RE: What is the advantage of RELAX in comparison to Schemas?

[Bob Kline <bkline@rksystems.com>]

On Tue, 30 Jan 2001, Bullard, Claude L (Len) wrote:

> Yes and no.  If done sensibly, context sensitive constraints in the
> schema are useful.  The problem comes when the information gets
> repurposed along a chain of users.  These rules can vary instance to
> instance, site to site.  Contracting for a schema that works in all
> of those sites is much harder if they have to share narrower and
> narrower context rules.  It may be that the most practical approach
> is to separate out the context rules either into the application or
> into a separately cited document such as TREX, Schematron, etc.

The problem with separating out context rules into the application is
that we would undermine one of the primary benefits of the current
project to replace the customer's legacy document creation/maintenance
system, in which it is impossible to modify document structures or
business rules without dragging in a programmer.

The problem with separating out context rules into a separate document
(such as Schematron) is the standard one of keeping modifications to
separate specifications of the document structures in sync.

We could ignore W3C's schema syntax altogether and simply adopt one of
the competing models (e.g., Schematron or RELAX) but this path incurs
the risk of much lower levels of support from third-party toolsets.

It may well be true that for some projects separating out different
components of document constraints will be the most appropriate
approach.  It is unfortunate, however, that the spec most likely to
attract third-party support (by virtue of its sponsorship by W3C)
assumes that this is the *only* valid approach.

-- 
Bob Kline
mailto:bkline@rksystems.com
http://www.rksystems.com