. Discussion on this list is also
archived.This page was previously the home page for a working group on adding versioning and configuration management capabilities to the World Wide Web. This working group has now been split -- the current working group is now focusing on remote configuration management of web content. Discussion of WWW versioning issues now takes place in the WWW Distributed Authoring and Versioning Working Group (webdav).
This page is still an excellent resource for pointers to work on WWW versioning and configuration management, as well as hypertext versioning.
Discussion of the addition of configuration management
capabilities to the World Wide Web takes place on the discussion list
<www-vers-wg@ics.uci.edu>. Requests to join this discussion list
may be sent to
<www-vers-wg-request@ics.uci.edu>
. Discussion on this list is also
archived.
Four Lessons Learned from Managing World Wide Web Digital Libraries,
Robert Pettengill and Guillermo Arango
This early paper describes a development and maintenance process for a
"digital document library" (a.k.a., a collection of WWW content), the
need to make this process repeatable and as automated as possible, and
the use of separate maintenance and publications areas for visibility
control. More relevant to this audience, the paper describes the need
for using version control on web content, the addition of a ",version"
to the requested URL, and explains the use of CGI scripts to
provide versioned access to a document collection.
Mortice Kern Systems (MKS)
Integrity Engine
Integrity Engine Data Sheet
MKS has developed HTTP server extensions for checkin, checkout, and
locking operations on specific entities. Individual versions of an
entity may be accessed by specifying the version with the addition of
";version=" at the end of the requested URL. The MKS approach,
described in a
white paper, makes no modifications to HTTP, and
instead decorates the requested URL with the information of the
desired operation.
P3 Software
web://keeper
P3 software has performed an integration of the P3 Configuration
Management system with the
Apache server, which P3 has named
web://keeper,
thus allowing GETs of versioned
URLs on any object within a P3 repository.
WWW Versioning Support, draft proposal (v 0.1)
(Postscript)
Jim Whitehead
This working draft describes a proposal for extending the HTTP
protocol with four new methods, FLAG, LOCK, UNLOCK, and USE, and
describes how they are used to provide style-independent versioning
with semantics controlled by the client. Two appendicies give
examples of how the RCS and CVS styles are implemented using these
methods. The proposal also describes a new entity type, the
configuration, which allows the versions of a collection of
related entities to be described in a single file.
NTT Software Laboratories, Palo Alto
NTT Software Laboratories in Palo Alto (SPLA) recently announced on
the HTTP Working Group mailing list that they have completed a
prototype of an HTTP server which manages versions and configurations
of web objects. While they apparently have a white paper which is
written in Japanese, and is currently undergoing translation into
English, some technical details were reported in the post. The
versioning and configuration functions were implemented using LINK,
PUT, and "related methods". Clients which understand how to use
these new functions have also been developed.
The NTT server is written in Perl. Two clients were developed, one using MetaCard, a GUI builder, along with a libwww library extended to handle the additional methods. The other client was written in Java.
Authoring Tools Breakout Session at
WWW4
Detecting Update Conflicts in HTTP
The authoring tools breakout session identified the "lost update"
problem (when people performing parallel development on an entity
overwrite each other's changes) as an open issue requiring attention.
David Long of NaviSoft and Dan Connolly of W3C subsequently produced a
W3C working draft on the lost update problem titled,
Detecting Update Conflicts in HTTP. This working draft presents
four levels at which this problem may be resolved: do nothing, detect
lost updates, prevent lost updates, and fairly prevent lost updates.
Formal Modeling of a Resource-Leasing Extension to HTTP
Rafal Boni, Rohit Khare, and Matthew Levine
This paper describes a check-out/check-in scheme for HTTP which
aims to guarantee exclusive write access to a resource while it
is checked-out. The scheme described does not handle parallel
development of resources. The paper begins with a
detailed discussion of the four-levels of potential resolution
of the lost update problem identified at the authoring tools
breakout session.
Using Versioning to Support Collaboration on the WWW,
Fabio Vitali,
David G. Durand
This paper, presented at the
WWW4 conference, presents a different, interesting perspective
on how versioning of WWW content may be performed. Their approach is
motivated by how to support asynchronous collaboration in the creation
and editing of text documents, which they feel requires extremely
fine-grain versioning. This paper describes VTML, the Versioned Text
Markup Language, which is a markup language for describing the version
history of a document. The VTML approach has the drawback that it
only applies to HTML content, and does not address the versioning
of bitmap images, an important class of web content.
Original Design Issues: Versioning,
Tim Berners-Lee
The World Wide Web Consortium has an archive of notes dating from the
original design of the web in 1990. One of the issues is
"keeping track of previous versions of nodes and their relationships."
Livelink Library for Document Management
Open Text Corporation
This marketing blurb for the Livelink
Library, a component of Open Text's Livelink Intranet product,
describes web content versioning capabilities including
a change history, viewing of previous versions, and a lock-based
overwrite protection scheme. Unfortunately, it is impossible
to determine the underlying technical approach from the
information presented.
Microsoft
FrontPage
FrontPage: A Technical Overview
Microsoft FrontPage, formerly Vermeer FrontPage, is an HTML editor
which can save work to an HTTP server which has been augmented with
the FrontPage server extensions.
Section C of the FrontPage technical overview describes the
FrontPage server extensions in more detail, including its use of
the POST method for writing content to an HTTP server.
The Internet Development site at Microsoft offers a wealth of additional material. Documents are available which describe Microsoft API calls in the client side to go over the web to talk to server-side. It also provides access to beta and alpha releases. Content changes daily. The overview paper is pretty interesting, since it may provide a convergence for document objects at a higher level than DMA provides - that is, cross-net delivery of content at the UI object level via OLE.
America Online PrimeHost
AOLpress
and AOLserver
Documentation for
AOLpress and
AOLserver
The AOL PrimtHost hosting Service, formerly known as GNN Hosting
Service, fromerly known as NaviSoft, provides a service for using
their GNNpress software to publish web pages on their server for a
monthly fee. Since you can currently
The America Online PrimeHost hosting service, formerly known as the
GNN Hosting Service, which in turn was formerly known as NaviSoft,
provides a service for using their AOLpress software to publish web
pages on their server for a monthly fee. Since you can currently
download
fully-functional, but non-supported versions of their AOLpress and
AOLserver tools, it is also possible to experiment with these
tools.
AOLpress employs the PUT method to write content to the AOLserver, which implements access control features which control, among other methods, who can PUT to particular namespaces within the server. The documentation for the AOLserver describes how it distinguishes BROWSE, PUT, MKDIR and DELETE as different administrative rights on operations.
Netscape
Navigator Gold
Navigator Gold Data Sheet
Netscape Navigator Gold provides authoring of HTML documents, along with
publishing capability. Navigator Gold uses the FTP protocol to write
content into the namespace of the HTTP server.
The topic of hypertext versioning has been researched outside of the WWW context within the academic hypertext community for several years, and offers many insights into the WWW versioning problem. Versioning of hypertexts was addressed by Ted Nelson in Literary Machines, and in Engelbart's NLS journal facility in the 60's and 70's. This issue was revisited and given renewed importance by Frank Halasz in his extremely influential paper, "Reflections on NoteCards: Seven Issues for the Next Generation of Hypermedia Systems," published in Communications of the ACM in July, 1988, in which he lists hypertext versioning as issue number 5. These issues were reexamined in a keynote address given by Halasz at Hypertext'91.
Proceedings of the Workshop on Versioning in Hypertext Systems, at
ACM European Conference on Hypermedia Technology (ECHT'94)
David Durand, Anja Haake, David Hicks, Fabio Vitali
The proceedings from this workshop features papers on hypertext
versioning in technical documentation, legal applications, and
design, giving both requirements and solutions in these areas.
Palimpsest: A Data Model for Revision Control
(Postscript)
David Durand
In Proceedings of the CSCW'94 Workshop on Collaborative Hypermedia
Systems, Chapel Hill, NC, available as GMD Studien Nr. 239. Gesellschaft f r
Mathematik und Datenverarbeitung MBH 1994.
The intellectual precursor to VTML, Palimpsest is a data model for
flexible merging and tracking of individual changes to shared hypertext
or multimedia documents. This work is motivated by providing support for
collaborative hypertext editors where multiple people may be working on the
same document simultaneously.
Version Control in Hypertext Systems,
David L. Hicks, John J. Leggett, and John L. Schnase
This paper, published as a technical report of the
Hypermedia Research Lab at
Texas A&M University in 1991, is an early, influential paper which
examines many different versioning systems, and then describes
how the Personal Information Environment (PIE) system (described in
"A Layered Approach to Software Design," by Ira P. Goldstein, and
Daniel G. Bobrow, published in the book "Interactive Programming
Environments," edited by David R. Barstow, Howard E. Schrobe, and
Erik Sandewall.) layered data model can be used for hypertext
versioning. The paper also gives requirements for hypertext
versioning.
VerSE: Towards Hypertext Versioning Styles,
Anja Haake and David Hicks,
Proc. Hypertext'96, the Seventh ACM Conference on Hypertext, 1996,
pages 224-234.
Under CoVer: The Implementation of a Contextual Version Server for
Hypertext Applications,
Anja Haake,
Proc. 1994 European Conference on Hypermedia Technology (ECHT'94),
pages 81-93.
Take CoVer: Exploiting Version Support in Cooperative Systems,
Anja Haake and Jörg M. Haake,
Proc. ACM INTERCHI'93, Conference on Human Factors in Computing Systems,
1993, pages 406-413.
Anja Haake has been
performing excellent research on hypertext versioning for several
years at GMD-IPSI. The papers listed above represent her most recent
work, and provide a comprehensive description of her research.
Structural and Cognitive Problems in Providing Version Control for Hypertext,
Kasper Østerbye,
Proc. Fourth ACM Conference on Hypertext (ECHT'92), 1992, pages 33-42.
This paper is notable for its clear distinction between structural
(data modeling) and cognitive (interface) issues of hypertext versioning,
and its detailed discussion of each.
It also describes the versioning facilities of the HyperPro system.
There is a large literature on software configuration management, including proceedings from the six software configuration management workshops (the most recent of which was SCM6, held in conjunction with the 18th International Conference on Software Engineering (ICSE18)). Papers on SCM also appear in the proceedings of ICSE. Papers listed below are ones that either have particular relevance to WWW versioning and configuration management, or provide relevant background material.
Configuration Management Models in Commercial Environments
Peter H. Feiler
Software Engineering Institute Technical Report CMU/SEI-91-TR-7
This early survey of configuration management tools contains an
excellent breakdown of these systems into four configuration
management models, or styles: checkout/checkin, composition, long
transaction model, and the change set model.
A Generic Peer-to-Peer Repository for Distributed Configuration Management
André van der Hoek
Proceedings of the 18th International Conference on Software Engineering,
Berlin, Germany, March, 1996.
This paper presents the NUCM system which allows for a NUCM client to
contact a distributed SCM repository and interact with it using
primitive operations, upon which are implemented higher-level CM styles.
If an analogy is made between a client of the NUCM system and a
user-agent, and between a NUCM repository and an HTTP server, this
paper has tremendous relevance for WWW versioning and CM.
Distributed Revision Control Via the World Wide Web
Jürgen Reuter, Stefan U. Hänßgen, James J. Hunt, and
Walter F. Tichy
Proceedings of the Sixth International Workshop on Software Configuration
Management, Berlin, Germany, March, 1996.
This paper describes a forms-based interface to the RCE (Revision
Control Engine, essentially an API to an RCS-like core of functionality)
which allows checkout, checkin, and viewing the version history of
artifacts in a distributed manner via the WWW. The system described
in this paper does not modify the HTTP protocol, instead relying
on custom MIME types (and associated helper applications) along with
point-to-point socket connections to handle the file tranfers
associated with checkout and checkin operations.
Configuration Management Yellow Pages
André van der Hoek
This is simply the best one-stop index to the burgeoning SCM tools
market, general information pages on CM, conferences on CM, job
openings, public-domain CM systems, consulting, education,
reviews, and more! Outrageously comprehensive.
Last modified: 07 Feb 1997