xmlStream = XMLInputFactory.newInstance().createXMLStreamReader( new StringReader( constraintString ) );
                // skip START_DOCUMENT
                xmlStream.nextTag();

                if ( versionConstraint.equals( new Version( 1, 1, 0 ) ) ) {

                    constraint = Filter110XMLDecoder.parse( xmlStream );

                } else if ( versionConstraint.equals( new Version( 1, 0, 0 ) ) ) {
                    constraint = Filter100XMLDecoder.parse( xmlStream );
                } else {
                    String msg = Messages.get( "CSW_FILTER_VERSION_NOT_SPECIFIED", versionConstraint,
                                               Version.getVersionsString( new Version( 1, 1, 0 ) ),
                                               Version.getVersionsString( new Version( 1, 0, 0 ) ) );
                    LOG.info( msg );
                    throw new InvalidParameterValueException( msg );
                }
            } catch ( XMLStreamException e ) {
                String msg = "FilterParsingException: There went something wrong while parsing the filter expression, so please check this!";
                LOG.debug( msg );
                throw new XMLParsingException( xmlStream, e.getMessage() );

        } catch ( OWSException e ) {
            LOG.debug( e.getMessage(), e );
            sendServiceException( e, response );
        } catch ( InvalidParameterValueException e ) {
            LOG.debug( e.getMessage(), e );
            sendServiceException( new OWSException( e ), response );
        } catch ( MissingParameterException e ) {
            LOG.debug( e.getMessage(), e );
            sendServiceException( new OWSException( e ), response );
        } catch ( Throwable t ) {
            String msg = "An unexpected error occured: " + t.getMessage();
            LOG.debug( msg, t );