[imp] Horde cache problem

[Michael M Slusarz]

Quoting Jochen Roderburg <Roderburg at Uni-Koeln.DE>:

> Zitat von Jan Schneider <jan at horde.org>:
>
>>> I delete the mail now in the Old IMP (IMAP delete) and it is shown  
>>> there as deleted. In Thunderbird it is also immediately shown as  
>>> deleted. In the New IMP
>>> it is *not* shown as deleted, and I do not find a way to persuade  
>>> it to display this correctly. No webmail refreshes help, no  
>>> Browser refreshes. I can logout and re-login. I can login on  
>>> different systems with different browsers, everywhere it is  
>>> displayed as not deleted. It even survives a complete server  
>>> restart.
>>
>> This is expected behavior. Due to limitations in the PHP imap  
>> extension, IMAP flag changes outside of IMP can't be detected when  
>> using either "msgcache" or "mlistcache" in the IMP configuration. I  
>> can't remember which one.
>
> Thanks for this important information. So this means that these  
> optimizations can also only be used when you don't use other mail  
> programs besides IMP. That is of course not an option here, we can't  
> force our 40000 university users to use only Webmail. What a pity,  
> the mailbox cache really made the mailbox displays noticeably faster.
>
> If it is really only one of the two options which causes the  
> problem, I would guess it *is* mlistcache. I'll try both of them  
> separately and see what happens.
>
> Is this a thing which will be different in your upcoming own IMAP  
> PHP library, which was mentioned occasionally here?

FYI, this is *not* an issue with Horde/IMP.  Instead, it is a  
limitation of the original definition of IMAP 4rev1 (RFC 3501).   
Disconnected IMAP clients (such as a webmail client) have no way of  
obtaining flag/keyword changes in a mailbox without rescan the mailbox  
on every page access.  Connected clients (i.e. Thunderbird, Outlook,  
etc.) maintain connections to the IMAP server the entire time, so they  
are immediately notified if something in a mailbox has changed.

This limitation is precisely what the CONDSTORE IMAP extension (RFC  
4551) addresses (and, to a lesser extent, QRESYNC (RFC 5162)).  IMP 5  
was the first open source webmail client to add support for these  
extensions in IMP 5.

michael

-- 
___________________________________
Michael Slusarz [slusarz at horde.org]