2.1.24 WWW Distributed Authoring and Versioning (webdav)

NOTE: This charter is a snapshot of the 39th IETF Meeting in Munich, Bavaria, Germany. It may now be out-of-date.


Jim Whitehead <ejw@ics.uci.edu>

Applications Area Director(s):

Keith Moore <moore+iesg@cs.utk.edu>
Harald Alvestrand <Harald.T.Alvestrand@uninett.no>

Applications Area Advisor:

Keith Moore <moore+iesg@cs.utk.edu>

Mailing Lists:

General Discussion: w3c-dist-auth@w3.org
To Subscribe: w3c-dist-auth-request@w3.org
In Body: Subject of subscribe
Archive: http://www.w3.org/pub/WWW/Archives/Public/w3c-dist-auth/

Description of Working Group:

This working group will define the HTTP extensions necessary to enable distributed web authoring tools to be broadly interoperable, while supporting user needs.

The HTTP protocol contains functionality that enables the editing of web content at a remote location, without direct access to the storage media via an operating system. This capability is exploited by several existing HTML distributed authoring tools, and by a growing number of mainstream applications (e.g. word processors) which allow users to write (publish) their work to an HTTP server. To date, experience from the HTML authoring tools has shown they are unable to meet their user's needs using the facilities of the HTTP protocol. The consequence of this is either postponed introduction of distributed authoring capability, or the addition of nonstandard extensions to the HTTP protocol. These extensions, developed in isolation, are not interoperable.

An ad-hoc group has analyzed the functional needs of several organizations, and has developed requirements for distributed authoring and versioning. These requirements encompass the following capabilities, which shall be considered by this working group:


· Locking: lock, lock status, unlock

· Name space manipulation: copy, move/rename, resource redirection (e.g. 3xx response codes)

· Containers: creation, access, modification, container-specific semantics

· Attributes: creation, access, modification, query, naming

· Notification of intent to edit: reserve, reservation status, release reservation

· Use of existing authentication schemes

· Access control

· Unprocessed source retrieval

· Informing proxies of an action's impact

· Versioning:

· Checkin/Checkout

· History graph

· Differencing

· Automatic Merging

· Naming and accessing resource versions

Further information on these requirements can be found in the document, "Requirements for Distributed Authoring and Versioning on the World Wide Web". <http://www.ics.uci.edu/~ejw/authoring/webdav-req-00.html

While the scope of activity of this working group may seem rather broad, in fact much of the functionality under consideration is well understood, and has been previously considered. This working group will leverage off of previous work when it is applicable. Discussion of the security issues concerning distributed authoring and versioning are essential to the creation of a protocol that implements this functionality.

Though the feature set described above bears a resemblance to the capabilities provided by a network file system, the intent of this working group is not to create a replacement distributed file system (e.g. NFS, CIFS). The WEBDAV emphasis on collaborative authoring of resources which are not necessarily stored in a file system, and which have associated metadata in the form of links and attributes, differentiate WEBDAV from a distributed file system.

Many decisions have been made to reduce the scope of effort of this working group. It is the intent of this working group to avoid the inclusion of the following functionality, unless it proves impossible to create a useful set of distributed authoring capabilities without it:


· Definition of core attribute sets, beyond those attributes necessary for the implementation of distributed authoring and versioning functionality

· Creation of new authentication schemes

· HTTP server to server communication protocols

· Distributed authoring via non-HTTP protocols (except email)

· Implementation of functionality by non-origin proxies

Eventually, it is desirable to provide access to WEBDAV capability by disconnected clients, or by clients whose only connectivity is via email. However, given the scope of developing requirements and specifications for disconnected operation, the initial target user group of fully connected clients, and the desire to work swiftly, the working group will address this issue by ensuring the protocol specification does not preclude a future body from developing an interoperability specification for disconnected operation via email.


The final output of this working group is expected to be three documents:

1) 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. Ora Lassila, Nokia, currently visiting with the World Wide Web Consortium, is editor of this document.

2) A requirements document, which describes the high-level functional requirements for distributed authoring and versioning, including rationale. Judith Slein, Xerox, is editor of this document.

3) A protocol specification, which describes new HTTP methods, headers, request bodies, and response bodies, to implement the distributed authoring and versioning requirements. Del Jensen, Novell, is editor of this document.

The most recent versions of these documents are accessible via links from the WEBDAV Web page.

Goals and Milestones:

Mar 97


(Specification) Produce revised distributed authoring and versioning protocol specification. Submit as Internet Draft.

Apr 97


(Meeting, Specification, Requirements) Meet at Memphis IETF and hold working group meeting to review the protocol specification and requirements document.

Apr 97


(Scenarios) Revise scenarios document. Submit as Internet Draft.

Aug 97


(Scenarios) Create final scenarios document. Submit as Informational RFC.

Aug 97


(Requirements) Create final version of distributed authoring and versioning requirements document. Submit as Informational RFC.

Aug 97


(Specification) Produce revised distributed authoring and versioning protocol specification. Submit as Internet Draft.

Dec 97


(Specification) Complete revisions to distributed authoring and versioning specification. Submit as a Proposed Standard RFC.


No Request For Comments

Current Meeting Report

Minutes of the WEBDAV Working Group

A meeting of the World Wide Web Distributed Authoring and Versioning (WEBDAV) Working Group was held at the Munich IETF on August 11, 1997. Jim Whitehead chaired the meeting, and Del Jensen recorded meeting notes. Over the duration of the meeting there were 54 attendees. These minutes, the agenda, and slides presented during the meeting are accessible on the Web at URL <http://www.ics.uci.edu/~ejw/authoring/munich/>.

The meeting began with a review of the agenda, which was accepted without modification. Following this, Jim Whitehead began a series of three presentations. The first presentation was a brief high-level overview of the functionality being considered by the WEBDAV working group. This included information on the status of the requirements document, which should have a new version out by August 27, 1997, the protocol document, which should have a new draft out by August 29, 1997, and the scenarios document, on which work has stalled. It is expected that the requirements document will begin a working group last call after this next draft has been released. This is the final step before forwarding this document along to the IESG.

After this presentation, Jim Whitehead gave another presentation outlining the key design elements of the properties, collections, and namespace operations aspects of the protocol specification. Notes on this presentation follow:

1. Properties

2. Collections

Q: Why have internal members? Why are not all members specified as external (absolute URIs)?
A: The well-defined specification of existing methods on external members can be problematic across namespace boundaries. Internal membership is convenient for modeling file system behavior, which one anticipates being a common use for collections. Container models that are more exotic than the simple hierarchical model are not excluded by the proposed structure for collections.

3. The Source Link

Once the two overview presentations were completed, Jim Whitehead led a discussion of open issues using slides that listed the issue, gave pro and con discussion on the issue, and then listed a recommended resolution to the issue. Discussion on these issues is summarized below - for more detail consult the original slide presentation.

A. Property Instance URL encoding
Problem: Get rid of the DAV switch
Solution: Discovery of Property names
Informal Poll: Adopted

B. Retrieval of Properties
Problem: Search is too complicated for WEBDAV scope
Solution: Simplified set of methods to retrieve property names and values on a by-resource basis.
Informal Poll: Adopted

C. Property Attributes
Problem: Resource level granularity for property attributes (e.g., live, read-only) can make schemas inconsistent
Solution: Raise attribute granularity to schema level.
Informal Poll: Adopted

D. Method Recursive Semantics for Collections
Problem: Agreement on well-defined extension of current methods is hard to get, and aspects of this problem are arguably outside the scope of WEBDAV.
Solution: Define only "level 0" behavior.
Informal Poll: Adopted

E. Atomic Locking of Collections
Problem: The current requirements document specifies that WEBDAV provide this functionality. The protocol draft may provide only a partial solution.
Solution: None

F. Support for Variants
Problem: The current specification is silent on how to add or change resource variants.
Solution: None at present, take to list (possibilities: transparent content negotiation, content-location header, translation-of/supercedes relationships)

Meeting adjourned.


WEBDAV Design Overview

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