cartoninjas.net

Even though JSONIX is a well recognized tool, I have discovered it recently, while looking into parsing WFS capabilities document in JS.

Once I had WFS operational, I started looking into WMS Caps parser, so can handle querying OGC services in a unified way regardless the mapping library (ol, leaflet).

It is pretty straight forward, all mappings are here: w3-schemas and ogc-schemas. Some problems will pop-out when a service happens to provide inspire extended capabilities. Using only the standard mappings will not do, jsonix will complain about missing mappings for {http://inspire.ec.europa.eu/schemas/inspire_vs/1.0}ExtendedCapabilities.

In order to get things right, it was required to provided the proper mappings. Luckily schemas are accessible via inspire-schemas one just needs to generate the mappings, as the repo does not provide them. Mapping generator can be obtained from https://github.com/highsource/jsonix-schema-compiler, then it's just a matter of executing the following:

java -jar jsonix-schema-compiler-full.jar -p INSPIRE_VS_1_0 -b inspire-schemas-1.0.0\schemas\src\main\resources\inspire.ec.europa.eu\schemas\inspire_vs\1.0\bindings.xjb -d mappings inspire-schemas-1.0.0\schemas\src\main\resources\inspire.ec.europa.eu\schemas\inspire_vs\1.0\inspire_vs.xsd

If you happen to get the following err:

[ERROR] Property "Title" is already defined. Use <jaxb:property> to resolve this conflict.
  line 232 of http://www.w3.org/1999/xlink.xsd

[ERROR] The following location is relevant to the above error
  line 219 of http://www.w3.org/1999/xlink.xsd

[ERROR] Property "Title" is already defined. Use <jaxb:property> to resolve this conflict.
  line 261 of http://www.w3.org/1999/xlink.xsd

[ERROR] The following location is relevant to the above error
  line 246 of http://www.w3.org/1999/xlink.xsd

[ERROR] org.hisrc.jsonix.execution.JsonixInvoker - The model is null, there was probably a problem parsing schemas.

Make sure to include binding for xlink:title

<?xml version="1.0" encoding="UTF-8"?>
<jxb:bindings version="1.0" xmlns:jxb="http://java.sun.com/xml/ns/jaxb" xmlns:xs="http://www.w3.org/2001/XMLSchema">
	<jxb:bindings schemaLocation="../../common/1.0/common.xsd" node="//xs:complexType[@name='service']">
		<jxb:class name="InspireService"/>
	</jxb:bindings>
	<jxb:bindings schemaLocation="../../common/1.0/common.xsd" node="//xs:complexType[@name='keyword']">
		<jxb:class name="InspireKeyword"/>
	</jxb:bindings>
	<jxb:bindings schemaLocation="inspire_vs.xsd" node="//xs:element[@name='ExtendedCapabilities']">
		<jxb:class name="InspireExtendedCapabilities"/>
	</jxb:bindings>
	<jxb:bindings scd="x-schema::xlink" xmlns:xlink="http://www.w3.org/1999/xlink">
		<jxb:bindings scd="/group::xlink:locatorModel/model::sequence/xlink:title">
			<jxb:property name="LocatorTitle"/>
		</jxb:bindings>
	</jxb:bindings>

</jxb:bindings>

The process of generating c# classes off the xsd is usually rather simple. One needs the xsd.exe utility (for example located here: C:\Program Files (x86)\Microsoft SDKs\Windows\v8.1A\bin\NETFX 4.5.1 Tools) and then a simple command to get things done:

xsd schema.xsd /c

Sometimes there may be some problems though with missing refs, namespaces and such.

In this example, I will generate classes for WMS 1.3.0 based on the OGC schemas - it is possible to grab them one by one, or all the goodies wrapped as a zip archive.

I have extracted WMS 1.3.0 schemas to f:\wms\schemas, so my command should look like this when in f:\wms (I have copied xsd.exe there too):

xsd schemas\capabilities_1_3_0.xsd /c

Unfortunately there are some problems and classes do not get generated:

The problem here is caused by unresolved references. Xsd was not able to find xlink.xsd. Although there is a xlink schema in OGC repo, this is not the one we're after. The one in question is the mentioned http://www.w3.org/1999/xlink, and its schema definition is http://www.w3.org/1999/xlink.xsd, pretty much as defined in the very beginning of the capabilities_1_3_0.xsd I am trying to process:

<?xml version="1.0" encoding="UTF-8"?>
<schema targetNamespace="http://www.opengis.net/wms" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:wms="http://www.opengis.net/wms" xmlns="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" version="1.3.0.2">
	
	<!--
		WMS is an OGC Standard.
		Copyright (c) 2004,2010 Open Geospatial Consortium.
		To obtain additional rights of use, visit http://www.opengeospatial.org/legal/ .
	-->

	<import namespace="http://www.w3.org/1999/xlink" schemaLocation="http://www.w3.org/1999/xlink.xsd"/>

Unfortunately xsd.exe does not resolve the import automatically, so in order to make it work I just copied the xlinx.xsd to my schemas folder and specified it in the command:

xsd schemas\xlink.xsd schemas\capabilities_1_3_0.xsd /c

Looks like this did the trick and the classes got generated as expected. The complete set of files is here: