About CalDAV

[Martin Konold]

Am Samstag, 22. Januar 2005 04:25 schrieb Helge Hess:

Hi Helge,

> As Martin mentions there are companies running tens of thousands of
> users against Cyrus for mail.

Good that you acknowledge this fact.

> But this isn't related to Kolab at all, 

Sorry, this statement is utter nonsense. 

Of course it relates to Kolab a lot as _all_ groupware objects are from the 
point of view of the server _plain_ email messages!

> since none of those setups run any of the Kolab clients with the
> additional functionality provided by Kolab, nor the Kolab specific
> server setup.

Actually due to the fact that Kolab works with disconnected imap instead of 
online imap Kolab scales even better than traditional IMAP clients.

The nice thing about the Kolab architecture is the fact that the Kolab 
groupware functionality is mostly in the smart clients so that additional 
features don't hurt the scalability of the server. 

Beyond that do smart clients allow for fully featured offline functionality 
which becomes more and more important.

Last but not least Kolab 2 has built in support for multi-location setups 
which help enormously when scaling beyond a single machine or location.

Currently I only see a theoretical limit in the generation of partialy 
freebusy lists. Though I don't consider this is a big issue due to several 
facts.

- pfbs are not latency critical
- pfbs are only a troughput issue
- Latency is what counts for interactive users
- pfb generation can _easily_ be scaled with using extra hardware 
- pfb generation is only required when _writing_ to a calendar folder
- the pfb code (php) can easily be speeded up by a factor of 5 by using a php 
accellerator
- the pfb generation code could be redesigned (about a speedup of maybe 20 
reachable). Though this would be some significant effort beyond one man 
month.

The same as with pfbs is valid for server side fbview.

> if you like, take the fastest server you have.

I don't have a fast server for disposal. Assuming that you can provide a 
testlab with all the required infrastructure (e.g. a big server or multiple 
big server, fast network, a linux/windows cluster for generating the load) I 
more than willing to take the challenge.

Maybe you can arrange for a shootout of Opengroupware and Kolab 2 in such a 
setting. Potential sponsors could be the big testing labs of a big HW vendor 
like IBM, HP or Siemens.

> You still can't show an  
> actual setup which uses 10.000 active users together with the Kolab 
> server and either the Outlook client or the Kolab resource with 
> Kontact.

Yes, Kolab is too young (Kolab was started less than two years ago) to already 
have such an installation. Though believe me that I have been contacted by 
several institutions about installations even beyond this scale. I personally 
feel rather comfortable with the prospect of such large installations.

Last but not least in all my Beta installations of Kolab 2 at customer sites 
(all below 1000 users) I sofar got feedback that the performance is stunning 
even on lower end server hardware.

Regards,
-- martin

-- 
"I am committed to helping Ohio deliver its electoral votes to the
President next year."  -- 2004, Wally O'Dell - CEO of Diebold, Inc. 
e r f r a k o n - Stuttgart, Germany
Erlewein, Frank, Konold & Partner - Beratende Ingenieure und Physiker