WebDAV

WebDAV,  the "Distributed Authoring and Versioning" standard, was approved by the IETF in December, 1998.  The goal of this specification is  to extend HTTP 1.1 for distributed authoring and versioning. WebDAV uses XML. It provides a set of extensions to the HTTP protocol to allow users to collaboratively edit and manage files on remote web servers. 

WebDAV has extended HTTP in the following ways:

• Metadata: 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. 
• Name space management: The ability to copy and move Web pages, and to receive a listing of pages at a particular hierarchy level (like a directory listing in a file system). 
• Overwrite prevention: 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. 
• Version management: The ability to store important revisions of a document for later retrieval. Version management can also support collaboration by allowing two or more authors to work on the same document in parallel tracks.

WebDAV differs from HTTP because it encodes method parameter information either in an Extensible Markup Language (XML) request entity body, or in an HTTP header. The use of XML to encode method parameters was chosen because one can add extra XML elements to existing structures, providing extensibility.  Also XML's ability to encode information in ISO 10646 character sets provide internationalization support. Parameters with bounded lengths may alternatively be encoded within HTTP headers.