[sc34wg3] first release of Versavant

[Steven R. Newcomb]

All,

Last night I released my "Versavant" multi-TMA topic mapping engine
under the Apache License 2.0.  It's supposed to appear at
http://versavant.sourceforge.net, but for some reason it hasn't shown
up there.  It's also available at http://www.versavant.org/releases.

It's an early release, in accordance with the open-source mantra,
"Release early, release often".  Expect problems, but be assured
that I care whether you have problems with it.  Also, be aware
that I can use some help, if you're interested and capable.

It's an implementation of the "Versavant Disclosure Discipline", which
is a particular way -- I think an attractively minimalist way -- to
disclose and implement a Topic Map Application.  Basically, a TMA
disclosure in Versavant is a small set of functions for each property
class, and a function for each "conferral rule" (see below).  Each of
the functions is an instance of a "function class" that Versavant
knows when and how to call.

Some talking points about Versavant:

* The Versavant software does not implement the TMDM, but I think if
  we can have a disclosure of TMDM in TMRM terms, a TMDM
  implementation can be plugged into it, along with implementations of
  other "Topic Map Applications (TMAs)".  The Versavant engine is a
  "TMA bus".  I also call it a "subject addressing engine".

* Versavant supports "conferral rules".  The draft TMRM says that TMA
  disclosures must disclose any rules for making whatever's implicit
  in a topic map explicit.  In Versavant, such rules are called
  "conferral rules" because they confer properties on subject proxies
  (aka "topics"), and subject proxies can even be "conferred into
  existence" by such rules.  Conferral rules are power tools for
  making subjects addressable.

* It supports the auditing of every property value.  You can see how a
  property value came to have the value that it has, through merging
  and conferral operations, back to all of the "original population
  tasks" from which its value was derived.

* It encapsulates the disclosures of the TMAs that govern a given
  topic map in the interchangeable form of the topic map.  When you
  receive a Versavant XML topic map, it knows how to merge itself with
  topic maps that are governed by any of the same TMAs.  If you want
  to merge it with topics that are governed by other TMAs, you can
  devise "bridging TMAs" that will automate the job, with full
  knowledge of how the existing governing TMAs work.  The disclosures
  are right there in the interchangeable topic map.

* TMAs -- their value types, property classes, and conferral rules --
  are reified in Versavant topic maps.  Versavant has a built-in TMA
  called "Vsys" that provides the value types and property classes
  necessary to allow this.  Thus, the metadata and the data are
  equally privileged in Versavant topic maps.  Vsys is just one of the
  TMAs that happens to be plugged into the bus.  No subjects -- not
  even the subjects that are the governing metadata of the topic map
  -- are exempt from merging and addressability in Versavant.

-- Steve

Steven R. Newcomb, Consultant
Coolheads Consulting

Co-editor, Topic Maps International Standard (ISO 13250)
Co-drafter, Topic Maps Reference Model 

srn@coolheads.com
http://www.coolheads.com

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