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Re: Minutes from the Prague IETF meeting

2007-04-23 11:54:59

On Mon, Apr 23, 2007, Nigel Swinson 
<Nigel(_dot_)Swinson(_at_)rockliffe(_dot_)com> said:


Alexey presented a new (not yet written) draft on "Externally stored 
lists".
The basic idea is to be able to store lists of users or email addresses in 
SQL/LDAP/ACAP/...
Such lists can be updated externally, without the need to update Sieve 
script.
The proposal is to extend redirect action and header/envelope tests to 
reference externally
stored lists.

FYI we support it this kind of way:

if header :is "From" "${Whitelist}" {...}

Where "Whitelist" is an externally configured list of email addresses.  Were 
I to re-implement, then I'd put "Whitelist" in a namespace.  I consider it 
along the lines of accessing server configuration, for which we've already 
discussed adding a namespace.

I would like to see a namespace or function space of some kind. A few
people pointed out that it might be good to specify an LDAP URI inside the
list description, so we're really talking about functions, imho.

The idea of IO bound operations from a sieve script such as LDAP/RBL lookups 
makes me twitchy about performance, but these concerns are of course 
solvable using multiple threads/processes.  I think it's the first time 
we've suggested doing this kind of thing, so may be a knock to the 
architecture of a few implementations and therefore make it difficult for 
them to implement.

By using strict evaluation of variables, we set ourselves up for a
performance problem because we may be asking the interpreter to first
expand the full external list and then pass that into the test. Variables
says that implementations should be able to pass unexpanded material into
a test, but we still have keep the syntax of list expansions in mind so
that we don't force everyone into nasty interpreter hacks.

Aaron

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