Switching to JBoss 5.1 - Failed to create a new SAX parser

Question

I am trying to deploy my application (packaged in a .war file) that works correctly on JBoss 4.2.3 on JBoss 5.1 (using java 5).

Currently, during deployment, I see an error on the .log server:

... caused by: org.jboss.xb.binding.JBossXBRuntimeException: Failed to create a new SAX parser

... Called: java.lang.ClassCastException: org.apache.xerces.parsers.XML11Configuration

According to this thread on the JBoss forums, I need to isolate my application. My questions:

• according to JBoss 5.1 Release Notes - The main differences from existing configurations are that there is default explode and default deployment. So I really need to implicitly isolate my application?
• I thought that isolation was mostly needed when the same application server runs multiple applications that collide with each other. In my case, I am trying to run only one application. So, do you need insulation?
• If the answer is yes for the above question, and I need to provide isolation - how to configure it? Suppose my war file is called "foo". I need to insert the section into the jboss-web.xml section:

<jboss-web> 
  <loader-repository>
 tld.mydomain:loader=foo.war
 </loader-repository>
</jboss-web>

Answer 1

. , xerces.jar web-inf/lib

- . .

Answer 2

- JAR WAR EAR, . , JARS, .