Mule Custom Transformer: No class for element custom-transformer

Question

I'm trying to create a simple flow that takes a string from an HTTP endpoint, changes it using a custom Java transformer, and then sends it back to the client. Unfortunately, Mule doesn't seem to be able to find or otherwise use my custom class when I attempt to run the flow. Examples of my code are below:

MyClass.java (the custom transformer class):

package myPackage;

import org.mule.api.MuleMessage;
import org.mule.api.transformer.TransformerException;
import org.mule.transformer.AbstractMessageTransformer;

public class MyClass extends AbstractMessageTransformer {
    @Override
    public Object transformMessage(MuleMessage message, String outputEncoding) throws TransformerException {
        Object[] payload = new Object[] {"Payload has been modified"};

        message.setPayload(payload);

        return message;
    }
}

myFlow.mflow (the flow using the HTTP and custom transformer components):

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:spring="http://www.springframework.org/schema/beans" version="EE-3.4.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd">
    <flow name="myFlow1" doc:name="myFlow1">
        <http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8081" doc:name="HTTP"/>
        <custom-transformer class="myPackage.MyClass" doc:name="Java"/>
    </flow>
</mule>

Error log:

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ New app 'myApp'                                          +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
INFO  2013-12-18 13:13:11,493 [main] org.mule.module.launcher.application.DefaultMuleApplication: 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Initializing app 'myApp'                                 +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
INFO  2013-12-18 13:13:11,674 [main] org.mule.lifecycle.AbstractLifecycleManager: Initialising RegistryBroker
INFO  2013-12-18 13:13:11,797 [main] org.mule.config.spring.MuleApplicationContext: Refreshing org.mule.config.spring.MuleApplicationContext@28d9a0c1: startup date [Wed Dec 18 13:13:11 GMT 2013]; root of context hierarchy
ERROR 2013-12-18 13:13:12,700 [main] org.mule.config.spring.parsers.generic.ChildDefinitionParser: could not load class: myPackage.MyClass
java.lang.ClassNotFoundException: myPackage.MyClass
    at org.mule.util.ClassUtils.loadClass(ClassUtils.java:316)
    at org.mule.util.ClassUtils.loadClass(ClassUtils.java:212)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getBeanClassFromAttribute(AbstractMuleBeanDefinitionParser.java:382)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getClassInternal(AbstractMuleBeanDefinitionParser.java:345)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.parseInternal(AbstractMuleBeanDefinitionParser.java:266)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.muleParse(AbstractMuleBeanDefinitionParser.java:497)
    at org.mule.config.spring.parsers.delegate.AbstractParallelDelegatingDefinitionParser.muleParse(AbstractParallelDelegatingDefinitionParser.java:44)
    at org.mule.config.spring.parsers.delegate.AbstractDelegatingDefinitionParser.parseInternal(AbstractDelegatingDefinitionParser.java:61)
    at org.springframework.beans.factory.xml.AbstractBeanDefinitionParser.parse(AbstractBeanDefinitionParser.java:59)
    at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:88)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:190)
    at org.mule.config.spring.MuleBeanDefinitionDocumentReader.parseBeanDefinitions(MuleBeanDefinitionDocumentReader.java:55)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174)
    at org.mule.config.spring.MuleApplicationContext.loadBeanDefinitions(MuleApplicationContext.java:113)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451)
    at org.mule.config.spring.SpringRegistry.doInitialise(SpringRegistry.java:89)
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:109)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.createSpringRegistry(SpringXmlConfigurationBuilder.java:119)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.doConfigure(SpringXmlConfigurationBuilder.java:73)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.config.builders.AutoConfigurationBuilder.autoConfigure(AutoConfigurationBuilder.java:101)
    at org.mule.config.builders.AutoConfigurationBuilder.doConfigure(AutoConfigurationBuilder.java:57)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.context.DefaultMuleContextFactory.createMuleContext(DefaultMuleContextFactory.java:84)
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:207)
    at org.mule.module.launcher.application.ApplicationWrapper.init(ApplicationWrapper.java:64)
    at org.mule.module.launcher.DefaultMuleDeployer.deploy(DefaultMuleDeployer.java:47)
    at org.mule.tooling.server.application.ApplicationDeployer.main(ApplicationDeployer.java:127)
ERROR 2013-12-18 13:13:12,716 [main] org.mule.module.launcher.application.DefaultMuleApplication: null
java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getClassInternal(AbstractMuleBeanDefinitionParser.java:358)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.parseInternal(AbstractMuleBeanDefinitionParser.java:266)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.muleParse(AbstractMuleBeanDefinitionParser.java:497)
    at org.mule.config.spring.parsers.delegate.AbstractParallelDelegatingDefinitionParser.muleParse(AbstractParallelDelegatingDefinitionParser.java:44)
    at org.mule.config.spring.parsers.delegate.AbstractDelegatingDefinitionParser.parseInternal(AbstractDelegatingDefinitionParser.java:61)
    at org.springframework.beans.factory.xml.AbstractBeanDefinitionParser.parse(AbstractBeanDefinitionParser.java:59)
    at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:88)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:190)
    at org.mule.config.spring.MuleBeanDefinitionDocumentReader.parseBeanDefinitions(MuleBeanDefinitionDocumentReader.java:55)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174)
    at org.mule.config.spring.MuleApplicationContext.loadBeanDefinitions(MuleApplicationContext.java:113)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451)
    at org.mule.config.spring.SpringRegistry.doInitialise(SpringRegistry.java:89)
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:109)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.createSpringRegistry(SpringXmlConfigurationBuilder.java:119)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.doConfigure(SpringXmlConfigurationBuilder.java:73)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.config.builders.AutoConfigurationBuilder.autoConfigure(AutoConfigurationBuilder.java:101)
    at org.mule.config.builders.AutoConfigurationBuilder.doConfigure(AutoConfigurationBuilder.java:57)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.context.DefaultMuleContextFactory.createMuleContext(DefaultMuleContextFactory.java:84)
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:207)
    at org.mule.module.launcher.application.ApplicationWrapper.init(ApplicationWrapper.java:64)
    at org.mule.module.launcher.DefaultMuleDeployer.deploy(DefaultMuleDeployer.java:47)
    at org.mule.tooling.server.application.ApplicationDeployer.main(ApplicationDeployer.java:127)
INFO  2013-12-18 13:13:12,717 [main] org.mule.module.launcher.application.DefaultMuleApplication: App 'myApp' never started, nothing to dispose of
Exception in thread "main" org.mule.module.launcher.DeploymentInitException: IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:219)
    at org.mule.module.launcher.application.ApplicationWrapper.init(ApplicationWrapper.java:64)
    at org.mule.module.launcher.DefaultMuleDeployer.deploy(DefaultMuleDeployer.java:47)
    at org.mule.tooling.server.application.ApplicationDeployer.main(ApplicationDeployer.java:127)
Caused by: org.mule.api.config.ConfigurationException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java} (org.mule.api.lifecycle.InitialisationException) (org.mule.api.config.ConfigurationException)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:52)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.context.DefaultMuleContextFactory.createMuleContext(DefaultMuleContextFactory.java:84)
    at org.mule.module.launcher.application.DefaultMuleApplication.init(DefaultMuleApplication.java:207)
    ... 3 more
Caused by: org.mule.api.config.ConfigurationException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java} (org.mule.api.lifecycle.InitialisationException)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:52)
    at org.mule.config.builders.AbstractResourceConfigurationBuilder.configure(AbstractResourceConfigurationBuilder.java:78)
    at org.mule.config.builders.AutoConfigurationBuilder.autoConfigure(AutoConfigurationBuilder.java:101)
    at org.mule.config.builders.AutoConfigurationBuilder.doConfigure(AutoConfigurationBuilder.java:57)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    ... 6 more
Caused by: org.mule.api.lifecycle.InitialisationException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:117)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.createSpringRegistry(SpringXmlConfigurationBuilder.java:119)
    at org.mule.config.spring.SpringXmlConfigurationBuilder.doConfigure(SpringXmlConfigurationBuilder.java:73)
    at org.mule.config.builders.AbstractConfigurationBuilder.configure(AbstractConfigurationBuilder.java:46)
    ... 10 more
Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from URL [file:/C:/mulestudio-3.5/workspace/.mule/apps/myApp/myApp.xml]; nested exception is java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:412)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:334)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:302)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:174)
    at org.mule.config.spring.MuleApplicationContext.loadBeanDefinitions(MuleApplicationContext.java:113)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:537)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:451)
    at org.mule.config.spring.SpringRegistry.doInitialise(SpringRegistry.java:89)
    at org.mule.registry.AbstractRegistry.initialise(AbstractRegistry.java:109)
    ... 13 more
Caused by: java.lang.IllegalStateException: No class for element custom-transformer{name=Java}
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.getClassInternal(AbstractMuleBeanDefinitionParser.java:358)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.parseInternal(AbstractMuleBeanDefinitionParser.java:266)
    at org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser.muleParse(AbstractMuleBeanDefinitionParser.java:497)
    at org.mule.config.spring.parsers.delegate.AbstractParallelDelegatingDefinitionParser.muleParse(AbstractParallelDelegatingDefinitionParser.java:44)
    at org.mule.config.spring.parsers.delegate.AbstractDelegatingDefinitionParser.parseInternal(AbstractDelegatingDefinitionParser.java:61)
    at org.springframework.beans.factory.xml.AbstractBeanDefinitionParser.parse(AbstractBeanDefinitionParser.java:59)
    at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:73)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:88)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.parseCustomElement(MuleHierarchicalBeanDefinitionParserDelegate.java:130)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1428)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:190)
    at org.mule.config.spring.MuleBeanDefinitionDocumentReader.parseBeanDefinitions(MuleBeanDefinitionDocumentReader.java:55)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:140)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:111)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:390)
    ... 22 more

.classpath contents (untouched, this is as it was generated by MuleStudio):

<?xml version="1.0" encoding="UTF-8"?>
<classpath>
    <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.7"/>
    <classpathentry exported="true" kind="con" path="MULE_RUNTIME"/>
    <classpathentry kind="src" path="src/main/java"/>
    <classpathentry kind="src" path="src/main/resources"/>
    <classpathentry kind="src" output="target/test-classes" path="src/test/java"/>
    <classpathentry kind="src" output="target/test-classes" path="src/test/resources"/>
    <classpathentry kind="output" path="target/classes"/>
</classpath>

MyClass.java is located at C:\mulestudio-3.5\workspace\myApp\src\main\java\myPackage\MyClass.java (where MuleStudio automatically put it), and all files in src\main are included in the BuildPath settings.

As far as I can tell, I've done everything I need to in order to use the custom transformer. Evidently, I've missed something out. What can I do to get my custom transformer working?

Answer 1

Your code is not compiling by the Studio hence the error. Many times working with newly created projects (from Import...) I catch myself struggling to find why my code is not compiling and Studio is spitting weird errors. First thing for me to check is "Java Build Path" - right click on your project. Make sure there is no red X's in you "Library" or "Source" caused by a missing jar or folder.

Answer 2

If you create a new java class in mule studio yoe have to stop and start to get the changes, the redeploy does not get the new .java, or at least it happended to me.

Answer 3

I fixed this problem by rolling back to MuleStudio 3.4.0. It would therefore appear to be an issue with my installation of 3.4.1.

Answer 4

Check the case you are using for the class name: public class myClass (lower m) and <custom-transformer class="myPackage.MyClass" (upper M).

You need to change your transformer class declaration to "myPackage.myClass".