WebDAV (Web-based Distributed Authoring and Versioning) extends the Hypertext Transfer Protocol (HTTP) to support asynchronous collaborative authoring on the Web.

As the standard protocol that allows Web browsers to communicate with Web servers, HTTP transformed the Web into a readable medium by allowing users to view and download individual static documents as read-only information. However, HTTP falls short of supporting write operations such as simultaneous editing of multiple resources on the Web.

WebDAV goes the next step by providing extensions to HTTP that create a distributed writable Web environment. Using WebDAV, multiple users can create content locally or remotely using WebDAV-enabled authoring tools, then save content directly to an URL on an HTTP server. For example, it provides a means to access not only an item's contents but also an extensible set of associated properties. The protocol also defines methods used to move, copy, delete, and make collections of items as well as check-in/check-out of resources. The encoding format used to transfer item properties across the network is the Extensible Markup Language (XML), defined in the World Wide Web Consortium Recommendation REC-xml-19980210.

A good intro on WebDAV is available from Microsoft : http://msdn.microsoft.com/standards/WebDAV.asp and IETF : http://www.ics.uci.edu/pub/ietf/webdav/

RFC 2518 constitute the official specification

When you install the ePortal WebDAV service, you will be able to create content in your favorite WebDAV-enabled authoring tool, yet take advantage of the document management features of the ePortal content management (CM) system on your server. The ePortal WebDAV service works with ePortal version 2.2.1 or higher and with any client that fully supports the WebDAV protocol.

You will be able to perform the following functions remotely from your WebDAV client application:

• Authentificate as a Portal user
• Save your content in the CM repository
• Get the latest version of your content from the CM repository for editing
• Lock content for editing in the CM repository and know that your changes will not be overwritten by another author
• Unlock content so it is available to other authors for editing
• Copy and move content across collections within the hierarchical physical infrastructure of the CM repository
• Delete content from the CM repository
• Create new collections (folders) in the CM repository
  

WebDAV-enabled clients implement these functions in different ways. Consult your client documentation to learn how to use specific third-party tools with the WebDAV protocol.

Interesting server implementations :

• SilverStream ePortal 2.2.1
• Jigsaw WebDAV Package
• Zope Open-source app server
• Jakarta (Apache) WebDav project Slide
• A Java module for Apache that implements a class 2 WebDAV server : designed to have a small footprint so it can be used on a wide range of devices, such as laptop and palmtop computers. Comes with a client application that exploits WebDAV for file sharing and instant messaging. Magi_Dav is open source and freely downloadable.
  

There are many non-java servers that support WebDAV including IIS, Apache, Microsoft Exchange, ...
Internet File System - iFS is Oracle's Internet File System product, supports WebDAV as one of the protocol interfaces to the iFS store.

• Adobe GoLive 5.0 and PhotoShop 6.0, InDesign, InCopy, InScope
• Websphere Dav for Java, a Java client and a servlet that with WebSphere AppServer extends the Apache Web server with the WebDAV Class 2 protocol (not really interesting) http://alphaworks.ibm.com/tech/DAV4J
• Macromedia Dreamweaver and DreamWeaver Ultradev 4.0
• WebDAV Explorer, an open-source Java WebDAV client
• Microsoft Office 2000
• Microsoft Internet Explorer supports DAV extensions from within its browser. Simply point IE to a WebDAV server and a Web Folder will appear in your browser window. Currently IE is the only browser that supports WebDAV extensions
• Windows 95, 98, and 2000 provide "Web Folders", which are an interface to a collection of resources stored on a DAV server.
• Apple MacOS X, with its native WebDAV support.