WebDAV
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WebDAV is an Internet Engineering Task Force working group. The abbreviation stands for Web-based Distributed Authoring and Versioning. The term is also used to refer to the protocol (more accurately, the extension to the HTTP protocol) which the group defined.
WebDAV started life when Jim Whitehead convinced the W3C to host two meetings where people interested in the problem of distributed authoring on the World Wide Web could get together to discuss possible solutions. The original vision of the World Wide Web as expounded by Tim Berners-Lee was a both readable and writable medium. In fact Tim's first web browser, called WorldWideWeb, was capable of both viewing and editing remote pages. However as the web grew it turned itself into a read only medium. Jim and other like minded people wanted to fix that limitation.
The group of people meeting at the W3C decided that the best way to proceed was to form an IETF working group. The IETF seemed a natural choice as the HTTP protocol was being standardized there and it was assumed that the output of this effort would consist of extensions to that protocol.
As work began on the protocol it became clear that handling both distributed authoring and versioning was just too much and that the tasks would have to be separated. The WebDAV working group therefore decided to just focus on distributed authoring and leave versioning for the future. In fact members commonly joked that the group should properly be called WebDA.
The WebDAV working group has to date produced several outputs:
- a requirements document: "Requirements for a Distributed Authoring and Versioning Protocol for the World Wide Web" RFC 2291 (http://www.ietf.org/rfc/rfc2291.txt),
- a base protocol document: "HTTP Extensions for Distributed Authoring -- WEBDAV" RFC 2518 (http://www.ietf.org/rfc/rfc2518.txt),
- the ordered collections protocol: "Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol" RFC 3648 (http://www.ietf.org/rfc/rfc3648.txt) and
- the access control protocol: "Web Distributed Authoring and Versioning (WebDAV) Access Control Protocol" RFC 3744 (http://www.ietf.org/rfc/rfc3744.txt).
The protocol consists of a set of new methods and headers for use in HTTP and has the distinction of almost certainly being the first protocol ever to use XML.
WebDAV added the following methods to HTTP:
- PROPFIND - Used to retrieve properties, persisted as XML, from a resource. It is also overloaded to allow one to retrieve the collection structure (a.k.a. directory hierarchy) 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 (a.k.a. directory)
- 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 - To remove a lock from a resource
Resource is HTTP's name for a referent: that which is pointed to by a URI.
The WebDAV working group is still working on a number of extensions to WebDAV including - redirection control, bindings, etc.
The WebDAV working group spawned other IETF working groups including the DAV Searching and Locating (DASL) working group and the Web Versioning and Configuration Management (DELTAV) working group.
DASL never produced any official standard although there are a number of implementations of its last draft (work continues as non-working-group activity, see DASL (http://www.webdav.org/dasl)).
DELTAV produced the Versioning Extensions to WebDAV RFC 3253 (http://www.ietf.org/rfc/rfc2353.txt) which put the V back into WebDAV.
The WebDAV Home Page (http://www.webdav.org) contains up-to-date information about implementations of WebDAV and WebDAV related standards efforts.
Software supporting WebDAV
- I(2) Drive WebDAV Server
- Apache HTTP Server
- davfs2
- GanttProject
- Jakarta Slide (also RFC3253, RFC3744)
- Jakarta Tomcat
- Jigsaw
- Kiwi (software)
- Microsoft Exchange
- Microsoft IIS
- OSAF Chandler
- Plone
- SAP Netweaver (Knowledge Management) (also RFC3253, RFC3648, RFC3744)
- Subversion (including versioning (checkout-merge-checkin)!)
- Virtuoso Universal Server (http://virtuoso.openlinksw.com/)
- Xythos WebFile Server and WebFile Client (also RFC3253, RFC3744)
- Zope
See also
External links
- WebDAV Resources (http://webdav.org/)
- Mailing List (http://lists.w3.org/Archives/Public/w3c-dist-auth/)
- Software Overview (http://webdav.org/projects/)
- RFCs
- Requirements (http://www.ietf.org/rfc/rfc2291.txt)
- HTTP Extensions (http://www.ietf.org/rfc/rfc2518.txt)
- Versioning Extensions (http://www.ietf.org/rfc/rfc3253.txt)
- Ordered Collections (http://www.ietf.org/rfc/rfc3648.txt)
- Access Control Protocol (http://www.ietf.org/rfc/rfc3744.txt)
- IETF Working Group (http://www.ietf.org/html.charters/webdav-charter.html) [1] (http://ftp.ics.uci.edu/pub/ietf/webdav/)
- Jim Whitehead (http://www.cse.ucsc.edu/~ejw/)
- Content Repository for Java™ technology API (http://jcp.org/en/jsr/detail?id=170)da:WebDAV
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