseault, L., Ed., "HTTP Extensions for Distributed 1471 Authoring - WebDAV RFC2518 bis", 1472 draft-ietf-webdav-rfc2518bis-17 (work in progress), 1473 December 2006. 1475 14.2. Informative References 1477 [RFC3253] Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. 1478 Whitehead, "Versioning Extensions to WebDAV (Web 1479 Distributed Authoring and Versioning)", RFC 3253, 1480 March 2002. 1482 [RFC3744] Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web 1483 Distributed Authoring and Versioning (WebDAV) Access 1484 Control Protocol", RFC 3744, May 2004. 1486 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 1487 Unique IDentifier (UUID) URN Namespace", RFC 4122, 1488 July 2005. 1490 Appendix A. Clarification to RFC2518bis' Usage of the term 'lock root' 1492 [draft-ietf-webdav-rfc2518bis], Section 9.10.1 claims: 1494 A LOCK request to an existing resource will create a lock on the 1495 resource identified by the Request-URI, provided the resource is 1496 not already locked with a conflicting lock. The resource 1497 identified in the Request-URI becomes the root of the lock. 1499 This is incorrect in that it implies that the "lock root" is a 1500 resource, not a URL 1501 (). 1502 However, should a directly locked resource have multiple bindings, 1503 only the one used in the Request-URI of the LOCK request will be the 1504 protected from changes of clients not supplying the lock token. 1506 A correct description would be: 1508 A LOCK request to an existing resource will create a lock on the 1509 resource identified by the Request-URI, provided the resource is 1510 not already locked with a conflicting lock. The Request-URI 1511 becomes the root of the lock. 1513 Note that this change makes the description consistent with the 1514 definition of the DAV:lockroot XML element in Section 14.12 of 1515 [draft-ietf-webdav-rfc2518bis]. 1517 The authors of this specification recommend that future revisions of 1518 [draft-ietf-webdav-rfc2518bis] will update the description as 1519 suggested above. 1521 Appendix B. Change Log (to be removed by RFC Editor before publication) 1523 B.1. Since draft-ietf-webdav-bind-02 1525 Add and resolve issues "2.3_COPY_SHARED_BINDINGS" and 1526 "2.3_MULTIPLE_COPY". Add issue "5.1_LOOP_STATUS" and proposed 1527 resolution, but keep it open. Add issues "ED_references" and 1528 "4_507_status". Started work on index. Rename document to "Binding 1529 Extensions to Web Distributed Authoring and Versioning (WebDAV)". 1530 Rename "References" to "Normative References". Close issue 1531 "ED_references". Close issue "4_507_status". 1533 B.2. Since draft-ietf-webdav-bind-03 1535 Add and close issues "9.2_redirect_loops", "ED_authors" and 1536 "ED_updates". Add section about capability discovery (DAV header). 1537 Close issues "5.1_LOOP_STATUS". Add and resolve new issue 1538 "5.1_506_STATUS_STREAMING". Update XML spec reference. Add issue 1539 "locking" and resolve as invalid. 1541 B.3. Since draft-ietf-webdav-bind-04 1543 Add and close issues "6_precondition_binding_allowed" and 1544 "6_lock_behaviour". Add mailing list and issues list pointers to 1545 front. 1547 B.4. Since draft-ietf-webdav-bind-05 1549 Editorial fixes. Add and resolve issues "1.3_error_negotiation", 1550 "2.5_language" and "7.1.1_add_resource_id". Add historical issue 1551 "4_LOCK_BEHAVIOR" and it's resolution for better tracking. 1553 B.5. Since draft-ietf-webdav-bind-06 1555 Rewrite Editorial Note. Open and resolve issues "2.6_identical", 1556 "specify_safeness_and_idempotence" and "ED_rfc2026_ref". 1558 B.6. Since draft-ietf-webdav-bind-07 1560 Add more index items (no change tracking). Add and resolve issues 1561 "2.3_copy_to_same", "bind_properties", "bind_vs_ACL", 1562 "6_rebind_intro" and "rfc2396bis" (actually an action item). Fix XML 1563 DTD fragment in section 3.3. Make spelling of "Request-URI" 1564 consistent. 1566 B.7. Since draft-ietf-webdav-bind-08 1568 Resolved editorial issues raised by Jim Whitehead in . 1570 Add and resolve issues "atomicity", "2_allow_destroy", 1571 "2.1_separate_loop_discussion", "2.1.1_bind_loops_vs_locks", 1572 "2.3_copy_depth_infinity", "2.3_copy_example", "2.3_copy_vs_loops", 1573 "2.6_resource-id_vs_versions", "3.2_example" and 1574 "6_rebind_premissions". Add issue "2.6_when_do_ids_change". Re-open 1575 and resolve "6_rebind_intro". 1577 B.8. Since draft-ietf-webdav-bind-09 1579 Add and resolve issue "6.1_rebind_vs_locks", adding proposed example 1580 text. Add action item "3.1_uuids". Close issue 1581 "2.6_when_do_ids_change". Add and resolve issues 1582 "2.6_bindings_vs_properties" and "uri_draft_ref". 1584 B.9. Since draft-ietf-webdav-bind-10 1586 Resolve action item "3.1_uuids". Add and resolve issue 1587 "2.7_unlock_vs_bindings". Revisit issue 1588 "2.6_bindings_vs_properties", and remove the part of the sentence 1589 that speaks about live properties. Update "rfc2396bis" references to 1590 "RFC3986". Add issue "9_ns_op_and_acl" and add potential resolution. 1591 Align artwork where applicable (new xml2rfc1.29rc2 feature). 1593 B.10. Since draft-ietf-webdav-bind-11 1595 Updated [draft-mealling-uuid-urn] to [RFC4122]. Add statement about 1596 live properties in Section 2.6. 1598 B.11. Since draft-ietf-webdav-bind-12 1600 Updated Author's address. Uppercase "Section" when referring to 1601 other documents. 1603 Updating from RFC2518 to RFC2518bis: 1605 o Remove own explanation of DTD syntax. 1607 o Remove own definition of precondition/postcondition. 1609 o Remove reference to broken RFC2518 language about DELETE and 1610 UNLOCK. 1612 o Remove own definition of DAV: request header. 1614 o Updated "Rationale for Distinguishing Bindings from URI Mappings" 1615 to reflect the changes in [draft-ietf-webdav-rfc2518bis], making 1616 proposals for more changes so that the issue can be closed (see 1617 also 1618 and ). 1621 B.12. Since draft-ietf-webdav-bind-13 1623 Update [draft-ietf-webdav-rfc2518-bis] to draft 14. Update one 1624 incorrect section reference. Remove Section "Rationale for 1625 Distinguishing Bindings from URI Mappings" as 1626 [draft-ietf-webdav-rfc2518-bis] now uses the proper definition of 1627 collection state. Examples use application/xml instead of text/xml 1628 MIME type. 1630 Fix IANA section (there are no IANA considerations). 1632 B.13. Since draft-ietf-webdav-bind-14 1634 Update [draft-ietf-webdav-rfc2518-bis] to draft 15. Update [XML] to 1635 4th edition. 1637 Markup ASCII art for box recognition (doesn't affect ASCII version). 1639 Identify Julian Reschke as Editor. 1641 B.14. Since draft-ietf-webdav-bind-15 1643 Fix typo in RFC2119 keywords section (sorry!). 1645 Update [draft-ietf-webdav-rfc2518-bis] to draft 17. 1647 Add and resolve issue "rfc2518bis-lock-root". 1649 Appendix C. Resolved issues (to be removed by RFC Editor before 1650 publication) 1652 Issues that were either rejected or resolved in this version of this 1653 document. 1655 C.1. rfc2518bis-lock-root 1657 Type: change 1659 julian.reschke@greenbytes.de (2007-01-04): 1660 draft-ietf-webdav-rfc2518bis-17 uses the term "lock root" 1661 inconsistently. Add an appendix explaining the problem and 1662 suggesting a clarification. 1664 Resolution (2007-01-04): Add appendix explaining the issue and 1665 recommending a fix to rfc2518bis. 1667 Appendix D. Open issues (to be removed by RFC Editor prior to 1668 publication) 1670 D.1. edit 1672 Type: edit 1674 julian.reschke@greenbytes.de (2004-05-30): Umbrella issue for 1675 editorial fixes/enhancements. 1677 Index 1679 2 1680 208 Already Reported (status code) 28 1682 5 1683 506 Loop Detected (status code) 31 1685 B 1686 BIND method 18 1687 Marshalling 19 1688 Postconditions 20 1689 Preconditions 19 1690 Binding 6 1692 C 1693 Collection 6 1694 Condition Names 1695 DAV:bind-into-collection (pre) 19 1696 DAV:bind-source-exists (pre) 19 1697 DAV:binding-allowed (pre) 20 1698 DAV:binding-deleted (post) 22, 25 1699 DAV:can-overwrite (pre) 20, 24 1700 DAV:cross-server-binding (pre) 20, 24 1701 DAV:cycle-allowed (pre) 20, 24 1702 DAV:lock-deleted (post) 22, 25 1703 DAV:locked-overwrite-allowed (pre) 20 1704 DAV:locked-source-collection-update-allowed (pre) 24 1705 DAV:locked-update-allowed (pre) 20, 22, 24 1706 DAV:name-allowed (pre) 20, 24 1707 DAV:new-binding (post) 20, 25 1708 DAV:protected-source-url-deletion-allowed (pre) 25 1709 DAV:protected-url-deletion-allowed (pre) 22 1710 DAV:protected-url-modification-allowed (pre) 24 1711 DAV:rebind-from-collection (pre) 24 1712 DAV:rebind-source-exists (pre) 24 1713 DAV:unbind-from-collection (pre) 22 1714 DAV:unbind-source-exists (pre) 22 1716 D 1717 DAV header 1718 compliance class 'bind' 31 1719 DAV:bind-into-collection precondition 19 1720 DAV:bind-source-exists precondition 19 1721 DAV:binding-allowed precondition 20 1722 DAV:binding-deleted postcondition 22, 25 1723 DAV:can-overwrite precondition 20, 24 1724 DAV:cross-server-binding precondition 20, 24 1725 DAV:cycle-allowed precondition 20, 24 1726 DAV:lock-deleted postcondition 22, 25 1727 DAV:locked-overwrite-allowed precondition 20 1728 DAV:locked-source-collection-update-allowed precondition 24 1729 DAV:locked-update-allowed precondition 20, 22, 24 1730 DAV:name-allowed precondition 20, 24 1731 DAV:new-binding postcondition 20, 25 1732 DAV:parent-set property 17 1733 DAV:protected-source-url-deletion-allowed precondition 25 1734 DAV:protected-url-deletion-allowed precondition 22 1735 DAV:protected-url-modification-allowed precondition 24 1736 DAV:rebind-from-collection precondition 24 1737 DAV:rebind-source-exists precondition 24 1738 DAV:resource-id property 17 1739 DAV:unbind-from-collection precondition 22 1740 DAV:unbind-source-exists precondition 22 1742 I 1743 Internal Member URI 6 1745 M 1746 Methods 1747 BIND 18 1748 REBIND 23 1749 UNBIND 21 1751 P 1752 Path Segment 6 1753 Properties 1754 DAV:parent-set 17 1755 DAV:resource-id 17 1757 R 1758 REBIND method 23 1759 Marshalling 23 1760 Postconditions 25 1761 Preconditions 24 1763 S 1764 Status Codes 1765 208 Already Reported 28 1766 506 Loop Detected 31 1768 U 1769 UNBIND method 21 1770 Marshalling 21 1771 Postconditions 22 1772 Preconditions 22 1773 URI Mapping 5 1775 Authors' Addresses 1777 Geoffrey Clemm 1778 IBM 1779 20 Maguire Road 1780 Lexington, MA 02421 1782 Email: geoffrey.clemm@us.ibm.com 1784 Jason Crawford 1785 IBM Research 1786 P.O. Box 704 1787 Yorktown Heights, NY 10598 1789 Email: ccjason@us.ibm.com 1791 Julian F. Reschke (editor) 1792 greenbytes GmbH 1793 Hafenweg 16 1794 Muenster, NW 48155 1795 Germany 1797 Email: julian.reschke@greenbytes.de 1799 Jim Whitehead 1800 UC Santa Cruz, Dept. of Computer Science 1801 1156 High Street 1802 Santa Cruz, CA 95064 1804 Email: ejw@cse.ucsc.edu 1806 Full Copyright Statement 1808 Copyright (C) The IETF Trust (2007). 1810 This document is subject to the rights, licenses and restrictions 1811 contained in BCP 78, and except as set forth therein, the authors 1812 retain all their rights. 1814 This document and the information contained herein are provided on an 1815 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 1816 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST, 1817 AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, 1818 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT 1819 THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY 1820 IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR 1821 PURPOSE. 1823 Intellectual Property 1825 The IETF takes no position regarding the validity or scope of any 1826 Intellectual Property Rights or other rights that might be claimed to 1827 pertain to the implementation or use of the technology described in 1828 this document or the extent to which any license under such rights 1829 might or might not be available; nor does it represent that it has 1830 made any independent effort to identify any such rights. Information 1831 on the procedures with respect to rights in RFC documents can be 1832 found in BCP 78 and BCP 79. 1834 Copies of IPR disclosures made to the IETF Secretariat and any 1835 assurances of licenses to be made available, or the result of an 1836 attempt made to obtain a general license or permission for the use of 1837 such proprietary rights by implementers or users of this 1838 specification can be obtained from the IETF on-line IPR repository at 1839 http://www.ietf.org/ipr. 1841 The IETF invites any interested party to bring to its attention any 1842 copyrights, patents or patent applications, or other proprietary 1843 rights that may cover technology that may be required to implement 1844 this standard. Please address the information to the IETF at 1845 ietf-ipr@ietf.org. 1847 Acknowledgment 1849 Funding for the RFC Editor function is currently provided by the 1850 Internet Society.