Java Tomcat - class loader is behaving differently on differenet machines - gradle

Issue started happening after upgrading Tomcat + Java (not that it matters)
I am getting AbstractMethodError (runtime) on some machines, the reason is due to class loader acting differnetly
I have 2 depenencies implementing ResponseBuilder (ResponseBuilderImpl)
Jbos-resteasy and cxf-rt-frontend
there is a method that is also abstract on cxf-rt-frontend so on some machine when the Class loader select this implementation and not jboss I get the above exception
If I log the jar loading on Tomcat I see the diff:
[Loaded org.jboss.resteasy.specimpl.ResponseBuilderImpl from file:/usr/local/tomcat/webapps/MedAwareDemo/WEB-INF/lib/resteasy-jaxrs-3.13.2.Final.jar]
[Loaded org.apache.cxf.jaxrs.impl.ResponseBuilderImpl from file:/usr/local/tomcat/webapps/MedAwareDemo/WEB-INF/lib/cxf-rt-frontend-jaxrs-3.1.8.jar]
I am not in a situation where I can just remove one of the implemetation and use a single one (I know this is the best approach).
We are using Gradle + Docker.
What are my options? why is there a different runtime behaviour?
Thanks!

Related

WebSphere Liberty and Eclipselink SDO

I am porting an old IBM Process Server application to IBM WebSphere Liberty. It contains a lot of code based on Service Data Objects (SDO). I have some good working code, running as standalone Java, using JDK8. I am using eclipselink 2.7.7, specifically 2 jar files;
eclipselink.jar
commonj.sdo_2.1.1v20111051852.jar
I have built this code into a Servlet to handle SOAP requests, and packaged it, along with other code, into an EAR file, which I deployed under IBM WebSphere Liberty 20. It doesn't work. There seems to be a clash with the Liberty version of EclipseLink.
If I deploy the code as a WAR file, and add a classloader of "PARENT_LAST", the code works fine.
However, if I try to deploy the code in an EAR file, and set a classloader of "PARENT_LAST" for the ear file, I get this error;
[ERROR ] CWWKZ0106E: Could not start web application S21.
[ERROR ] CWWKZ0002E: An exception occurred while starting the application S21. The exception message was: com.ibm.ws.container.service.state.StateChangeException: java.lang.LinkageError: loader constraint violation in interface itable initialization: when resolving method "org.eclipse.persistence.jpa.PersistenceProvider.getProviderUtil()Ljavax/persistence/spi/ProviderUtil;" the class loader (instance of com/ibm/ws/classloading/internal/ParentLastClassLoader) of the current class, org/eclipse/persistence/jpa/PersistenceProvider, and the class loader (instance of org/eclipse/osgi/internal/loader/EquinoxClassLoader) for interface javax/persistence/spi/PersistenceProvider have different Class objects for the type javax/persistence/spi/ProviderUtil used in the signature
Does anyone know whether I can replace the IBM Liberty implementation of EclipseLink with my version 2.7.7 version?
My application also uses JPA, which is working fine under Liberty, so I don't want to break that.
Any help / guidance appreciated... it's been a very long saturday.
PS:
I tried running the java code using only the SDO library (commonj.sdo_2.1.1v20111051852.jar), and relying on the WebSphere Liberty runtime jars to provide Eclipselink functionality, and I got the following errors, which is why I then moved to adding the "matching pair" of Eclipselink / SDO jars mentioned above;
Caught Exception : org.eclipse.persistence.internal.security.PrivilegedAccessHelper.getSystemPropertyBoolean(Ljava/lang/String;Z)Z
java.lang.NoSuchMethodError: org.eclipse.persistence.internal.security.PrivilegedAccessHelper.getSystemPropertyBoolean(Ljava/lang/String;Z)Z
at org.eclipse.persistence.sdo.helper.SDOHelperContext.<init>(SDOHelperContext.java:93)
at org.eclipse.persistence.sdo.helper.SDOHelperContext$DefaultHelperContextResolver.getHelperContext(SDOHelperContext.java:1432)
at org.eclipse.persistence.sdo.helper.SDOHelperContext.getHelperContext(SDOHelperContext.java:492)
at org.eclipse.persistence.sdo.helper.SDOHelperContext.getHelperContext(SDOHelperContext.java:471)
at org.eclipse.persistence.sdo.helper.SDOHelperContext.getHelperContext(SDOHelperContext.java:456)
at org.eclipse.persistence.sdo.helper.delegates.SDOXMLHelperDelegator.getXMLHelperDelegate(SDOXMLHelperDelegator.java:178)
at org.eclipse.persistence.sdo.helper.delegates.SDOXMLHelperDelegator.load(SDOXMLHelperDelegator.java:78)
at com.ebs.solas2021.port.adapter.ui.SOAPRequestHandler.main(SOAPRequestHandler.java:237)
It's amazing what you find whgen you re-read the documentation in the cold light of a new day. It turns out that it's possible to install a JPA 2.2 Container on Liberty, while supplying one's own implementation of EclipseLink. Works like a charm.
Documented here: https://openliberty.io/blog/2018/06/29/full_java_ee_8_liberty_18002.html

LinkageError on WebSphere 9 for javax.transaction.* classes

I have a web application that used to run fine on many web servers (tomcat, jboss, weblogic and websphere). Now, however, it has an error when deploying on WebSphere 9.
The app contains the jar javax.transaction-api-1.2. Some of its classes, e.g., javax.transaction.xa.XAResource, are also included in Java SE, but not all of them. Some are specific to Java EE and are required by some 3rd-party libraries in my app. The app is always deploying with child-first (parent-last) classloader.
WebSphere 9 throws this error during startup when the app tries to load the Oracle JDBC driver:
java.lang.LinkageError: loading constraint violation: loader "com/ibm/ws/classloader/CompoundClassLoader#7157be44" previously initiated loading for a different type with name
"javax/transaction/xa/XAResource" defined by loader "com/ibm/oti/vm/BootstrapClassLoader#422c7b1b"
Note that we aren't actually using XA transactions in the app, we are using regular transactions.
On other servers, and previous versions of WebSphere, it was never a problem. The server didn't care that we load XAResource from inside the war, even if it was previously loaded somewhere in the server. Now WebSphere 9 is different, it says that the app classloader already loaded this class from the server, but I don't know why or when did this happen.
Any idea how to solve this?
Remove the transaction API from your application. JTA 1.2 is already included in the server and provides no value in your applications. It's always risky to bring Java EE/SE APIs in a parent-last class loader unless you are 100% certain that they are technically necessary, because they can lead to issues like this one.
I can't say how this worked in previous server versions (there have been some Java-level changes in enforcing linkage issues like this), but the solution is reasonably straightforward.
At the end we did two things to solve this problem.
1) We upgraded the jta jar to version 1.3 (link here). This jar solves the problem by avoiding duplicate classes - it contains only J2EE classes and omits the J2SE classes that are already included in the JVM.
2) We upgraded WebSphere server from 9.0.0.7 to 9.0.0.11.
At the time, I suspected just upgrading the jar should suffice, but our QA had some issues with it and they also upgraded the server. Due to lack of time, we didn't investigate it further and just decided to do both.

Apache Tomee session Management with gemFire Integration

I am trying to do session management using tomcat modules in gemFire. Reference link we used is [https://gemfire.docs.pivotal.io/95/geode/tools_modules/http_session_mgmt/tomcat_installing_the_module.html].
Application server that we are using is tomee 7.0.5. After making the changes mentioned in the link. When i tried to make the server up, we were getting an error "getContainer() method not found in class DeltaSessionManager".There is a module geode-modules-9.5.1.jar provided by gemFire(gfsh Client) which helps for session management. Inside that there is a class DeltaSessionManager which extends another class org.apache.catalina.session.ManagerBase . But the ManagerBase class in catalina.jar inside tomee 7.0.5 doesn't have this method. But when we downloaded tomcat catalina jar separately we were able to see this method. Is there any difference in the approach for tomee.
Any help would be appreciable
Looking at the tomee source code, I suspect tomee 7.0.5 is actually embedding Tomcat 8. In that case, you need to use Tomcat8DeltaSessionManager, which supports Tomcat 8 and above.

websphere multiple classloaders fixes class not found exception

Hi we use websphere in my company
The websphere installation has two ears ear1 and ear2
We have a policy of a singleclassloader
When set to singleclassloader we get a class not found exception from ear2
spring-oxm3.1.0.RELEASE.jar
org.springframework.oxm.MarshallingFailureException class not found
But by enabling "multiple classloaders" the problem goes away.
Why would the company have a policy of enforcing "single classloader" ?
Is the classnotfound exception caused because a class is defined a jar in both
ear1 and ear2?
eg ear1:jar1 and ear2:spring-oxm3.1.0.RELEASE.jar
And X is loaded from ear1:jar1 and thereby is spring-oxm3.1.0.RELEASE.jar is not loaded ? And when the request runs it fails and complains that MarshallingFailureException is not found?
Would that explain why the class is not found?
So is the solution to find what is the jar in ear1 that is causing spring-oxm3.1.0.Release.jar not to load? And remove it?
Could it be xerces or jaxb?
(We're running java version 1.5)
Thanks in advance.
In that old version of Java, all XML-related jars had many problems.
Your error details will tell you why the class is not being loaded. Most likely, it is a class with the same package/name but in a different jar
Company policies have to do with all the factors involved - development, maintenance, dependency management, and so on.

WebSphere 8 : JAX-WS client for Axis2 WS

I am trying to write a JAX WS client for a service exposed using Axis2, WebSphere8, Java 1.6.
Standalone client(i.e. client running in my local machine) works fine but when I deploy the client in a application running in same websphere server I get
java.lang.ClassCastException: Cannot cast class org.apache.axis2.jaxws.spi.Provider to class javax.xml.ws.spi.Provider
at line OpenPortType service = OpenService
.create(wsdlFile.toURL(),
new QName( "http://www.test.com/schemas/public/open-api/Open/","OpenService")).getPort(
OpenPortType.class);
When I tried to google I found similar problem existed in weblogic : https://wso2.org/jira/browse/CARBON-4835
When we see source of axis2.jaxws.spi.Provider class we come to know that it's a subclass of javax.xml.ws.spi.Provider !!
I'm wondering what could be wrong ? Any idea ?
Unless you are calling Axis2 capabilities directly, rather than simply using JAX-WS APIs, you do not want to package Axis into your EAR. WebSphere does provide its own JAX-WS implementation which I'm not surprised conflicts with another JAX-WS implementation you've deployed in your app. (In particular, note that WebSphere's own implementation is based on Axis2.)
If you do need to deploy a different implementation, you'll probably have to at least adjust your WebSphere classloader policy to parent_last. There might be more to do as well; it's been a while since we did this ourselves. But it's much easier and cleaner to use the built-in JAX-WS implementation, which means not deploying any of those jars at all.

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