Re: [Exim] LDAP attribute extraction

B.Candler@??? (Brian Candler) wrote on 07.08.00 in <20000807100355.B13919@???>:

> On Mon, Aug 07, 2000 at 09:39:31AM +0100, Philip Hazel wrote:
> > Exim just hands the query over to LDAP - using the ldap_url_search()
> > function. It doesn't try to be clever about analysing the query in any
> > way. (That was supposedly the beauty of using this interface - leave the
> > work to somebody else. :-)
> >
> > It occurs to me that a sensible LDAP search engine should be doing its
> > own caching. Do you have any information on whether this is actually the
> > case?
>
> I notice there is a function ldap_enable_cache in the OpenLDAP SDK. But it
> doesn't say whether it does 'clever' re-use of queries, or just returns
> the results from identical queries.

It occurs to me that here would be a place for a dedicated cache. That is,
Exim would forward the query to a caching process, which would do the
actual queries if it couldn't satisfy them from the cache.

Now, obviously, there are all manner of considerations for getting te
caching right, but it seems to me this would (if implemented) solve the
non-caching problems caused by Exim usually doing its queries from a short-
lived process.

Before starting to think about this more seriously, do people (preferrably
people familiar with Exim's internals) think this might be useful, and
what would people think is a reasonable interface to such a cache? I'm
thinking of caching just about anything that Exim requests from external
sources, except lsearch or db type stuff. That is, ldap queries, DNS
queries, NIS queries, and so on and so forth.

MfG Kai