Web Distributed Authoring and Versioning is an extension of the Hypertext Transfer Protocol
that facilitates collaboration between users in editing and managing documents and files
stored on World Wide Web servers.
A working group of the Internet Engineering Task Force defined WebDAV in RFC 4918.
The WebDAV protocol makes the Web a readable and writable medium.
It provides a framework for users to create, change and move documents on a server; typically
a web server or web share.
The most important features of the WebDAV protocol include the maintenance of properties
about an author or modification date, namespace management, collections, and overwrite protection.
Maintenance of properties includes such things as the creation, removal, and querying of
file information.
Namespace management deals with the ability to copy and move web pages within a server’s
namespace.
Collections deal with the creation, removal, and listing of various resources.
Lastly, overwrite protection handles aspects related to locking of files.
The WebDAV working group concluded its work in March 2007, after the Internet Engineering
Steering Group accepted an incremental update to RFC 2518.
Other extensions left unfinished at that time, such as the BIND method, have been finished
by their individual authors, independent of the formal working group.
Many modern operating systems provide built-in client-side support for WebDAV.
History WebDAV began in 1996 when Jim Whitehead, a
PhD graduate from UC Irvine, worked with the World Wide Web Consortium to host two meetings
to discuss the problem of distributed authoring on the World Wide Web with interested people.
Tim Berners-Lee's original vision of the Web was that of a medium for both reading and
writing.
In fact, Berners-Lee's first web browser, called WorldWideWeb, was able to both view
and edit web pages; but, as the Web grew, it became a read-only medium for most users.
Whitehead and other like-minded people wanted to fix that limitation.
The W3C meeting decided to form an IETF working group, because the new effort would lead to
extensions to HTTP, which was being standardized at the IETF.
As work began on the protocol, it became clear that handling both distributed authoring and
versioning would involve too much work and that the tasks would have to be separated.
The WebDAV group focused on distributed authoring, and left versioning for the future.
Versioning was added later by the Delta-V extension — see the Extensions section below.
The protocol consists of a set of new methods and headers for use in HTTP.
The added methods include: PROPFIND — used to retrieve properties,
stored as XML, from a web resource.
It is also overloaded to allow one to retrieve the collection structure of a remote system.
PROPPATCH — used to change and delete multiple properties on a resource in a single atomic
act MKCOL — used to create collections
COPY — used to copy a resource from one URI to another
MOVE — used to move a resource from one URI to another
LOCK — used to put a lock on a resource.
WebDAV supports both shared and exclusive locks.
UNLOCK — used to remove a lock from a resource Implementations
Servers The cross-platform Apache HTTP Server provides
WebDAV modules based on both davfs and Apache Subversion.
Microsoft's IIS also has a WebDAV module.
Cloud services like Box, DriveHQ and OneDrive support WebDAV.
Clients Linux users can mount WebDAV shares using
the davfs2 and the fusedav file system modules which mount them as Coda or FUSE filesystems.
KDE has native WebDAV support as part of kio_http.
This enables the file managers Dolphin & Konqueror, and every other KDE application to interact
directly with WebDAV servers.
All applications using the GIO library, including the Nautilus file manager, have access to
WebDAV through GNOME Virtual File System.
Many Linux distributions also include the cadaver command-line client interface, which
provides an FTP-like command set.
Mac OS X version 10.0 and following support WebDAV shares natively as a type of filesystem.
The system can mount WebDAV-enabled server directories to the filesystem using the traditional
BSD mounting mechanism or through the "Connect to Server" dialog found in the Finder.
Mac OS X version 10.1.1 introduced support for HTTP Digest Access authentication.
Mac OS X 10.4 extended WebDAV interoperability to include support for the HTTPS scheme, proxies,
and additional methods of authentication.
The Finder presents a WebDAV share as an external disk, allowing users to interact with WebDAV
just as they would with any other filesystem.
Apple's iDisk, part of its former MobileMe service, used WebDAV for file access.
Microsoft introduced WebDAV client support in Microsoft Windows 98 with a feature called
"Web folders".
This client consisted of an OLE object which could be accessed by any OLE software, and
was installed as an extension to Windows Explorer and was later included in Windows 2000.
In Windows XP, Microsoft added the Web Client service also known as the WebDAV mini-redirector
which is preferred by default over the old Web folders client.
This newer client works as a system service at the network-redirector level, allowing
WebDAV shares to be assigned to a drive letter and used by any software.
The redirector also allows WebDAV shares to be addressed via UNC paths for compatibility
with Windows filesystem APIs.
Some versions of the redirector are reported to have some limitations in authentication
support.
In addition, WebDAV over HTTPS works only if a computer has KB892211-version files or
newer installed.
Otherwise Windows displays "The folder you entered does not appear to be valid.
Please choose another" when adding a network resource.
NOTE: 892211 has been superseded by KB907306.
Windows Vista includes only the WebDAV redirector, but if you install a version of Office, Internet
Explorer, OLE-DB or "Microsoft Update for Web Folders" you will get the original "Web
folders" client.
The update will only work on the 32-bit version of XP/Vista.
Microsoft states that 64 bit versions of Windows will never support the "Web folders" client.
Instead users are limited to using WebDAV via the native Web Client service redirector.
Alternatives to WebDAV File Transfer Protocol, a simple network protocol
based on IP, allows users to transfer files between network hosts.
FTPS extends FTP for secure traffic.
SSH File Transfer Protocol, an extension of the Secure Shell protocol version 2.0, provides
secure file-transfer capability A distributed file system such as the Server
Message Block protocol allows Microsoft Windows and open-source Samba clients to access and
manage files and folders remotely on a suitable file server
AtomPub, an HTTP-based protocol for creating and updating web resources, can be used for
some of the use cases of WebDAV.
It is based on standard HTTP verbs with standardized collection resources that behave somewhat
like the WebDAV model of directories.
CMIS, a standard consisting of a set of Web services for sharing information among disparate
content repositories, seeks to ensure interoperability for people and applications using multiple
content repositories; it has both SOAP- and AtomPub-based interfaces
Documents produced by the working group The WebDAV working group produced several
works: a requirements document: "Requirements for
a Distributed Authoring and Versioning Protocol for the World Wide Web" RFC 2291, issued February
1998 a base protocol document: "HTTP Extensions
for Web Distributed Authoring and Versioning" RFC 4918, issued June 2007
the ordered collections protocol: "Web Distributed Authoring and Versioning Ordered Collections
Protocol" RFC 3648, issued December 2003 the access control protocol: "Web Distributed
Authoring and Versioning Access Control Protocol" RFC 3744, issued May 2004
a quota specification: "Quota and Size Properties for Distributed Authoring and Versioning Collections"
RFC 4331, issued February 2006 a redirect specification: "Web Distributed
Authoring and Versioning Redirect Reference Resources" RFC 4437, issued March 2006
Other documents published through IETF the versioning protocol: "Versioning Extensions
to WebDAV" RFC 3253 a specification of WebDAV property datatypes:
"Datatypes for Web Distributed Authoring and Versioning Properties" RFC 4316
a document defining how to initiate mounting of a WebDAV resource: "Mounting Web Distributed
Authoring and Versioning Servers" RFC 4709 a calendar access protocol: "Calendaring Extensions
to WebDAV" RFC 4791 a query protocol: "Web Distributed Authoring
and Versioning SEARCH" RFC 5323 an extension to the WebDAV ACL specification:
"WebDAV Current Principal Extension" RFC 5397 an extension to the WebDAV MKCOL method: "Extended
MKCOL for Web Distributed Authoring and Versioning" RFC 5689
an extension of the collection model, defining creation and discovery of additional bindings
to a resource: "Binding Extensions to Web Distributed Authoring and Versioning" RFC
5842 an application of POST to WebDAV collections:
"Using POST to Add Members to Web Distributed Authoring and Versioning Collections" RFC
5995 an extension which allows synchronizing large
collections efficiently: "Collection Synchronization for Web Distributed Authoring and Versioning"
RFC 6578 Extensions and derivatives
For versioning, the Delta-V protocol under the Web Versioning and Configuration Management
working group adds resource revision tracking, published in RFC 3253.
For searching and locating, the DAV Searching and Locating working group never produced
any official standard although there are a number of implementations of its last draft.
Work continued as non-working-group activity.
The WebDAV Search specification attempts to pick up where the working group left off,
and was published as RFC 5323 in November 2008.
For calendaring, CalDAV is a protocol allowing calendar access via WebDAV.
CalDAV models calendar events as HTTP resources in iCalendar format, and models calendars
containing events as WebDAV collections.
For groupware, GroupDAV is a variant of WebDAV which allows client/server groupware systems
to store and fetch objects such as calendar items and address book entries instead of
web pages.
For MS Exchange interoperability, WebDAV can be used for readingdeleting items in a mailbox
or public folder.
WebDAV for Exchange has been extended by Microsoft to accommodate working with messaging data.
Exchange Server version 2000, 2003, and 2007 support WebDAV.
However, WebDAV support has been discontinued in Exchange 2010 in favor of Exchange Web
Services, a SOAP/XML based API.
Additional Windows-specific extensions As part of the Windows Server Protocols documentation
set, Microsoft published the following protocol documents detailing extensions to WebDAV:
[MS-WDVME]: Web Distributed Authoring and Versioning Protocol: Microsoft Extensions.
These extensions include a new verb and new headers, and properties that enable previously
unmanageable file types and optimize protocol interactions for file system clients.
These extensions introduce new functionality into WebDAV, optimize processing, and eliminate
the need for special-case processing.
[MS-WDV]: Web Distributed Authoring and Versioning Protocol: Client Extensions.
The client extensions in this specification extend the WebDAV Protocol by introducing
new headers that both enable the file types that are not currently manageable and optimize
protocol interactions for file system clients.
These extensions do not introduce new functionality into the WebDAV Protocol, but instead optimize
processing and eliminate the need for special-case processing.
[MS-WDVSE]: Web Distributed Authoring and Versioning Protocol: Server Extensions.
The server extensions in this specification extend WebDAV by introducing new HTTP request
and response headers that both enable the file types that are not currently manageable
and optimize protocol interactions for file system clients.
This specification also introduces a new WebDAV method that is used to send search queries
to disparate search providers.
[MS-WEBDAVE]: Web Distributed Authoring and Versioning Error Extensions Protocol Specification.
This SharePoint Front-End Protocol describes extended error codes and extended error handling
mechanism specified in [MS-WDV] to enable compliant servers to report error condition
details on a server response.
See also CalDAV
CardDAV GroupDAV
Content management Distributed file system
Filing OSID ICE
References
External links WebDAV Resources
Davfs2 project Fusedav project
WebDAV Apache modules