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XML export/import is cool! (Was Deprecating XML export/import?)



--On 24. MÃrz 2006 11:07:06 -0500 Jim Fulton <jim (at) zope.com> wrote:

Andreas Jung wrote: 
Zope supports the export of content either through Python pickles
(.zexp) or as XML. Unfortunatly the XML export/import has several
problems:

- the generated XML is pretty much too low-level to use it e.g.
  for migration issues


I have been working on a Zope 2 project lately and have found
XML export to be extremely usable.  Templates and other
large strings are enclosed in CDATA sections, which make them
surprisingly readable.

We've had sucess writing XSLT templates to transform the pickle data
into formats easily parsable for particular applications.


That's a good argument :-)


- it was broken multiple times in the past, it still has problems

How so?

XML export did not work properly over some major Zope release (I think until Dieter fixed it). And there is at least one unicode related bug report pending (when I read such reports I am thinking about the following options: a) ignore the report and b) who the hell wrote the code and could fix it).


- it has no maintainer, nobody wants to touch it without gloves

Is that any more true than for lots of other things?

Right, but for duplicate functionality that is not widely used and that I consider buggy it is legitimate to propose the deprecation. But as usually I am open to good arguments :-)




As I said above, I've been finding it surprisingly useful lately.

When I first wrote it, I viewed it as someowhat of an academic
exercise, but I've come to realize that it is far more useful than
I originally thought.


I still have the impression that the implementation was made an academic
excercie  rather than something stable for production (.zexp works fine
for production).

This is more so now that XSLT is widely used
and quite capable of transforming the pickles into useful forms.



Note that, IMO, there isn't likely to be a more generally useful
form because usefullness is generally determined by a particular
application.  XSLT + XML pickles together provide a general mechanism
that can adapt to particular application needs.


In this case it has to be fixed if it should be used a general mechanism.


I think the XML export is a facility that is and should be advertized
as a legitimate escape hatch for data kept in Zope.  People really
shouldn't feel afraid of putting data in Zope/ZODB as there
really is a useful way to get it out.

Reasonable export/import should happen on a higher level. This low-level
XML import/export is not really helpful when you want to migrate data between applications and frameworks. E.g. on the Plone/Archetypes level we have some mechanisms to export/import data defined through schemas (possibly
we have something in Zope 3 (at least I once wrote a similar solution for Zope 3). The export/import mechanism is basically for moving data from one
Zope instance to another instance. It should work in a reliable way and should not try to solve issues that should be solved on another level.

To bring it to a point: further Zope 2 versions should get rid of buggy and esoteric features and apparently don't work for lots of ppl resulting in frustration and a bad image for Zope.

Andreas


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  -   Andreas Jung            ZOPYX Ltd. & Co KG                        -
 -   E-mail: info (at) zopyx.com   Web: www.zopyx.com, www.zopyx.de         -
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