[Kde-pim] [PATCH] imap resource: Support multiple IDLE folders.

[Rüdiger Sonderfeld]

On Monday 22 October 2012 20:15:29 Kevin Ottens wrote:
> On Monday 22 October 2012 17:48:21 Rüdiger Sonderfeld wrote:
> > This certainly is a problem. But I think it's a problem the users and
> > sysadmins have to solve. Imap server software such as dovecot or courier
> > has max connections settings for each user and this should prevent users
> > from watching too many folders. We are not putting servers at risk here
> > and sysadmins already have the tools to protect themselves. And other
> > imap clients such as Offlineimap already support watching several
> > folders.
> > 
> > We certainly should keep the settings in the Advanced-part of KMail and
> > warn users that opening too many connections might cause problems.
> 
> Not really a pleasant experience unfortunately, no way for the user to know
> which mailbox will end up being monitored or not and when...

Other MUAs support several idle folders as well. We are not creating a new 
problem here. E.g., Thunderbird uses up to 5 idle connections and can be 
configured to use more.

The server should report a problem when there are too many connections open. I 
don't know how KMail currently presents this to the user. But as long as we 
keep this feature in the Advanced-options we should be fine.

> > >  2) Implement the support for NOTIFY instead. It's definitely the better
> > > 
> > > option to me, but it's clearly getting further away from your existing
> > > patch. It also requires investigating which servers support it of
> > > course.
> > 
> > I hope that NOTIFY will replace IDLE in the future. But it is not
> > available
> > at the moment and so far I only know about Dovecot planning to support it.
> > That's why I don't think it's an option for now.
> 
> OTOH it is a chicken and egg problem, if clients don't ask for it there's no
> incentive for server implementations. The fact that dovecot is going to
> implement it is IMO good enough to pursue that route. Yes it'll take time
> to get deployed but we'll be ready and no nasty hack in the codebase
> (rotation or several idling connections).

We can easily switch to NOTIFY support in the future. But the RFC is only a 
draft and no server seems to support it at the moment. If Dovecot 2.2 gets 
released with NOTIFY then I will probably look into it. For now there is no 
other solution than opening several idle connections.

I've added a config dialog now and it contains a warning text in the UI and 
warns users with a message box if they want to watch more than 4 folders. (4 
seems to be the default limit with Courier-IMAP.)

I'll send the new version of the patch in another reply.

Regards
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