invoking data connector dynamically in attribute resolver

[Robert A Basch]

Is there any way to invoke data connector dependencies within the IdP
(version 2.3) attribute resolver dynamically, or conditionally based
(for example) on a dependency attribute having a value?

We have a use case here where we would like to invoke one or more
additional data connectors (in addition to the one which pulls in
our standard attributes	from our LDAP directory), but only for a small
number of SPs, which account for a small percentage of our IdP
transactions.  These additional connectors could be performing special
queries against LDAP, and/or a database, and we would like to avoid
adding to the load unnecessarily (on both ends) if we know dynamically
that the query will return no results, or that the results will not be
used to construct any attributes.

A script attribute would process the results of these queries, and
construct the appropriate attributes.  It would be helpful to have a
straightforward way for the script code to invoke a defined data connector
to perform the queries when needed, and process the results, or perhaps
for the connector to conditionally return no results when a dependency
attribute has no value (without performing any actual query).

It looks like our options include: 1) write script code to perform the
desired queries explicitly, i.e. not using a data connector at all, or 2)
use the template language in the data connector to conditionally construct
an effective "no-op" filter or query that would return no results (which
could still use resources unnecessarily, though).

Is there another option?

Thanks,
Bob