XSLT ClassCastException in WebSphere when Spring tries to create an AnnotationMethodHandlerAdapter - spring

Question

When starting WebSphere, I get this exception:
Could not instantiate bean class [org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter]:
Constructor threw exception; nested exception is java.lang.ClassCastException:
com.ibm.xtq.xslt.jaxp.compiler.TransformerFactoryImpl incompatible with
javax.xml.transform.TransformerFactory
Caused by: java.lang.ClassCastException: com.ibm.xtq.xslt.jaxp.compiler.TransformerFactoryImpl
incompatible with javax.xml.transform.TransformerFactory
at javax.xml.transform.TransformerFactory.newInstance(Unknown Source)
at org.springframework.http.converter.xml.AbstractXmlHttpMessageConverter.<init>(AbstractXmlHttpMessageConverter.java:47)
at org.springframework.http.converter.xml.SourceHttpMessageConverter.<init>(SourceHttpMessageConverter.java:45)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.<init>(AnnotationMethodHandlerAdapter.java:197)
This doesn't seem have any impact on any beans in my applicationContext.xml but it's still odd. For me, this looks as if IBM classes are leaking into my application.
How can I fix this? I already set the option "Access to internal server classes" to "Restrict".

Answer 1

It was indeed a class-loading issue, however this cannot be solved by changing class-loader settings.
The problem was that the xml-apis and javax.xml jars were being imported over some maven dependencies.
Since we already set the class loader policies for the application to PARENT_LAST, the javax.xml.transform.TransformerFactory was being loaded from the WebApp-Class loader from our jar files.
However its implementation 'com.ibm.xtq.xslt.jaxp.compiler.TransformerFactoryImpl' was coming from the server class loader, this one was linked to the javax.xml.transform.TransformerFactory provided by the JDK/JRE.
Since the classes were loaded from different sources a ClassCastException was thrown.
Removing all dependencies to xml-apis / xerces / javax.xml jars solved the problem.
Since these APIs are now part of the JDK they no longer need to be imported.
... and if you wonder why I know so much about this issue: I work together with Aaron. ;)

Answer 2

I can't speak for Restrict as I have no personal experience with it,But I think the problem is more to do with IBM Class Loader. The class you are referring to is part of IBM Java implementation of TransformerFactory, I think you can try one of the following to solve this issue on hand
Either change the server class loader policy to PARENT_LAST (This way class loader will find the class from application's local class path, before going to up the chain all the way to java run time)
The other option would be look at the jaxp.properties file, I think it is located in (was_root\java\jre\lib), I only read about this option never actually used it

Answer 3

Why do you say IBM classes are leaking into your application?
The TransformerFactory is asked to create a newInstance. It follows a sequence of steps to determine which TransformerFactory to use. If none of the config is specified, it simply chooses to use the default factory.
Here is the javadoc for TransformerFactory:
http://download.oracle.com/javase/1.5.0/docs/api/javax/xml/transform/TransformerFactory.html#newInstance()
What is the OS ? Is that AIX?
http://www.ibm.com/developerworks/java/jdk/aix/j664/sdkguide.aix64.html
Looking at this doc (link above) for AIX it tells me that this is the default Impl:
javax.xml.transform.TransformerFactory
Selects the XSLT processor. Possible values are:
com.ibm.xtq.xslt.jaxp.compiler.TransformerFactoryImpl
Use the XL TXE-J compiler. This value is the default.
Post back additional information so that we can try and troubleshoot this.
HTH
Manglu