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List:       kde-pim
Subject:    Re: [Kde-pim] XML format for kabc
From:       Cornelius Schumacher <schumacher () kde ! org>
Date:       2002-05-20 11:30:30
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On Monday 20 May 2002 12:38, Tobias Koenig wrote:
> On Mon, May 20, 2002 at 04:26:22AM +0200, Cornelius Schumacher wrote:
> > On Sunday 19 May 2002 18:59, Tobias Koenig wrote:
> > > at the moment I'm writing a xml format for kabc.
> >
> > Why?
>
> Why not? ;)
> At the moment vcard doesn't save all available attributes of
> addressee and xml will (hopefully) become an importent data exchange
> format in the future.

What attributes of Addressee does vCard not save? As an extensible 
format there are no attributes which vCard is not able to handle.

XML is an important data exchange standard, but it is not euqivalent to 
vCard, because XML does only specify a way how to define the syntax of 
a format, but it doesn't define a concrete syntax and does not say 
anything about semantics.

You can make up an DTD to define an addressbook syntax, but the main 
problem is that without a detailed specification of the meaning of all 
fields, there is no data exchange possible.

vCard does have this depcification and it's widely accepted as a 
standard (see the relevant RFCs and what products support it). There is 
nothing comparable in XML and we certainly aren't able to develop a 
comparable standard by ourselves.

It's a very common misunderstanding that XML in itself would make data 
exchangable. That's simply not true.

As storage backend XML also has some drawbacks, because it's more 
complex than vCard and requires more resources. I don't think that 
another text-based format makes much sense as storage backend for 
libkabc. Maybe a binary format backend would be useful, as libkabc 
doesn't perform well with larger sets of data.

> > > Now my questions
> > > is, are there already defined tags for pim xml documents or can I
> > > define my own ones?
> >
> > E. g. Qtopia uses XML to store PIM data.
>
> So I'll take a look on it

There probably already is some code in the opie connector of 
kitchensync.

> > Another approach would be to translate vCard to XML so that all
> > properties and parameters are represented by corresponding XML
> > elements.
>
> The problem with converters is, that everybody how needs such a
> special format has to convert the backend database every time he
> changed a single value. That lacks if e.g. a web frontend (that only
> use XML format) and kaddressbook want to work together.

I'm not talking about converting data, but to convert the structure of 
the standard, so that the XML version is quivalent with the vCard 
version. This might be useful for some purposes as the semantics of the 
XML format would be defined by the vCard standard.

With vCard we already support the format which works best for exchanging 
data. Of course there are additional formats, but these require 
conversion anyway. It would be nice to provide converters for formats 
which are used by other programs, if these are important enough and 
there is somebody willing to implement the code, but there is no point 
in adding an XML backend to libkabc just for the sake of using XML.

-- 
Cornelius Schumacher <schumacher@kde.org>
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