[Kolab-devel] Horde can now store Preferences in IMAP (was: Horde preferences: LDAP or IMAP?)

[Jan Schneider]

Zitat von Gunnar Wrobel <wrobel at pardus.de>:

> Quoting Alain Spineux <aspineux at gmail.com>:
>
>> 2008/12/21 Gunnar Wrobel <wrobel at pardus.de>:
>>> Hi!
>>>
>>> A while back (beginning of this year) we had a discussion on how to store
>>> the user preferences of the Kolab webclient (based on Horde).
>>>
>>> Horde preferences are being handled by a single module called "prefs". This
>>> module supports several backends. Among them are
>>>
>>> - SQL
>>> - LDAP
>>> - File based
>>> - IMAP
>>>
>>> Horde usually uses SQL. Kolab has traditionally used the LDAP backend. This
>>> LDAP backend has been replaced with the file based backend for Kolab Server
>>> 2.2.1 beta 1. An alternative would also be the storage in IMAP similar to
>>> the other groupware data of the Kolab server.
>>>
>>> The decision to switch to the file based approach was made since the
>>> developer team did not consider LDAP to be a decent place for such data
>>> anymore. It makes the LDAP entries rather complex and LDAP is usually meant
>>> primarily for read access rater than a standard storage space.
>>>
>>> We decided not to use IMAP at the moment as that would mean we  
>>> would need to
>>> discuss the Kolab format for such entries wich would take a while until we
>>> finalize it.
>>>
>>> So the file based approach has been selected for now.
>>>
>>> This does not hinder anyone to choose any of the other possible backends.
>>> People that like to remain on LDAP can do so without problems while people
>>> preferring IMAP storage can also choose to do so.
>>>
>>> But the question still is: What is the best default?
>>>
>>> It would be great if people could add the pros and cons they see for the
>>> different solutions. I'll try to add an overview once we have some opinions
>>> and I'll include the relevant pieces from the discussion we had at the
>>> beginning of this year.
>>>
>>> I would like to add that I personally see the IMAP driver as the best
>>> choice. For me the Kolab server architecture results in one simple
>>> conclusion: User data belongs into IMAP. And preferences are user data.
>>
>> Pro IMAP too.
>> File based approach require to add something into the backup or the
>> migration procedure.
>> Anyway, when does these data need to be READ or WRITTEN ?
>> At each mail access, or at each folrder access, or just once at login
>> and logout ?
>
> The data needs to be READ on nearly every page access. Preferences  
> are  used at many different places within the Kolab web client. E.g.  
> which  calendars to display, the last time you logged in, your real  
> name etc.

This is not quite true, because preferences are only read once per  
session and application and cached in the user session after that.

> This data needs to be WRITTEN whenever one or several of these   
> preferences changes. This may sometimes be the result of user action  
>  where you don't actually see that you changed something (e.g. the   
> login -> your last login time gets stored in the preferences  
> backend)  but usually only when you actually switch a setting.

Jan.

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