Kolab XML Format: Proposal for an XSD friendly update

Jeroen van Meeuwen (Kolab Systems) vanmeeuwen at kolabsys.com
Tue Oct 18 23:04:37 CEST 2011

On 2011-10-18 20:35, Gunnar Wrobel wrote:
> Hi Christian,

Hi Gunnar,

> Quoting Christian Mollekopf <mollekopf at kolabsys.com>:
>> Preserving unknown tags is far from trivial and a rather big
>> development effort. I understand the use of an extensible format as 
>> it
>> makes it very easy for vendors to implement their own special 
>> features
>> using extensions (aka unknown tags). Also the idea that old clients 
>> can
>> still make use of a subset of the data of
>> newer versions of the format is intriguing. However I think there 
>> are a
>> couple of severe drawbacks which make me think unknown tags are not 
>> a
>> good idea after all.
>> - If vendors can implement their features with unknown tags, no one
>> else can make use of it. This effectively works against the idea 
>> that
>> all clients support the same features
> I do not think it is very likely that all Kolab clients will ever
> support the same feature set. I do not consider this to be a central
> idea of the format specification. The Kolab format forces the clients
> to adhere to it for Kolab features supported the clients. It does not
> force the clients to support all features though.
> Why shouldn't there be a client that only knows how to use the
> "summary" and "body" field of the "note" object? Yes, not very 
> useful.
> But what would force the vendor of this imaginary client to support
> the full Kolab format feature set if he has customers that are happy
> with this extremely reduced set of capabilities?

The addition of a feature to a Kolab Format XSD (i.e. the availability 
of a new tag) does not mandate the client application also implement the 
functionality associated with the feature, these are two different 

Kind regards,

Jeroen van Meeuwen

Senior Engineer, Kolab Systems AG

e: vanmeeuwen at kolabsys.com
t: +44 144 340 9500
m: +44 74 2516 3817
w: http://www.kolabsys.com

pgp: 9342 BF08

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