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A Brief Introduction to WEBDAV

Today the typical use of the World Wide Web is to browse information in a largely read-only manner. However, this was not the original conception of the Web; as early as 1990, a prototype Web editor and browser was operational on the Next platform, demonstrating how Web content could be read and written. Unfortunately, most of the world never saw this editor/browser, instead developing their view of the Web from the widely distributed text-based line mode browser. When NCSA Mosaic was developed, it improved the line mode browser by adding a graphical user interface and inline images, but had no provision for editing. As Mosaic 2.4 reached critical mass in 1993-4, "publish/browse" became the dominant model for the Web.

However, the original view of the Web as a readable and writable collaborative medium was not lost. In 1995 two browser/editor products were released: NaviPress by NaviSoft and FrontPage by Vermeer. These products began developing a market for authoring tools which allow a user to edit HyperText Markup Language (HTML) pages remotely, taking advantage of the ability to work at a distance over the Internet. In early 1996, NaviSoft and Vermeer were purchased by America Online and Microsoft respectively, presaging major corporate interest in Web distributed authoring technology. In 1995-96, Netscape released Navigator Gold, a Web browser/editor tool, with the ability to publish pages to a remote Web server. 1996-7 also saw the release of Web-integrated word processors, with Microsoft Word 97, Lotus WordPro 97, and Corel WordPerfect 7 all having HTML editing and remote publishing capability.

In this setting, an ad-hoc collection of people interested in remote authoring (now known as the WEBDAV working group) met first at the WWW4 conference in December, 1995, and then next at America Online in June, 1996. Comprised of developers working on remote authoring tools, and people generally interested in extending the Web for authoring, this group identified key issues encountered in writing these authoring tools. The group also found that there was a pressing need to develop standard extensions to the HyperText Transfer Protocol (HTTP) for the following capabilities:

• 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.

From its inception, the WEBDAV group has been working steadily to produce an interoperability specification which defines HTTP methods and their semantics for the above capabilities. Work in this direction has focused on three documents, a scenarios document, which gives a series of short descriptions of how distributed authoring and versioning functionality can be used, typically from an end-user perspective, a requirements document, which describes the high-level functional requirements for distributed authoring and versioning, including rationale, and a protocol specification, which describes new HTTP methods, headers, request bodies, and response bodies, to implement the distributed authoring and versioning requirements. On March 20, 1997, the Internet Engineering Steering Group (IESG) of the Internet Engineering Task Force (IETF) approved the charter of the WEBDAV Working Group, making WEBDAV an official working group in the Applications Area. WEBDAV is working cooperatively with the World Wide Web Consortium, which provides technical assistance and help contacting interested people within the Web community.

Want to know more?
A high-level overview of WebDAV and DASL is the article "WEBDAV: IETF Standard for Collaborative Authoring on the Web", by Jim Whitehead and Meredith Wiggins, which appeared in the September/October, 1998 issue of IEEE Internet Computing, pages 34-40.

Another introduction to WEBDAV appeared in IEEE Internet Computing, Vol. 1, No. 2, March/April 1997, in the column, Distributed Authoring and Versioning, by Gail Kaiser and Jim Whitehead.

Last modified: September 18, 1998