Okay, so here's the short of what I'm trying to achieve. I am developing a small Google App Engine application that generates XML given a particular object.
Now, I run into issues because I need to use a Relax NG schema and validate it against my Document object. This works fine on my local machine (Eclipse Helios Java EE, Mac OS X Snow Leopard, Google Web Toolkit 2.2.0, App Engine 1.4.2), but as soon as I deploy to App Engine, my code fails and throws an IllegalArgumentException.
The specific exception is this:
java.lang.IllegalArgumentException: No SchemaFactory that implements the schema language specified by: http://relaxng.org/ns/structure/1.0 could be loaded
The specific line(s) of code that it is complaining about are the following:
System.setProperty(SchemaFactory.class.getName() + ":" + XMLConstants.RELAXNG_NS_URI, "com.thaiopensource.relaxng.jaxp.CompactSyntaxSchemaFactory");
SchemaFactory schemaFac = SchemaFactory.newInstance(XMLConstants.RELAXNG_NS_URI);
The last line is the line that throws the Exception.
I have tried looking online, and posted in several Google Groups, but no one came forth with an idea.
Note: I took the use of some of the above code from this example: How to validate an XML document using a RELAX NG schema and JAXP?
My suspicion is that App Engine is not loading Jing.jar for some reason. I don't know how I can check that it is/isn't.
Any help would be appreciated! Thanks!
Well, I actually found a workaround of sorts that completely takes out the (practically hackish) use of System.setProperty.
It turns out that Jing has a little class called "CompactSyntaxSchemaFactory".
Here is how I used it:
DocumentBuilderFactory docFactory = null;
CompactSyntaxSchemaFactory scReader = new CompactSyntaxSchemaFactory();
URL relaxSchemaURL = new URL("http://example.com/myschema.rng");
Schema2 relaxSchema = scReader.newSchema(relaxSchemaURL);
docFactory = DocumentBuilderFactory.newInstance();
docFactory.setSchema(relaxSchema);
Worked like a charm.