By default, the OpenACS Request Processor runs as an AOLserver preauth
filter and intercepts
all requests. This isn't really
necessary to the OpenACS design, and it's definitely possible to hack
it to do something different. E.g., you could probably change it to
ignore some URLs.
Several folks here and/or on the AOLserver list have talked about
tweaking the Request Processor to integrate more nicely with other
AOLserver filters, but AFAIK no one has contributed any such changes
back to OpenACS.
It is feasible to make the OpenACS db_* API (and lots other useful
stuff from the acs-tcl package) run standalone in AOLserver without
OpenACS. I did that once long ago, for ACS 4.2. However, the OpenACS
code currently does not come set up to work that way out of
the box, you'd have to hack on it.
The OpenACS maintainers I've talked to about this are basically in
favor of changing the Tcl code to work out of the box both with and
without OpenACS (and ideally both in AOLserver and tclsh as well),
it's just never been a priority for anyone to actually do. (Including
me - I volunteered to do it sometime, but I've no idea when I might
actually get to it.)