draft-ietf-webdav-bind-27.txt   draft-ietf-webdav-bind-latest.txt 
Network Working Group G. Clemm Network Working Group G. Clemm
Internet-Draft IBM Internet-Draft IBM
Intended status: Experimental J. Crawford Intended status: Experimental J. Crawford
Expires: June 18, 2010 IBM Research Expires: October 3, 2010 IBM Research
J. Reschke, Ed. J. Reschke, Ed.
greenbytes greenbytes
J. Whitehead J. Whitehead
U.C. Santa Cruz U.C. Santa Cruz
December 15, 2009 April 2010
Binding Extensions to Web Distributed Authoring and Versioning (WebDAV) Binding Extensions to Web Distributed Authoring and Versioning (WebDAV)
draft-ietf-webdav-bind-27 draft-ietf-webdav-bind-latest
Abstract Abstract
This specification defines bindings, and the BIND method for creating This specification defines bindings, and the BIND method for creating
multiple bindings to the same resource. Creating a new binding to a multiple bindings to the same resource. Creating a new binding to a
resource causes at least one new URI to be mapped to that resource. resource causes at least one new URI to be mapped to that resource.
Servers are required to ensure the integrity of any bindings that Servers are required to ensure the integrity of any bindings that
they allow to be created. they allow to be created.
Editorial Note (To be removed by RFC Editor before publication) Status of This Memo
Please send comments to the Distributed Authoring and Versioning
(WebDAV) working group at <mailto:w3c-dist-auth@w3.org>, which may be
joined by sending a message with subject "subscribe" to
<mailto:w3c-dist-auth-request@w3.org>. Discussions of the WEBDAV
working group are archived at
<http://lists.w3.org/Archives/Public/w3c-dist-auth/>.
<http://www.webdav.org/bind/draft-ietf-webdav-bind-issues.html> lists
all registered issues since draft 02.
Status of this Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Method Preconditions and Postconditions . . . . . . . . . 8 1.2. Method Preconditions and Postconditions . . . . . . . . . 6
2. Overview of Bindings . . . . . . . . . . . . . . . . . . . . . 8 2. Overview of Bindings . . . . . . . . . . . . . . . . . . . . . 7
2.1. Bindings to Collections . . . . . . . . . . . . . . . . . 8 2.1. Bindings to Collections . . . . . . . . . . . . . . . . . 7
2.1.1. Bind Loops . . . . . . . . . . . . . . . . . . . . . . 9 2.1.1. Bind Loops . . . . . . . . . . . . . . . . . . . . . . 8
2.2. URI Mappings Created by a new Binding . . . . . . . . . . 10 2.2. URI Mappings Created by a New Binding . . . . . . . . . . 8
2.3. COPY and Bindings . . . . . . . . . . . . . . . . . . . . 10 2.3. COPY and Bindings . . . . . . . . . . . . . . . . . . . . 9
2.3.1. Example: COPY with 'Depth: infinity' in Presence 2.3.1. Example: COPY with "Depth: infinity" in Presence
of Bind Loops . . . . . . . . . . . . . . . . . . . . 12 of Bind Loops . . . . . . . . . . . . . . . . . . . . 11
2.3.2. Example: COPY updating multiple Bindings . . . . . . . 14 2.3.2. Example: COPY Updating Multiple Bindings . . . . . . . 13
2.3.3. Example: COPY with 'Depth: infinity' with Multiple 2.3.3. Example: COPY with "Depth: infinity" with Multiple
Bindings to a Leaf Resource . . . . . . . . . . . . . 15 Bindings to a Leaf Resource . . . . . . . . . . . . . 14
2.4. DELETE and Bindings . . . . . . . . . . . . . . . . . . . 16 2.4. DELETE and Bindings . . . . . . . . . . . . . . . . . . . 15
2.5. MOVE and Bindings . . . . . . . . . . . . . . . . . . . . 16 2.5. MOVE and Bindings . . . . . . . . . . . . . . . . . . . . 15
2.5.1. Example: Simple MOVE . . . . . . . . . . . . . . . . . 17 2.5.1. Example: Simple MOVE . . . . . . . . . . . . . . . . . 16
2.5.2. Example: MOVE Request causing a Bind Loop . . . . . . 17 2.5.2. Example: MOVE Request Causing a Bind Loop . . . . . . 16
2.6. PROPFIND and Bindings . . . . . . . . . . . . . . . . . . 19 2.6. PROPFIND and Bindings . . . . . . . . . . . . . . . . . . 18
2.7. Determining Whether Two Bindings Are to the Same 2.7. Determining Whether Two Bindings Are to the Same
Resource . . . . . . . . . . . . . . . . . . . . . . . . . 19 Resource . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.8. Discovering the Bindings to a Resource . . . . . . . . . . 20 2.8. Discovering the Bindings to a Resource . . . . . . . . . . 19
3. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3. Properties . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.1. DAV:resource-id Property . . . . . . . . . . . . . . . . . 20 3.1. DAV:resource-id Property . . . . . . . . . . . . . . . . . 19
3.2. DAV:parent-set Property . . . . . . . . . . . . . . . . . 21 3.2. DAV:parent-set Property . . . . . . . . . . . . . . . . . 20
3.2.1. Example for DAV:parent-set Property . . . . . . . . . 21 3.2.1. Example for DAV:parent-set Property . . . . . . . . . 20
4. BIND Method . . . . . . . . . . . . . . . . . . . . . . . . . 22 4. BIND Method . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.1. Example: BIND . . . . . . . . . . . . . . . . . . . . . . 25 4.1. Example: BIND . . . . . . . . . . . . . . . . . . . . . . 24
5. UNBIND Method . . . . . . . . . . . . . . . . . . . . . . . . 25 5. UNBIND Method . . . . . . . . . . . . . . . . . . . . . . . . 24
5.1. Example: UNBIND . . . . . . . . . . . . . . . . . . . . . 27 5.1. Example: UNBIND . . . . . . . . . . . . . . . . . . . . . 26
6. REBIND Method . . . . . . . . . . . . . . . . . . . . . . . . 27 6. REBIND Method . . . . . . . . . . . . . . . . . . . . . . . . 26
6.1. Example: REBIND . . . . . . . . . . . . . . . . . . . . . 29 6.1. Example: REBIND . . . . . . . . . . . . . . . . . . . . . 28
6.2. Example: REBIND in Presence of Locks and Bind Loops . . . 30 6.2. Example: REBIND in Presence of Locks and Bind Loops . . . 29
7. Additional Status Codes . . . . . . . . . . . . . . . . . . . 32 7. Additional Status Codes . . . . . . . . . . . . . . . . . . . 31
7.1. 208 Already Reported . . . . . . . . . . . . . . . . . . . 32 7.1. 208 Already Reported . . . . . . . . . . . . . . . . . . . 31
7.1.1. Example: PROPFIND by Bind-Aware Client . . . . . . . . 33 7.1.1. Example: PROPFIND by Bind-Aware Client . . . . . . . . 32
7.1.2. Example: PROPFIND by Non-Bind-Aware Client . . . . . . 35 7.1.2. Example: PROPFIND by Non-Bind-Aware Client . . . . . . 34
7.2. 506 Loop Detected . . . . . . . . . . . . . . . . . . . . 35 7.2. 508 Loop Detected . . . . . . . . . . . . . . . . . . . . 34
8. Capability Discovery . . . . . . . . . . . . . . . . . . . . . 35 8. Capability Discovery . . . . . . . . . . . . . . . . . . . . . 34
8.1. OPTIONS Method . . . . . . . . . . . . . . . . . . . . . . 35 8.1. OPTIONS Method . . . . . . . . . . . . . . . . . . . . . . 34
8.2. 'DAV' Request Header . . . . . . . . . . . . . . . . . . . 35 8.2. 'DAV' Request Header . . . . . . . . . . . . . . . . . . . 34
9. Relationship to Locking in WebDAV . . . . . . . . . . . . . . 36 9. Relationship to Locking in WebDAV . . . . . . . . . . . . . . 35
9.1. Example: Locking and Multiple Bindings . . . . . . . . . . 37 9.1. Example: Locking and Multiple Bindings . . . . . . . . . . 35
10. Relationship to WebDAV Access Control Protocol . . . . . . . . 38 10. Relationship to WebDAV Access Control Protocol . . . . . . . . 37
11. Relationship to Versioning Extensions to WebDAV . . . . . . . 38 11. Relationship to Versioning Extensions to WebDAV . . . . . . . 37
12. Security Considerations . . . . . . . . . . . . . . . . . . . 41 12. Security Considerations . . . . . . . . . . . . . . . . . . . 40
12.1. Privacy Concerns . . . . . . . . . . . . . . . . . . . . . 41 12.1. Privacy Concerns . . . . . . . . . . . . . . . . . . . . . 40
12.2. Bind Loops . . . . . . . . . . . . . . . . . . . . . . . . 41 12.2. Bind Loops . . . . . . . . . . . . . . . . . . . . . . . . 40
12.3. Bindings, and Denial of Service . . . . . . . . . . . . . 41 12.3. Bindings and Denial of Service . . . . . . . . . . . . . . 40
12.4. Private Locations May Be Revealed . . . . . . . . . . . . 41 12.4. Private Locations May Be Revealed . . . . . . . . . . . . 40
12.5. DAV:parent-set and Denial of Service . . . . . . . . . . . 42 12.5. DAV:parent-set and Denial of Service . . . . . . . . . . . 41
13. Internationalization Considerations . . . . . . . . . . . . . 42 13. Internationalization Considerations . . . . . . . . . . . . . 41
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41
15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 42 15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 41
16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 42 16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41
16.1. Normative References . . . . . . . . . . . . . . . . . . . 42 16.1. Normative References . . . . . . . . . . . . . . . . . . . 41
16.2. Informative References . . . . . . . . . . . . . . . . . . 43 16.2. Informative References . . . . . . . . . . . . . . . . . . 42
Appendix A. Change Log (to be removed by RFC Editor before Appendix A. Resolved issues (to be removed by RFC Editor
publication) . . . . . . . . . . . . . . . . . . . . 43 before publication) . . . . . . . . . . . . . . . . . 42
A.1. Since draft-ietf-webdav-bind-02 . . . . . . . . . . . . . 43 A.1. edit . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
A.2. Since draft-ietf-webdav-bind-03 . . . . . . . . . . . . . 43 A.2. auth48 . . . . . . . . . . . . . . . . . . . . . . . . . . 42
A.3. Since draft-ietf-webdav-bind-04 . . . . . . . . . . . . . 44 A.3. iana.statuscode . . . . . . . . . . . . . . . . . . . . . 42
A.4. Since draft-ietf-webdav-bind-05 . . . . . . . . . . . . . 44 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
A.5. Since draft-ietf-webdav-bind-06 . . . . . . . . . . . . . 44
A.6. Since draft-ietf-webdav-bind-07 . . . . . . . . . . . . . 44
A.7. Since draft-ietf-webdav-bind-08 . . . . . . . . . . . . . 44
A.8. Since draft-ietf-webdav-bind-09 . . . . . . . . . . . . . 44
A.9. Since draft-ietf-webdav-bind-10 . . . . . . . . . . . . . 44
A.10. Since draft-ietf-webdav-bind-11 . . . . . . . . . . . . . 45
A.11. Since draft-ietf-webdav-bind-12 . . . . . . . . . . . . . 45
A.12. Since draft-ietf-webdav-bind-13 . . . . . . . . . . . . . 45
A.13. Since draft-ietf-webdav-bind-14 . . . . . . . . . . . . . 45
A.14. Since draft-ietf-webdav-bind-15 . . . . . . . . . . . . . 46
A.15. Since draft-ietf-webdav-bind-16 . . . . . . . . . . . . . 46
A.16. Since draft-ietf-webdav-bind-17 . . . . . . . . . . . . . 46
A.17. Since draft-ietf-webdav-bind-18 . . . . . . . . . . . . . 46
A.18. Since draft-ietf-webdav-bind-19 . . . . . . . . . . . . . 46
A.19. Since draft-ietf-webdav-bind-20 . . . . . . . . . . . . . 46
A.20. Since draft-ietf-webdav-bind-21 . . . . . . . . . . . . . 46
A.21. Since draft-ietf-webdav-bind-22 . . . . . . . . . . . . . 47
A.22. Since draft-ietf-webdav-bind-23 . . . . . . . . . . . . . 47
A.23. Since draft-ietf-webdav-bind-24 . . . . . . . . . . . . . 47
A.24. Since draft-ietf-webdav-bind-25 . . . . . . . . . . . . . 47
A.25. Since draft-ietf-webdav-bind-26 . . . . . . . . . . . . . 47
Appendix B. Resolved issues (to be removed by RFC Editor
before publication) . . . . . . . . . . . . . . . . . 47
B.1. edit . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
B.2. bind-vs-hierarchy . . . . . . . . . . . . . . . . . . . . 47
B.3. copying-complex-loops . . . . . . . . . . . . . . . . . . 48
B.4. locking2 . . . . . . . . . . . . . . . . . . . . . . . . . 49
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 52
1. Introduction 1. Introduction
This specification extends the WebDAV Distributed Authoring Protocol This specification extends the WebDAV Distributed Authoring Protocol
([RFC4918]) to enable clients to create new access paths to existing ([RFC4918]) to enable clients to create new access paths to existing
resources. This capability is useful for several reasons: resources. This capability is useful for several reasons:
URIs of WebDAV-compliant resources are hierarchical and correspond to URIs of WebDAV-compliant resources are hierarchical and correspond to
a hierarchy of collections in resource space. The WebDAV Distributed a hierarchy of collections in resource space. The WebDAV Distributed
Authoring Protocol makes it possible to organize these resources into Authoring Protocol makes it possible to organize these resources into
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cars and boats, a description of a combination car/boat vehicle could cars and boats, a description of a combination car/boat vehicle could
belong in either collection. Ideally, the description should be belong in either collection. Ideally, the description should be
accessible from both. Allowing clients to create new URIs that accessible from both. Allowing clients to create new URIs that
access the existing resource lets them put that resource into access the existing resource lets them put that resource into
multiple collections. multiple collections.
Hierarchies also make resource sharing more difficult, since Hierarchies also make resource sharing more difficult, since
resources that have utility across many collections are still forced resources that have utility across many collections are still forced
into a single collection. For example, the mathematics department at into a single collection. For example, the mathematics department at
one university might create a collection of information on fractals one university might create a collection of information on fractals
that contains bindings to some local resources, but also provides that contains bindings to some local resources but also provides
access to some resources at other universities. For many reasons, it access to some resources at other universities. For many reasons, it
may be undesirable to make physical copies of the shared resources on may be undesirable to make physical copies of the shared resources on
the local server: to conserve disk space, to respect copyright the local server, for example, to conserve disk space, to respect
constraints, or to make any changes in the shared resources visible copyright constraints, or to make any changes in the shared resources
automatically. Being able to create new access paths to existing visible automatically. Being able to create new access paths to
resources in other collections or even on other servers is useful for existing resources in other collections or even on other servers is
this sort of case. useful for this sort of case.
The BIND method defined here provides a mechanism for allowing The BIND method, defined here, provides a mechanism for allowing
clients to create alternative access paths to existing WebDAV clients to create alternative access paths to existing WebDAV
resources. HTTP [RFC2616] and WebDAV [RFC4918] methods are able to resources. HTTP [RFC2616] and WebDAV [RFC4918] methods are able to
work because there are mappings between URIs and resources. A method work because there are mappings between URIs and resources. A method
is addressed to a URI, and the server follows the mapping from that is addressed to a URI, and the server follows the mapping from that
URI to a resource, applying the method to that resource. Multiple URI to a resource, applying the method to that resource. Multiple
URIs may be mapped to the same resource, but until now there has been URIs may be mapped to the same resource, but until now, there has
no way for clients to create additional URIs mapped to existing been no way for clients to create additional URIs mapped to existing
resources. resources.
BIND lets clients associate a new URI with an existing WebDAV BIND lets clients associate a new URI with an existing WebDAV
resource, and this URI can then be used to submit requests to the resource, and this URI can then be used to submit requests to the
resource. Since URIs of WebDAV resources are hierarchical, and resource. Since URIs of WebDAV resources are hierarchical, and
correspond to a hierarchy of collections in resource space, the BIND correspond to a hierarchy of collections in resource space, the BIND
method also has the effect of adding the resource to a collection. method also has the effect of adding the resource to a collection.
As new URIs are associated with the resource, it appears in As new URIs are associated with the resource, it appears in
additional collections. additional collections.
A BIND request does not create a new resource, but simply makes A BIND request does not create a new resource, but simply makes a new
available a new URI for submitting requests to an existing resource. URI for submitting requests to an existing resource available. The
The new URI is indistinguishable from any other URI when submitting a new URI is indistinguishable from any other URI when submitting a
request to a resource. Only one round trip is needed to submit a request to a resource. Only one round trip is needed to submit a
request to the intended target. Servers are required to enforce the request to the intended target. Servers are required to enforce the
integrity of the relationships between the new URIs and the resources integrity of the relationships between the new URIs and the resources
associated with them. Consequently, it may be very costly for associated with them. Consequently, it may be very costly for
servers to support BIND requests that cross server boundaries. servers to support BIND requests that cross server boundaries.
This specification is organized as follows. Section 1.1 defines This specification is organized as follows. Section 1.1 defines
terminology used in the rest of the specification, while Section 2 terminology used in the rest of the specification, while Section 2
overviews bindings. Section 3 defines the new properties needed to overviews bindings. Section 3 defines the new properties needed to
support multiple bindings to the same resource. Section 4 specifies support multiple bindings to the same resource. Section 4 specifies
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document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
This document uses XML DTD fragments ([XML]) as a notational This document uses XML DTD fragments ([XML]) as a notational
convention, using the rules defined in Section 17 of [RFC4918]. convention, using the rules defined in Section 17 of [RFC4918].
"URI Mapping" "URI Mapping"
A relation between an absolute URI and a resource. For an A relation between an absolute URI and a resource. For an
absolute URI U and the resource it identifies R, the URI mapping absolute URI U and the resource it identifies R, the URI mapping
can be thought of as (U => R). Since a resource can represent can be thought of as (U => R). Since a resource can represent
items that are not network retrievable, as well as those that are, items that are not network retrievable as well as those that are,
it is possible for a resource to have zero, one, or many URI it is possible for a resource to have zero, one, or many URI
mappings. Mapping a resource to an "http" scheme URI makes it mappings. Mapping a resource to an "http"-scheme URI makes it
possible to submit HTTP protocol requests to the resource using possible to submit HTTP requests to the resource using the URI.
the URI.
"Path Segment" "Path Segment"
Informally, the characters found between slashes ("/") in a URI. Informally, the characters found between slashes ("/") in a URI.
Formally, as defined in Section 3.3 of [RFC3986]. Formally, as defined in Section 3.3 of [RFC3986].
"Binding" "Binding"
A relation between a single path segment (in a collection) and a A relation between a single path segment (in a collection) and a
resource. A binding is part of the state of a collection. If two resource. A binding is part of the state of a collection. If two
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R) makes it possible to use the URI R) makes it possible to use the URI
http://www.example.com/CollX/foo.html to access R. http://www.example.com/CollX/foo.html to access R.
"Collection" "Collection"
A resource that contains, as part of its state, a set of bindings A resource that contains, as part of its state, a set of bindings
that identify internal member resources. that identify internal member resources.
"Internal Member URI" "Internal Member URI"
The URI that identifies an internal member of a collection, and The URI that identifies an internal member of a collection and
that consists of the URI for the collection, followed by a slash that consists of the URI for the collection, followed by a slash
character ('/'), followed by the path segment of the binding for character ('/'), followed by the path segment of the binding for
that internal member. that internal member.
"Binding Integrity" "Binding Integrity"
The property of a binding that says that: The property of a binding that says that:
* the binding continues to exist, and * the binding continues to exist, and
* the identity of the resource identified by that binding does * the identity of the resource identified by that binding does
not change, not change,
unless an explicit request is executed that is defined to delete unless an explicit request is executed that is defined to delete
that binding (examples of requests that delete a binding are that binding (examples of requests that delete a binding are
DELETE, MOVE, and - defined later on - UNBIND, and REBIND). DELETE, MOVE, and -- defined later on -- UNBIND and REBIND).
1.2. Method Preconditions and Postconditions 1.2. Method Preconditions and Postconditions
See Section 16 of [RFC4918] for the definitions of "precondition" and See Section 16 of [RFC4918] for the definitions of "precondition" and
"postcondition". "postcondition".
2. Overview of Bindings 2. Overview of Bindings
Bindings are part of the state of a collection. They define the Bindings are part of the state of a collection. They define the
internal members of the collection, and the names of those internal internal members of the collection and the names of those internal
members. members.
Bindings are added and removed by a variety of existing HTTP methods. Bindings are added and removed by a variety of existing HTTP methods.
A method that creates a new resource, such as PUT, COPY, and MKCOL, A method that creates a new resource, such as PUT, COPY, and MKCOL,
adds a binding. A method that deletes a resource, such as DELETE, adds a binding. A method that deletes a resource, such as DELETE,
removes a binding. A method that moves a resource (e.g. MOVE) both removes a binding. A method that moves a resource (e.g., MOVE) both
adds a binding (in the destination collection) and removes a binding adds a binding (in the destination collection) and removes a binding
(in the source collection). The BIND method introduced here provides (in the source collection). The BIND method introduced here provides
a mechanism for adding a second binding to an existing resource. a mechanism for adding a second binding to an existing resource.
There is no difference between an initial binding added by PUT, COPY, There is no difference between an initial binding added by PUT, COPY,
or MKCOL, and additional bindings added with BIND. or MKCOL and additional bindings added with BIND.
It would be very undesirable if one binding could be destroyed as a It would be very undesirable if one binding could be destroyed as a
side effect of operating on the resource through a different binding. side effect of operating on the resource through a different binding.
In particular, the removal of one binding to a resource (e.g. with a In particular, the removal of one binding to a resource (e.g., with a
DELETE or a MOVE) MUST NOT disrupt another binding to that resource, DELETE or a MOVE) MUST NOT disrupt another binding to that resource,
e.g. by turning that binding into a dangling path segment. The e.g., by turning that binding into a dangling path segment. The
server MUST NOT reclaim system resources after removing one binding, server MUST NOT reclaim system resources after removing one binding,
while other bindings to the resource remain. In other words, the while other bindings to the resource remain. In other words, the
server MUST maintain the integrity of a binding. It is permissible, server MUST maintain the integrity of a binding. It is permissible,
however, for future method definitions (e.g., a DESTROY method) to however, for future method definitions (e.g., a DESTROY method) to
have semantics that explicitly remove all bindings and/or immediately have semantics that explicitly remove all bindings and/or immediately
reclaim system resources. reclaim system resources.
Note: the collection model described herein is not compatible with Note: the collection model described herein is not compatible with
systems in which resources inherit properties based solely on the systems in which resources inherit properties based solely on the
access path, as the ability to create additional bindings will access path, as the ability to create additional bindings will
skipping to change at page 9, line 7 skipping to change at page 7, line 50
Creating a new binding to a collection makes each resource associated Creating a new binding to a collection makes each resource associated
with a binding in that collection accessible via a new URI, and thus with a binding in that collection accessible via a new URI, and thus
creates new URI mappings to those resources but no new bindings. creates new URI mappings to those resources but no new bindings.
For example, suppose a new binding CollY is created for collection C1 For example, suppose a new binding CollY is created for collection C1
in the figure below. It immediately becomes possible to access in the figure below. It immediately becomes possible to access
resource R1 using the URI /CollY/x.gif and to access resource R2 resource R1 using the URI /CollY/x.gif and to access resource R2
using the URI /CollY/y.jpg, but no new bindings for these child using the URI /CollY/y.jpg, but no new bindings for these child
resources were created. This is because bindings are part of the resources were created. This is because bindings are part of the
state of a collection, and associate a URI that is relative to that state of a collection, and they associate a URI that is relative to
collection with its target resource. No change to the bindings in that collection with its target resource. No change to the bindings
Collection C1 is needed to make its children accessible using /CollY/ in Collection C1 is needed to make its children accessible using
x.gif and /CollY/y.jpg. /CollY/x.gif and /CollY/y.jpg.
+-------------------------+ +-------------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollX CollY | | CollX CollY |
+-------------------------+ +-------------------------+
| / | /
| / | /
| / | /
+------------------+ +------------------+
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2.1.1. Bind Loops 2.1.1. Bind Loops
Bindings to collections can result in loops ("cycles"), which servers Bindings to collections can result in loops ("cycles"), which servers
MUST detect when processing "Depth: infinity" requests. It is MUST detect when processing "Depth: infinity" requests. It is
sometimes possible to complete an operation in spite of the presence sometimes possible to complete an operation in spite of the presence
of a loop. For instance, a PROPFIND can still succeed if the server of a loop. For instance, a PROPFIND can still succeed if the server
uses the new status code 208 (Already Reported) defined in uses the new status code 208 (Already Reported) defined in
Section 7.1. Section 7.1.
However, the 506 (Loop Detected) status code is defined in However, the 508 (Loop Detected) status code is defined in
Section 7.2 for use in contexts where an operation is terminated Section 7.2 for use in contexts where an operation is terminated
because a loop was encountered. because a loop was encountered.
Support for loops is OPTIONAL: servers MAY reject requests that would Support for loops is OPTIONAL: servers MAY reject requests that would
lead to the creation of a bind loop (see DAV:cycle-allowed lead to the creation of a bind loop (see DAV:cycle-allowed
precondition defined in Section 4). precondition defined in Section 4).
2.2. URI Mappings Created by a new Binding 2.2. URI Mappings Created by a New Binding
Suppose a binding from "Binding-Name" to resource R is to be added to Suppose a binding from "Binding-Name" to resource R is to be added to
a collection, C. Then if C-MAP is the set of URIs that were mapped to a collection, C. Then if C-MAP is the set of URIs that were mapped to
C before the BIND request, then for each URI "C-URI" in C-MAP, the C before the BIND request, then for each URI "C-URI" in C-MAP, the
URI "C-URI/Binding-Name" is mapped to resource R following the BIND URI "C-URI/Binding-Name" is mapped to resource R following the BIND
request. request.
For example, if a binding from "foo.html" to R is added to a For example, if a binding from "foo.html" to R is added to a
collection C, and if the following URIs are mapped to C: collection C, and if the following URIs are mapped to C:
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and the following infinite number of additional mappings to R are and the following infinite number of additional mappings to R are
introduced: introduced:
http://www.example.com/A/1/myself/foo.html http://www.example.com/A/1/myself/foo.html
http://www.example.com/A/1/myself/myself/foo.html http://www.example.com/A/1/myself/myself/foo.html
... ...
2.3. COPY and Bindings 2.3. COPY and Bindings
As defined in Section 9.8 of [RFC4918], COPY causes the resource As defined in Section 9.8 of [RFC4918], COPY causes the resource
identified by the Request-URI to be duplicated, and makes the new identified by the Request-URI to be duplicated and makes the new
resource accessible using the URI specified in the Destination resource accessible using the URI specified in the Destination
header. Upon successful completion of a COPY, a new binding is header. Upon successful completion of a COPY, a new binding is
created between the last path segment of the Destination header, and created between the last path segment of the Destination header and
the destination resource. The new binding is added to its parent the destination resource. The new binding is added to its parent
collection, identified by the Destination header minus its final collection, identified by the Destination header minus its final
segment. segment.
The following figure shows an example: Suppose that a COPY is issued The following figure shows an example: suppose that a COPY is issued
to URI-3 for resource R (which is also mapped to URI-1 and URI-2), to URI-3 for resource R (which is also mapped to URI-1 and URI-2),
with the Destination header set to URI-X. After successful with the Destination header set to URI-X. After successful
completion of the COPY operation, resource R is duplicated to create completion of the COPY operation, resource R is duplicated to create
resource R', and a new binding has been created which creates at resource R', and a new binding has been created that creates at least
least the URI mapping between URI-X and the new resource (although the URI mapping between URI-X and the new resource (although other
other URI mappings may also have been created). URI mappings may also have been created).
URI-1 URI-2 URI-3 URI-X URI-1 URI-2 URI-3 URI-X
| | | | | | | |
| | | <---- URI Mappings ----> | | | | <---- URI Mappings ----> |
| | | | | | | |
+---------------------+ +------------------------+ +---------------------+ +------------------------+
| Resource R | | Resource R' | | Resource R | | Resource R' |
+---------------------+ +------------------------+ +---------------------+ +------------------------+
It might be thought that a COPY request with "Depth: 0" on a It might be thought that a COPY request with "Depth: 0" on a
skipping to change at page 11, line 35 skipping to change at page 10, line 35
request does not apply to a collection's members. Consequently, a request does not apply to a collection's members. Consequently, a
COPY with "Depth: 0" does not duplicate the bindings contained by the COPY with "Depth: 0" does not duplicate the bindings contained by the
collection. collection.
If a COPY request causes an existing resource to be updated, the If a COPY request causes an existing resource to be updated, the
bindings to that resource MUST be unaffected by the COPY request. bindings to that resource MUST be unaffected by the COPY request.
Using the preceding example, suppose that a COPY request is issued to Using the preceding example, suppose that a COPY request is issued to
URI-X for resource R', with the Destination header set to URI-2. The URI-X for resource R', with the Destination header set to URI-2. The
content and dead properties of resource R would be updated to be a content and dead properties of resource R would be updated to be a
copy of those of resource R', but the mappings from URI-1, URI-2, and copy of those of resource R', but the mappings from URI-1, URI-2, and
URI-3 to resource R remain unaffected. If because of multiple URI-3 to resource R remain unaffected. If, because of multiple
bindings to a resource, more than one source resource updates a bindings to a resource, more than one source resource updates a
single destination resource, the order of the updates is server single destination resource, the order of the updates is server
defined (see Section 2.3.2 for an example). defined (see Section 2.3.2 for an example).
If a COPY request would cause a new resource to be created as a copy If a COPY request would cause a new resource to be created as a copy
of an existing resource, and that COPY request has already created a of an existing resource, and that COPY request has already created a
copy of that existing resource, the COPY request instead creates copy of that existing resource, the COPY request instead creates
another binding to the previous copy, instead of creating a new another binding to the previous copy, instead of creating a new
resource (see Section 2.3.3 for an example). resource (see Section 2.3.3 for an example).
2.3.1. Example: COPY with 'Depth: infinity' in Presence of Bind Loops 2.3.1. Example: COPY with "Depth: infinity" in Presence of Bind Loops
As an example of how COPY with Depth infinity would work in the As an example of how COPY with "Depth: infinity" would work in the
presence of bindings, consider the following collection: presence of bindings, consider the following collection:
+------------------+ +------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollX | | CollX |
+------------------+ +------------------+
| |
| |
+-------------------------------+ +-------------------------------+
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+-------------+ | bindings: | | +-------------+ | bindings: | |
| y.gif CollZ | | | y.gif CollZ | |
+------------------+ | +------------------+ |
| | | | | |
| +--------+ | +--------+
| |
+-------------+ +-------------+
| Resource R2 | | Resource R2 |
+-------------+ +-------------+
If a COPY with Depth infinity is submitted to /CollX, with If a COPY request with "Depth: infinity" is submitted to /CollX, with
destination of /CollA, the outcome of the copy operation is that a a destination of /CollA, the outcome of the copy operation is that a
copy of the tree is replicated to the target /CollA: copy of the tree is replicated to the target /CollA:
+------------------+ +------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollX CollA | | CollX CollA |
+------------------+ +------------------+
| | | |
| +---------------------------+ | +---------------------------+
| | | |
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+-----------------+ | +-----------------+ |
| | | | | |
| +-------+ | +-------+
| |
+-------------+ +-------------+
| Resource R4 | | Resource R4 |
+-------------+ +-------------+
Note that the same would apply for more complex loops. Note that the same would apply for more complex loops.
2.3.2. Example: COPY updating multiple Bindings 2.3.2. Example: COPY Updating Multiple Bindings
Given the following collection hierarchy: Given the following collection hierarchy:
+------------------+ +------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollX CollY | | CollX CollY |
+------------------+ +------------------+
/ \ / \
/ \ / \
skipping to change at page 14, line 30 skipping to change at page 13, line 30
| Collection C1 | | Collection C2 | | Collection C1 | | Collection C2 |
| bindings: | | bindings: | | bindings: | | bindings: |
| x.gif y.gif | | x.gif y.gif | | x.gif y.gif | | x.gif y.gif |
+--------------------------+ +-----------------+ +--------------------------+ +-----------------+
| | | | | | | |
| | | | | | | |
+-------------+ +-------------+ +-------------+ +-------------+ +-------------+ +-------------+
| Resource R1 | | Resource R2 | | Resource R3 | | Resource R1 | | Resource R2 | | Resource R3 |
+-------------+ +-------------+ +-------------+ +-------------+ +-------------+ +-------------+
A COPY of /CollX with Depth infinity to /CollY will not result in a A COPY of /CollX with "Depth: infinity" to /CollY will not result in
changed hierarchy, and Resource R3 will be updated with the content a changed hierarchy, and Resource R3 will be updated with the content
of either Resource R1 or Resource R2. of either Resource R1 or Resource R2.
2.3.3. Example: COPY with 'Depth: infinity' with Multiple Bindings to a 2.3.3. Example: COPY with "Depth: infinity" with Multiple Bindings to a
Leaf Resource Leaf Resource
Given the following collection hierarchy: Given the following collection hierarchy:
+------------------+ +------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollX | | CollX |
+------------------+ +------------------+
| |
skipping to change at page 15, line 29 skipping to change at page 14, line 29
| Collection C1 | | Collection C1 |
| bindings: | | bindings: |
| x.gif y.gif | | x.gif y.gif |
+----------------+ +----------------+
| | | |
| | | |
+-------------+ +-------------+
| Resource R1 | | Resource R1 |
+-------------+ +-------------+
A COPY of /CollX with Depth infinity to /CollY results in the A COPY of /CollX with "Depth: infinity" to /CollY results in the
following collection hierarchy: following collection hierarchy:
+------------------+ +------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollX CollY | | CollX CollY |
+------------------+ +------------------+
| \ | \
| \ | \
| \ | \
skipping to change at page 16, line 12 skipping to change at page 15, line 12
| Resource R1 | | Resource R2 | | Resource R1 | | Resource R2 |
+-------------+ +-------------+ +-------------+ +-------------+
2.4. DELETE and Bindings 2.4. DELETE and Bindings
When there are multiple bindings to a resource, a DELETE applied to When there are multiple bindings to a resource, a DELETE applied to
that resource MUST NOT remove any bindings to that resource other that resource MUST NOT remove any bindings to that resource other
than the one identified by the Request-URI. For example, suppose the than the one identified by the Request-URI. For example, suppose the
collection identified by the URI "/a" has a binding named "x" to a collection identified by the URI "/a" has a binding named "x" to a
resource R, and another collection identified by "/b" has a binding resource R, and another collection identified by "/b" has a binding
named "y" to the same resource R. Then a DELETE applied to "/a/x" named "y" to the same resource R. Then, a DELETE applied to "/a/x"
removes the binding named "x" from "/a" but MUST NOT remove the removes the binding named "x" from "/a" but MUST NOT remove the
binding named "y" from "/b" (i.e. after the DELETE, "/y/b" continues binding named "y" from "/b" (i.e., after the DELETE, "/y/b" continues
to identify the resource R). to identify the resource R).
When DELETE is applied to a collection, it MUST NOT modify the When DELETE is applied to a collection, it MUST NOT modify the
membership of any other collection that is not itself a member of the membership of any other collection that is not itself a member of the
collection being deleted. For example, if both "/a/.../x" and collection being deleted. For example, if both "/a/.../x" and
"/b/.../y" identify the same collection, C, then applying DELETE to "/b/.../y" identify the same collection, C, then applying DELETE to
"/a" must not delete an internal member from C or from any other "/a" must not delete an internal member from C or from any other
collection that is a member of C, because that would modify the collection that is a member of C, because that would modify the
membership of "/b". membership of "/b".
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Request-URI from the collection identified by the Request-URI minus Request-URI from the collection identified by the Request-URI minus
its final segment. Although [RFC4918] allows a DELETE to be a non- its final segment. Although [RFC4918] allows a DELETE to be a non-
atomic operation, when the DELETE operation is implemented as an atomic operation, when the DELETE operation is implemented as an
UNBIND, the operation is atomic. In particular, a DELETE on a UNBIND, the operation is atomic. In particular, a DELETE on a
hierarchy of resources is simply the removal of a binding to the hierarchy of resources is simply the removal of a binding to the
collection identified by the Request-URI. collection identified by the Request-URI.
2.5. MOVE and Bindings 2.5. MOVE and Bindings
When MOVE is applied to a resource, the other bindings to that When MOVE is applied to a resource, the other bindings to that
resource MUST be unaffected, and if the resource being moved is a resource MUST be unaffected; and if the resource being moved is a
collection, the bindings to any members of that collection MUST be collection, the bindings to any members of that collection MUST be
unaffected. Also, if MOVE is used with Overwrite:T to delete an unaffected. Also, if MOVE is used with Overwrite:T to delete an
existing resource, the constraints specified for DELETE apply. existing resource, the constraints specified for DELETE apply.
If the destination collection of a MOVE request supports the REBIND If the destination collection of a MOVE request supports the REBIND
method (see Section 6), a MOVE of a resource into that collection MAY method (see Section 6), a MOVE of a resource into that collection MAY
be implemented as a REBIND request. Although [RFC4918] allows a MOVE be implemented as a REBIND request. Although [RFC4918] allows a MOVE
to be a non-atomic operation, when the MOVE operation is implemented to be a non-atomic operation, when the MOVE operation is implemented
as a REBIND, the operation is atomic. In particular, applying a MOVE as a REBIND, the operation is atomic. In particular, applying a MOVE
to a Request-URI and a Destination URI has the effect of removing a to a Request-URI and a Destination URI has the effect of removing a
binding to a resource (at the Request-URI), and creating a new binding to a resource (at the Request-URI) and creating a new binding
binding to that resource (at the Destination URI). Even when the to that resource (at the Destination URI). Even when the Request-URI
Request-URI identifies a collection, the MOVE operation involves only identifies a collection, the MOVE operation involves only removing
removing one binding to that collection and adding another. one binding to that collection and adding another.
2.5.1. Example: Simple MOVE 2.5.1. Example: Simple MOVE
As an example, suppose that a MOVE is issued to URI-3 for resource R As an example, suppose that a MOVE is issued to URI-3 for resource R
below (which is also mapped to URI-1 and URI-2), with the Destination below (which is also mapped to URI-1 and URI-2), with the Destination
header set to URI-X. After successful completion of the MOVE header set to URI-X. After successful completion of the MOVE
operation, a new binding has been created which creates the URI operation, a new binding has been created that creates the URI
mapping between URI-X and resource R. The binding corresponding to mapping between URI-X and resource R. The binding corresponding to
the final segment of URI-3 has been removed, which also causes the the final segment of URI-3 has been removed, which also causes the
URI mapping between URI-3 and R to be removed. If resource R were a URI mapping between URI-3 and R to be removed. If resource R were a
collection, old URI-3 based mappings to members of R would have been collection, old URI-3-based mappings to members of R would have been
removed, and new URI-X based mappings to members of R would have been removed, and new URI-X-based mappings to members of R would have been
created. created.
>> Before Request: >> Before Request:
URI-1 URI-2 URI-3 URI-1 URI-2 URI-3
| | | | | |
| | | <---- URI Mappings | | | <---- URI Mappings
| | | | | |
+---------------------+ +---------------------+
| Resource R | | Resource R |
skipping to change at page 17, line 39 skipping to change at page 16, line 39
>> After Request: >> After Request:
URI-1 URI-2 URI-X URI-1 URI-2 URI-X
| | | | | |
| | | <---- URI Mappings | | | <---- URI Mappings
| | | | | |
+---------------------+ +---------------------+
| Resource R | | Resource R |
+---------------------+ +---------------------+
2.5.2. Example: MOVE Request causing a Bind Loop 2.5.2. Example: MOVE Request Causing a Bind Loop
Note that in the presence of collection bindings, a MOVE request can Note that in the presence of collection bindings, a MOVE request can
cause the creating of a bind loop. cause the creation of a bind loop.
Consider a the top level collections C1 and C2 with URIs "/CollW/" Consider the top-level collections C1 and C2 with URIs "/CollW/" and
and "/CollX/". C1 also contains an additional binding named "CollY" "/CollX/". C1 also contains an additional binding named "CollY" to
to C2: C2:
+------------------+ +------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollW CollX | | CollW CollX |
+------------------+ +------------------+
| | | |
| | | |
+------------------+ | +------------------+ |
| Collection C1 | | | Collection C1 | |
skipping to change at page 19, line 35 skipping to change at page 18, line 35
| | | |
| | | |
+-------------------+ +-------------------+
2.6. PROPFIND and Bindings 2.6. PROPFIND and Bindings
Consistent with [RFC4918], the value of a dead property MUST be Consistent with [RFC4918], the value of a dead property MUST be
independent of the number of bindings to its host resource or of the independent of the number of bindings to its host resource or of the
path submitted to PROPFIND. On the other hand, the behavior for each path submitted to PROPFIND. On the other hand, the behavior for each
live property depends on its individual definition (for example, see live property depends on its individual definition (for example, see
[RFC3744], Section 5, paragraph 2 for a case where the value is [RFC3744], Section 5, Paragraph 2 for a case where the value is
independent of path and bindings, and [RFC4918], Section 8.8 for a independent of its path and bindings, and [RFC4918], Section 8.8 for
discussion about the live properties DAV:getetag and DAV: a discussion about the live properties DAV:getetag and DAV:
getlastmodified, which may behave differently). getlastmodified, which may behave differently).
2.7. Determining Whether Two Bindings Are to the Same Resource 2.7. Determining Whether Two Bindings Are to the Same Resource
It is useful to have some way of determining whether two bindings are It is useful to have some way of determining whether two bindings are
to the same resource. Two resources might have identical contents to the same resource. Two resources might have identical contents
and properties, but not be the same resource (e.g. an update to one and properties, but not be the same resource (e.g., an update to one
resource does not affect the other resource). resource does not affect the other resource).
The REQUIRED DAV:resource-id property defined in Section 3.1 is a The REQUIRED DAV:resource-id property defined in Section 3.1 is a
resource identifier, which MUST be unique across all resources for resource identifier, which MUST be unique across all resources for
all time. If the values of DAV:resource-id returned by PROPFIND all time. If the values of DAV:resource-id returned by PROPFIND
requests through two bindings are identical character by character, requests through two bindings are identical character by character,
the client can be assured that the two bindings are to the same the client can be assured that the two bindings are to the same
resource. resource.
The DAV:resource-id property is created, and its value assigned, when The DAV:resource-id property is created, and its value assigned, when
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A DAV:allprop PROPFIND request SHOULD NOT return any of the A DAV:allprop PROPFIND request SHOULD NOT return any of the
properties defined by this document. This allows a binding server to properties defined by this document. This allows a binding server to
perform efficiently when a naive client, which does not understand perform efficiently when a naive client, which does not understand
the cost of asking a server to compute all possible live properties, the cost of asking a server to compute all possible live properties,
issues a DAV:allprop PROPFIND request. issues a DAV:allprop PROPFIND request.
3.1. DAV:resource-id Property 3.1. DAV:resource-id Property
The DAV:resource-id property is a REQUIRED property that enables The DAV:resource-id property is a REQUIRED property that enables
clients to determine whether two bindings are to the same resource. clients to determine whether two bindings are to the same resource.
The value of DAV:resource-id is a URI, and may use any registered URI The value of DAV:resource-id is a URI, and may use any registered URI
scheme that guarantees the uniqueness of the value across all scheme that guarantees the uniqueness of the value across all
resources for all time (e.g. the urn:uuid: URN namespace defined in resources for all time (e.g., the urn:uuid: URN namespace defined in
[RFC4122] or the opaquelocktoken: URI scheme defined in [RFC4918]). [RFC4122] or the opaquelocktoken: URI scheme defined in [RFC4918]).
<!ELEMENT resource-id (href)> <!ELEMENT resource-id (href)>
3.2. DAV:parent-set Property 3.2. DAV:parent-set Property
The DAV:parent-set property is an OPTIONAL property that enables The DAV:parent-set property is an OPTIONAL property that enables
clients to discover what collections contain a binding to this clients to discover what collections contain a binding to this
resource (i.e. what collections have that resource as an internal resource (i.e., what collections have that resource as an internal
member). It contains an href/segment pair for each collection that member). It contains an href/segment pair for each collection that
has a binding to the resource. The href identifies the collection, has a binding to the resource. The href identifies the collection,
and the segment identifies the binding name of that resource in that and the segment identifies the binding name of that resource in that
collection. collection.
A given collection MUST appear only once in the DAV:parent-set for A given collection MUST appear only once in the DAV:parent-set for
any given binding, even if there are multiple URI mappings to that any given binding, even if there are multiple URI mappings to that
collection. collection.
<!ELEMENT parent-set (parent)*> <!ELEMENT parent-set (parent)*>
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<!-- PCDATA value: segment, as defined in Section 3.3 of <!-- PCDATA value: segment, as defined in Section 3.3 of
[RFC3986] --> [RFC3986] -->
3.2.1. Example for DAV:parent-set Property 3.2.1. Example for DAV:parent-set Property
For example, if collection C1 is mapped to both /CollX and /CollY, For example, if collection C1 is mapped to both /CollX and /CollY,
and C1 contains a binding named "x.gif" to a resource R1, then either and C1 contains a binding named "x.gif" to a resource R1, then either
[/CollX, x.gif] or [/CollY, x.gif] can appear in the DAV:parent-set [/CollX, x.gif] or [/CollY, x.gif] can appear in the DAV:parent-set
of R1, but not both. But if C1 also had a binding named "y.gif" to of R1, but not both. But if C1 also had a binding named "y.gif" to
R1, then there would be two entries for C1 in the DAV:parent-set of R1, then there would be two entries for C1 in the DAV:parent-set of
R1 (i.e. both [/CollX, x.gif] and [/CollX, y.gif] or, alternatively, R1 (i.e., both [/CollX, x.gif] and [/CollX, y.gif] or, alternatively,
both [/CollY, x.gif] and [/CollY, y.gif]). both [/CollY, x.gif] and [/CollY, y.gif]).
+-------------------------+ +-------------------------+
| Root Collection | | Root Collection |
| bindings: | | bindings: |
| CollX CollY | | CollX CollY |
+-------------------------+ +-------------------------+
| / | /
| / | /
| / | /
skipping to change at page 22, line 25 skipping to change at page 21, line 25
| bindings: | | bindings: |
| x.gif y.gif | | x.gif y.gif |
+-----------------+ +-----------------+
| | | |
| | | |
| | | |
+-------------+ +-------------+
| Resource R1 | | Resource R1 |
+-------------+ +-------------+
In this case, one possible value for DAV:parent-set property on In this case, one possible value for the DAV:parent-set property on
"/CollX/x.gif" would be: "/CollX/x.gif" would be:
<parent-set xmlns="DAV:"> <parent-set xmlns="DAV:">
<parent> <parent>
<href>/CollX</href> <href>/CollX</href>
<segment>x.gif</segment> <segment>x.gif</segment>
</parent> </parent>
<parent> <parent>
<href>/CollX</href> <href>/CollX</href>
<segment>y.gif</segment> <segment>y.gif</segment>
skipping to change at page 23, line 4 skipping to change at page 21, line 51
The BIND method modifies the collection identified by the Request- The BIND method modifies the collection identified by the Request-
URI, by adding a new binding from the segment specified in the BIND URI, by adding a new binding from the segment specified in the BIND
body to the resource identified in the BIND body. body to the resource identified in the BIND body.
If a server cannot guarantee the integrity of the binding, the BIND If a server cannot guarantee the integrity of the binding, the BIND
request MUST fail. Note that it is especially difficult to maintain request MUST fail. Note that it is especially difficult to maintain
the integrity of cross-server bindings. Unless the server where the the integrity of cross-server bindings. Unless the server where the
resource resides knows about all bindings on all servers to that resource resides knows about all bindings on all servers to that
resource, it may unwittingly destroy the resource or make it resource, it may unwittingly destroy the resource or make it
inaccessible without notifying another server that manages a binding inaccessible without notifying another server that manages a binding
to the resource. For example, if server A permits creation of a to the resource. For example, if server A permits the creation of a
binding to a resource on server B, server A must notify server B binding to a resource on server B, server A must notify server B
about its binding and must have an agreement with B that B will not about its binding and must have an agreement with B that B will not
destroy the resource while A's binding exists. Otherwise server B destroy the resource while A's binding exists. Otherwise, server B
may receive a DELETE request that it thinks removes the last binding may receive a DELETE request that it thinks removes the last binding
to the resource and destroy the resource while A's binding still to the resource and destroy the resource while A's binding still
exists. The precondition DAV:cross-server-binding is defined below exists. The precondition DAV:cross-server-binding is defined below
for cases where servers fail cross-server BIND requests because they for cases where servers fail cross-server BIND requests because they
cannot guarantee the integrity of cross-server bindings. cannot guarantee the integrity of cross-server bindings.
By default, if there already is a binding for the specified segment By default, if there already is a binding for the specified segment
in the collection, the new binding replaces the existing binding. in the collection, the new binding replaces the existing binding.
This default binding replacement behavior can be overridden using the This default binding replacement behavior can be overridden using the
Overwrite header defined in Section 10.6 of [RFC4918]. Overwrite header defined in Section 10.6 of [RFC4918].
skipping to change at page 24, line 35 skipping to change at page 23, line 35
URI namespace (servers that do not support cycles can use this URI namespace (servers that do not support cycles can use this
condition code to signal the client exactly why the request condition code to signal the client exactly why the request
failed). failed).
(DAV:locked-update-allowed): If the collection identified by the (DAV:locked-update-allowed): If the collection identified by the
Request-URI is write-locked, then the appropriate token MUST be Request-URI is write-locked, then the appropriate token MUST be
specified in an If request header. specified in an If request header.
(DAV:locked-overwrite-allowed): If the collection already contains (DAV:locked-overwrite-allowed): If the collection already contains
a binding with the specified path segment, and if that binding is a binding with the specified path segment, and if that binding is
protected by a write-lock, then the appropriate token MUST be protected by a write lock, then the appropriate token MUST be
specified in an If request header. specified in an If request header.
Postconditions: Postconditions:
(DAV:new-binding): The collection MUST have a binding that maps (DAV:new-binding): The collection MUST have a binding that maps
the segment specified in the DAV:segment element in the request the segment specified in the DAV:segment element in the request
body, to the resource identified by the DAV:href element in the body to the resource identified by the DAV:href element in the
request body. request body.
4.1. Example: BIND 4.1. Example: BIND
>> Request: >> Request:
BIND /CollY HTTP/1.1 BIND /CollY HTTP/1.1
Host: www.example.com Host: www.example.com
Content-Type: application/xml; charset="utf-8" Content-Type: application/xml; charset="utf-8"
Content-Length: 172 Content-Length: 172
skipping to change at page 25, line 35 skipping to change at page 24, line 35
The server added a new binding to the collection, The server added a new binding to the collection,
"http://www.example.com/CollY", associating "bar.html" with the "http://www.example.com/CollY", associating "bar.html" with the
resource identified by the URI resource identified by the URI
"http://www.example.com/CollX/foo.html". Clients can now use the URI "http://www.example.com/CollX/foo.html". Clients can now use the URI
"http://www.example.com/CollY/bar.html" to submit requests to that "http://www.example.com/CollY/bar.html" to submit requests to that
resource. resource.
5. UNBIND Method 5. UNBIND Method
The UNBIND method modifies the collection identified by the Request- The UNBIND method modifies the collection identified by the Request-
URI, by removing the binding identified by the segment specified in URI by removing the binding identified by the segment specified in
the UNBIND body. the UNBIND body.
Once a resource is unreachable by any URI mapping, the server MAY Once a resource is unreachable by any URI mapping, the server MAY
reclaim system resources associated with that resource. If UNBIND reclaim system resources associated with that resource. If UNBIND
removes a binding to a resource, but there remain URI mappings to removes a binding to a resource, but there remain URI mappings to
that resource, the server MUST NOT reclaim system resources that resource, the server MUST NOT reclaim system resources
associated with the resource. associated with the resource.
If an UNBIND request fails, the server state preceding the request If an UNBIND request fails, the server state preceding the request
MUST be restored. This method is unsafe and idempotent (see MUST be restored. This method is unsafe and idempotent (see
skipping to change at page 26, line 32 skipping to change at page 25, line 29
collection. collection.
(DAV:unbind-source-exists): The DAV:segment element MUST identify (DAV:unbind-source-exists): The DAV:segment element MUST identify
a binding in the collection identified by the Request-URI. a binding in the collection identified by the Request-URI.
(DAV:locked-update-allowed): If the collection identified by the (DAV:locked-update-allowed): If the collection identified by the
Request-URI is write-locked, then the appropriate token MUST be Request-URI is write-locked, then the appropriate token MUST be
specified in the request. specified in the request.
(DAV:protected-url-deletion-allowed): If the binding identified by (DAV:protected-url-deletion-allowed): If the binding identified by
the segment is protected by a write-lock, then the appropriate the segment is protected by a write lock, then the appropriate
token MUST be specified in the request. token MUST be specified in the request.
Postconditions: Postconditions:
(DAV:binding-deleted): The collection MUST NOT have a binding for (DAV:binding-deleted): The collection MUST NOT have a binding for
the segment specified in the DAV:segment element in the request the segment specified in the DAV:segment element in the request
body. body.
(DAV:lock-deleted): If the internal member URI of the binding (DAV:lock-deleted): If the internal member URI of the binding
specified by the Request-URI and the DAV:segment element in the specified by the Request-URI and the DAV:segment element in the
request body was protected by a write-lock at the time of the request body was protected by a write lock at the time of the
request, that write-lock must have been deleted by the request. request, that write lock must have been deleted by the request.
5.1. Example: UNBIND 5.1. Example: UNBIND
>> Request: >> Request:
UNBIND /CollX HTTP/1.1 UNBIND /CollX HTTP/1.1
Host: www.example.com Host: www.example.com
Content-Type: application/xml; charset="utf-8" Content-Type: application/xml; charset="utf-8"
Content-Length: 117 Content-Length: 117
skipping to change at page 28, line 50 skipping to change at page 27, line 50
condition code to signal the client exactly why the request condition code to signal the client exactly why the request
failed). failed).
(DAV:locked-update-allowed): If the collection identified by the (DAV:locked-update-allowed): If the collection identified by the
Request-URI is write-locked, then the appropriate token MUST be Request-URI is write-locked, then the appropriate token MUST be
specified in the request. specified in the request.
(DAV:protected-url-modification-allowed): If the collection (DAV:protected-url-modification-allowed): If the collection
identified by the Request-URI already contains a binding with the identified by the Request-URI already contains a binding with the
specified path segment, and if that binding is protected by a specified path segment, and if that binding is protected by a
write-lock, then the appropriate token MUST be specified in the write lock, then the appropriate token MUST be specified in the
request. request.
(DAV:locked-source-collection-update-allowed): If the collection (DAV:locked-source-collection-update-allowed): If the collection
identified by the parent collection prefix of the DAV:href URI is identified by the parent collection prefix of the DAV:href URI is
write-locked, then the appropriate token MUST be specified in the write-locked, then the appropriate token MUST be specified in the
request. request.
(DAV:protected-source-url-deletion-allowed): If the DAV:href URI (DAV:protected-source-url-deletion-allowed): If the DAV:href URI
is protected by a write lock, then the appropriate token MUST be is protected by a write lock, then the appropriate token MUST be
specified in the request. specified in the request.
skipping to change at page 29, line 25 skipping to change at page 28, line 25
(DAV:new-binding): The collection MUST have a binding that maps (DAV:new-binding): The collection MUST have a binding that maps
the segment specified in the DAV:segment element in the request the segment specified in the DAV:segment element in the request
body, to the resource that was identified by the DAV:href element body, to the resource that was identified by the DAV:href element
in the request body. in the request body.
(DAV:binding-deleted): The URL specified in the DAV:href element (DAV:binding-deleted): The URL specified in the DAV:href element
in the request body MUST NOT be mapped to a resource. in the request body MUST NOT be mapped to a resource.
(DAV:lock-deleted): If the URL specified in the DAV:href element (DAV:lock-deleted): If the URL specified in the DAV:href element
in the request body was protected by a write-lock at the time of in the request body was protected by a write lock at the time of
the request, that write-lock must have been deleted by the the request, that write lock must have been deleted by the
request. request.
6.1. Example: REBIND 6.1. Example: REBIND
>> Request: >> Request:
REBIND /CollX HTTP/1.1 REBIND /CollX HTTP/1.1
Host: www.example.com Host: www.example.com
Content-Type: application/xml; charset="utf-8" Content-Type: application/xml; charset="utf-8"
Content-Length: 176 Content-Length: 176
skipping to change at page 29, line 51 skipping to change at page 28, line 51
<D:href>http://www.example.com/CollY/bar.html</D:href> <D:href>http://www.example.com/CollY/bar.html</D:href>
</D:rebind> </D:rebind>
>> Response: >> Response:
HTTP/1.1 200 OK HTTP/1.1 200 OK
The server added a new binding to the collection, The server added a new binding to the collection,
"http://www.example.com/CollX", associating "foo.html" with the "http://www.example.com/CollX", associating "foo.html" with the
resource identified by the URI resource identified by the URI
"http://www.example.com/CollY/bar.html", and removes the binding "http://www.example.com/CollY/bar.html" and removes the binding named
named "bar.html" from the collection identified by the URI "bar.html" from the collection identified by the URI
"http://www.example.com/CollY". Clients can now use the URI "http://www.example.com/CollY". Clients can now use the URI
"http://www.example.com/CollX/foo.html" to submit requests to that "http://www.example.com/CollX/foo.html" to submit requests to that
resource, and requests on the URI resource, and requests on the URI
"http://www.example.com/CollY/bar.html" will fail with a 404 (Not "http://www.example.com/CollY/bar.html" will fail with a 404 (Not
Found) response. Found) response.
6.2. Example: REBIND in Presence of Locks and Bind Loops 6.2. Example: REBIND in Presence of Locks and Bind Loops
To illustrate the effects of locks and bind loops on a REBIND To illustrate the effects of locks and bind loops on a REBIND
operation, consider the following collection: operation, consider the following collection:
skipping to change at page 33, line 16 skipping to change at page 32, line 14
requests, and that it is of particular importance when the multiple requests, and that it is of particular importance when the multiple
collection bindings cause a bind loop as discussed in Section 2.2. collection bindings cause a bind loop as discussed in Section 2.2.
A client can request the DAV:resource-id property in a PROPFIND A client can request the DAV:resource-id property in a PROPFIND
request to guarantee that they can accurately reconstruct the binding request to guarantee that they can accurately reconstruct the binding
structure of a collection with multiple bindings to a single structure of a collection with multiple bindings to a single
resource. resource.
For backward compatibility with clients not aware of the 208 status For backward compatibility with clients not aware of the 208 status
code appearing in multistatus response bodies, it SHOULD NOT be used code appearing in multistatus response bodies, it SHOULD NOT be used
unless the client has signalled support for this specification using unless the client has signaled support for this specification using
the "DAV" request header (see Section 8.2). Instead, a 506 status the "DAV" request header (see Section 8.2). Instead, a 508 status
should be returned when a binding loop is discovered. This allows should be returned when a binding loop is discovered. This allows
the server to return the 506 as the top level return status, if it the server to return the 508 as the top-level return status, if it
discovers it before it started the response, or in the middle of a discovers it before it started the response, or in the middle of a
multistatus, if it discovers it in the middle of streaming out a multistatus, if it discovers it in the middle of streaming out a
multistatus response. multistatus response.
7.1.1. Example: PROPFIND by Bind-Aware Client 7.1.1. Example: PROPFIND by Bind-Aware Client
For example, consider a PROPFIND request on /Coll (bound to For example, consider a PROPFIND request on /Coll (bound to
collection C), where the members of /Coll are /Coll/Foo (bound to collection C), where the members of /Coll are /Coll/Foo (bound to
resource R) and /Coll/Bar (bound to collection C). resource R) and /Coll/Bar (bound to collection C).
skipping to change at page 35, line 10 skipping to change at page 34, line 10
<D:status>HTTP/1.1 208 Already Reported</D:status> <D:status>HTTP/1.1 208 Already Reported</D:status>
</D:propstat> </D:propstat>
</D:response> </D:response>
</D:multistatus> </D:multistatus>
7.1.2. Example: PROPFIND by Non-Bind-Aware Client 7.1.2. Example: PROPFIND by Non-Bind-Aware Client
In this example, the client isn't aware of the 208 status code In this example, the client isn't aware of the 208 status code
introduced by this specification. As the "Depth: infinity" PROPFIND introduced by this specification. As the "Depth: infinity" PROPFIND
request would cause a loop condition, the whole request is rejected request would cause a loop condition, the whole request is rejected
with a 506 status. with a 508 status.
>> Request: >> Request:
PROPFIND /Coll/ HTTP/1.1 PROPFIND /Coll/ HTTP/1.1
Host: www.example.com Host: www.example.com
Depth: infinity Depth: infinity
Content-Type: application/xml; charset="utf-8" Content-Type: application/xml; charset="utf-8"
Content-Length: 125 Content-Length: 125
<?xml version="1.0" encoding="utf-8" ?> <?xml version="1.0" encoding="utf-8" ?>
<D:propfind xmlns:D="DAV:"> <D:propfind xmlns:D="DAV:">
<D:prop> <D:displayname/> </D:prop> <D:prop> <D:displayname/> </D:prop>
</D:propfind> </D:propfind>
>> Response: >> Response:
HTTP/1.1 506 Loop Detected HTTP/1.1 508 Loop Detected
7.2. 506 Loop Detected 7.2. 508 Loop Detected
The 506 (Loop Detected) status code indicates that the server The 508 (Loop Detected) status code indicates that the server
terminated an operation because it encountered an infinite loop while terminated an operation because it encountered an infinite loop while
processing a request with "Depth: infinity". This status indicates processing a request with "Depth: infinity". This status indicates
that the entire operation failed. that the entire operation failed.
8. Capability Discovery 8. Capability Discovery
8.1. OPTIONS Method 8.1. OPTIONS Method
If the server supports bindings, it MUST return the compliance class If the server supports bindings, it MUST return the compliance class
name "bind" as a field in the "DAV" response header (see [RFC4918], name "bind" as a field in the "DAV" response header (see [RFC4918],
Section 10.1) from an OPTIONS request on any resource implemented by Section 10.1) from an OPTIONS request on any resource implemented by
that server. A value of "bind" in the "DAV" header MUST indicate that server. A value of "bind" in the "DAV" header MUST indicate
that the server supports all MUST level requirements and REQUIRED that the server supports all MUST-level requirements and REQUIRED
features specified in this document. features specified in this document.
8.2. 'DAV' Request Header 8.2. 'DAV' Request Header
Clients SHOULD signal support for all MUST level requirements and Clients SHOULD signal support for all MUST-level requirements and
REQUIRED features by submitting a "DAV" request header containing the REQUIRED features by submitting a "DAV" request header containing the
compliance class name "bind". In particular, the client MUST compliance class name "bind". In particular, the client MUST
understand the 208 status code defined in Section 7.1. understand the 208 status code defined in Section 7.1.
9. Relationship to Locking in WebDAV 9. Relationship to Locking in WebDAV
Locking is an optional feature of WebDAV ([RFC4918]). The base Locking is an optional feature of WebDAV ([RFC4918]). The base
WebDAV specification and this protocol extension have been designed WebDAV specification and this protocol extension have been designed
in parallel, making sure that all features of WebDAV can be in parallel, making sure that all features of WebDAV can be
implemented on a server that implements this protocol as well. implemented on a server that implements this protocol as well.
skipping to change at page 36, line 41 skipping to change at page 35, line 40
through which the lock was created, not a resource. This URI, and through which the lock was created, not a resource. This URI, and
potential aliases of this URI ([RFC4918], Section 5), are said to be potential aliases of this URI ([RFC4918], Section 5), are said to be
"protected" by the lock. "protected" by the lock.
As defined in the introduction to Section 7 of [RFC4918], write As defined in the introduction to Section 7 of [RFC4918], write
operations that modify the state of a locked resource require that operations that modify the state of a locked resource require that
the lock token is submitted with the request. Consistent with the lock token is submitted with the request. Consistent with
WebDAV, the state of the resource consists of the content ("any WebDAV, the state of the resource consists of the content ("any
variant"), dead properties, lockable live properties (item 1), plus, variant"), dead properties, lockable live properties (item 1), plus,
for a collection, all its bindings (item 2). Note that this, by for a collection, all its bindings (item 2). Note that this, by
definition, does not depend on the request URI to which the write definition, does not depend on the Request-URI to which the write
operation is applied (the locked state is a property of the resource, operation is applied (the locked state is a property of the resource,
not its URI). not its URI).
However, the lock root is the URI through which the lock was However, the lock-root is the URI through which the lock was
requested. Thus, the protection defined in item 3 of the list does requested. Thus, the protection defined in item 3 of the list does
not apply to additional URIs that may be mapped to the same resource not apply to additional URIs that may be mapped to the same resource
due to the existence of multiple bindings. due to the existence of multiple bindings.
9.1. Example: Locking and Multiple Bindings 9.1. Example: Locking and Multiple Bindings
Consider a root collection "/", containing the two collections C1 and Consider a root collection "/", containing the two collections C1 and
C2, named "/CollX" and "/CollY", and a child resource R, bound to C1 C2, named "/CollX" and "/CollY", and a child resource R, bound to C1
as "/CollX/test" and bound to C2 as "/CollY/test": as "/CollX/test" and bound to C2 as "/CollY/test":
skipping to change at page 37, line 35 skipping to change at page 36, line 30
| | | |
| | | |
+------------------+ +------------------+
| Resource R | | Resource R |
+------------------+ +------------------+
Given a host name of "www.example.com", applying a depth-zero write Given a host name of "www.example.com", applying a depth-zero write
lock to "/CollX/test" will lock the resource R, and the lock-root of lock to "/CollX/test" will lock the resource R, and the lock-root of
this lock will be "http://www.example.com/CollX/test". this lock will be "http://www.example.com/CollX/test".
Thus the following operations will require that the associated lock Thus, the following operations will require that the associated lock
token is submitted with the "If" request header ([RFC4918], Section token is submitted with the "If" request header ([RFC4918], Section
10.4): 10.4):
o a PUT or PROPPATCH request modifying the content or lockable o a PUT or PROPPATCH request modifying the content or lockable
properties of resource R (as R is locked) -- no matter which URI properties of resource R (as R is locked) -- no matter which URI
is used as request target, is used as request target, and
o a MOVE, REBIND, UNBIND or DELETE request causing "/CollX/test" not o a MOVE, REBIND, UNBIND, or DELETE request causing "/CollX/test"
being mapped to resource R anymore (be it addressed to "/CollX" or not to be mapped to resource R anymore (be it addressed to
"/CollX/test"). "/CollX" or "/CollX/test").
The following operations will not require submission of the lock The following operations will not require submission of the lock
token: token:
o a DELETE request addressed to "/CollY" or /CollY/test", as it does o a DELETE request addressed to "/CollY" or "/CollY/test", as it
not affect the resource R, nor the lock-root, does not affect the resource R, nor the lock-root,
o for the same reason, an UNBIND request removing the binding "test" o for the same reason, an UNBIND request removing the binding "test"
from collection C2, or the binding "CollY" from the root from collection C2, or the binding "CollY" from the root
collection, collection, and
o similarly, a MOVE or REBIND request causing "/CollY/test" not o similarly, a MOVE or REBIND request causing "/CollY/test" not
being mapped to resource R anymore. being mapped to resource R anymore.
Note that despite the lock root being Note that despite the lock-root being
"http://www.example.com/CollX/test", an UNLOCK request can be "http://www.example.com/CollX/test", an UNLOCK request can be
addressed through any URI mapped to resource R, as UNLOCK operates on addressed through any URI mapped to resource R, as UNLOCK operates on
the resource identified by the request URI, not that URI (see the resource identified by the Request-URI, not that URI (see
[RFC4918], Section 9.11). [RFC4918], Section 9.11).
10. Relationship to WebDAV Access Control Protocol 10. Relationship to WebDAV Access Control Protocol
Note that the WebDAV Access Control Protocol has been designed for Note that the WebDAV Access Control Protocol has been designed for
compatibility with systems that allow multiple URIs to map to the compatibility with systems that allow multiple URIs to map to the
same resource (see [RFC3744], Section 5): same resource (see [RFC3744], Section 5):
...Access control properties (especially DAV:acl and DAV: Access control properties (especially DAV:acl and DAV:inherited-
inherited-acl-set) are defined on the resource identified by the acl-set) are defined on the resource identified by the Request-URI
Request-URI of a PROPFIND request. A direct consequence is that of a PROPFIND request. A direct consequence is that if the
if the resource is accessible via multiple URI, the value of resource is accessible via multiple URI, the value of access
access control properties is the same across these URI. ... control properties is the same across these URI.
Furthermore, note that BIND and REBIND behave the same as MOVE with Furthermore, note that BIND and REBIND behave the same as MOVE with
respect to the DAV:acl property (see [RFC3744], Section 7.3). respect to the DAV:acl property (see [RFC3744], Section 7.3).
11. Relationship to Versioning Extensions to WebDAV 11. Relationship to Versioning Extensions to WebDAV
Servers that implement Workspaces ([RFC3253], Section 6) and Version Servers that implement Workspaces ([RFC3253], Section 6) and Version-
Controlled Collections ([RFC3253], Section 14) already need to Controlled Collections ([RFC3253], Section 14) already need to
implement BIND-like behavior in order to handle UPDATE and UNCHECKOUT implement BIND-like behavior in order to handle UPDATE and UNCHECKOUT
semantics. semantics.
Consider a workspace "/ws1/", containing the version-controlled, Consider a workspace "/ws1/", containing the version-controlled,
checked-out collections C1 and C2, named "/ws1/CollX" and "/ws1/ checked-out collections C1 and C2, named "/ws1/CollX" and "/ws1/
CollY", and a version-controlled resource R, bound to C1 as "/ws1/ CollY", and a version-controlled resource R, bound to C1 as "/ws1/
CollX/test": CollX/test":
+-------------------------+ +-------------------------+
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+------------------+ +------------------+
| Resource R | | Resource R |
+------------------+ +------------------+
The MOVE semantics defined in Section 3.15 of [RFC3253] already The MOVE semantics defined in Section 3.15 of [RFC3253] already
require that "/ws1/CollX/test" and "/ws1/CollY/test" will have the require that "/ws1/CollX/test" and "/ws1/CollY/test" will have the
same version history (as exposed in the DAV:version-history same version history (as exposed in the DAV:version-history
property). Furthermore, the UNCHECKOUT semantics (which in this case property). Furthermore, the UNCHECKOUT semantics (which in this case
is similar to UPDATE, see Section 14.11 of [RFC3253]) require: is similar to UPDATE, see Section 14.11 of [RFC3253]) require:
...If a new version-controlled member is in a workspace that If a new version-controlled member is in a workspace that already
already has a version-controlled resource for that version has a version-controlled resource for that version history, then
history, then the new version-controlled member MUST be just a the new version-controlled member MUST be just a binding (i.e.,
binding (i.e., another name for) that existing version-controlled another name for) that existing version-controlled resource.
resource...
Thus, "/ws1/CollX/test" and "/ws1/CollY/test" will be bindings to the Thus, "/ws1/CollX/test" and "/ws1/CollY/test" will be bindings to the
same resource R, and have identical DAV:resource-id properties. same resource R, and have identical DAV:resource-id properties.
12. Security Considerations 12. Security Considerations
This section is provided to make WebDAV implementors aware of the This section is provided to make WebDAV implementers aware of the
security implications of this protocol. security implications of this protocol.
All of the security considerations of HTTP/1.1 ([RFC2616], Section All of the security considerations of HTTP/1.1 ([RFC2616], Section
15) and the WebDAV Distributed Authoring Protocol specification 15) and the WebDAV Distributed Authoring Protocol specification
([RFC4918], Section 20) also apply to this protocol specification. ([RFC4918], Section 20) also apply to this protocol specification.
In addition, bindings introduce several new security concerns and In addition, bindings introduce several new security concerns and
increase the risk of some existing threats. These issues are increase the risk of some existing threats. These issues are
detailed below. detailed below.
12.1. Privacy Concerns 12.1. Privacy Concerns
skipping to change at page 41, line 34 skipping to change at page 40, line 34
12.2. Bind Loops 12.2. Bind Loops
Although bind loops were already possible in HTTP 1.1, the Although bind loops were already possible in HTTP 1.1, the
introduction of the BIND method creates a new avenue for clients to introduction of the BIND method creates a new avenue for clients to
create loops accidentally or maliciously. If the binding and its create loops accidentally or maliciously. If the binding and its
target are on the same server, the server may be able to detect BIND target are on the same server, the server may be able to detect BIND
requests that would create loops. Servers are required to detect requests that would create loops. Servers are required to detect
loops that are caused by bindings to collections during the loops that are caused by bindings to collections during the
processing of any requests with "Depth: infinity". processing of any requests with "Depth: infinity".
12.3. Bindings, and Denial of Service 12.3. Bindings and Denial of Service
Denial of service attacks were already possible by posting URIs that Denial-of-service attacks were already possible by posting URIs that
were intended for limited use at heavily used Web sites. The were intended for limited use at heavily used Web sites. The
introduction of BIND creates a new avenue for similar denial of introduction of BIND creates a new avenue for similar denial-of-
service attacks. If cross-server bindings are supported, clients can service attacks. If cross-server bindings are supported, clients can
now create bindings at heavily used sites to target locations that now create bindings at heavily used sites to target locations that
were not designed for heavy usage. were not designed for heavy usage.
12.4. Private Locations May Be Revealed 12.4. Private Locations May Be Revealed
If the DAV:parent-set property is maintained on a resource, the If the DAV:parent-set property is maintained on a resource, the
owners of the bindings risk revealing private locations. The owners of the bindings risk revealing private locations. The
directory structures where bindings are located are available to directory structures where bindings are located are available to
anyone who has access to the DAV:parent-set property on the resource. anyone who has access to the DAV:parent-set property on the resource.
skipping to change at page 42, line 20 skipping to change at page 41, line 20
the list. the list.
13. Internationalization Considerations 13. Internationalization Considerations
All internationalization considerations mentioned in Section 19 of All internationalization considerations mentioned in Section 19 of
[RFC4918] also apply to this document. [RFC4918] also apply to this document.
14. IANA Considerations 14. IANA Considerations
Section 7 defines the HTTP status codes 208 (Already Reported) and Section 7 defines the HTTP status codes 208 (Already Reported) and
506 (Loop Detected), to be added to the registry at 508 (Loop Detected), which have been added to the HTTP Status Code
<http://www.iana.org/assignments/http-status-codes>. Registry.
15. Acknowledgements 15. Acknowledgements
This document is the collaborative product of the authors and Tyson This document is the collaborative product of the authors and Tyson
Chihaya, Jim Davis, Chuck Fay and Judith Slein. It has benefited Chihaya, Jim Davis, Chuck Fay and Judith Slein. It has benefited
from thoughtful discussion by Jim Amsden, Peter Carlson, Steve from thoughtful discussion by Jim Amsden, Peter Carlson, Steve
Carter, Ken Coar, Ellis Cohen, Dan Connolly, Bruce Cragun, Cyrus Carter, Ken Coar, Ellis Cohen, Dan Connolly, Bruce Cragun, Cyrus
Daboo, Spencer Dawkins, Mark Day, Werner Donne, Rajiv Dulepet, David Daboo, Spencer Dawkins, Mark Day, Werner Donne, Rajiv Dulepet, David
Durand, Lisa Dusseault, Stefan Eissing, Roy Fielding, Yaron Goland, Durand, Lisa Dusseault, Stefan Eissing, Roy Fielding, Yaron Goland,
Joe Hildebrand, Fred Hitt, Alex Hopmann, James Hunt, Marcus Jager, Joe Hildebrand, Fred Hitt, Alex Hopmann, James Hunt, Marcus Jager,
skipping to change at page 43, line 32 skipping to change at page 42, line 28
March 2002. March 2002.
[RFC3744] Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web [RFC3744] Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web
Distributed Authoring and Versioning (WebDAV) Access Distributed Authoring and Versioning (WebDAV) Access
Control Protocol", RFC 3744, May 2004. Control Protocol", RFC 3744, May 2004.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122, Unique IDentifier (UUID) URN Namespace", RFC 4122,
July 2005. July 2005.
Appendix A. Change Log (to be removed by RFC Editor before publication) Appendix A. Resolved issues (to be removed by RFC Editor before
A.1. Since draft-ietf-webdav-bind-02
Add and resolve issues "2.3_COPY_SHARED_BINDINGS" and
"2.3_MULTIPLE_COPY". Add issue "5.1_LOOP_STATUS" and proposed
resolution, but keep it open. Add issues "ED_references" and
"4_507_status". Started work on index. Rename document to "Binding
Extensions to Web Distributed Authoring and Versioning (WebDAV)".
Rename "References" to "Normative References". Close issue
"ED_references". Close issue "4_507_status".
A.2. Since draft-ietf-webdav-bind-03
Add and close issues "9.2_redirect_loops", "ED_authors" and
"ED_updates". Add section about capability discovery (DAV header).
Close issues "5.1_LOOP_STATUS". Add and resolve new issue
"5.1_506_STATUS_STREAMING". Update XML spec reference. Add issue
"locking" and resolve as invalid.
A.3. Since draft-ietf-webdav-bind-04
Add and close issues "6_precondition_binding_allowed" and
"6_lock_behaviour". Add mailing list and issues list pointers to
front.
A.4. Since draft-ietf-webdav-bind-05
Editorial fixes. Add and resolve issues "1.3_error_negotiation",
"2.5_language" and "7.1.1_add_resource_id". Add historical issue
"4_LOCK_BEHAVIOR" and it's resolution for better tracking.
A.5. Since draft-ietf-webdav-bind-06
Rewrite Editorial Note. Open and resolve issues "2.6_identical",
"specify_safeness_and_idempotence" and "ED_rfc2026_ref".
A.6. Since draft-ietf-webdav-bind-07
Add more index items (no change tracking). Add and resolve issues
"2.3_copy_to_same", "bind_properties", "bind_vs_ACL",
"6_rebind_intro" and "rfc2396bis" (actually an action item). Fix XML
DTD fragment in section 3.3. Make spelling of "Request-URI"
consistent.
A.7. Since draft-ietf-webdav-bind-08
Resolved editorial issues raised by Jim Whitehead in <http://
lists.w3.org/Archives/Public/w3c-dist-auth/2004OctDec/0129.html>.
Add and resolve issues "atomicity", "2_allow_destroy",
"2.1_separate_loop_discussion", "2.1.1_bind_loops_vs_locks",
"2.3_copy_depth_infinity", "2.3_copy_example", "2.3_copy_vs_loops",
"2.6_resource-id_vs_versions", "3.2_example" and
"6_rebind_premissions". Add issue "2.6_when_do_ids_change". Re-open
and resolve "6_rebind_intro".
A.8. Since draft-ietf-webdav-bind-09
Add and resolve issue "6.1_rebind_vs_locks", adding proposed example
text. Add action item "3.1_uuids". Close issue
"2.6_when_do_ids_change". Add and resolve issues
"2.6_bindings_vs_properties" and "uri_draft_ref".
A.9. Since draft-ietf-webdav-bind-10
Resolve action item "3.1_uuids". Add and resolve issue
"2.7_unlock_vs_bindings". Revisit issue
"2.6_bindings_vs_properties", and remove the part of the sentence
that speaks about live properties. Update "rfc2396bis" references to
"RFC3986". Add issue "9_ns_op_and_acl" and add potential resolution.
Align artwork where applicable (new xml2rfc1.29rc2 feature).
A.10. Since draft-ietf-webdav-bind-11
Updated [draft-mealling-uuid-urn] to [RFC4122]. Add statement about
live properties in Section 2.6.
A.11. Since draft-ietf-webdav-bind-12
Updated Author's address. Uppercase "Section" when referring to
other documents.
Updating from RFC2518 to RFC2518bis:
o Remove own explanation of DTD syntax.
o Remove own definition of precondition/postcondition.
o Remove reference to broken RFC2518 language about DELETE and
UNLOCK.
o Remove own definition of DAV: request header.
o Updated "Rationale for Distinguishing Bindings from URI Mappings"
to reflect the changes in [draft-ietf-webdav-rfc2518bis], making
proposals for more changes so that the issue can be closed (see
also <http://ietf.cse.ucsc.edu:8080/bugzilla/show_bug.cgi?id=227>
and <http://greenbytes.de/tech/webdav/
draft-ietf-webdav-rfc2518bis-12.html#rfc.section.5.2>).
A.12. Since draft-ietf-webdav-bind-13
Update [draft-ietf-webdav-rfc2518-bis] to draft 14. Update one
incorrect section reference. Remove Section "Rationale for
Distinguishing Bindings from URI Mappings" as
[draft-ietf-webdav-rfc2518-bis] now uses the proper definition of
collection state. Examples use application/xml instead of text/xml
MIME type.
Fix IANA section (there are no IANA considerations).
A.13. Since draft-ietf-webdav-bind-14
Update [draft-ietf-webdav-rfc2518-bis] to draft 15. Update [XML] to
4th edition.
Markup ASCII art for box recognition (doesn't affect ASCII version).
Identify Julian Reschke as Editor.
A.14. Since draft-ietf-webdav-bind-15
Fix typo in RFC2119 keywords section (sorry!).
Update [draft-ietf-webdav-rfc2518-bis] to draft 17.
Add and resolve issue "rfc2518bis-lock-root".
A.15. Since draft-ietf-webdav-bind-16
Add and resolve issue "iana-vs-http-status".
A.16. Since draft-ietf-webdav-bind-17
Update rfc2518bis reference to draft 18 (note that the bug reported
in <http://ietf.osafoundation.org:8080/bugzilla/show_bug.cgi?id=251>
is still present).
A.17. Since draft-ietf-webdav-bind-18
Update: draft-ietf-webdav-rfc2518bis replaced by RFC4918.
A.18. Since draft-ietf-webdav-bind-19
Add and resolve issues "2.1.1-bind-loops", "2.1.1-cycles", "2.5-move-
creating-cycles", "3.1-clarify-resource-id" and "4-precondition-
language".
A.19. Since draft-ietf-webdav-bind-20
Use "urn:uuid:" instead of "opaquelocktoken:" scheme in examples.
Replace RFC2518bis issue link by pointer to RFC Errata Page.
Add issues "relation-to-deltav" and "status-codes".
A.20. Since draft-ietf-webdav-bind-21
Resolve issues "relation-to-deltav" and "status-codes".
Add correct content length values to examples (no change bars).
A.21. Since draft-ietf-webdav-bind-22
Set "Intended Status" to "Experimental".
Update XML reference to "Extensible Markup Language (XML) 1.0 (Fifth
Edition)".
A.22. Since draft-ietf-webdav-bind-23
Remove surplus white space from one example.
Fix typo: "DAV:binding-set" -> "DAV:parent-set".
Add and resolve issues "clarify-alternate-uri", "def-integrity", "ex-
copy-multiple-update", "ex-copy-graph", and "ex-live-property".
A.23. Since draft-ietf-webdav-bind-24
Add and resolve issues "clarify-clarify", "sec-cons-references",
"should-not-update-4918", "should-update-2616", and "webdav-wg-gone".
A.24. Since draft-ietf-webdav-bind-25
Add and resolve issue "locking-example".
A.25. Since draft-ietf-webdav-bind-26
Add and resolve issues "bind-vs-hierarchy", "copying-complex-loops"
and "locking2".
Appendix B. Resolved issues (to be removed by RFC Editor before
publication) publication)
Issues that were either rejected or resolved in this version of this Issues that were either rejected or resolved in this version of this
document. document.
B.1. edit A.1. edit
Type: edit Type: edit
julian.reschke@greenbytes.de (2004-05-30): Umbrella issue for julian.reschke@greenbytes.de (2004-05-30): Umbrella issue for
editorial fixes/enhancements. editorial fixes/enhancements.
B.2. bind-vs-hierarchy A.2. auth48
Type: edit
julian.reschke@greenbytes.de (2009-11-29): Note that a system based
on the BIND collection model will be inherently incompatible with a
system that inherits information based on just the naming hierarchy,
not taking multiple bindings into account. In particular, Access
Control implementations based on path inheritance come to mind.
(This is not a problem of the BIND data model itself, but a known
issue when an attempt is made to build a hybrid system).
Resolution (2009-12-12): Add a note to the overview, and also clarify
the "Relation to WebDAV ACL" section.
B.3. copying-complex-loops
In Section 2:
Type: edit Type: edit
rjsparks@nostrum.com (2009-06-03): julian.reschke@greenbytes.de (2010-02-27): Issues resolved during
RFC-Editor's AUTH48 phase.
The document provides some discussion of the ramifications of simple
loops, but its not immediately obvious that the recommendations for
handling them are sufficient for dealing with more complex loops.
Are there additional issues introduced when each added level of depth
adds an exponentially growing number of elements?
(view in fixed width)
+---------+
| root |
| |
| start |
+---------+
|
v
+---------+ +---------+
+---->| C1 | | C2 |<---+
| +->| | | |<-+ |
| | | a b | | a b | | |
| | +---------+ +---------+ | |
| | | | | | | |
| | | | +----+ | | |
| | | | | | | |
| | | +----------c---+ | | |
| | | | | | | |
| | | +----------+ | | | |
| | v v v v | |
| | +---------+ +---------+ | |
| | | C3 | | C4 | | |
| | | | | | | |
| | | a b | | a b | | |
| | +---------+ +---------+ | |
| | | | | | | |
| +----+ | +----+ +-----+ |
| | | |
| +----------c-----------------+
| |
+-----------------------+
Resolution (2009-11-29): The authors discussed this question and came A.3. iana.statuscode
to the conclusion that the considerations for complex loops are
identical to those for simple loops; a COPY operation still
duplicates the binding graph. A short note pointing this out was
added to the end of the example.
B.4. locking2 In Section 7:
Type: change Type: change
julian.reschke@greenbytes.de (2010-01-25): IANA rightfully points out
that status code 506 is taken by RFC 2295. Let's use 508 instead.
julian.reschke@greenbytes.de (2009-11-29): We have failed to reach Resolution (2010-01-25): Done.
consensus about the RFC 4918 clarification. Thus we'll have to
accept that it says what it says, and need to clarify how it applies
to locking, essentially pointing out which behavior we expect. To do
this, create a new section about locking, which will explain the
"lock root" as required by a server that supports multiple bindings.
Also keep the example.
Resolution (2009-12-12): Added new section specifying the locking
behavior, removed the appendix.
Index Index
2 2
208 Already Reported (status code) 32, 42 208 Already Reported (status code) 31, 41
5 5
506 Loop Detected (status code) 35, 42 508 Loop Detected (status code) 34, 41
B B
BIND method 22 BIND method 21
Marshalling 23 Marshalling 22
Postconditions 24 Postconditions 23
Preconditions 23 Preconditions 22
Binding 7 Binding 6
Binding Integrity 7-8, 22 Binding Integrity 6-7, 21
C C
Collection 7 Collection 6
Condition Names Condition Names
DAV:bind-into-collection (pre) 23 DAV:bind-into-collection (pre) 22
DAV:bind-source-exists (pre) 23 DAV:bind-source-exists (pre) 22
DAV:binding-allowed (pre) 24 DAV:binding-allowed (pre) 23
DAV:binding-deleted (post) 26, 29 DAV:binding-deleted (post) 25, 28
DAV:can-overwrite (pre) 24, 28 DAV:can-overwrite (pre) 23, 27
DAV:cross-server-binding (pre) 24, 28 DAV:cross-server-binding (pre) 23, 27
DAV:cycle-allowed (pre) 24, 28 DAV:cycle-allowed (pre) 23, 27
DAV:lock-deleted (post) 26, 29 DAV:lock-deleted (post) 25, 28
DAV:locked-overwrite-allowed (pre) 24 DAV:locked-overwrite-allowed (pre) 23
DAV:locked-source-collection-update-allowed (pre) 29 DAV:locked-source-collection-update-allowed (pre) 28
DAV:locked-update-allowed (pre) 24, 26, 28 DAV:locked-update-allowed (pre) 23, 25, 27
DAV:name-allowed (pre) 24, 28 DAV:name-allowed (pre) 23, 27
DAV:new-binding (post) 24, 29 DAV:new-binding (post) 23, 28
DAV:protected-source-url-deletion-allowed (pre) 29 DAV:protected-source-url-deletion-allowed (pre) 28
DAV:protected-url-deletion-allowed (pre) 26 DAV:protected-url-deletion-allowed (pre) 25
DAV:protected-url-modification-allowed (pre) 28 DAV:protected-url-modification-allowed (pre) 27
DAV:rebind-from-collection (pre) 28 DAV:rebind-into-collection (pre) 27
DAV:rebind-source-exists (pre) 28 DAV:rebind-source-exists (pre) 27
DAV:unbind-from-collection (pre) 26 DAV:unbind-from-collection (pre) 25
DAV:unbind-source-exists (pre) 26 DAV:unbind-source-exists (pre) 25
D D
DAV header DAV header
compliance class 'bind' 35 compliance class 'bind' 34
DAV:bind-into-collection precondition 23
DAV:bind-source-exists precondition 23 DAV:bind-into-collection precondition 22
DAV:binding-allowed precondition 24 DAV:bind-source-exists precondition 22
DAV:binding-deleted postcondition 26, 29 DAV:binding-allowed precondition 23
DAV:can-overwrite precondition 24, 28 DAV:binding-deleted postcondition 25, 28
DAV:cross-server-binding precondition 24, 28 DAV:can-overwrite precondition 23, 27
DAV:cycle-allowed precondition 24, 28 DAV:cross-server-binding precondition 23, 27
DAV:lock-deleted postcondition 26, 29 DAV:cycle-allowed precondition 23, 27
DAV:locked-overwrite-allowed precondition 24 DAV:lock-deleted postcondition 25, 28
DAV:locked-source-collection-update-allowed precondition 29 DAV:locked-overwrite-allowed precondition 23
DAV:locked-update-allowed precondition 24, 26, 28 DAV:locked-source-collection-update-allowed precondition 28
DAV:name-allowed precondition 24, 28 DAV:locked-update-allowed precondition 23, 25, 27
DAV:new-binding postcondition 24, 29 DAV:name-allowed precondition 23, 27
DAV:parent-set property 21 DAV:new-binding postcondition 23, 28
DAV:protected-source-url-deletion-allowed precondition 29 DAV:parent-set property 20
DAV:protected-url-deletion-allowed precondition 26 DAV:protected-source-url-deletion-allowed precondition 28
DAV:protected-url-modification-allowed precondition 28 DAV:protected-url-deletion-allowed precondition 25
DAV:rebind-from-collection precondition 28 DAV:protected-url-modification-allowed precondition 27
DAV:rebind-source-exists precondition 28 DAV:rebind-into-collection precondition 27
DAV:resource-id property 20 DAV:rebind-source-exists precondition 27
DAV:unbind-from-collection precondition 26 DAV:resource-id property 19
DAV:unbind-source-exists precondition 26 DAV:unbind-from-collection precondition 25
DAV:unbind-source-exists precondition 25
I I
Internal Member URI 7 Internal Member URI 6
L L
Locking 36 Locking 35
M M
Methods Methods
BIND 22 BIND 21
REBIND 27 REBIND 26
UNBIND 25 UNBIND 24
P P
Path Segment 6 Path Segment 5
Properties Properties
DAV:parent-set 21 DAV:parent-set 20
DAV:resource-id 20 DAV:resource-id 19
R R
REBIND method 27 REBIND method 26
Marshalling 27 Marshalling 26
Postconditions 29 Postconditions 28
Preconditions 28 Preconditions 27
S S
Status Codes Status Codes
208 Already Reported 32, 42 208 Already Reported 31, 41
506 Loop Detected 35, 42 508 Loop Detected 34, 41
U U
UNBIND method 25 UNBIND method 24
Marshalling 25 Marshalling 24
Postconditions 26 Postconditions 25
Preconditions 26 Preconditions 25
URI Mapping 6 URI Mapping 5
Authors' Addresses Authors' Addresses
Geoffrey Clemm Geoffrey Clemm
IBM IBM
20 Maguire Road 550 King Street
Lexington, MA 02421 Littleton, MA 01460
Email: geoffrey.clemm@us.ibm.com EMail: geoffrey.clemm@us.ibm.com
Jason Crawford Jason Crawford
IBM Research IBM Research
P.O. Box 704 P.O. Box 704
Yorktown Heights, NY 10598 Yorktown Heights, NY 10598
Email: ccjason@us.ibm.com EMail: ccjason@us.ibm.com
Julian F. Reschke (editor) Julian F. Reschke (editor)
greenbytes GmbH greenbytes GmbH
Hafenweg 16 Hafenweg 16
Muenster, NW 48155 Muenster, NW 48155
Germany Germany
Email: julian.reschke@greenbytes.de EMail: julian.reschke@greenbytes.de
Jim Whitehead Jim Whitehead
UC Santa Cruz, Dept. of Computer Science UC Santa Cruz, Dept. of Computer Science
1156 High Street 1156 High Street
Santa Cruz, CA 95064 Santa Cruz, CA 95064
Email: ejw@cse.ucsc.edu EMail: ejw@cse.ucsc.edu
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