[Geotools-gt2-users] GML 3.1.1 bindings for encoding Geometry types in GeoTools 8.3

[Jurrian H. <jha...@gm...>]

Dear GeoTools users,

I've successfully created GeoTools (8.3) bindings for parsing and encoding
XML bindings as described  in their tutorial:
http://docs.geotools.org/latest/userguide/library/xml/internal/bindings.html

I can parse the XML data + GML 3.1.1 geometries successfully, including
combining multiple XSD's and using the binding context for factories, etc..
but the encoding seems to result in XML data with geometries that are not
linked to a particular namespace ('null:'). Since the above tutorial (or
anything else I could find) doesn't mention specifics about encoding
GML-geometies I have the following question(s):

- Which bindings do I have to make myself and which can be handled by
GeoTools?
- In the repository I see a number of util classes (e.g.
GML3EncodingUtils), Geometry type bindings (implemented) and normal
geometry bindings (unimplemented). Does anyone have experience using these?
Again, which to implement, and which not?

I'm only interested in a limited part specifying the geometries. Here's the
fragment of the XSD that connects to GML geometries (Dutch Cadastral data):

    <?xml version="1.0" encoding="UTF-8"?>
    ...
    <xs:import namespace="http://www.opengis.net/gml"
schemaLocation="../../gml/bag-gml.xsd"/>
    ...
    <xs:complexType name="PuntOfVlak">
        <xs:annotation>
            <xs:documentation>Keuze tussen een punt (gml:Point) of een vlak
(gml:Surface).</xs:documentation>
        </xs:annotation>
        <xs:choice>
            <xs:element ref="gml:Point"/>
            <xs:element ref="gml:_Surface"/>
        </xs:choice>
    </xs:complexType>
    ...
    <xs:complexType name="VlakOfMultiVlak">
        <xs:choice>
    <xs:element ref="gml:_Surface"/>
    <xs:element ref="gml:MultiSurface"/>
        </xs:choice>
    </xs:complexType>
    ...


So basically, its about how to implement the encode(..) or getProperty(..)
method of my PuntOfVlakBinding and VlakOfMultiVlakBinding.

The original XSD's can be found here:

- The GML XSD: http://pastebin.com/nMisVg2Q

The VlakOfMultiVlakBinding:

    ...

    public class VlakOfMultiVlakBinding extends AbstractComplexBinding {

        private static final String SURFACE = "_Surface";
        private static final String POLYGON = "Polygon";
        private static final String MULTI_POLYGON = "MultiSurface";

        @Override
        public Object getProperty(Object object, QName name) throws
Exception {

            if (SURFACE.equals(name.getLocalPart())) {
                return object;
            }

            if (POLYGON.equals(name.getLocalPart())) {
                return object;
            }

            if (MULTI_POLYGON.equals(name.getLocalPart())) {
                return object;
            }

            return null;
        }

        @Override
        public QName getTarget() {
            return BAGType.VlakOfMultiVlak;
        }

        @Override
        public Class<?> getType() {
            return Geometry.class;
        }

        @Override
        public Object parse(ElementInstance instance, Node node, Object
value) throws Exception {

            if (node.hasChild(SURFACE)) {
                return node.getChildValue(SURFACE);
            }

            if (node.hasChild(POLYGON)) {
                return node.getChildValue(POLYGON);
            }

            if (node.hasChild(MULTI_POLYGON)) {
                return node.getChildValue(MULTI_POLYGON);
            }

            throw new IllegalArgumentException("Unsupported GML type
detected for binding " + VlakOfMultiVlakBinding.class.toString());
        }
    }

I can also post attempts at the _SurfaceBinding.java in case this might
help.
I've also posted my question at
http://gis.stackexchange.com/questions/48115/how-to-couple-geotools-gml-bindings-for-encoding-to-gml-3-1-1Once
I know what to do I'll post my answer both here and to mailing list
(I'm actually not sure why I didnt think of the mailing list in the first
place!).