[provision] Reuse in SPML

[Gearard Woods <gewoods@us.ibm.com>]

I've been absent from the discussion for a while so I apologise if this is
an old chestnut but following on the heels of Matthias' question about
batch operations in SPML, I'd like to ask the committee if the advantages
of maintaining the dependency on DSML are really working out?  I can
certainly understand the argument for the use of the DSML Filter, athough
that could be adressed if necessary, but I'm more curious about the use of
DsmlMessages.  As everyone knows, DsmlMessages really encapsulate a set of
controls and an optional request ID.  This is such a trivial class and all
of the SPML messages are derived from it so it seems to me that SPML is
building in a dependency for very little gain in this case.  This also
raises the issue of discovery of supported controls, as with LDAP/DSML.  In
LDAP of course, the specification calls for the server to provide a root
DSE where vendors generally publish the set of supported controls and
extensions.  I notice that the SPML schema includes the ability to define
extended operations but I don't see a place for controls.

I've been trying to catch up on the minutes of the meetings that I've
missed but I don't see any discussion so far of the use of yet another
schema language.  Propagating an LDAP style schema language when the
specification is written in a more expressive language, XML-Schema, seems a
little anachronistic to me.  I'm sure there is a reason, and I'm sure there
was discussion on the subject, but it appears on the surface that a lot of
time could be saved by re-using XML-Schema rather that re-defining another
schema langauge in XML-Schema.  This leads to my final question on
appropriate re-use and that is the definition of extended operations in a
world where considerable effort and tool support has been put into the
WSDL.  For that matter, it seems likely to me that the SPML might be
frequently used within an WSDL context.  In that case, the batch request
and response mechanisms adopted from DSML don't seem very useful and
extended operations would more naturally be defined using WSDL's
capabilities.

Again, apologies if I'm covering old ground,
Gerry