One document matched: draft-ietf-webdav-protocol-05.txt
Differences from draft-ietf-webdav-protocol-04.txt
INTERNET DRAFT E.J. Whitehead, Jr., UC Irvine
<draft-ietf-webdav-protocol-05> A. Faizi, Netscape
S.R. Carter, Novell
D. Jensen, Novell
Expires April, 1998 November 19, 1997
Extensions for Distributed Authoring on the World Wide Web -- WEBDAV
Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or made obsolete by other
documents at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress".
To learn the current status of any Internet-Draft, please check the
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ftp.isi.edu (US West Coast).
Distribution of this document is unlimited. Please send comments to
the Distributed Authoring and Versioning (WEBDAV) working group at
<w3c-dist-auth@w3.org>, which may be joined by sending a message
with subject "subscribe" to <w3c-dist-auth-request@w3.org>.
Discussions of the WEBDAV working group are archived at
<URL:http://www.w3.org/pub/WWW/Archives/Public/w3c-dist-auth>.
Abstract
This document specifies a set of methods, headers, and content-types
ancillary to HTTP/1.1 for the management of resource properties,
creation and management of resource collections, namespace
manipulation, resource locking (collision avoidance), and efficient
transmission of resource changes.
Changes
1.1. Changes since draft-ietf-webdav-protocol-04.txt
[Editor's note: This section will not appear in the final form of
this document. Its purpose is to provide a concise list of changes
from the previous revision of the draft for use by reviewers.]
Added this change section.
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Removed scoping for namespaces so the namespace for
every element is explicitly stated.
Changed the syntax from <?XML:Namespace.../> to <?namespace...?>.
Removed propfindresult, this was left over from the old search
format.
Changed all the DAV XML element names to lower case.
Changed the property format to use Name and Namespace rather than
name and schema.
Removed proploc attribute and removed section on GETting, DELETEing,
and PUTing properties since we do not provide a mechanism for
getting a URI for properties. Also removed the requirement that
properties be URI addressable.
Removed quoted string choice from owner header, it is just XML.
Made all the HTTP error codes use the same format.
Changed the name of the create element in PROPPATCH to set, the new
name seems to cause less confusion.
Moved all headers in the draft to a single section.
Deleted the state token section of the draft and moved the state
token headers to the header section of the draft. Removed the state
token header.
Changed the write lock section to state that a Lock-Token request
header, not a state-token request header, is to be submitted on
request for write locked resources.
Created a "generic" XML element section for XML elements that get
repeatedly re-used throughout the spec. I moved LINK XML element to
this section.
Made multistatus and Schema discovery their own level one sections.
Collected all the properties together.
Removed all references to the possibility of properties have their
own URIs. This includes removing the property identifier section.
Separated the section on web collections and namespaces into two
separate sections.
Collected all the new response codes together into their own
section.
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Changed the XML multiresponse element name to multistatus.
Added a stand alone section on levels of DAV compliance. I also went
method by method, property by property, to specify compliance
requirements.
Added an introduction.
Changed all the "True" and "False" to "T" and "F".
Altered the first two paragraphs of the Property Names section to
make the relationship between a property's name and its schema a
little clearer. I also added some text in the same section defining
a property name as a namespace and element.
Added a second paragraph to property model for http resources -
overview. This paragraph clarifies why XML was chosen.
Added a 409 Conflict error to move to cover attempts to move a
collection with members.
Changed the collection requirement to read the collections SHOULD
end with "/". Also added a SHOULD about returning a location header
if the client submits a URL for a collection without a trailing "/".
Moved the owner header into the body due to size concerns.
Replaced the iscollection xml element with resourcetype.
Moved the DAV property to the DAV header that is returned with
OPTIONS.
Folded the tree draft into this draft. Changed the DELETE, COPY,
and MOVE sections to include their effect on collections as taken
from the tree draft. Created a Depth header section and put in the
general rules that were in the introduction to the tree draft. I
also added the 102 response and response-status header.
Removed the versioning section.
Put all the methods into a single section.
Replaced the PROPFIND request body with a propfind header. Now the
response can be cached just using vary.
Nuked resinfo for INDEX and combined it with multistatus which is
now used for both INDEX and PROPFIND. Stripped down INDEX as
agreed.
Removed the problem definition and proposed solution sections. We
can always cut and paste them together from the older version if we
feel we need them but this draft is supposed to be a dry run for
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last call and last call documents do not have problem
definition/proposed solution sections.
Killed the section on schema discovery, it is controversial and we
aren't going to be able to require it. We should specify it in a
different spec.
Added a section on notational conventions used within the document.
Moved the terminology section to the end of the document to provide
better flow from the high-level introduction to the specific
introduction sections.
Increased the numeric value of the 4xx status codes introduced in
this specification to avoid conflicts with the new revision of the
HTTP/1.1 specification, which introduces two new 4xx status codes.
Wrote internationalization concerns section.
Added XML version number to all examples.
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Contents
STATUS OF THIS MEMO...................................................1
ABSTRACT..............................................................1
CHANGES...............................................................1
1.1. Changes since draft-ietf-webdav-protocol-04.txt..................1
CONTENTS..............................................................5
2. INTRODUCTION.......................................................8
3. DATA MODEL FOR RESOURCE PROPERTIES.................................9
3.1. The Resource Property Model......................................9
3.2. Existing Metadata Proposals.....................................10
3.3. Properties and HTTP Headers.....................................10
3.4. Property Values.................................................10
3.5. Property Names..................................................11
4. COLLECTIONS OF WEB RESOURCES......................................11
4.1. Collection Resources............................................11
4.2. Creation and Retrieval of Collection Resources..................12
4.3. HTTP URL Namespace Model........................................13
4.4. Source Resources and Output Resources...........................13
5. LOCKING...........................................................14
5.1. Exclusive Vs. Shared Locks......................................14
5.2. Required Support................................................15
5.3. Lock Tokens.....................................................16
5.4. opaquelocktoken Lock Token URI Scheme...........................16
5.5. Lock Capability Discovery.......................................16
5.6. Active Lock Discovery...........................................17
6. WRITE LOCK........................................................17
6.1. Methods Restricted by Write Locks...............................17
6.2. Write Locks and Properties......................................17
6.3. Write Locks and Null Resources..................................17
6.4. Write Locks and Collections.....................................18
6.5. Write Locks and COPY/MOVE.......................................18
6.6. Re-issuing Write Locks..........................................18
6.7. Write Locks and The Lock-Token Request Header...................18
7. NOTATIONAL CONVENTIONS............................................19
8. HTTP METHODS FOR DISTRIBUTED AUTHORING............................19
8.1. PROPFIND........................................................19
8.2. PROPPATCH.......................................................23
8.3. MKCOL Method....................................................25
8.4. INDEX Method....................................................26
8.5. DELREF Method...................................................28
8.6. ADDREF Method...................................................28
8.7. GET, HEAD for Collections.......................................29
8.8. POST for Collections............................................29
8.9. DELETE..........................................................29
8.10. PUT............................................................31
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8.11. COPY Method....................................................31
8.12. MOVE Method....................................................35
8.13. LOCK Method....................................................38
8.14. UNLOCK Method..................................................42
8.15. PATCH Method...................................................43
9. DAV HEADERS.......................................................47
9.1. Collection-Member Header........................................47
9.2. DAV Header......................................................47
9.3. Depth Header....................................................47
9.4. Destination Header..............................................48
9.5. Destroy Header..................................................48
9.6. Enforce-Live-Properties Header..................................49
9.7. If-None-State-Match.............................................49
9.8. If-State-Match..................................................50
9.9. Lock-Info Request Header........................................50
9.10. Lock-Token Request Header......................................51
9.11. Lock-Token Response Header.....................................51
9.12. Overwrite Header...............................................52
9.13. Propfind Request Header........................................52
9.14. Status-URI Response Header.....................................52
9.15. Timeout Header.................................................52
10. RESPONSE CODE EXTENSIONS TO RFC 2068.............................54
10.1. 102 Processing.................................................54
10.2. 207 Multi-Status...............................................54
10.3. 418 Unprocessable Entity.......................................54
10.4. 419 Insufficient Space on Resource.............................54
10.5. 420 Method Failure.............................................54
11. MULTI-STATUS RESPONSE............................................54
11.1. multistatus XML Element........................................55
11.2. response XML Element...........................................55
11.3. status XML Element.............................................55
11.4. responsedescription XML Element................................55
12. GENERIC DAV XML ELEMENTS.........................................55
12.1. href XML Element...............................................56
12.2. link XML Element...............................................56
12.3. prop XML element...............................................57
13. DAV PROPERTIES...................................................57
13.1. creationdate Property..........................................57
13.2. displayname Property...........................................57
13.3. get-content-language Property..................................58
13.4. get-content-length Property....................................58
13.5. get-content-type Property......................................58
13.6. get-etag Property..............................................58
13.7. get-last-modified Property.....................................59
13.8. index-content-language Property................................59
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13.9. index-content-length Property..................................59
13.10. index-content-type Property...................................59
13.11. index-etag Property...........................................59
13.12. index-last-modified Property..................................60
13.13. lockdiscovery Property........................................60
13.14. resourcetype Property.........................................62
13.15. Source Link Property Type.....................................62
13.16. supportedlock Property........................................63
14. DAV COMPLIANCE LEVELS............................................64
14.1. Level 1........................................................64
14.2. Level 2........................................................64
15. INTERNATIONALIZATION SUPPORT.....................................65
16. SECURITY CONSIDERATIONS..........................................66
17. TERMINOLOGY......................................................66
18. COPYRIGHT........................................................66
19. ACKNOWLEDGEMENTS.................................................67
20. REFERENCES.......................................................69
21. AUTHORS' ADDRESSES...............................................71
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2. Introduction
This document describes an extension to the HTTP/1.1 protocol that
allows clients to perform remote web content authoring operations.
This extension provides a coherent set of methods, headers, request
entity body formats, and response entity body formats that provide
operations for:
Properties: The ability to create, remove, and query information
about Web pages, such as its author, creation date, etc. Also, the
ability to link pages of any media type to related pages.
Collections: The ability to create sets of related documents, and to
receive a listing of pages at a particular hierarchy level (like a
directory listing in a file system).
Locking: The ability to keep more than one person from working on a
document at the same time. This prevents the "lost update problem"
in which modifications are lost as first one author, then another
writes their changes without merging the other author's changes
Namespace Operations: The ability to copy and move Web resources
Efficient Update: The ability to send changes which are proportional
to the size of the change rather than retransmitting the entire
resource.
Requirements and rationale for these operations are described in a
companion document, "Requirements for a Distributed Authoring and
Versioning Protocol for the World Wide Web" [Slein et al., 1997].
The sections below provide a detailed introduction to resource
properties (Section 3), collections of resources (Section 4), and
locking operations (Section 5). These sections introduce the
abstractions manipulated by the WebDAV-specific HTTP methods
described in Section 8, "HTTP Methods for Distributed Authoring".
In HTTP/1.1, method parameter information was exclusively encoded in
HTTP headers. Unlike HTTP/1.1, WebDAV, encodes method parameter
information either in an Extensible Markup Language (XML) [Bray,
Sperberg-McQueen, 1997] request entity body, or in an HTTP header.
The use of XML to encode method parameters was motivated by the
ability to add extra XML elements to existing structures, providing
extensibility, and by XML's ability to encode information in ISO
10646 character sets, providing internationalization support. As a
rule of thumb, parameters are encoded in XML entity bodies when they
have unbounded length, or when they may be shown to a human user and
hence require encoding in an ISO 10646 character set. Otherwise,
parameters are encoded within an HTTP header. Section 9 describes
the new HTTP headers used with WebDAV methods.
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In addition to encoding method parameters, XML is used in WebDAV to
encode the responses from methods, providing the extensibility and
internationalization advantages of XML for method output, as well as
input. XML elements used in this specification are defined in
Section 12.
While the response codes provided by HTTP/1.1 are sufficient to
describe the preponderance of error conditions encountered by WebDAV
methods, there are some errors that do not fall neatly into the
existing categories. New status codes developed for the WebDAV
methods are defined in Section 10. Since some WebDAV methods may
operate over many resources, the multiresponse status type has been
introduced to return status information for multiple resources.
Multiresponse status is described in Section 11.
The properties mechanism is employed by WebDAV to store information
about the current state of the resource. For example, when a lock
is taken out on a resource, a lock information property describes
the current state of the lock. Section 13 defines the properties
used within the WebDAV specification.
Finishing off the specification are sections on what it means to be
compliant with this specification (Section 14), on
internationalization support (Section 15), and on security (Section
16).
3. Data Model for Resource Properties
3.1. The Resource Property Model
Properties are pieces of data that describe the state of a resource.
Properties are data about data.
Properties are used in distributed authoring environments to provide
for efficient discovery and management of resources. For example, a
'subject' property might allow for the indexing of all resources by
their subject, and an 'author' property might allow for the
discovery of what authors have written which documents.
The DAV property model consists of name/value pairs. The name of a
property identifies the property's syntax and semantics, and
provides an address by which to refer to that syntax and semantics.
There are two categories of properties: "live" and "non-live". A
live property has its syntax and semantics enforced by the server.
This represents the two cases of a) the value of a property is read-
only, maintained by the server, and b) the value of the property is
maintained by the client, but server performs syntax checking on
submitted values. A non-live property has its syntax and semantics
enforced by the client; the server merely records the value of the
property verbatim.
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3.2. Existing Metadata Proposals
Properties have long played an essential role in the maintenance of
large document repositories, and many current proposals contain some
notion of a property, or discuss web metadata more generally. These
include PICS [Miller et al., 1996], PICS-NG, the Rel/Rev draft
[Maloney, 1996], Web Collections, XML [Bray, Sperberg-McQueen,
1997], several proposals on representing relationships within HTML,
digital signature manifests (DCMF), and a position paper on Web
metadata architecture [Berners-Lee, 1997]. Work on PICS-NG and Web
Collections has been subsumed by the Resource Definition Framework
(RDF) metadata activity of the World Wide Web Consortium, which
consists of a network-based data model and an XML representation of
that model.
Some proposals come from a digital library perspective. These
include the Dublin Core [Weibel et al., 1995] metadata set and the
Warwick Framework [Lagoze, 1996], a container architecture for
different metadata schemas. The literature includes many examples
of metadata, including MARC [MARC, 1994], a bibliographic metadata
format, and RFC 1807 [Lasher, Cohen, 1995], a technical report
bibliographic format employed by the Dienst system. Additionally,
the proceedings from the first IEEE Metadata conference describe
many community-specific metadata sets.
Participants of the 1996 Metadata II Workshop in Warwick, UK
[Lagoze, 1996], noted that, "new metadata sets will develop as the
networked infrastructure matures" and "different communities will
propose, design, and be responsible for different types of
metadata." These observations can be corroborated by noting that
many community-specific sets of metadata already exist, and there is
significant motivation for the development of new forms of metadata
as many communities increasingly make their data available in
digital form, requiring a metadata format to assist data location
and cataloging.
3.3. Properties and HTTP Headers
Properties already exist, in a limited sense, in HTTP message
headers. However, in distributed authoring environments a
relatively large number of properties are needed to describe the
state of a resource, and setting/returning them all through HTTP
headers is inefficient. Thus a mechanism is needed which allows a
principal to identify a set of properties in which the principal is
interested and to then set or retrieve just those properties.
3.4. Property Values
The value of a property is expressed as a well-formed XML document.
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XML has been chosen because it is a flexible, self-describing,
structured data format that supports rich schema definitions, and
because of its support for multiple character sets. XML's self-
describing nature allows any property's value to be extended by
adding new elements. Older clients will not break because they will
still have the data specified in the original schema and will ignore
elements they do not understand. XML's support for multiple
character sets allows human-readable properties to be encoded and
read in a character set familiar to the user.
3.5. Property Names
A property name is a universally unique identifier that is
associated with a schema that provides information about the syntax
and semantics of the property.
Because a property's name is universally unique, clients can depend
upon consistent behavior for a particular property across multiple
resources, so long as that property is "live" on the resources in
question.
The XML namespace mechanism, which is based on URIs, is used to name
properties because it provides a mechanism to prevent namespace
collisions and for varying degrees of administrative control.
The property namespace is flat; that is, no hierarchy of properties
is explicitly recognized. Thus, if a property A and a property A/B
exist on a resource, there is no recognition of any relationship
between the two properties. It is expected that a separate
specification will eventually be produced which will address issues
relating to hierarchical properties.
Finally, it is not possible to define the same property twice on a
single resource, as this would cause a collision in the resource's
property namespace.
4. Collections of Web Resources
This section provides a description of a new type of Web resource,
the collection, and discusses its interactions with the HTTP URL
namespace. The purpose of a collection resource is to model
collection-like objects (e.g., filesystem directories) within a
server's namespace.
All DAV compliant resources MUST support the HTTP URL namespace
model specified herein.
4.1. Collection Resources
A collection is a resource whose state consists of an unordered list
of internal members, an unordered list of external members, and a
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set of properties. An internal member resource MUST have a URI that
is immediately relative to the base URI of the collection, that is,
a relative URI in which "../" is illegal, which MUST begin with "./"
and which SHOULD contain a "/" at the end of the URI if the internal
member resource is itself a collection.
An external member resource MUST be an absolute URI that is not an
internal URI. Any given internal or external URI MUST only belong
to the collection once, i.e., it is illegal to have multiple
instances of the same URI in a collection. Properties defined on
collections behave exactly as do properties on non-collection
resources.
There is a standing convention that when a collection is referred to
by its name without a trailing slash, the trailing slash is
automatically appended. Due to this, a resource MAY accept a URI
without a trailing "/" to point to a collection. In this case it
SHOULD return a location header in the response pointing to the URL
ending with the "/". For example, if a client performs an INDEX on
http://foo.bar/blah (no trailing slash), the resource
http://foo.bar/blah/ (trailing slash) MAY respond as if the
operation were invoked on it, and SHOULD return a location header
with http://foo.bar/blah/ in it.
4.2. Creation and Retrieval of Collection Resources
This document specifies the MKCOL method to create new collection
resources, rather than using the existing HTTP/1.1 PUT or POST
method, for the following reasons
In HTTP/1.1, the PUT method is defined to store the request body at
the location specified by the Request-URI. While a description
format for a collection can readily be constructed for use with PUT,
the implications of sending such a description to the server are
undesirable. For example, if a description of a collection that
omitted some existing resources were PUT to a server, this might be
interpreted as a command to remove those members. This would extend
PUT to perform DELETE functionality, which is undesirable since it
changes the semantics of PUT, and makes it difficult to control
DELETE functionality with an access control scheme based on methods.
While the POST method is sufficiently open-ended that a _create a
collection_ POST command could be constructed, this is undesirable
because it would be difficult to separate access control for
collection creation from other uses of POST.
This document specifies the INDEX method for listing the contents of
a collection, rather than relying on the existing HTTP/1.1 GET
method. This is to avoid conflict with the de-facto standard
practice of redirecting a GET request on a directory to its
index.html resource.
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The exact definition of the behavior of GET and PUT on collections
is defined later in this document.
4.3. HTTP URL Namespace Model
The HTTP URL Namespace is a hierarchical namespace where the
hierarchy is delimited with the "/" character. DAV compliant
resources MUST maintain the consistency of the HTTP URL namespace.
Any attempt to create a resource (excepting the root member of a
namespace) that would not be the internal member of a collection
MUST fail. For example, if the collection http://www.foo.bar.org/a/
exists, but http://www.foo.bar.org/a/b/does not exist, an attempt to
create http://www.foo.bar.org/a/b/c must fail.
4.4. Source Resources and Output Resources
For many resources, the entity returned by a GET method exactly
matches the persistent state of the resource, for example, a GIF
file stored on a disk. For this simple case, the URL at which a
resource is accessed is identical to the URL at which the source
(the persistent state) of the resource is accessed. This is also
the case for HTML source files that are not processed by the server
prior to transmission.
However, the server can sometimes process HTML resources before they
are transmitted as a return entity body. For example, server-side-
include directives within an HTML file instruct a server to replace
the directive with another value, such as the current date. In this
case, what is returned by GET (HTML plus date) differs from the
persistent state of the resource (HTML plus directive). Typically
there is no way to access the HTML resource containing the
unprocessed directive.
Sometimes the entity returned by GET is the output of a data-
producing process that is described by one or more source resources
(that may not even have a location in the URL namespace). A single
data-producing process may dynamically generate the state of a
potentially large number of output resources. An example of this is
a CGI script that describes a "finger" gateway process that maps
part of the namespace of a server into finger requests, such as
http://www.foo.bar.org/finger_gateway/user@host.
In the absence of distributed authoring capabilities, it is
acceptable to have no mapping of source resource(s) to the URI
namespace. In fact, preventing access to the source resource(s) has
desirable security benefits. However, if remote editing of the
source resource(s) is desired, the source resource(s) should be
given a location in the URI namespace. This source location should
not be one of the locations at which the generated output is
retrievable, since in general it is impossible for the server to
differentiate requests for source resources from requests for
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process output resources. There is often a many-to-many
relationship between source resources and output resources.
On WebDAV compliant servers, for all output resources which have a
single source resource (and that source resource has a URI), the URI
of the source resource SHOULD be stored in a link on the output
resource with type http://www.ietf.org/standards/dav/source. Note
that by storing the source URIs in links on the output resources,
the burden of discovering the source is placed on the authoring
client.
5. Locking
The ability to lock a resource provides a mechanism for serializing
access to that resource. Using a lock, an authoring client can
provide a reasonable guarantee that another principal will not
modify a resource while it is being edited. In this way, a client
can prevent the "lost update" problem.
This specification allows locks to vary over two client-specified
parameters, the number of principals involved (exclusive vs. shared)
and the type of access to be granted. Furthermore, this document
only provides the definition of locking for one lock access type,
the write lock. However, the syntax is extensible, and permits the
eventual specification of other access types.
5.1. Exclusive Vs. Shared Locks
The most basic form of lock is an exclusive lock. This is a lock
where the access right in question is only granted to a single
principal. The need for this arbitration results from a desire to
avoid having to constantly merge results.
However, there are times when the goal of a lock is not to exclude
others from exercising an access right but rather to provide a
mechanism for principals to indicate that they intend to exercise
their access right. Shared locks are provided for this case. A
shared lock allows multiple principals to receive a lock. Hence any
principal with appropriate access can get the lock.
With shared locks there are two trust sets that affect a resource.
The first trust set is created by access permissions. Principals
who are trusted, for example, may have permission to write the
resource. Those who are not, don't. Among those who have access
permission to write the resource, the set of principals who have
taken out a shared lock also must trust each other, creating a
(typically) smaller trust set within the access permission write
set.
Starting with every possible principal on the Internet, in most
situations the vast majority of these principals will not have write
INTERNET-DRAFT WebDAV November 19, 1997
access to a given resource. Of the small number who do have write
access, some principals may decide to guarantee their edits are free
from overwrite conflicts by using exclusive write locks. Others may
decide they trust their collaborators will not overwrite their work
(the potential set of collaborators being the set of principals who
have write permission) and use a shared lock, which informs their
collaborators that a principal is potentially working on the
resource.
The WebDAV extensions to HTTP do not need to provide all of the
communications paths necessary for principals to coordinate their
activities. When using shared locks, principals may use any out of
band communication channel to coordinate their work (e.g., face-to-
face interaction, written notes, post-it notes on the screen,
telephone conversation, Email, etc.) The intent of a shared lock is
to let collaborators know who else is potentially working on a
resource.
Shared locks are included because experience from web distributed
authoring systems has indicated that exclusive write locks are often
too rigid. An exclusive write lock is used to enforce a particular
editing process: take out exclusive write lock, read the resource,
perform edits, write the resource, release the lock. This editing
process has the problem that locks are not always properly released,
for example when a program crashes, or when a lock owner leaves
without unlocking a resource. While both timeouts and
administrative action can be used to remove an offending lock,
neither mechanism may be available when needed; the timeout may be
long or the administrator may not be available.
Despite their potential problems, exclusive write locks are
extremely useful, since often a guarantee of freedom from overwrite
conflicts is what is needed. This specification provides both
exclusive write locks and the less strict mechanism of shared locks.
5.2. Required Support
A WebDAV compliant server is not required to support locking in any
form. If the server does support locking it MAY choose to support
any combination of exclusive and shared locks for any access types.
The reason for this flexibility is that locking policy strikes to
the very heart of the resource management and versioning systems
employed by various storage repositories. These repositories
require control over what sort of locking will be made available.
For example, some repositories only support shared write locks while
others only provide support for exclusive write locks while yet
others use no locking at all. As each system is sufficiently
different to merit exclusion of certain locking features, this
specification leaves locking as the sole axis of negotiation within
WebDAV.
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5.3. Lock Tokens
A lock token is a URI that identifies a particular lock. A lock
token is returned by every successful LOCK operation in the lock-
token response header, and can also be discovered through lock
discovery on a resource.
Lock token URIs are required to be unique across all resources for
all time. This uniqueness constraint allows lock tokens to be
submitted across resources and servers without fear of confusion.
This specification provides a lock token URI scheme called
opaquelocktoken that meets the uniqueness requirements. However
resources are free to return any URI scheme so long as it meets the
uniqueness requirements.
5.4. opaquelocktoken Lock Token URI Scheme
The opaquelocktoken URI scheme is designed to be unique across all
resources for all time. Due to this uniqueness quality, a client
MAY submit an opaque lock token in a Lock-Token request header and
an if-state[-not]-match header on a resource other than the one that
returned it.
All resources MUST recognize the opaquelocktoken scheme and, at
minimum, recognize that the lock token was not generated by the
resource. Note, however, that resources are not required to
generate opaquelocktokens in LOCK method responses.
In order to guarantee uniqueness across all resources for all time
the opaquelocktoken requires the use of the GUID mechanism.
Opaquelocktoken generators, however, have a choice of how they
create these tokens. They can either generate a new GUID for every
lock token they create, which is potentially very expensive, or they
can create a single GUID and then add extension characters. If the
second method is selected then the program generating the extensions
MUST guarantee that the same extension will never be used twice with
the associated GUID.
Opaque-Lock-Token = "opaquelocktoken" ":" GUID [Extension]
GUID = ; As defined in [Leach, Salz, 1997]
Extension = *urlc ;urlc is defined in [Berners-Lee et al., 1997]
(draft-fielding-url-syntax-07.txt)
5.5. Lock Capability Discovery
Since server lock support is optional, a client trying to lock a
resource on a server can either try the lock and hope for the best,
or perform some form of discovery to determine what lock
capabilities the server supports. This is known as lock capability
discovery. Lock capability discovery differs from discovery of
INTERNET-DRAFT WebDAV November 19, 1997
supported access control types, since there may be access control
types without corresponding lock types. A client can determine what
lock types the server supports by retrieving the supportedlock
property.
Any DAV compliant resource that supports the LOCK method MUST
support the supportedlock property.
5.6. Active Lock Discovery
If another principal locks a resource that a principal wishes to
access, it is useful for the second principal to be able to find out
who the first principal is. For this purpose the lockdiscovery
property is provided. This property lists all outstanding locks,
describes their type, and provides their lock token.
Any DAV compliant resource that supports the LOCK method MUST
support the lockdiscovery property.
6. Write Lock
This section describes the semantics specific to the write access
type for locks. The write lock is a specific instance of a lock
type, and is the only lock type described in this specification. A
DAV compliant resource MAY support the write lock.
6.1. Methods Restricted by Write Locks
A write lock prevents a principal without the lock from successfully
executing a PUT, POST, PATCH, PROPPATCH, MOVE, DELETE, MKCOL, ADDREF
or DELREF on the locked resource. All other current methods, GET in
particular, function independent of the lock.
Note, however, that as new methods are created it will be necessary
to specify how they interact with a write lock.
6.2. Write Locks and Properties
While those without a write lock may not alter a property on a
resource it is still possible for the values of live properties to
change, even while locked, due to the requirements of their schemas.
Only dead properties and live properties defined to respect locks
are guaranteed not to change while write locked.
6.3. Write Locks and Null Resources
It is possible to assert a write lock on a null resource in order to
lock the name. Please note, however, that locking a null resource
effectively makes the resource non-null, as the resource now has
lock related properties defined on it.
INTERNET-DRAFT WebDAV November 19, 1997
6.4. Write Locks and Collections
A write lock on a collection prevents the addition or removal of
members of the collection. As a consequence, when a principal
issues a request to create a new internal member of a collection
using PUT or POST, or to remove an existing internal member of a
collection using DELETE, this request MUST fail if the principal
does not have a write lock on the collection.
However, if a write lock request is issued to a collection
containing internal member resources that are currently locked in a
manner which conflicts with the write lock, the request MUST fail
with a 409 Conflict status code.
6.5. Write Locks and COPY/MOVE
The owner of a write lock MUST NOT execute a MOVE method on a
resource he has locked. This specification intentionally does not
define what happens if a MOVE method request is made on a locked
resource by the lock's owner.
A COPY method invocation MUST NOT duplicate any write locks active
on the source.
6.6. Re-issuing Write Locks
If a principal already owns a write lock on a resource, any future
requests for the same type of write lock, on the same resource,
while the principal's previous write lock is in effect, MUST result
in a successful response with the same lock token as provided for
the currently existing lock. Two lock requests are defined to be
identical if their Lock-Info headers are identical.
6.7. Write Locks and The Lock-Token Request Header
If a user agent is not required to have knowledge about a lock when
requesting an operation on a locked resource, the following scenario
might occur. Program A, run by User A, takes out a write lock on a
resource. Program B, also run by User A, has no knowledge of the
lock taken out by Program A, yet performs a PUT to the locked
resource. In this scenario, the PUT succeeds because locks are
associated with a principal, not a program, and thus program B,
because it is acting with principal A's credential, is allowed to
perform the PUT. However, had program B known about the lock, it
would not have overwritten the resource, preferring instead to
present a dialog box describing the conflict to the user. Due to
this scenario, a mechanism is needed to prevent different programs
from accidentally ignoring locks taken out by other programs with
the same authorization.
INTERNET-DRAFT WebDAV November 19, 1997
In order to prevent these collisions the lock token request header
is introduced. Please refer to the Lock Token Request Header
section for details and requirements.
6.7.1. Write Lock Token Example
COPY /~fielding/index.html HTTP/1.1
Host: www.ics.uci.edu
Destination: http://www.ics.uci.edu/users/f/fielding/index.html
Lock-Token: <opaquelocktoken:123AbcEfg1284h23h2>
<opaquelocktoken:AAAASDFcalkjfdas12312>
HTTP/1.1 200 OK
In this example, both the source and destination are locked so two
lock tokens must be submitted. If only one of the two resources was
locked, then only one token would have to be submitted.
7. Notational Conventions
Since this document describes a set of extensions to the HTTP/1.1
protocol, the augmented BNF used herein to describe protocol
elements is exactly the same as described in Section 2.1 of RFC
2068, _Hypertext Transfer Protocol -- HTTP/1.1_ [Fielding et al.,
1997]. Since this augmented BNF uses the basic production rules
provided in Section 2.2 of RFC 2068, these rules apply to this
document as well.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [Bradner,
1997].
8. HTTP Methods for Distributed Authoring
8.1. PROPFIND
The PROPFIND method retrieves properties defined on the Request-URI,
if it is a non-collection resource, or on the Request-URI and
potentially its member resources, if the resource is a collection.
All DAV compliant resources MUST support the PROPFIND method.
A client MAY submit a Depth header with a PROPFIND on a collection
with a value of "0", "1" or "infinity". DAV compliant servers MUST
support the "0", "1" and "infinity" behaviors. By default, the
PROPFIND method on a collection without a Depth header MUST act as
if a Depth = infinity header was included.
INTERNET-DRAFT WebDAV November 19, 1997
A client MUST submit a Propfind request header describing what
information is being requested. It is possible to request
particular property values, all property values, or a list of the
names of the resource's properties.
The response is a text/xml message body that contains a multistatus
XML element that describes the results of the attempts to retrieve
the various properties. If a property was successfully retrieved
then its value MUST be returned in a prop XML element. If the scope
of PROPFIND covers more than a single resource, as is the case with
Depth values of "1" and "infinity", each response XML element MUST
contain an href XML element which identifies the resource on which
the properties in the prop XML element are defined. In the case of
allprop and propname, if a principal does not have the right to know
if a particular property exists, an error MUST NOT be returned. The
results of this method SHOULD NOT be cached.
8.1.1. Example: Retrieving Named Properties
PROPFIND /files/ HTTP/1.1
Host: www.foo.bar
Depth: 0
Propfind: <http://www.foo.bar/boxschema/bigbox> <http://www.foo.bar/
boxschema/author> <http://www.foo.bar/boxschema/DingALing> <http://w
ww.foo.bar/boxschema/Random>
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href ="http://www.ietf.org/standards/dav/" AS = "D"?>
<?namespace href = "http://www.foo.bar/boxschema" AS = R"?>
<D:multistatus>
<D:response>
<D:prop>
<R:bigbox>
<R:BoxType>Box type A</R:BoxType>
</R:bigbox>
<R:author>
<R:Name>J.J. Dingleheimerschmidt</R:Name>
</R:author>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:response>
<D:response>
<D:prop><R:DingALing/><R:Random/></D:prop>
<D:status>HTTP/1.1 403 Forbidden</D:status>
<D:responsedescription> The user does not have access to the
DingALing property.
</D:responsedescription>
</D:response>
INTERNET-DRAFT WebDAV November 19, 1997
<D:responsedescription> There has been an access violation error.
</D:responsedescription>
</D:multistatus>
In this example, PROPFIND is executed on the collection
http://www.foo.bar/files/. The specified depth is zero, hence the
PROPFIND applies only to the collection itself, and not to any of
its members. The Propfind header specifies the name of four
properties whose values are being requested. In this case only two
properties were returned, since the principal issuing the request
did not have sufficient access rights to see the third and fourth
properties.
8.1.2. Example: Using allprop to Retrieve All Properties
PROPFIND /container/ HTTP/1.1
Host: www.foo.bar
Depth: 1
Propfind: allprop
HTTP/1.1 200 OK
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" As = "S"?>
<?namespace href = "http://www.foo.bar/boxschema/" AS = R"?>
<S:multistatus>
<S:response>
<S:href>http://www.foo.bar/container/</S:href>
<S:prop>
<R:bigbox>
<R:BoxType>Box type A</R:BoxType>
</R:bigbox>
<R:author>
<R:Name>Hadrian</R:Name>
</R:author>
</S:prop>
<S:status>HTTP 1.1 200 OK</S:status>
</S:response>
<S:response>
<S:href>http://www.foo.bar/container/index.html</S:href>
<S:prop>
<R:bigbox>
<R:BoxType>Box type B</R:BoxType>
</R:bigbox>
</S:prop>
<S:status>HTTP 1.1 200 OK</S:status>
</S:response>
</S:multistatus>
INTERNET-DRAFT WebDAV November 19, 1997
In this example, PROPFIND was invoked on the resource
http://www.foo.bar/container/ with a Depth header of 1, meaning the
request applies to the resource and its children, and a Propfind
header of "allprop", meaning the request should return the name and
value of all properties defined on each resource.
The resource http://www.foo.bar/container/ has two properties
defined on it, named http://www.foo.bar/boxschema/bigbox, and
http://www.foo.bar/boxschema/author, while resource
http://www.foo.bar/container/index.html has only a single resource
defined on it, named http://www.foo.bar/boxschema/bigbox, another
instance of the "bigbox" property type.
8.1.3. Example: Using propname to Retrieve all Property Names
PROPFIND /container/ HTTP/1.1
Host: www.foo.bar
Propfind: propname
HTTP/1.1 200 OK
Content-Type: text/xml
Content-Length: xxxx
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" As = "D"?>
<?namespace href = "http://www.foo.bar/boxschema/" AS = "R"?>
<D:multistatus>
<D:response>
<D:href>http://www.foo.bar/container/</D:href>
<D:prop>
<R:bigbox/>
<R:author/>
</D:prop>
<D:status>HTTP 1.1 200 OK</D:status>
</D:response>
<D:response>
<D:href>http://www.foo.bar/container/index.html</D:href>
<D:prop>
<R:bigbox/>
</D:prop>
<D:status>HTTP 1.1 200 OK</D:status>
</D:response>
</D:multistatus>
In this example, PROPFIND is invoked on the collection resource
http://www.foo.bar/container/, with a Propfind header set to
"propname", meaning the name of all properties should be returned.
Since no depth header is present, it assumes its default value of
"infinity", meaning the name of the properties on the collection and
all its progeny should be returned.
INTERNET-DRAFT WebDAV November 19, 1997
Consistent with the previous example, resource
http://www.foo.bar/container/ has two properties defined on it,
http://www.foo.bar/boxschema/bigbox, and
http://www.foo.bar/boxschema/author. The resource
http://www.foo.bar/container/index.html, a member of the "container"
collection, has only one property defined on it,
http://www.foo.bar/boxschema/bigbox.
8.2. PROPPATCH
The PROPPATCH method processes instructions specified in the request
body to set and/or remove properties defined on the resource
identified by Request-URI.
All DAV compliant resources MUST support the PROPPATCH method and
MUST process instructions that are specified using the
propertyupdate, set, and remove XML elements of the DAV schema.
Execution of the directives in this method is, of course, subject to
access control constraints. DAV compliant resources MUST support
the setting of arbitrary dead properties.
The request message body of a PROPPATCH method MUST contain at least
one propertyupdate XML element. Instruction processing MUST occur
in the order instructions are received (i.e., from top to bottom),
and MUST be performed atomically.
8.2.1. propertyupdate XML element
Name: propertyupdate
Namespace: http://www.ietf.org/standards/dav/
Purpose: To contain a request to alter the properties on a
resource.
Parent: None
Values= 1*(set | remove)
Description: This XML element is a container for the information
required to modify the properties on the resource. This XML element
is multi-valued.
8.2.2. set XML element
Name: set
Namespace: http://www.ietf.org/standards/dav/
Purpose: To set the DAV properties specified inside the set XML
element.
Parent: propertyupdate
Values= prop
Description: This XML element MUST contain only a prop XML element.
The elements contained by prop specify the name and value of
properties that are set on the Request-URI. If a property already
exists then its value is replaced.
INTERNET-DRAFT WebDAV November 19, 1997
8.2.3. remove XML element
Name: remove
Namespace: http://www.ietf.org/standards/dav/
Purpose: To remove the DAV properties specified inside the remove
XML element.
Parent: propertyupdate
Values= prop
Description: Remove specifies that the properties specified in prop
should be removed. Specifying the removal of a property that does
not exist is not an error. All the elements in prop MUST be empty,
as only the names of properties to be removed are required.
8.2.4. Response Codes
200 OK - The command succeeded. As there can be a mixture of sets
and removes in a body, a 201 Create seems inappropriate.
403 Forbidden - The client, for reasons the server chooses not to
specify, cannot alter one of the properties.
405 Conflict - The client has provided a value whose semantics are
not appropriate for the property. This includes trying to set read-
only properties.
413 Request Entity Too Long - If a particular property is too long
to be recorded then a composite XML error will be returned
indicating the offending property.
8.2.5. Example
PROPPATCH /bar.html HTTP/1.1
Host: www.foo.com
Content-Type: text/xml
Content-Length: xxxx
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" AS = "D"?>
<?namespace href = "http://www.w3.com/standards/z39.50/" AS = "Z"?>
<D:propertyupdate>
<D:set>
<D:prop>
<Z:authors>
<Z:Author>Jim Whitehead</Z:Author>
<Z:Author>Roy Fielding</Z:Author>
</Z:authors>
</D:prop>
</D:set>
<D:remove>
<D:prop><Z:Copyright-Owner/></D:prop>
</D:remove>
</D:propertyupdate>
INTERNET-DRAFT WebDAV November 19, 1997
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href="http://www.ietf.org/standards/dav/" AS = "D"?>
<?namespace href="http://www.w3.com/standards/z39.50/" AS = "Z"?>
<D:multistatus>
<D:response>
<D:prop><Z:Authors/></D:prop>
<D:status>HTTP/1.1 420 Method Failure</D:status>
</D:response>
<D:response>
<D:prop><Z:Copyright-Owner/></D:prop>
<D:status>HTTP/1.1 409 Conflict</D:status>
</D:response>
<D:responsedescription> Copyright Owner can not be deleted or
altered.</D:responsedescription>
</D:multistatus>
In this example, the client requests the server to set the value of
the http://www.w3.com/standards/z39.50/Authors property, and to
remove the property http://www.w3.com/standards/z39.50/Copyright-
Owner. Since the Copyright-Owner property could not be removed, no
property modifications occur. The Method Failure response code for
the Authors property indicates this action would have succeeded if
it were not for the conflict with removing the Copyright-Owner
property.
8.3. MKCOL Method
The MKCOL method is used to create a new collection. All DAV
compliant resources MUST support the MKCOL method.
8.3.1. Request
MKCOL creates a new collection resource at the location specified by
the Request-URI. If the Request-URI exists, then MKCOL must fail.
During MKCOL processing, a server MUST make the Request-URI a member
of its parent collection. If no such ancestor exists, the method
MUST fail. When the MKCOL operation creates a new collection
resource, all ancestors MUST already exist, or the method MUST fail
with a 409 Conflict status code. For example, if a request to
create collection /a/b/c/d/ is made, and neither /a/b/ nor /a/b/c/
exists, the request MUST fail.
When MKCOL is invoked without a request body, the newly created
collection has no members.
INTERNET-DRAFT WebDAV November 19, 1997
A MKCOL request message MAY contain a message body. The behavior of
a MKCOL request when the body is present is limited to creating
collections, members of a collection, bodies of members and
properties on the collections or members. If the server receives a
MKCOL request entity type it does not support or understand it MUST
respond with a 415 Unsupported Media Type status code. The exact
behavior of MKCOL for various request media types is undefined in
this document, and will be specified in separate documents.
8.3.2. Response Codes
Responses from a MKCOL request are not cacheable, since MKCOL has
non-idempotent semantics.
201 Created - The collection or structured resource was created in
its entirety.
403 Forbidden - This indicates at least one of two conditions: 1)
The server does not allow the creation of collections at the given
location in its namespace, and 2) The parent collection of the
Request-URI exists but cannot accept members.
405 Method Not Allowed - MKCOL can only be executed on a
deleted/non-existent resource.
409 Conflict - A collection cannot be made at the Request-URI until
one or more intermediate collections have been created.
415 Unsupported Media Type- The server does not support the request
type of the body.
419 Insufficient Space on Resource - The resource does not have
sufficient space to record the state of the resource after the
execution of this method.
8.3.3. Example
This example creates a collection called /webdisc/xfiles/ on the
server www.server.org.
MKCOL /webdisc/xfiles/ HTTP/1.1
Host: www.server.org
HTTP/1.1 201 Created
8.4. INDEX Method
The INDEX method is used to enumerate the members of a resource.
All DAV compliant resources MUST support the INDEX method if they
have members.
INTERNET-DRAFT WebDAV November 19, 1997
8.4.1. The Request
For a collection, INDEX MUST return a list of its members. All
WebDAV compliant resources MUST support the text/xml response entity
described below. The INDEX result for a collection MAY also return
a list of the members of child collections, to any depth.
Collections that respond to an INDEX method with a text/xml entity
MUST contain a single multistatus XML element which contains a
response XML element for each member.
A resource that supports INDEX MUST return the resourcetype property
for each member.
Note that the prop XML element MAY contain additional properties.
8.4.2. Example
INDEX /user/yarong/dav_drafts/ HTTP/1.1
Host: www.microsoft.com
HTTP/1.1 200 OK
Content-Type: text/xml
Content-Length: xxx
Last-Modified: Thu, 11 Sep 1997 23:45:12 GMT
ETag: _fooyyybar_
<?XML version="1.0">
<?namespace href = _http://www.ietf.org/standards/dav/_ as = _D_?>
<D:multistatus>
<D:response>
<D:href>http://www.microsoft.com/user/yarong/dav_drafts/
</D:href>
<D:prop>
<D:resourcetype>
<D:collection/>
</D:resourcetype>
</D:prop>
<D:status>HTTP 1.1 200 OK</D:status>
</D:response>
<D:response>
<D:href>
http://www.microsoft.com/user/yarong/dav_drafts/base
</D:href>
<D:prop>
<D:resourcetype/>
</D:prop>
<D:status>HTTP 1.1 200 OK</D:status>
</D:response>
</D:multistatus>
INTERNET-DRAFT WebDAV November 19, 1997
8.5. ADDREF Method
The ADDREF method is used to add external members to a resource.
All DAV compliant collection resources MUST support the ADDREF
method. All other DAV compliant resources MAY support the ADDREF
method as appropriate.
8.5.1. The Request
The ADDREF method adds the URI specified in the Collection-Member
header as an external member to the collection specified by the
Request-URI. The value in the Collection-Member header MUST be an
absolute URI meeting the requirements of an external member URI.
It is not an error if the URI specified in the Collection-Member
header already exists as an external member of the collection.
However, after processing the ADDREF there MUST be only one instance
of the URI in the collection. If the URI specified in the
Collection-Member header already exists as an internal member of the
collection, the ADDREF method MUST fail with a 412 Precondition
Failed status code.
8.5.2. Example
ADDREF /~ejw/dav/ HTTP/1.1
Host: www.ics.uci.edu
Collection-Member: http://www.ietf.org/standards/dav/
HTTP/1.1 200 OK
This example adds the URI http://www.ietf.org/standards/dav/ as an
external member resource of the collection
http://www.ics.uci.edu/~ejw/dav/.
8.6. DELREF Method
The DELREF method is used to remove external members from a
resource. All DAV compliant collection resources MUST support the
DELREF method. All other DAV compliant resources MUST support the
DELREF method only if they support the ADDREF method.
8.6.1. The Request
The DELREF method removes the URI specified in the Collection-Member
header from the collection specified by the Request-URI.
DELREFing a URI which is not a member of the collection is not an
error. DELREFing an internal member MUST fail with a 412
Precondition Failed status code.
INTERNET-DRAFT WebDAV November 19, 1997
8.6.2. Example
DELREF /~ejw/dav/ HTTP/1.1
Host: www.ics.udi.edu
Collection-Member: http://www.ietf.org/standards/dav/
HTTP/1.1 200 OK
This example removes the URI http://www.ietf.org/standards/dav/, an
external member resource, from the collection
http://www.ics.uci.edu/~ejw/dav/.
8.7. GET, HEAD for Collections
The semantics of GET are unchanged when applied to a collection,
since GET is defined as, _retrieve whatever information (in the form
of an entity) is identified by the Request-URI_ [Fielding et al.,
1997]. GET when applied to a collection MAY return the contents of
an _index.html_ resource, a human-readable view of the contents of
the collection, or something else altogether, and hence it is
possible the result of a GET on a collection will bear no
correlation to the state of the collection.
Similarly, since the definition of HEAD is a GET without a response
message body, the semantics of HEAD are unmodified when applied to
collection resources.
8.8. POST for Collections
Since by definition the actual function performed by POST is
determined by the server and often depends on the particular
resource, the behavior of POST when applied to collections cannot be
meaningfully modified because it is largely undefined. Thus the
semantics of POST are unmodified when applied to a collection.
8.9. DELETE
8.9.1. DELETE Method for Non-Collection Resources
If the DELETE method is issued to a non-collection resource which is
an internal member of a collection, then during DELETE processing a
server MUST remove the Request-URI from its parent collection. A
server MAY remove the URI of a deleted resource from any collections
of which the resource is an external member.
8.9.2. DELETE for Collections
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The DELETE method on a collection MUST act as if a Depth = Infinity
header was used on it. A client MUST NOT submit a Depth header on a
DELETE on a collection with any value but Infinity.
DELETE instructs that the collection specified in the request-URI,
the records of its external member resources, and all its internal
member resources, are to be deleted.
If any member cannot be deleted then all of the member's progeny
MUST NOT be deleted, so as to maintain the namespace.
Any headers included with DELETE MUST be applied in processing every
resource to be deleted. In this case, a header of special interest
is the Destroy header, which specifies the method to be used to
delete all resources in the scope of the DELETE.
When the DELETE method has completed processing it MUST return a
consistent namespace.
The response SHOULD be a Multi-Status response that describes the
result of the DELETE on each affected resource.
8.9.2.1. Example
DELETE /container/ HTTP/1.1
Host: www.foo.bar
Destroy: NoUndelete
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" As = "d"?>
<d:multistatus>
<d:response>
<d:href>http://www.foo.bar/container/resource1</d:href>
<d:href>http://www.foo.bar/container/resource2</d:href>
<d:status>HTTP/1.1 200 OK</d:status>
</d:response>
<d:response>
<d:href>http://www.foo.bar/container/</d:href>
<d:status>HTTP/1.1 420 Method Failure</d:status>
</d:response>
<d:response>
<d:href>http://www.foo.bar/container/resource3</d:href>
<d:status>HTTP/1.1 412 Precondition Failed</d:status>
</d:response>
</d:multistatus>
INTERNET-DRAFT WebDAV November 19, 1997
In this example the attempt to delete
http://www.foo.bar/container/resource3 failed because the server was
unable to guarantee that resource3 would not be able to be
undeleted. Consequently, the attempt to delete
http://www.foo.bar/container/ also failed, but resource1 and
resource2 were deleted. Even though a Depth header has not been
included, a depth of infinity is assumed because the method is on a
collection. As this example illustrates, DELETE processing need not
be atomic.
8.10. PUT
8.10.1. PUT for Non-Collection Resources
A PUT performed on an existing resource replaces the GET response
entity of the resource. Properties defined on the resource MAY be
recomputed during PUT processing. For example, if a server
recognizes the content type of the request body, it may be able to
automatically extract information that could be profitably exposed
as properties.
A PUT that would result in the creation of a resource without an
appropriately scoped parent collection MUST fail with a 405 Method
Not Allowed.
8.10.2. PUT for Collections
As defined in the HTTP/1.1 specification [Fielding et al., 1997],
the "PUT method requests that the enclosed entity be stored under
the supplied Request-URI." Since submission of an entity
representing a collection would implicitly encode creation and
deletion of resources, this specification intentionally does not
define a transmission format for creating a collection using PUT.
Instead, the MKCOL method is defined to create collections. If a
PUT is invoked on a collection resource it MUST fail.
When the PUT operation creates a new non-collection resource all
ancestors MUST already exist. If all ancestors do not exist, the
method MUST fail with a 409 Conflict status code. For example, if
resource /a/b/c/d.html is to be created and /a/b/c/ does not exist,
then the request must fail.
8.11. COPY Method
The COPY method creates a duplicate of the specified resource. All
DAV compliant resources MUST support the COPY method.
Support for the COPY method does not guarantee the ability to copy a
resource. For example, separate programs may control resources on
the same server. As a result, it may not even be possible to copy a
resource to a location that appears to be on the same server.
INTERNET-DRAFT WebDAV November 19, 1997
8.11.1. The Request
The COPY method creates a duplicate of the source resource, given by
the Request-URI, in the destination resource, given by the
Destination header. The Destination header MUST be present. The
exact behavior of the COPY method depends on the type of the source
resource.
8.11.1.1. COPY for HTTP/1.1 resources
When the source resource is not a collection the body of the
destination resource MUST be octet-for-octet identical to the body
of the source resource. Alterations to the destination resource do
not modify the source resource. Alterations to the source resource
do not modify the destination resource. Thus, all copies are
performed _by-value_.
All properties on the source resource MUST be duplicated on the
destination resource, subject to modifying headers, following the
definition for copying properties.
8.11.1.2. COPY for Properties
The following section defines how properties on a resource are
handled during a COPY operation.
Live properties SHOULD be duplicated as identically behaving live
properties at the destination resource. Since they are live
properties, the server determines the syntax and semantics of these
properties. Properties named by the Enforce-Live-Properties header
MUST be live on the destination resource, or the method MUST fail.
If a property is not named by Enforce-Live-Properties and cannot be
copied live, then its value MUST be duplicated, octet-for-octet, in
an identically named, dead property on the destination resource.
If a property on the source already exists on the destination
resource and the Overwrite header is set to "T" then the property at
the destination MUST be overwritten with the property from the
source. If the Overwrite header is "F" and the previous situation
exists, then the COPY MUST fail with a 409 Conflict.
8.11.1.3. COPY for Collections
The COPY method on a collection without a Depth header MUST act as
if a Depth = infinity header was included. A client MAY submit a
Depth header on a COPY on a collection with a value of "0" or
"infinity". DAV compliant servers MUST support the "0" and
"infinity" behaviors.
A COPY of depth infinity instructs that the collection specified in
the Request-URI, the records of its external member resources, and
INTERNET-DRAFT WebDAV November 19, 1997
all its internal member resources, are to be copied to a location
relative to the Destination header.
A COPY of depth "0" only instructs that the collection, the
properties, and its external members, not its internal members, are
to be copied.
Any headers included with a COPY are to be applied in processing
every resource to be copied.
The exception to this rule is the Destination header. This header
only specifies the destination for the Request-URI. When applied to
members of the collection specified in the request-URI the value of
Destination is to be modified to reflect the current location in the
hierarchy. So, if the request-URI is "a" and the destination is "b"
then when a/c/d is processed it MUST use a destination of b/c/d.
When the COPY method has completed processing it MUST have created a
consistent namespace at the destination. Thus if it is not possible
to COPY a collection with internal members, the internal members may
still be copied but a collection will have to be created at the
destination to contain them.
The response is a Multi-Status response that describes the result of
the COPY on each affected resource. The response is given for the
resource that was to be copied, not the resource that was created as
a result of the copy. In other words, each entry indicates whether
the copy on the resource specified in the href succeeded or failed
and why.
The exception to this rule is for errors that occurred on the
destination. For example, if the destination was locked the
response would indicate the destination URL and a 421 Destination
Locked error.
8.11.1.4. Type Interactions
If the destination resource identifies a collection and the
Overwrite header is _T_, prior to performing the copy the server
MUST perform a DELETE operation on the collection.
8.11.2. Response Codes
200 OK - The source resource was successfully copied to a pre-
existing destination resource.
201 Created - The source resource was successfully copied. The copy
operation resulted in the creation of a new resource.
412 Precondition Failed - This status code MUST be returned if the
server was unable to maintain the liveness of the properties listed
INTERNET-DRAFT WebDAV November 19, 1997
in the Enforce-Live-Properties header, or if the Overwrite header is
"F", and the state of the destination resource is non-null.
419 Insufficient Space on Resource - The destination resource does
not have sufficient space to record the state of the resource after
the execution of this method.
421 Destination Locked _ The destination resource was locked and
either a valid Lock-Token header was not submitted, or the Lock-
Token header identifies a lock held by another principal.
500 Server Error - The resource was in such a state that it could
not be copied. This may occur if the Destination header specifies a
resource that is outside the namespace the resource is able to
interact with.
8.11.3. Overwrite Example
This example shows resource
http://www.ics.uci.edu/~fielding/index.html being copied to the
location http://www.ics.uci.edu/users/f/fielding/index.html. The
contents of the destination resource were overwritten, if non-null.
COPY /~fielding/index.html HTTP/1.1
Host: www.ics.uci.edu
Destination: http://www.ics.uci.edu/users/f/fielding/index.html
HTTP/1.1 200 OK
8.11.4. No Overwrite Example
The following example shows the same copy operation being performed,
except with the Overwrite header set to _F._ A response of 412
Precondition Failed is returned because the destination resource has
a non-null state.
COPY /~fielding/index.html HTTP/1.1
Host: www.ics.uci.edu
Destination: http://www.ics.uci.edu/users/f/fielding/index.html
Overwrite: _F_
HTTP/1.1 412 Precondition Failed
8.11.5. Collection Example
COPY /container/ HTTP/1.1
Host: www.foo.bar
Destination: http://www.foo.bar/othercontainer/
Enforce-Live-Properties: *
Depth: Infinity
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HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" As = "d"?>
<d:multistatus>
<d:response>
<d:href>http://www.foo.bar/othercontainer/resource1</d:href>
<d:href>http://www.foo.bar/othercontainer/resource2</d:href>
<d:href>http://www.foo.bar/othercontainer/</d:href>
<d:href>http://www.foo.bar/othercontainer/R2/D2</d:href>
<d:status>HTTP/1.1 201 Created</d:status>
</d:response>
<d:response>
<d:href>http://www.foo.bar/othercontainer/R2/</d:href>
<d:status>HTTP/1.1 412 Precondition Failed</d:status>
</d:response>
</d:multistatus>
The Depth header is unnecessary as the default behavior of COPY on a
collection is to act as if a "Depth: Infinity" header had been
submitted. In this example most of the resources, along with the
collection, were copied successfully. However the collection R2
failed, most likely due to a problem with enforcing live properties.
R2's member D2 was successfully copied. As a result a collection
was created at www.foo.bar/othercontainer/R2 to contain D2.
8.12. MOVE Method
The move operation on a resource is the logical equivalent of a copy
followed by a delete, where the actions are performed atomically.
All DAV compliant resources MUST support the MOVE method.
However, support for the MOVE method does not guarantee the ability
to move a resource to a particular destination. For example,
separate programs may actually control different sets of resources
on the same server. Therefore, it may not even be possible to move
a resource within a namespace that appears to belong to the same
server.
8.12.1. The Request
If a resource exists at the destination, the destination resource
will be DELETEd as a side effect of the MOVE operation, subject to
the restrictions of the Overwrite header.
8.12.2. MOVE for Collections
MOVE instructs that the collection specified in the Request-URI, the
records of its external member resources, and all its internal
INTERNET-DRAFT WebDAV November 19, 1997
member resources, are to be moved to a location relative to the
Destination header.
The MOVE method on a collection MUST act as if a Depth "infinity"
header was used on it. A client MUST NOT submit a Depth header on a
MOVE on a collection with any value but "infinity".
Any headers included with MOVE are to be applied in processing every
resource to be moved.
The exception to this rule is the Destination header. The behavior
of this header is the same as given for COPY on collections.
When the MOVE method has completed processing it MUST have created a
consistent namespace on both the source and destination, creating
collections at the source or destination as necessary.
As specified in the definition of MOVE, a MOVE of a collection over
another collection causes the destination collection and all its
members to be deleted.
The response is a Multi-Status response that describes the result of
the MOVE on each effected resource. The response is given for the
resource that was to be moved, not the resource that was created as
a result of the move. In other words, each entry indicates whether
the move on the resource specified in the href succeeded or failed
and why.
The exception to this rule is for errors that occurred on the
destination. For example, if the destination was locked the
response would indicate the destination URL and a 421 Destination
Locked error.
8.12.3. Response Codes
200 OK - The move operation was successful.
409 Conflict _ The MOVE was attempted on a collection with members.
While the COPY part of this operation could succeed the DELETE could
not. Therefore the MOVE MUST fail.
412 Precondition Failed - This status code MUST be returned if the
server was unable to maintain the liveness of the properties listed
in the Enforce-Live-Properties header, or if the Overwrite header is
"F", and the state of the destination resource is non-null.
421 Destination Locked - The destination resource was locked and
either a valid Lock-Token header was not submitted, or the Lock-
Token header identifies a lock held by another principal.
502 Bad Gateway - This may occur when the destination is
o
n another
server and the destination server refuses to accept the resource
INTERNET-DRAFT WebDAV November 19, 1997
8.12.4. Overwrite Example
This example shows resource
http://www.ics.uci.edu/~fielding/index.html being moved to the
location http://www.ics.uci.edu/users/f/fielding/index.html. The
contents of the destination resource were overwritten, if non-null.
MOVE /~fielding/index.html HTTP/1.1
Host: www.ics.uci.edu
Destination: http://www.ics.uci.edu/users/f/fielding/index.html
HTTP/1.1 200 OK
8.12.5. Collection Example
MOVE /container/ HTTP/1.1
Host: www.foo.bar
Destination: http://www.foo.bar/othercontainer/
Enforce-Live-Properties: *
Overwrite: False
Lock-Token: <OpaqueLockToken:xxxx> <OpaqueLockToken:xxxx>
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" As = "D"?>
<d:multistatus>
<d:response>
<d:href>http://www.foo.bar/container/resource1</d:href>
<d:href>http://www.foo.bar/container/resource2</d:href>
<d:href>http://www.foo.bar/container/</d:href>
<d:href>http://www.foo.bar/container/C2/R2</d:href>
<d:status>HTTP/1.1 201 Created</d:status>
</d:response>
<d:response>
<d:href>http://www.foo.bar/container/C2</d:href>
<d:status>HTTP/1.1 420 Method Failure</d:status>
<d:response>
<d:href>http://www.foo.bar/othercontainer/C2</d:href>
<d:status>HTTP/1.1 409 Conflict</d:status>
</d:response>
</d:multistatus>
In this example the client has submitted a number of lock tokens
with the request. A lock token will need to be submitted for every
resource, both source and destination, anywhere in the scope of the
INTERNET-DRAFT WebDAV November 19, 1997
method, that is locked. In this case the proper lock token was not
submitted for the destination http://www.foo.bar/othercontainer/C2.
This means that the resource continer/c2 could not be moved,
although its child container/C2/R2 could be moved.
8.13. LOCK Method
The following sections describe the LOCK method, which is used to
take out a lock of any access type. These sections on the LOCK
method describe only those semantics that are specific to the LOCK
method and are independent of the access type of the lock being
requested. Once the general LOCK method has been described,
subsequent sections describe the semantics of the "write" access
type, and the write lock.
8.13.1. Operation
A LOCK method invocation creates the lock specified by the Lock-Info
header on the Request-URI. Lock method requests SHOULD have a XML
request body which contains an Owner XML element for this lock
request. The LOCK request MAY have a Timeout header.
A successful response to a lock invocation MUST include Lock-Token
and Timeout headers. Clients MUST assume that locks may arbitrarily
disappear at any time, regardless of the value given in the Timeout
header. The Timeout header only indicates the behavior of the
server if "extraordinary" circumstances do not occur. For example,
an administrator may remove a lock at any time or the system may
crash in such a way that it loses the record of the lock's
existence. The response MUST also contain the value of the
lockdiscovery property in a prop XML element.
8.13.2. The Effect of Locks on Properties and Collections
By default the scope of a lock is the entire state of the resource,
including its body and associated properties. As a result, a lock
on a resource also locks the resource's properties, and a lock on a
property may lock a property's resource or may restrict the ability
to lock the property's resource. Only a single lock token MUST be
used when a lock extends to cover both a resource and its
properties. Note that certain lock types MAY override this
behavior.
For collections, a lock also affects the ability to add or remove
members. The nature of the effect depends upon the type of access
control involved.
8.13.3. Locking Replicated Resources
Some servers automatically replicate resources across multiple URLs.
In such a circumstance the server MAY only accept a lock on one of
INTERNET-DRAFT WebDAV November 19, 1997
the URLs if the server can guarantee that the lock will be honored
across all the URLs.
8.13.4. Locking Multiple Resources
The LOCK method supports locking multiple resources simultaneously
by allowing for the listing of several URIs in the LOCK request.
These URIs, in addition to the Request-URI, are then to be locked as
a result of the LOCK method's invocation. When multiple resources
are specified the LOCK method only succeeds if all specified
resources are successfully locked.
The Lock-Tree option of the lock request specifies that the resource
and all its internal children (including internal collections, and
their internal members) are to be locked. This is another mechanism
by which a request for a lock on multiple resources can be
specified.
Currently existing locks can not be extended to cover more or less
resources, and any request to expand or contract the number of
resources in a lock MUST fail with a 409 Conflict status code. So,
for example, if resource A is exclusively write locked and then the
same principal asks to exclusively write lock resources A, B, and C,
the request will fail as A is already locked and the lock can not be
extended.
A successful result will return a single lock token which represents
all the resources that have been locked. If an UNLOCK is executed
on this token, all associated resources are unlocked.
If the lock cannot be granted to all resources, a 409 Conflict
status code MUST be returned with a response entity body containing
a multistatus XML element describing which resource(s) prevented the
lock from being granted.
8.13.5. Interaction with other Methods
The interaction of a LOCK with various methods is dependent upon the
lock type. However, independent of lock type, a successful DELETE
of a resource MUST cause all of its locks to be removed.
8.13.6. Lock Compatibility Table
The table below describes the behavior that occurs when a lock
request is made on a resource.
Current lock state/ Shared Lock Exclusive
Lock request Lock
None True True
Shared Lock True False
Exclusive Lock False False*
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Legend: True = lock MAY be granted. False = lock MUST NOT be
granted. *=if the principal requesting the lock is the owner of the
lock, the lock MAY be regranted.
The current lock state of a resource is given in the leftmost
column, and lock requests are listed in the first row. The
intersection of a row and column gives the result of a lock request.
For example, if a shared lock is held on a resource, and an
exclusive lock is requested, the table entry is _false_, indicating
the lock must not be granted.
If an exclusive or shared lock is re-requested by the principal who
owns the lock, the lock MUST be regranted. If the lock is
regranted, the same lock token that was previously issued MUST be
returned.
8.13.7. Owner XML Element
Name: owner
Namespace: http://www.ietf.org/standards/dav/
Purpose: Provide information about the principal taking out a
lock.
Parent: Any
Values: XML Elements
Descripton: The Owner XML element provides information sufficient
for either directly contacting a principal (such as a telephone
number or Email URI), or for discovering the principal (such as the
URL of a homepage) who owns a lock.
8.13.8. Lock Response
A successful lock response MUST contain a Lock-Token response
header, a Timeout header and a prop XML element in the response body
which contains the value of the lockdiscovery property.
8.13.9. Response Codes
409 Conflict - The resource is locked, so the method has been
rejected.
412 Precondition Failed - The included Lock-Token was not
enforceable on this resource or the server could not satisfy the
request in the Lock-Info header.
8.13.10. Example - Simple Lock Request
LOCK /workspace/webdav/proposal.doc HTTP/1.1
Host: webdav.sb.aol.com
Lock-Info: LockType=Write LockScope=Exclusive
Timeout: Infinite; Second-4100000000
Content-Type: text/xml
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Content-Length: xyz
<?XML version="1.0">
<?namespace href="http://www.ietf.org/standards/dav/" AS = "D"?>
<D:owner>
<D:href>http://www.ics.uci.edu/~ejw/contact.html</D:href>
</D:owner>
HTTP/1.1 200 OK
Lock-Token: opaquelocktoken:xyz122393481230912asdfa09s8df09s7df
Timeout: Second-604800
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href ="http://www.ietf.org/standards/dav/" AS = "D"?>
<D:prop>
<D:lockdiscovery>
<D:activelock>
<D:locktype>write</D:locktype>
<D:lockscope>exclusive</D:lockscope>
<D:addlocks/>
<D:owner>
<D:href>
http://www.ics.uci.edu/~ejw/contact.html
</D:href>
</D:owner>
<D:timeout>Second-604800</D:timeout>
<D:locktoken>
<D:href>
opaquelocktoken:xyz122393481230912asdfa09s8df09s7df
</D:href>
</D:locktoken>
</D:activelock>
</D:lockdiscovery>
</D:prop>
This example shows the successful creation of an exclusive write
lock on resource
http://webdav.sb.aol.com/workspace/webdav/proposal.doc. The
resource http://www.ics.uci.edu/~ejw/contact.html contains contact
information for the owner of the lock. The server has an activity-
based timeout policy in place on this resource, which causes the
lock to automatically be removed after 1 week (604800 seconds). The
response has a Lock-Token header that gives the lock token URL that
uniquely identifies the lock created by this lock request.
8.13.11. Example - Multi-Resource Lock Request
LOCK /workspace/webdav/proposal.doc HTTP/1.1
Host: webdav.sb.aol.com
INTERNET-DRAFT WebDAV November 19, 1997
Lock-Info: LockType=Write LockScope=Exclusive
Addlocks=<http://webdav.sb.aol.com/workspace/><http://foo.bar/blah>
Timeout: Infinite, Second-4100000000
<?XML version="1.0">
<?namespace href="http://www.ietf.org/standards/dav/" AS = "D"?>
<D:href>http://www.ics.uci.edu/~ejw/contact.html<D:href>
HTTP/1.1 409 Conflict
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" As = "D"?>
<D:multistatus>
<D:response>
<D:href>
http://webdav.sb.aol.com/workspace/webdav/proposal.doc
</D:href>
<D:href>
http://webdav.sb.aol.com/workspace/webdav/
</D:href>
<D:status>HTTP/1.1 202 Accepted</D:status>
</D:response>
<D:response>
<D:href>http://foo.bar/blah</D:href>
<D:status>HTTP/1.1 403 Forbidden</D:status>
</D:response>
</D:multistatus>
This example shows a request for an exclusive write lock on three
resources, http://webdav.sb.aol.com/workspace/webdav/proposal.doc,
http://webdav.sb.aol.com/workspace/, and http://foo.bar/blah. In
this request, the client has specified that it desires an infinite
length lock, if available, otherwise a timeout of 4.1 billion
seconds, if available. The Owner header field specifies the web
address for contact information for the principal taking out the
lock.
This lock request has failed, because the server rejected the lock
request for http://foo.bar/blah. The 409 Conflict status code
indicates that the server was unable to satisfy the request because
there is a conflict between the state of the resources and the
operation named in the request. Within the multistatus, the 202
Accepted status code indicates that the lock method was accepted by
the resources, and would have been completed if all resources named
in the request were able to be locked. The 403 Forbidden status
code indicates that the server does not allow lock requests on this
resource.
8.14. UNLOCK Method
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The UNLOCK method removes the lock identified by the lock token in
the Lock-Token header from the Request-URI, and all other resources
included in the lock.
Any DAV compliant resource which supports the LOCK method MUST
support the UNLOCK method.
8.14.1. Example
UNLOCK /workspace/webdav/info.doc HTTP/1.1
Host: webdav.sb.aol.com
Lock-Token:opaquelocktoken:123AbcEfg1284h23h2
HTTP/1.1 200 OK
In this example, the lock identified by the lock token
"opaquelocktoken:123AbcEfg1284h23h2" is successfully removed from
the resource http://webdav.sb.aol.com/workspace/webdav/info.doc. If
this lock included more than just one resource, the lock was removed
from those resources as well.
8.15. PATCH Method
The PATCH method is used to modify parts of the entity returned in
the response to a GET method. DAV compliant resources MAY support
the PATCH method.
8.15.1. The Request
The request entity of the PATCH method contains a list of
differences between the resource identified by the Request-URI and
the desired content of the resource after the PATCH action has been
applied. The list of differences is in a format defined by the
media type of the entity (e.g., "application/diff") and must include
sufficient information to allow the server to convert the original
version of the resource to the desired version. Processing
performed by PATCH is atomic. Hence all changes MUST be
successfully executed or the method fails. PATCH MUST fail if
executed on a non-existent resource; i.e., PATCH does not create a
resource as a side effect.
If the request appears (at least initially) to be acceptable, the
server MUST transmit an interim 100 response message after receiving
the empty line terminating the request headers and continue
processing the request. Since the semantics of PATCH are non-
idempotent, responses to this method are not cacheable.
While server support for PATCH is optional, if a server does support
PATCH, it MUST support at least the text/xml diff format defined
INTERNET-DRAFT WebDAV November 19, 1997
below. Support for the VTML difference format [VTML] is
recommended, but not required.
8.15.2. text/xml elements for PATCH
The resourceupdate XML element contains a set of XML sub-entities
that describe modification operations. The name and meaning of
these XML elements are given below. Processing of these directives
MUST be performed in the order encountered within the XML document.
A directive operates on the resource as modified by all previous
directives (executed in sequential order). The length of the
resource MAY be extended or reduced by a PATCH.
The changes specified by the resourceupdate XML element MUST be
executed atomically.
8.15.2.1. resourceupdate XML Element
Name: resourceupdate
Namespace: http://www.ietf.org/standards/dav/patch/
Purpose: Contains an ordered set of changes to a non-collection,
non-property resource.
Parent: None
Value= *(insert | delete | replace)
8.15.2.2. insert XML Element
Name: insert
Namespace: http://www.ietf.org/standards/dav/patch/
Purpose: Insert the XML element's contents starting at the
specified octet.
Parent: resourceupdate
Value: The insert XML element MUST contain an octet-range XML
attribute that specifies an octet position within the body of a
resource. A value of _end_ specifies the end of the resource. The
body of the insert XML element contains the octets to be inserted.
Please note that in order to protect the white space contained in
this XML element the following attribute/value MUST be included in
the element: XML-SPACE = "PRESERVE". This attribute is defined in
the XML specification [Bray, Sperberg-McQueen, 1997].
8.15.2.3. delete XML Element
Name: delete
Namespace: http://www.ietf.org/standards/dav/patch/
Purpose: Removes the specified range of octets.
Parent: resourceupdate
Value: The delete XML element MUST contain an octet-range XML
attribute.
INTERNET-DRAFT WebDAV November 19, 1997
Discussion: The octets that are deleted are removed, which means the
resource is collapsed and the length of the resource is decremented
by the size of the octet range. It is not appropriate to replace
deleted octets with zeroed-out octets, since zero is a valid octet
value.
8.15.2.4. replace XML Element
Name: replace
Namespace: http://www.ietf.org/standards/dav/patch/
Purpose: Replaces the specified range of octets with the contents
of the XML element. If the number of octets in the XML element is
different from the number of octets specified, the update MUST be
rejected.
Parent: resourceupdate
Value: The replace XML element MUST contain an octet-range XML
attribute. The contents of the entity are the replacement octets.
Please note that in order to protect the white space contained in
this XML element the following attribute/value MUST be included in
the element: XML-SPACE = "PRESERVE"
.
This attribute is defined in the
XML specification [Bray, Sperberg-McQueen, 1997].
8.15.2.5. octet-range Attribute
Name: octet-range
Namespace: http://www.ietf.org/standards/dav/patch/
Purpose: Specifies a range of octets that the enclosing property
affects.
Parent: insert | delete | replace
Value: number [_-_ (number | _end_)]
Number = 1*Digit
Description: Octet numbering begins with 0. If the octet contains a
single number then the operation is to begin at that octet and to
continue for a length specified by the operation. In the case of a
delete, this would mean to delete a single octet. In the case of an
insert this would mean to begin the insertion at the specified octet
and to continue for the length of the included value, extending the
resource if necessary. In the case of replace, the replace begins
at the specified octet and overwrites all that follow to the length
of the included value.
8.15.3. Response Codes
200 OK - The request entity body was processed without error,
resulting in an update to the state of the resource.
409 Conflict - If the update information in the request message body
does not make sense given the current state of the resource (e.g.,
an instruction to delete a non-existent line), this status code MAY
be returned.
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415 Unsupported Media Type - The server does not support the content
type of the update instructions in the request message body.
418 Unprocessable Entity - The entity body submitted with the PATCH
was not understood by the resource.
419 Insufficient Space on Resource - The resource does not have
sufficient space to record the state of the resource after the
execution of this method.
8.15.4. HTML file modification Example
The following example shows a modification of the title and contents
of the HTML resource http://www.example.org/hello.html.
Before:
<HTML>
<HEAD>
<TITLE>Hello world HTML page</TITLE>
</HEAD>
<BODY>
<P>Hello, world!</P>
</BODY>
</HTML>
PATCH Request: Response:
PATCH hello.html HTTP/1.1
Host: www.example.org
Content-Type: text/xml
Content-Length: xxx
HTTP/1.1 100 Continue
<?XML version="1.0">
<?namespace href = _http://www.ietf.org/standards/dav/patch/_ AS =
_D_?>
<D:resourceupdate>
<D:replace XML-SPACE = "PRESERVE">
<D:octet-range>14</D:octet-range>&003CTITLE&003ENew
Title&003C/TITLE&003E</D:replace>
<D:delete><D:octet-range>38-50</D:octet-range></D:delete>
<D:insert XML-SPACE = "PRESERVE"><D:octet-range>86</D:octet-
range>&003CP&003ENew paragraph&003C/P&003E</D:insert>
</D:resourceupdate>
HTTP/1.1 200 OK
After:
<HTML>
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<HEAD>
<TITLE>New Title</TITLE>
</HEAD>
<BODY>
<P>Hello, world!</P>
<P>New paragraph</P>
</BODY>
</HTML>
9. HTTP Headers for Distributed Authoring
9.1. Collection-Member Header
CollectionMember = "Collection-Member" ":" URI ; URI is defined in
section 3.2.1 of [Fielding et al., 1997]
The Collection-Member header specifies the URI of an external
resource to be added/deleted to/from a collection.
9.2. DAV Header
DAV = "DAV" ":" ("1" | "2" | extend)
This header indicates that the resource supports the DAV schema and
protocol to the level indicated. All DAV compliant resources MUST
return the DAV header on all OPTIONS responses.
9.3. Depth Header
Depth = "Depth" ":" ("0" | "1" | "infinity")
The Depth header is used with methods executed on collections to
indicate whether the method is to be applied only to the collection
(Depth = 0), to the collection and its immediate children, (Depth =
1), or the collection and all its progeny (Depth = infinity). Note
that Depth = 1 and Depth = infinity behavior only applies to
internal member resources, and not to external member resources.
The Depth header is only supported if a method's definition
explicitly provides for such support.
The following rules are the default behavior for any method that
supports the depth header. A method MAY override these defaults by
defining different behavior in its definition.
Methods which support the depth header MAY choose not to support all
of the header's values and MAY define, on a case by case basis, the
behavior of the method on a collection if a depth header is not
present. For example, the MOVE method only supports Depth = infinity
and if a depth header is not present will act as if a Depth =
infinity header had been applied.
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Clients MUST NOT rely upon methods executing on members of their
hierarchies in any particular order or the execution being atomic.
Note that methods MAY provide guarantees on ordering and atomicity.
Upon execution, a method with a depth header will perform as much of
its assigned task as possible and then return a response specifying
what it was able to accomplish and what it failed to do.
So, for example, an attempt to COPY a hierarchy may result in some
of the members being copied and some not.
Any headers on a method with a depth header MUST be applied to all
resources in the scope of the method. For example, an if-match
header will have its value applied against every resource in the
method's scope and will cause the method to fail if the header fails
to match.
If a resource, source or destination, within the scope of the method
is locked in such a way as to prevent the successful execution of
the method, then the lock token for that resource MUST be submitted
with the request in the Lock-Token request header.
9.4. Destination Header
Destination = "Destination" ":" URI
The Destination header specifies a destination resource for methods
such as COPY and MOVE, which take two URIs as parameters.
9.5. Destroy Header
DestroyHeader = "Destroy" ":" #Choices
Choices = "VersionDestroy" | "NoUndelete" | "Undelete" | extend
Extend = RFC-Reg | Coded-URL
RFC-Req = Token ; This is a token value (defined in section 2.2 of
[Fielding et al., 1997]) that has been published as an RFC.
Coded-URL = "<" URI ">"
When deleting a resource the client often wishes to specify exactly
what sort of delete should be performed. The Destroy header, used
with the Mandatory header, allows the client to specify the end
result it desires. The Destroy header is specified as follows:
The Undelete token requests that, if possible, the resource should
be left in a state such that it can be undeleted. The server is not
required to honor this request.
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The NoUndelete token requests that the resource MUST NOT be left in
a state such that it can be undeleted.
The VersionDestroy token includes the functionality of the
NoUndelete token and extends it to include having the server remove
all versioning references to the resource that it has control over.
9.6. Enforce-Live-Properties Header
EnforceLiveProperties = "Enforce-Live-Properties_ _:" (_*_ | "Omit"
| 1*(Property-Name))
Property-Name = Coded-URL
The Enforce-Live-Properties header specifies properties that MUST be
_live_ after they are copied (moved) to the destination resource of
a copy (or move). If the value _*_ is given for the header, then it
designates all live properties on the source resource. If the value
is "Omit" then the server MUST NOT duplicate on the destination
resource any properties that are defined on the source resource. If
this header is not included then the server is expected to act as
defined by the default property handling behavior of the associated
method.
9.7. If-None-State-Match
If-None-State-Match = "If-None-State-Match" ":" 1#Coded-URL
The If-None-State-Match header is intended to have similar
functionality to the If-None-Match header defined in section 14.26
of RFC 2068. However the if-none-state-match header is intended for
use with any URI which represents state information about a
resource, referred to as a state token. A typical example is a lock
token.
If any of the state tokens identifies the current state of the
resource, the server MUST NOT perform the requested method.
Instead, if the request method was GET, HEAD, INDEX, or PROPFIND,
the server SHOULD respond with a 304 Not Modified response,
including the cache-related entity-header fields (particularly ETag)
of the current state of the resource. For all other request
methods, the server MUST respond with a status of 412 Precondition
Failed.
If none of the state tokens identifies the current state of the
resource, the server MAY perform the requested method.
If any of the tokens is not recognized then the method MUST fail
with a 412 Precondition Failed.
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Note that the "AND" and "OR" keywords specified with the If-State-
Match header are intentionally not defined for If-None-State-Match,
because this functionality is not required.
9.8. If-State-Match
If-State-Match = "If-State-Match" ":" ("AND" | "OR") 1#Coded-URL
The If-State-Match header is intended to have similar functionality
to the If-Match header defined in section 14.25 of RFC 2068.
However the If-State-Match header is intended for use with any URI
which represents state information about a resource. A typical
example is a lock token.
If the AND keyword is used and all of the state tokens identify the
state of the resource, then the server MAY perform the requested
method. If the OR keyword is used and any of the state tokens
identifies the current state of the resource, then the server MAY
perform the requested method. If the keyword requirement for the
the keyword used is not met, the server MUST NOT perform the
requested method, and MUST return a 412 Precondition Failed
response.
If any of the tokens is not recognized then the method MUST fail
with a 412 Precondition Failed.
9.9. Lock-Info Request Header
LockInfo = "Lock-Info" ":" DAVLockType SP DAVLockScope [SP
AdditionalLocks] [SP Lock-Tree]
DAVLockType = "LockType" "=" DAVLockTypeValue
DAVLockTypeValue = ("Write" | Extend)
DAVLockScope = "LockScope" "=" DAVLockScopeValue
DAVLockScopeValue = ("Exclusive" |"Shared" | Extend)
AdditionalLocks = "AddLocks" "=" 1*("<" URI ">")
Lock-Tree = "Lock-Tree" "=" ("T" | "F")
The Lock-Info request header specifies the scope and type of a lock
for a LOCK method request. The syntax specification below is
extensible, allowing new type and scope identifiers to be added.
The LockType field specifies the access type of the lock. At
present, this specification only defines one lock type, the "Write"
lock. The LockScope field specifies whether the lock is an
exclusive lock, or a shared lock. The AddLocks field specifies
additional URIs, beyond the Request-URI, to which the lock request
applies. The LockTree field is used to specify recursive locks. If
the LockTree field is "T", the lock request applies to the hierarchy
traversal of the internal member resources of the Request-URI, and
the AddLocks URIs, inclusive of the Request-URI and the AddLocks
URIs. It is not an error if LockTree is "T", and the Request-URI or
the AddLocks URIs have no internal member resources. By default,
INTERNET-DRAFT WebDAV November 19, 1997
the value of LockTree is "F", and this field MAY be omitted when its
value is "F".
9.10. Lock-Token Request Header
Lock-Token = "Lock-Token" ":" 1#Coded-URL
The Lock-Token request header, containing a lock token owned by the
requesting principal, is used by the principal to indicate that the
principal is aware of the existence of the lock specified by the
lock token.
If the following conditions are met:
1) The method is restricted by a lock type that requires the
submission of a lock token, such as a write lock,
2) The user-agent has authenticated itself as a principal,
3) The user-agent is submitting a method request to a resource on
which the principal owns a write lock,
Then:
1) The method request MUST include a Lock-Token header with the lock
token, or,
2) The method MUST fail with a 409 Conflict status code.
If multiple resources are involved with a method, such as a COPY or
MOVE method, then the lock tokens, if any, for all involved
resources, MUST be included in the Lock-Token request header.
For example, Program A, used by user A, takes out a write lock on a
resource. Program A then makes a number of PUT requests on the
locked resource. All the requests contain a Lock-Token request
header that includes the write lock state token. Program B, also
run by User A, then proceeds to perform a PUT to the locked
resource. However, program B was not aware of the existence of the
lock and so does not include the appropriate Lock-Token request
header. The method is rejected even though principal A is
authorized to perform the PUT. Program B can, if it so chooses, now
perform lock discovery and obtain the lock token. Note that
programs A and B can perform GETs without using the Lock-Token
header because the ability to perform a GET is not affected by a
write lock.
Having a lock token provides no special access rights. Anyone can
find out anyone else's lock token by performing lock discovery.
Locks are to be enforced based upon whatever authentication
mechanism is used by the server, not based on the secrecy of the
token values.
9.11. Lock-Token Response Header
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Lock-Token = "Lock-Token" ":" Coded-URL
If a resource is successfully locked then a Lock-Token header will
be returned containing the lock token that represents the lock.
9.12. Overwrite Header
Overwrite = "Overwrite" ":" ("T" | "F")
The Overwrite header specifies whether the server should overwrite
the state of a non-null destination resource during a COPY or MOVE.
A value of _F_ states that the server MUST NOT perform the COPY or
MOVE operation if the state of the destination resource is non-null.
By default, the value of Overwrite is _T,_ and a client MAY omit
this header from a request when its value is _T._ While the
Overwrite header appears to duplicate the functionality of the If-
Match: * header of HTTP/1.1, If-Match applies only to the Request-
URI, and not to the Destination of a COPY or MOVE.
If a COPY or MOVE is not performed due to the value of the Overwrite
header, the method MUST fail with a 409 Conflict status code.
9.13. Propfind Request Header
Propfind = "Propfind" ":" ("allprop" | "propname" | RFC-Reg |
1*(Property-Name))
The Propfind header is used to specify which properties are to be
returned in a PROPFIND method. The properties are identified by
their URIs. Two special tokens are defined for use with the
Propfind header, allprop and propname. The allprop token specifies
that all property names and values on the resource are to be
returned. The propname token specifies that only a list of property
names on the resource are to be returned.
9.14. Status-URI Response Header
The Status-URI response header MAY be used with the 102 Processing
response code to inform the client as to the status of a method.
Status-URI = "Status-URI" ":" *(Status-Code "<" URI ">") ; Status-
Code is defined in 6.1.1 of [Fielding et al., 1997]
The URIs listed in the header are source resources which have been
affected by the outstanding method. The status code indicates the
resolution of the method on the identified resource. So, for
example, if a MOVE method on a collection is outstanding and a 102
"Processing" response with a Status-URI response header is returned,
the included URIs will indicate resources that have had move
attempted on them and what the result was.
9.15. Timeout Header
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TimeOut = "Timeout" ":" 1#TimeType
TimeType = ("Second-" DAVTimeOutVal | "Infinite" | Other)
DAVTimeOutVal = 1*digit
Other = Extend field-value ; See section 4.2 of RFC 2068
Clients MAY include Timeout headers in their LOCK requests.
However, the server is not required to honor or even consider these
requests. Clients MUST NOT submit a Timeout request header with any
method other than a LOCK method.
A Timeout request header MUST contain at least one TimeType and MAY
contain multiple TimeType entries. The purpose of listing multiple
TimeType entries is to indicate multiple different values and value
types that are acceptable to the client. The client lists the
TimeType entries in order of preference.
The Timeout response header MUST use a Second value, Infinite, or a
TimeType the client has indicated familiarity with. The server MAY
assume a client is familiar with any TimeType submitted in a Timeout
header.
The _Second_ TimeType specifies the number of seconds that MUST
elapse between granting of the lock at the server, and the automatic
removal of the lock. A server MUST not generate a timeout value for
_Second_ greater than 2^32-1.
The timeout counter is restarted any time an owner of the lock sends
a method to any member of the lock, including unsupported methods,
or methods which are unsuccessful. It is recommended that the HEAD
method be used when the goal is simply to restart the timeout
counter.
If the timeout expires then the lock is lost. Specifically the
server SHOULD act as if an UNLOCK method was executed by the server
on the resource using the lock token of the timed-out lock,
performed with its override authority. Thus logs should be updated
with the disposition of the lock, notifications should be sent,
etc., just as they would be for an UNLOCK request.
Servers are advised to pay close attention to the values submitted
by clients, as they will be indicative of the type of activity the
client intends to perform. For example, an applet running in a
browser may need to lock a resource, but because of the instability
of the environment within which the applet is running, the applet
may be turned off without warning. As a result, the applet is
likely to ask for a relatively small timeout value so that if the
applet dies, the lock can be quickly harvested. However, a document
management system is likely to ask for an extremely long timeout
because its user may be planning on going off-line.
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10. Response Code Extensions to HTTP/1.1
The following response codes are added to those defined in HTTP/1.1
[Fielding et al., 1997].
10.1. 102 Processing
Methods can potentially take a long period of time to process,
especially methods that support the Depth header. In such cases the
client may time-out the connection while waiting for a response. To
prevent this the server MAY return a 102 response code to indicate
to the client that the server is still processing the method.
If a method is taking longer than 20 seconds (a reasonable, but
arbitrary value) to process the server SHOULD return a 102
"Processing" response.
10.2. 207 Multi-Status
The response requires providing status for multiple independent
operations.
10.3. 418 Unprocessable Entity
The server understands the content type of the request entity, but
was unable to process the contained instructions.
10.4. 419 Insufficient Space on Resource
The resource does not have sufficient space to record the state of
the resource after the execution of this method.
10.5. 420 Method Failure
The method was not executed on a particular resource within its
scope because some part of the method's execution failed causing the
entire method to be aborted. For example, if a resource could not
be moved as part of a MOVE method, all the other resources would
fail with a 420 Method Failure.
10.6. 421 Destination Locked
The destination resource of a method is locked, and either the
request did not contain a valid Lock-Info header, or the Lock-Info
header identifies a lock held by another principal.
11. Multi-Status Response
The default 207 Multi-Status response body is a text/xml HTTP entity
that contains a single XML element called multistatus, which
contains a set of XML elements called response, one for each 200,
INTERNET-DRAFT WebDAV November 19, 1997
300, 400, and 500 series status code generated during the method
invocation. 100 series status codes MUST NOT be recorded in a
response XML element.
11.1. multistatus XML Element
Name: multistatus
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains multiple response messages.
Parent: Any
Value: 1*response [responsedescription]
Description: The responsedescription at the top level is used to
provide a general message describing the overarching nature of the
response. If this value is available an application MAY use it
instead of presenting the individual response descriptions contained
within the responses.
11.2. response XML Element
Name: response
Namespace: http://www.ietf.org/standards/dav/
Purpose: Holds a single response
Parent: multistatus
Value: href [prop] status [responsedescription]
Description: Prop MUST contain one or more empty XML elements
representing the names of properties. Multiple properties may be
included if the same response applies to them all. If href is used
then the response refers to a problem with the referenced resource,
not a property.
11.3. status XML Element
Name: status
Namespace: http://www.ietf.org/standards/dav/
Purpose: Holds a single HTTP status-line
Parent: response
Value: status-line ;status-line defined in [Fielding et al.,
1997]
11.4. responsedescription XML Element
Name: responsedescription
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains a message that can be displayed to the user
explaining the nature of the response.
Parent: multistatus | response
Value: Any
Description: This XML element provides information suitable to be
presented to a user.
12. Generic DAV XML Elements
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12.1. href XML Element
Name: href
Namespace: http://www.ietf.org/standards/dav/
Purpose: To identify that the content of the element is a URI.
Parent: Any
Value: URI ; See section 3.2.1 of [Fielding et al., 1997]
12.2. link XML Element
Name: link
Namespace: http://www.ietf.org/standards/dav/
Purpose: To identify a property as a link and to contain the
source and destination of that link.
Values= 1*src 1*dst
Description: Link is used to provide the sources and destinations of
a link. The type of the property containing the link XML element
provides the type of the link. Link is a multi-valued element, so
multiple Links may be used together to indicate multiple links with
the same type.
12.2.1. src XML Element
Name: src
Namespace: http://www.ietf.org/standards/dav/
Purpose: To indicate the source of a link.
Parent: link
Values= URI
12.2.2. dst XML Element
Name: dst
Namespace: http://www.ietf.org/standards/dav/
Purpose: To indicate the destination of a link
Parent: link
Values= URI
12.2.3. Example
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" AS = "D"?>
<?namespace href = "http://www.foocorp.com/Project/" AS = "F"?>
<D:prop>
<D:Source>
<D:link>
<F:projfiles>Source</F:projfiles>
<D:src>http://foo.bar/program</D:src>
<D:dst>http://foo.bar/src/main.c</D:dst>
</D:link>
<D:link>
<F:projfiles>Library</F:projfiles>
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<D:src>http://foo.bar/program</D:src>
<D:dst>http://foo.bar/src/main.lib</D:dst>
</D:link>
<D:link>
<F:projfiles>Makefile</F:projfiles>
<D:src>http://foo.bar/program</D:src>
<D:dst>http://foo.bar/src/makefile</D:dst>
</D:link>
</D:Source>
</D:prop>
In this example the resource http://foo.bar/program has a source
property that contains three links. Each link contains three
elements, two of which, src and dst, are part of the DAV schema
defined in this document, and one which is defined by the schema
http://www.foocorp.com/project/ (Source, Library, and Makefile). A
client which only implements the elements in the DAV spec will not
understand the foocorp elements and will ignore them, thus seeing
the expected source and destination links. An enhanced client may
know about the foocorp elements and be able to present the user with
additional information about the links. This example demonstrates
the power of XML markup that allows for element values to be
enhanced without breaking older clients.
12.3. prop XML element
Name: prop
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains properties related to a resource.
Parent: Any
Values: XML Elements
Description: The prop XML element is a generic container for
properties defined on resources. All elements inside prop MUST
define properties related to the resource. No other elements may be
used inside of a prop element.
13. DAV Properties
13.1. creationdate Property
Name: creationdate
Namespace: http://www.ietf.org/standards/dav/
Purpose: The time and date the resource was created.
Value: The time and date MUST be given in ISO 8601 format
[ISO8601]
Description: This property SHOULD be defined on all DAV compliant
resources. If present, it contains a timestamp of the moment when
the resource was created (i.e., the moment it had non-null state).
13.2. displayname Property
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Name: displayname
Namespace: http://www.ietf.org/standards/dav/
Purpose: A name for the resource that is suitable for
presentation to a user.
Value: Any valid XML character data (as defined in [Bray,
Sperberg-McQueen, 1997])
Description:This property SHOULD be defined on all DAV compliant
resources. If present, the property contains a description of the
resource that is suitable for presentation to a user.
13.3. get-content-language Property
Name: get-content-language
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Content-Language header returned by a GET
without accept headers. If no Content-Language header is available,
this property MUST NOT exist.
Value: language-tag ;language-tag is defined in section 14.13
of RFC 2068
13.4. get-content-length Property
Name: get-content-length
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Content-Length header returned by a GET
without accept headers. If no Content-Length header is available,
this property MUST NOT exist.
Value: content-length ; see section 14.14 of RFC 2068
13.5. get-content-type Property
Name: get-content-type
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Content-Type header returned by a GET
without accept headers. If no Content-Type header is available,
this property MUST NOT exist.
Value: media-type ; defined in Section 3.7 of [Fielding et
al., 1997]
13.6. get-etag Property
Name: get-etag
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the ETag header returned by a GET without
accept headers. If no ETag header is available, this property MUST
NOT exist.
Value: entity-tag ; defined in Section 3.11 of [Fielding et
al., 1997]
Description:Note that the ETag on some resource may reflect changes
in any part of the state of the resource, not necessarily just a
change to the response to the GET method. For example, a change in
the ACL may cause the ETag to change.
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13.7. get-last-modified Property
Name: get-last-modified
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Last-Modified header returned by a GET
method without accept headers. If no Last-Modified header is
available, this property MUST NOT exist.
Value: HTTP-date ; defined in Section 3.3.1 of [Fielding et
al., 1997]
Description:Note that the last-modified date on some resource may
reflect changes in any part of the state of the resource, not
necessarily just a change to the response to the GET method. For
example, a change in a property may cause the last-modified date to
change.
13.8. index-content-language Property
Name: index-content-language
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Content-Language header returned by an
INDEX without accept headers. If no Content-Language header is
available, this property MUST NOT exist.
Value: language-tag ;language-tag is defined in section 14.13
of RFC 2068
13.9. index-content-length Property
Name: index-content-length
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Content-Length header returned by an INDEX
without accept headers. If no Content-Length header is available,
this property MUST NOT exist.
Value: content-length ; see section 14.14 of RFC 2068
13.10. index-content-type Property
Name: index-content-type
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Content-Type header returned by an INDEX
without accept headers. If no Content-Type header is available,
this property MUST NOT exist.
Value: media-type ; defined in Section 3.7 of [Fielding et
al., 1997]
13.11. index-etag Property
Name: index-etag
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the ETag header returned by an INDEX without
accept headers. If no ETag header is available, this property MUST
NOT exist.
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Value: entity-tag ; defined in Section 3.11 of [Fielding et
al., 1997]
Description:Note that the ETag on some resource may reflect changes
in any part of the state of the resource, not necessarily just a
change to the response to the INDEX method. For example, a change
in the ACL may cause the ETag to change.
13.12. index-last-modified Property
Name: index-last-modified
Namespace: http://www.ietf.org/standards/dav/
Purpose: Contains the Last-Modified header returned by an INDEX
method without accept headers. If no Last-Modified header is
available, this property MUST NOT exist.
Value: HTTP-date ; defined in Section 3.3.1 of [Fielding et
al., 1997]
Description:Note that the last-modified date on some resource may
reflect changes in any part of the state of the resource, not
necessarily just a change to the response to the INDEX method. For
example, a change in a property may cause the last-modified date to
change.
13.13. lockdiscovery Property
Name: lockdiscovery
Namespace: http://www.ietf.org/standards/dav/
Purpose: To discover what locks are active on a resource
Values= *activelock
Description:The lockdiscovery property returns a listing of who has
a lock, what type of lock he have, the timeout type and the time
remaining on the timeout, and the associated lock token. The server
is free to withhold any or all of this information if the requesting
principal does not have sufficient access rights to see the
requested data. A server which supports locks MUST provide the
lockdiscovery property on any resource with locks on it.
13.13.1. activelock XML Element
Name: activelock
Namespace: http://www.ietf.org/standards/dav/
Purpose: A multivalued XML element that describes a particular
active lock on a resource
Parent: lockdiscovery
Values= locktype lockscope [addlocks] owner timeout locktoken
13.13.2. owner XML Element
Name: owner
Namespace: http://www.ietf.org/standards/dav/
Purpose: Returns owner information
Parent: activelock
Values= XML:REF | *PCDATA
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13.13.3. timeout XML Element
Name: timeout
Namespace: http://www.ietf.org/standards/dav/
Purpose: Returns information about the timeout associated with
the lock
Parent: activelock
Values= TimeType
13.13.4. addlocks XML Element
Name: addlocks
Namespace: http://www.ietf.org/standards/dav/
Purpose: Lists additional resources associated with this lock, if
any.
Parent: activelock
Values= 1*href
13.13.5. locktoken XML Element
Name: locktoken
Namespace: http://www.ietf.org/standards/dav/
Purpose: Returns the lock token
Parent: activelock
Values= href
Description:The href contains a Lock-Token-URL.
13.13.6. Example
PROPFIND /container/ HTTP/1.1
Host: www.foo.bar
Content-Length: xxxx
Content-Type: text/xml
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" AS = "D"?>
<D:propfind>
<D:prop><lockdiscovery/></D:prop>
</D:propfind>
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href ="http://www.ietf.org/standards/dav/" AS = "D"?>
<D:multistatus>
<D:response>
<D:prop>
<D:lockdiscovery>
<D:activelock>
INTERNET-DRAFT WebDAV November 19, 1997
<D:locktype>write</D:locktype>
<D:lockscope>exclusive</D:lockscope>
<D:addlocks>
<D:href>http://foo.com/doc/</D:href>
</D:addlocks>
<D:owner>Jane Smith</D:owner>
<D:timeout>Infinite</D:timeout>
<D:locktoken>
<D:href>iamuri:unique!!!!!</D:href>
</D:locktoken>
</D:activelock>
</D:lockdiscovery>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:response>
</D:multistatus>
This resource has a single exclusive write lock on it, with an
infinite timeout. This same lock also covers the resource
http://foo.com/doc/.
13.14. resourcetype Property
Name: resourcetype
Namespace: http://www.ietf.org/standards/dav/
Purpose: This property contains a series of XML elements that
specify information regarding the nature of the resource. This
specification only defines a single value, collection.
Value: XML elements
Description:This property MUST be defined on all DAV compliant
resources. The default value is empty.
13.14.1. collection XML Element
Name: collection
Namespace: http://www.ietf.org/standards/dav/
Purpose: Identifies the associated resource as a collection.
Collection resources MUST define this value with the resourcetype
property.
Parent: resourcetype
Values: None
13.15. Source Link Property Type
Name: source
Namespace: http://www.ietf.org/standards/dav/link/
Purpose: The destination of the source link identifies the
resource that contains the unprocessed source of the link's source.
Parent: None
Value: An XML document with zero or more link XML elements.
INTERNET-DRAFT WebDAV November 19, 1997
Discussion: The source of the link (src) is typically the URI of the
output resource on which the link is defined, and there is typically
only one destination (dst) of the link, which is the URI where the
unprocessed source of the resource may be accessed. When more than
one link destination exists, this specification asserts no policy on
ordering.
13.16. supportedlock Property
Name: supportedlock
Namespace: http://www.ietf.org/standards/dav/
Purpose: To provide a listing of the lock capabilities supported
by the resource.
Values: An XML document containing zero or more LockEntry XML
elements.
Description:The supportedlock property of a resource returns a
listing of the combinations of scope and access types which may be
specified in a lock request on the resource. Note that the actual
contents are themselves controlled by access controls so a server is
not required to provide information the client is not authorized to
see. If supportedlock is available on _*_ then it MUST define the
set of locks allowed on all resources on that server.
13.16.1. lockentry XML Element
Name: lockentry
Namespace: http://www.ietf.org/standards/dav/
Purpose: Defines a DAVLockType/LockScope pair that may be legally
used with a LOCK on the specified resource.
Parent: supportedlock
Values= locktype lockscope
13.16.2. locktype XML Element
Name: locktype
Namespace: http://www.ietf.org/standards/dav/
Purpose: Lists a DAVLockType
Parent: lockentry
Values= DAVLockTypeValue
13.16.3. lockscope XML Element
Name: lockscope
Namespace: http://www.ietf.org/standards/dav/
Purpose: Lists a DAVLockScope
Parent: lockentry
Values: DAVLockScopeValue
13.16.4. Example
PROPFIND /container/ HTTP/1.1
Host: www.foo.bar
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Content-Length: xxxx
Content-Type: text/xml
<?XML version="1.0">
<?namespace href = "http://www.ietf.org/standards/dav/" AS = "D"?>
<D:propfind>
<D:prop><supportedlock/></D:prop>
</D:propfind>
HTTP/1.1 207 Multi-Status
Content-Type: text/xml
Content-Length: xxxxx
<?XML version="1.0">
<?namespace href ="http://www.ietf.org/standards/dav/" AS = "D"?>
<D:multistatus>
<D:response>
<D:prop>
<D:supportedlock>
<D:LockEntry>
<D:locktype>Write</D:locktype>
<D:lockscope>Exclusive</D:lockscope>
</D:LockEntry>
<D:LockEntry>
<D:locktype>Write</D:locktype>
<D:lockscope>Shared</D:lockscope>
</D:LockEntry>
</D:supportedlock>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:response>
</D:multistatus>
14. DAV Compliance Levels
A DAV compliant resource can choose from two levels of compliance.
A client can discover which level a resource supports by executing
OPTIONS on the resource, and examining the "DAV" header which is
returned.
Since this document describes extensions to the HTTP/1.1 protocol,
minimally all DAV compliant resources, clients, and proxies MUST be
compliant with RFC 2068 [Fielding et al., 1997].
14.1. Level 1
A level 1 compliant resource MUST meet all "MUST" requirements in
all sections of this document.
14.2. Level 2
INTERNET-DRAFT WebDAV November 19, 1997
A level 2 compliant resource MUST meet all level 1 requirements and
support the supportedlock property as well as the LOCK method.
15. Internationalization Considerations
In the realm of internationalization issues, this specification is
substantively in compliance with the IETF Character Set Policy
[Alvestrand, 1997]. In this specification, human-readable fields can
be found in either the value of a property, or in an error message
returned in a response entity body. In both cases, the human-
readable content is encoded using XML, which has explicit provisions
for character set tagging and encoding, and requires by default that
XML processors read XML elements encoded using the UTF-8 and UCS-2
encodings of the ISO 10646 basic multilingual plane. Furthermore,
XML contains provisions for encoding XML elements using other
encoding schemes, notable among them UCS-4, which permits encoding
of characters from any ISO 10646 character plane.
The default character set encoding for XML data in this
specification, and in general, is UTF-8. WebDAV compliant
applications MUST support the UTF-8 and UCS-2 character set
encodings for XML elements, and SHOULD support the UCS-4 encoding.
The XML character set encoding declaration for each supported
character set MUST also be supported, since it is by using this
encoding declaration that an XML processor determines the encoding
of an element.
XML also provides language tagging capability which provides the
ability to specify the language of the contents of a particular XML
element. Although XML, and hence WebDAV, does not use RFC 1766
language tags for its language names, the benefit of using standard
XML in this context outweighs the advantage of using RFC 1766
language tags.
Names used within this specification fall into two categories: names
specific to protocol elements such as methods and headers, names of
XML elements, and names of properties. Naming of protocol elements
follows the precedent of HTTP, using English names encoded in
USASCII for methods and headers. Since these protocol elements are
not visible to users, and are in fact simply long token identifiers,
they do not need to support encoding in multiple character sets.
Similarly, though the names of XML elements used in this
specification are English names encoded in UTF-8, these names are
not visible to the user, and hence do not need to support multiple
character set encodings.
The name of a property defined on a resource is a URI. Although
some applications (e.g., a generic property viewer) will display
property URIs directly to their users, it is expected that the
typical application will use a fixed set of properties, and will
provide a mapping from the property name URI to a human-readable
INTERNET-DRAFT WebDAV November 19, 1997
field when displaying the property name to a user. It is only in
the case where the set of properties is not known ahead of time that
an application need display a property name URI to a user. We
recommend that applications provide human-readable property names
wherever feasible.
For error reporting, we follow the convention of HTTP/1.1 status
codes, including with each status code a short, English description
of the code (e.g., 421 Destination Locked). While the possibility
exists that a poorly crafted user agent would display this message
to a user, internationalized applications will ignore this message,
and display an appropriate message in the user's language and
character set.
Since interoperation of clients and servers does not require locale
information, this specification does not specify any mechanism for
transmission of this information.
16. Security Considerations
[TBD]
17. Terminology
Collection - A resource that contains member resources.
Member Resource - A resource contained by a collection. There are
two types of member resources: external and internal.
Internal Member Resource _ A member resource of a collection whose
URI is relative to the URI of the collection.
External Member Resource - A member resource of a collection with an
absolute URI that is not relative to its parent's URI.
Property - A name/value pair that contains descriptive information
about a resource.
Live Property _ A property whose semantics and syntax are enforced
by the server. For example, a live "content-length" property would
have its value, the length of the entity returned by a GET request,
automatically calculated by the server.
Dead Property _ A property whose semantics and syntax are not
enforced by the server. The server only records the value of a dead
property; the client is responsible for maintaining the consistency
of the syntax and semantics of a dead property.
18. Copyright
INTERNET-DRAFT WebDAV November 19, 1997
The following copyright notice is copied from RFC 2026 chapter 10.4,
and describes the applicable copyright for this document
Copyright (C) The Internet Society November 19, 1997. All Rights
Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
19. Acknowledgements
A specification such as this thrives on piercing critical review and
withers from apathetic neglect. The authors gratefully acknowledge
the contributions of the following people, whose insights were so
valuable at every stage of our work.
Terry Allen, Harald Alvestrand, Alan Babich, Dylan Barrell, Bernard
Chester, Tim Berners-Lee, Dan Connolly, Jim Cunningham, Ron Daniel,
Jr., Jim Davis, Keith Dawson, Mark Day, Martin Duerst, David Durand,
Lee Farrell, Chuck Fay, Roy Fielding, Mark Fisher, Alan Freier,
George Florentine, Jim Gettys, Phill Hallam-Baker, Dennis Hamilton,
Steve Henning, Alex Hopmann, Andre van der Hoek, Ben Laurie, Paul
Leach, Ora Lassila, Karen MacArthur, Steven Martin, Larry Masinter,
Michael Mealling, Keith Moore, Henrik Nielsen, Kenji Ota, Bob
Parker, Glenn Peterson, Jon Radoff, Saveen Reddy, Henry Sanders,
Christopher Seiwald, Judith Slein, Mike Spreitzer, Einar Stefferud,
Ralph Swick, Kenji Takahashi, Richard N. Taylor, Robert Thau, John
Turner, Sankar Virdhagriswaran, Fabio Vitali, Gregory Woodhouse, and
Lauren Wood.
INTERNET-DRAFT WebDAV November 19, 1997
One from this list deserves special mention. The contributions by
Larry Masinter have been invaluable, both in helping the formation
of the working group and in patiently coaching the authors along the
way. In so many ways he has set high standards we have toiled to
meet.
INTERNET-DRAFT WebDAV November 19, 1997
20. References
[Alvestrand, 1997] H. T. Alvestrand, "IETF Policy on Character Sets
and Languages." Internet-draft, work-in-progress.
ftp://ds.internic.net/internet-drafts/draft-alvestrand-charset-
policy-02.txt
[Berners-Lee, 1997] T. Berners-Lee, "Metadata Architecture."
Unpublished white paper, January 1997.
http://www.w3.org/pub/WWW/DesignIssues/Metadata.html.
[Bradner, 1997] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels." RFC 2119, BCP 14. Harvard University. March,
1997.
[Bray, Sperberg-McQueen, 1997] T. Bray, C. M. Sperberg-McQueen,
"Extensible Markup Language (XML): Part I. Syntax", WD-xml-
lang.html, http://www.w3.org/pub/WWW/TR/WD-xml-lang.html.
[Fielding et al., 1997] R. Fielding, J. Gettys, J. Mogul, H.
Frystyk, T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1."
RFC 2068. U.C. Irvine, DEC, MIT/LCS. January, 1997.
ftp://ds.internic.net/rfc/rfc2068.txt
[Lasher, Cohen, 1995] R. Lasher, D. Cohen, "A Format for
Bibliographic Records," RFC 1807. Stanford, Myricom. June, 1995.
ftp://ds.internic.net/rfc/rfc1807.txt
[Leach, Salz, 1997] P. J. Leach, R. Salz, "UUIDs and GUIDs."
Internet-draft (expired), work-in-progress, February, 1997.
http://www.internic.net/internet-drafts/draft-leach-uuids-guids-
00.txt
[Maloney, 1996] M. Maloney, "Hypertext Links in HTML." Internet
draft (expired), work-in-progress, January, 1996.
[MARC, 1994] Network Development and MARC Standards, Office, ed.
1994. "USMARC Format for Bibliographic Data", 1994. Washington, DC:
Cataloging Distribution Service, Library of Congress.
[Miller et al., 1996] J. Miller, T. Krauskopf, P. Resnick, W.
Treese, "PICS Label Distribution Label Syntax and Communication
Protocols" Version 1.1, W3C Recommendation REC-PICS-labels-961031.
http://www.w3.org/pub/WWW/TR/REC-PICS-labels-961031.html.
[Slein et al., 1997] J. A. Slein, F. Vitali, E. J. Whitehead, Jr.,
D. Durand, "Requirements for Distributed Authoring and Versioning
Protocol for the World Wide Web." RFC XXXX. Xerox, Univ. of Bologna,
U.C. Irvine, Boston Univ. YYY, 1997.
ftp://ds.internic.net/rfc/rfcXXXX.txt
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[WebDAV, 1997] WEBDAV Design Team. "A Proposal for Web Metadata
Operations." Unpublished manuscript.
http://www.ics.uci.edu/~ejw/authoring/proposals/metadata.html
[Weibel et al., 1995] S. Weibel, J. Godby, E. Miller, R. Daniel,
"OCLC/NCSA Metadata Workshop Report."
http://purl.oclc.org/metadata/dublin_core_report.
[Yergeau, 1997] F. Yergeau, "UTF-8, a transformation format of
Unicode and ISO 10646", Internet Draft, work-in-progress, draft-
yergeau-utf8-rev-00.txt, http://www.internic.net/internet-
drafts/draft-yergeau-utf8-rev-00.txt.
INTERNET-DRAFT WebDAV November 19, 1997
21. Authors' Addresses
Y. Y. Goland
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
Email: yarong@microsoft.com
E. J. Whitehead, Jr.
Dept. Of Information and Computer Science
University of California, Irvine
Irvine, CA 92697-3425
Email: ejw@ics.uci.edu
A. Faizi
Netscape
685 East Middlefield Road
Mountain View, CA 94043
Email: asad@netscape.com
S. R. Carter
Novell
1555 N. Technology Way
M/S ORM F111
Orem, UT 84097-2399
Email: srcarter@novell.com
D. Jensen
Novell
1555 N. Technology Way
M/S ORM F111
Orem, UT 84097-2399
Email: dcjensen@novell.com
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