Unable to create XsltPayloadTransformer when Saxon HE is in the classpath.

[stoussaint]

Affects Version(s): 4.3.19.RELEASE

---

After upgrading to spring-integration-xml:4.3.19.RELEASE (from 4.3.18.RELEASE), my application failed to start with the following exception :

Error creating bean with name 'XsltPayloadTransformer': Invocation of init method failed;

...

Caused by: java.lang.IllegalArgumentException: Unknown configuration property http://javax.xml.XMLConstants/property/accessExternalDTD

The cause of the exception seems to be related to the following changes

- transformerFactory = TransformerFactory.newInstance();
+ transformerFactory = TransformerFactoryUtils.newInstance();

The TransformerFactoryUtils.newInstance() force the XMLConstants.ACCESS_EXTERNAL_DTD property which doesn't seems to be supported by Saxon. If I quote answers from Michael Kay about similar subject, I understand that Saxon does not handle Xml Parser related properties.

Saxon doesn't have control of the XML parsing: we invoke the parser that the application supplies and configures.

As the problem is related to a third party dependency, I provide a side sample project as a regression test case

[garyrussell]

This is fixed in spring-ws on master but it looks like it is not yet in a build.

/cc @gregturn

[artembilan]

I think the store is about:

if (this.templates == null) {
			TransformerFactory transformerFactory;
			if (this.transformerFactoryClassName != null) {
				transformerFactory = TransformerFactory.newInstance(this.transformerFactoryClassName, this.classLoader);
			}
			else {
				transformerFactory = TransformerFactoryUtils.newInstance();
			}
			transformerFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
			transformerFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "file,jar:file");
			try {
				this.templates = transformerFactory.newTemplates(createStreamSourceOnResource(this.xslResource));
			}
			catch (TransformerConfigurationException | IOException e) {
				throw new IllegalStateException(e);
			}
		}

exactly in the XsltPayloadTransformer. So, that is what we have to fix here in SI.

As a workaround you can inject Templates into this XsltPayloadTransformer based on the default TransformerFactoryUtils.newInstance().

[stoussaint]

Maybe the following method could be added to (spring-ws) TransformerFactoryUtils :

public static TransformerFactory newInstance(Class<? extends TransformerFactory> transformerFactoryClass, ClassLoader classLoader)

Then XsltPayloadTransformer.onInit() can be factored this way :

TransformerFactory transformerFactory;
if (this.transformerFactoryClassName != null) {
    transformerFactory = TransformerFactoryUtils.newInstance(this.transformerFactoryClassName, this.classLoader);
} else {
    transformerFactory = TransformerFactoryUtils.newInstance();
}

Hence the unsupported properties will be ignored (with warning) in a centralized manner.

[artembilan]

I factored XsltPayloadTransformer to this:

if (this.transformerFactoryClassName != null) {
			@SuppressWarnings("unchecked")
			Class<TransformerFactory> transformerFactoryClass =
					(Class<TransformerFactory>) ClassUtils.forName(this.transformerFactoryClassName, this.classLoader);
			transformerFactory = TransformerFactoryUtils.newInstance(transformerFactoryClass);
		}
		else {
			transformerFactory = TransformerFactoryUtils.newInstance();
		}
		try {
			transformerFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "file,jar:file");
		}
		catch (IllegalArgumentException ex) {
			if (logger.isWarnEnabled()) {
				logger.warn("The '" + XMLConstants.ACCESS_EXTERNAL_STYLESHEET + "' property is not supported by "
						+ transformerFactory.getClass().getCanonicalName());
			}
		}

so, no need to add anything new to S-WS.