activemq in apache karaf, loading configuration with xbean

Question

I want to create embedded ActiveMQ broker using xbean configuration inside OSGi bundle running on Apache Karaf. This code:

brokerService = BrokerFactory.createBroker("xbean:file:etc/config.xml");

fails with the following exception:

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to load type: org.apache.activemq.xbean.XBeanBrokerService. Reason: java.lang.ClassNotFoundException: org.apache.activemq.xbean.XBeanBrokerService not found by org.apache.xbean.spring [81]; nested exception is java.lang.ClassNotFoundException: org.apache.activemq.xbean.XBeanBrokerService not found by org.apache.xbean.spring [81]
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.getBeanInfo(XBeanQNameHelper.java:75)
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.coerceNamespaceAwarePropertyValues(XBeanQNameHelper.java:54)
        at org.apache.xbean.spring.context.v2c.XBeanBeanDefinitionParserDelegate.parseBeanDefinitionElement(XBeanBeanDefinitionParserDelegate.java:59)
        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:396)
        at org.apache.xbean.spring.context.v2c.XBeanNamespaceHandler.parseBeanFromExtensionElement(XBeanNamespaceHandler.java:224)
        at org.apache.xbean.spring.context.v2c.XBeanNamespaceHandler.parseBeanFromExtensionElement(XBeanNamespaceHandler.java:276)
        at org.apache.xbean.spring.context.v2c.XBeanNamespaceHandler.parse(XBeanNamespaceHandler.java:156)
        at org.apache.xbean.spring.context.v2.XBeanNamespaceHandler.parse(XBeanNamespaceHandler.java:49)
        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1338)
        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1328)
        at org.apache.xbean.spring.context.v2.XBeanBeanDefinitionDocumentReader.parseBeanDefinitions(XBeanBeanDefinitionDocumentReader.java:84)
        at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:93)
        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:493)
        at org.apache.xbean.spring.context.v2.XBeanXmlBeanDefinitionReader.registerBeanDefinitions(XBeanXmlBeanDefinitionReader.java:79)
        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.apache.xbean.spring.context.ResourceXmlApplicationContext.loadBeanDefinitions(ResourceXmlApplicationContext.java:111)
        at org.apache.xbean.spring.context.ResourceXmlApplicationContext.loadBeanDefinitions(ResourceXmlApplicationContext.java:104)
        at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
        at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:467)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:397)
        at org.apache.xbean.spring.context.ResourceXmlApplicationContext.<init>(ResourceXmlApplicationContext.java:64)
        at org.apache.xbean.spring.context.ResourceXmlApplicationContext.<init>(ResourceXmlApplicationContext.java:52)
        at org.apache.activemq.xbean.XBeanBrokerFactory$1.<init>(XBeanBrokerFactory.java:114)
        at org.apache.activemq.xbean.XBeanBrokerFactory.createApplicationContext(XBeanBrokerFactory.java:114)
        at org.apache.activemq.xbean.XBeanBrokerFactory.createBroker(XBeanBrokerFactory.java:70)
        at org.apache.activemq.broker.BrokerFactory.createBroker(BrokerFactory.java:71)
        at org.apache.activemq.broker.BrokerFactory.createBroker(BrokerFactory.java:54)
        at org.apache.activemq.broker.BrokerFactory.createBroker(BrokerFactory.java:85)
        at jmstest.bundle.TestActivator.start(TestActivator.java:18)
        at org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:629)
        at org.apache.felix.framework.Felix.activateBundle(Felix.java:1842)
        at org.apache.felix.framework.Felix.startBundle(Felix.java:1759)
        at org.apache.felix.framework.Felix.setActiveStartLevel(Felix.java:1163)
        at org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:264)
        at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassNotFoundException: org.apache.activemq.xbean.XBeanBrokerService not found by org.apache.xbean.spring [81]
        at org.apache.felix.framework.ModuleImpl.findClassOrResourceByDelegation(ModuleImpl.java:787)
        at org.apache.felix.framework.ModuleImpl.access$400(ModuleImpl.java:71)
        at org.apache.felix.framework.ModuleImpl$ModuleClassLoader.loadClass(ModuleImpl.java:1768)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.loadClass(XBeanQNameHelper.java:107)
        at org.apache.xbean.spring.context.v2c.XBeanQNameHelper.getBeanInfo(XBeanQNameHelper.java:72)
        ... 36 more

All needed bundles (activemq, activemq-spring, xbean-spring) are loaded and running, and my bundle has them all in Import-Package.

Same configuration file loaded from standalone ActiveMQ broker works as it should.

I believe this is happening because xbean cannot access classes from the bundle which it does not import. Is there a way around this?

Answer 1

Solved this myself, but it looks like a hack. Appreciate if someone tell how to make it right if it is possible.

The idea is to substitute default class loader with the one that loaded current class (bundle activator in my case):

ClassLoader c = Thread.currentThread().getContextClassLoader();
Thread.currentThread().setContextClassLoader(this.getClass().getClassLoader());

brokerService = BrokerFactory.createBroker("xbean:file:etc/config.xml");
brokerService.start();

Thread.currentThread().setContextClassLoader(c);

XBean tries several classloaders when it is loading a class, including the thread context classloader. Of course, getClass().getClassLoader() loader knows about imports of my bundle, thus XBean manages to load all needed classes (provided they are in Import-Package header). Maybe this will be helpful to someone else too.