[TinyOWS-users] Should the feature attributes order in XML matter ?

[Gissur Þórhallsson]

I suddenly started getting this message too.

I'm not entirely sure what happened - I've had tinyOWS running without a
hitch for a couple of months now and then all of a sudden I start to get
"xml is not valid"
And peeping into the logs gives me:
[Sat Feb 19 12:42:34 2011] [ERROR] Element '{
http://my.namespaceurl.com/}area': This element is not expected. Expected is
one of ( {http://my.namespaceurl.com/}date_created, {
http://my.namespaceurl.com/}date_modified, {
http://my.namespaceurl.com/}username, {
http://geoserver.loftmyndir.is/}origin ).

Funnily enough this does not happen to all layers - simple layers (as in
with few attributes, in my case only numeric area and a text field for
comments) seem unaffected.

I can't for the life of my figure out why this popped up all of sudden - the
only thing I can relate this to is a system-wide upgrade I made on my box,
which is running ubuntu 8.0.4. LTS box- and if I correlate my tinyows.logs
with /var/log/apt/term.log I see that the "Expected is one of [...]" only
start to appear around the time I upgraded libxml2 to  libxml2
(2.6.31.dfsg-2ubuntu1.5) (I have no idea what version I was running before
that).

I'm going to see whether I can downgrade libxml2 and see if it changes
anything.

Or am I maybe barking up the completely wrong tree here?

Kind regards,
Gissur



On Mon, Jan 31, 2011 at 10:05 PM, Jean-François Gigand <
jean-francois at gigand.fr> wrote:

> Hi,
>
> For an 1.0.0 insert request, I get the exception "xml isn't valid"
> with the following error:
> [Mon Jan 31 21:11:05 2011] [ERROR] Element '{http://domain.net/}name':
> This element is not expected. Expected is (
> {http://domain.net/}deleted ).
>
> "name" and "deleted" are (among others) valid feature attributes.
> If I change the attribute elements order in my test request XML file,
> and follow exactly the PostgreSQL column order for that table, it
> works.
>
> I am surprised. The WFS spec doesn't require a proper feature
> attribute order in the list, does it?
>
> Having checked the w3schools doc about XML Schema, the <xs:sequence>
> element requires the element order to be respected.
> I see that validation is done by libxml2, and of course is done well.
>
> The problem, within the use cases of TinyOWS, is that PostgreSQL does
> not provide any way to alter columns position.
>
> You would say that the app should anyway fetch the feature schema by
> issuing a DescribeFeatureType request, and deal with the features
> according to it...
>
> Actually, the OpenLayers serializer (exactly:
> OpenLayers.Format.GML.Base.prototype.writers.feature._typeName)
> creates the geometry first, then the attributes in object property
> (for .. in).
> If the geometry column in the PostgreSQL table is not the first (or
> second after identifier), I could never insert any feature, and a
> workaround with OpenLayers would be really messy.
>
> This would be an issue of OpenLayers of course. But I think it
> wouldn't break the logic to add to the TinyOWS configuration an
> optional "columns-order" attribute on the <layer> elements.
> That attribute would contain the comma-separated list of columns to
> export to the WFS client in the order they should be listed in the
> DescribeFeatureType sequence.
>
> It would also allow to restrict the columns to export.
>
> What do you think?
>
> --
> Jeff
> _______________________________________________
> TinyOWS-users mailing list
> TinyOWS-users at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/tinyows-users
>



-- 
Gissur Þórhallsson

Loftmyndir ehf.
Laugavegur 13
IS 101 Reykjavík - Iceland
sími (tel): (+354) 540 2500
tölvupóstur (email): gissur at loftmyndir.is
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