[ingo] Selecting backends based on current Imp mail server

[Chris Hastie]

On Mon, 29 Mar 2004, Jan Schneider <jan at horde.org> wrote
>Zitat von Chris Hastie <lists at oak-wood.co.uk>:
>
>> On Mon, 29 Mar 2004, Jan Schneider <jan at horde.org> wrote:
>>
>>> Zitat von Chris Hastie <lists at oak-wood.co.uk>:
>>> >
>>> > Is it possible to select backend based on the current mailserver that
>>> > Imp is connected to?
>>>
>>> Not currently. But a patch would be great.
>>>
>>
>> I may have a go if I get time. Can you suggest what is the best way to access
>> the current Imp server setting? Also, does Ingo need to be able to function
>> independantly of Imp? I'm guessing it does.
>
>Yes, it does. The interaction should probably be done best with an api call.
>"mail/getPreferredServer" or something similar.

I had a think about this and a bit of a play yesterday evening. I could
do with some feedback before I do anything finally. I could also do with
doing a cvs update before I go any further, so if this is all completely
irrelevant to the current code, sorry :(

There are probably dozens of ways of arranging the interaction. I could
think of three main ones:

1)  An additional parameter in ingo/config/backends.php, similar to
    'preferred', where the mail server could be specified. If this
    matches Imp's current mail server that backend is used. Possibly
    even add it within the existing 'preferred' hierarchy, but this
    makes backwards compatibility a bit more complicated. Possible
    drawback is that mail server is not necessarily unique to an Imp
    config - you may have two running on different ports on the same
    host for example.

2)  Similar to one, but match on something more unique in the Imp
    config, possibly 'name' or the key to $servers. Only the key can
    really be guaranteed to be both present and unique, and I'm not sure
    it's currently used much so it may be trickier to access.

3)  Come at it the other way around. Add an additional parameter to
    imp/config/servers.php, say 'ingokey', specifying the key from the
    $backends array to use with this particular Imp configuration.

Whilst 3) does add an additional config parameter to the already
considerable list for imp/config/servers.php, it looks to me to be much
easier to code and arguably more intuitive to admins. So this is what I
played with.

Something like this should accomplish the task relatively easily:

include INGO_BASE . '/config/backends.php';
if (!isset($backends) || !is_array($backends)) {
    Horde::fatal(PEAR::raiseError(_("No backends configured in backends.php")), __FILE__, __LINE__);
}

if ($registry->hasMethod('mail/whichSieve')) {
    $confkey = $registry->call('mail/whichSieve');
}

if (!empty($confkey) && isset($backends[$confkey])) {
    $backend = $backends[$confkey];
} else {
    foreach ($backends as $temp) {
        if (!isset($backend)) {
           [... existing code]
    }
}

Does it make sense to go down this route?

The other question I have is do I need to add an Imp api function,
mail/whichSieve in the above, to return the value of the 'ingokey'
parameter, or can I just access $_SESSION['imp']['ingokey'] directly?
Both work, but I've never quite grasped if one is better than the other,
and why.
-- 
Chris Hastie