Liberty Server - ClassLoader.getSystemResource returns null - java

Developed a rest service which uses third party jars. Reviewing their code I found that they are using ClassLoader.getSystemResource("log4j.properties") to retrieve the data. This code returns null and henceforth I get null pointer exception always. The same code if I deploy in websphere 8.5.5.7 and set server classpath it is working fine.
Since I am using Liberty in my local machine this is not retrieving the path.
I also tried setting classloader in server.xml but no use.
<library id="config">
<folder dir="/properties/dev/" includes="*.properties" scanInterval="5s"/>
</library>
<enterpriseApplication id="AbcEAR"location="AbcEAR.ear" name="AbcEAR">
<classloader privateLibraryRef="config"/>
</enterpriseApplication>

Using ClassLoader.getSystemResource() will use the system classloader, which will only be able to see things from the JDK and whatever is on the classpath. Since Liberty does not use a traditional classpath and instead uses OSGi, the system loader will be of little use in Liberty from an application perspective.
Instead, use ClassLoader.getResource() from the thread context classloader, which will take into account the Liberty classloaders.

Related

WAS Liberty profile - Read property using ClassLoader.getSystemResourceAsStream

We are migrating our application from WAS 6.1 to Liberty. Our application uses third party jars that read property files byInputStream is = ClassLoader.getSystemResource("myproperty.properties").
In WAS 6.1, we set server classpath to the location of myproperty.properties. We tried the below approaches to set classpath in Liberty, but nothing works
Approach 1: Set the below in jvm.options (D:\ConfigFiles\DEV\ - path containing myproperty.properties)
-Djava.class.path=D:\\ConfigFiles\\DEV\\
Approach 2: Setting the classloader in server.xml,
<library id="config">
<folder dir="${server.config.dir}/config/" includes="*.properties" scanInterval="5s"/>
</library>
<enterpriseApplication id="applicationEAR" location="application.ear" name="application">
<classloader privateLibraryRef="config"/>
</enterpriseApplication>
Please let us know if there is any other ways to override/set classpath in Liberty profile?
Try setting this property in jvm.options (instead of -Djava.class.path=path/to/propertyDir):
-Xbootclasspath/a:path/to/propertyDir
This will append the path of the property directory (containing your resource file) to the JVM's bootstrap classpath. Because this is an append, it should also work in Java 9+ (some related options have been removed in Java 9).
I suspect that the reason -Djava.class.path=... doesn't work is that the JVM gets the classpath from the WLP server script - so the system property is essentially applied too late in the startup of the server JVM.
You might also be able to put the properties file(s) in your JVM's lib/ext directory, but I haven't tested that. The -Xbootclasspath/a:path approach works for me on Mac - I assume it will also work on Windows.
HTH, Andy
If your end goal is to load a properties file, a more straightforward way to do this would be using a bootstrap/env/system property or <jndiEntry> in server.xml to store the location of the properties file, and then load it. For example, using an environment variable:
(in server.xml file)
<server>
<featureManager>
<feature>jndi-1.0</feature>
...
</featureManager>
<jndiEntry jndiName="configDir" value="D:\\ConfigFiles\\Dev"/>
</server>
Then, you can load the resource in your application like this:
#Resource(lookup = "configDir")
String configDir;
InputStream is = new FileInputStream(configDir + "/myproperty.properties");
Or, if you will always put your config property files somewhere under ${server.config.dir}, then you can utilize the built-in SERVER_CONFIG_DIR environment variable in Liberty:
String configDir = System.getenv("SERVER_CONFIG_DIR"); // equivalent to ${server.config.dir} in server.xml
InputStream is = new FileInputStream(configDir + "/myproperty.properties");
On the topic of managing configuration, check out MicroProfile Config (e.g. <feature>microProfile-1.2</feature>) which you may find useful: Configuring microservices with Liberty

WSDL parsing exception creating Webservice client with CXF JaxWSClientFactoryBean

I've written some code to create and run webservice client using CXF. I used JaxWsClientFactoryBean (not sure it's the best solution) to create client from .wsdl file.
The goal here was to do this programmatically avoiding Spring etc. Just pure code with Java and CXF.
JaxWsClientFactoryBean cfb = new JaxWsClientFactoryBean();
cfb.setAddress(getServiceProperty(intClass, PROPERTY_KEY_URL_SUFFIX));
cfb.setServiceClass(intClass);
cfb.setOutInterceptors(getOutInterceptors(intClass));
cfb.setServiceName(SERVICE_NAME);
cfb.setWsdlURL("classpath:wsdl/" + intClass.getSimpleName() + ".wsdl");
cfb.setEndpointName(ENDPOINT_NAME);
Client client = cfb.create();
ClientProxy cp = new ClientProxy(client);
I intService = (I)
Proxy.newProxyInstance(intClass.getClassLoader(), new Class[] { intClass }, cp);
I'm really not sure if this is done correctly, but it works when I run this code locally and when I deploy it on Tomcat.
Unfortunatelly I need to run this code on Weblogic and this results in strange exception:
Caused by: javax.wsdl.WSDLException: WSDLException: faultCode=PARSER_ERROR: org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR: An attempt was
made to insert a node where it is not permitted.
at org.apache.cxf.wsdl11.WSDLManagerImpl.loadDefinition(WSDLManagerImpl.java:235)
at org.apache.cxf.wsdl11.WSDLManagerImpl.getDefinition(WSDLManagerImpl.java:186)
at org.apache.cxf.wsdl11.WSDLServiceFactory.<init>(WSDLServiceFactory.java:92)
... 26 more
Caused by: org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR: An attempt was made to insert a node where it is not permitted.
at com.sun.org.apache.xerces.internal.dom.ParentNode.internalInsertBefore(ParentNode.java:356)
at com.sun.org.apache.xerces.internal.dom.ParentNode.insertBefore(ParentNode.java:284)
at com.sun.org.apache.xerces.internal.dom.CoreDocumentImpl.insertBefore(CoreDocumentImpl.java:399)
at com.sun.org.apache.xerces.internal.dom.NodeImpl.appendChild(NodeImpl.java:235)
at org.apache.cxf.staxutils.StaxUtils.readDocElements(StaxUtils.java:1019)
at org.apache.cxf.staxutils.StaxUtils.readDocElements(StaxUtils.java:939)
at org.apache.cxf.staxutils.StaxUtils.read(StaxUtils.java:866)
at org.apache.cxf.wsdl11.WSDLManagerImpl.loadDefinition(WSDLManagerImpl.java:226)
... 28 more
This happens during application deployment. It looks like there is something wrong with .wsdl file, but wait... It was working on Tomcat!
I think that there could be some difference in com.sun.org.apache.xerces.* classes implementation within Weblogic with its JRockit VM and standard JVM, but I have no idea how to solve it.
I spent many hours trying differend ways of client creation. Most of them worked locally and in Tomcat, but none on WebLogic.
Any hints what to try next? I'm kinda tired of this topic :D
I agree with your suspicion that the problem is related to the used version of Xerces. The stacktrace shows that the Sun implementation of Xerces which is derivative of the Apache Xerces is used in your case.
Please check the Apache CFX Application Server Configuration Guide instructions related to WebLogic.
WebLogic ClassLoading
In WebLogic Server, any .jar file present in the system classpath is loaded by the WebLogic Server system classloader. All applications running within a server instance are loaded in application classloaders which are children of the system classloader. In this implementation of the system classloader, applications cannot use different versions of third-party jars which are already present in the system classloader. Every child classloader asks the parent (the system classloader) for a particular class and cannot load classes which are seen by the parent.
For example, if a class called com.foo.Baz exists in both $CLASSPATH as well as the application EAR, then the class from the $CLASSPATH is loaded and not the one from the EAR. Since weblogic.jar is in the $CLASSPATH, applications can not override any WebLogic Server classes.
In order to use an alternate version of Xerces you have to create a FilteringClassLoader.
Usage of FilteringClassLoader
The FilteringClassLoader provides a mechanism for you to configure deployment descriptors to explicitly specify that certain packages should always be loaded from the application, rather than being loaded by the system classloader. This allows you to use alternate versions of applications such as Xerces and Ant.
The FilteringClassLoader sits between the application classloader and the system. It is a child of the system classloader and the parent of the application classloader. The FilteringClassLoader intercepts the loadClass(String className) method and compares the className with a list of packages specified in weblogic-application.xml file.
In conclusion, check the steps included in the Apache CFX Application Server Configuration Guide and take care to explicitly specify that the org.apache.xerces.* package is loaded from the application, rather than being loaded from the system classloader.
For example the weblogic-application.xml file in the META-INF should look like:
<?xml version="1.0" encoding="UTF-8"?>
<weblogic-application xmlns="http://www.bea.com/ns/weblogic/90">
<application-param>
<param-name>webapp.encoding.default</param-name>
<param-value>UTF-8</param-value>
</application-param>
<prefer-application-packages>
<package-name>javax.jws.*</package-name>
<package-name>org.apache.xerces.*</package-name>
</prefer-application-packages>
</weblogic-application>
I hope this helps.

How to configure EAR to access exisiting Websphere Shared Lib?

I am using JSF2 with Websphere 7 . I have created a shared lib successfully and have pointed application using Webpsphere Admin Console and it works successfully . But what we really want to do is to not have to point to that Shared Lib via WAS Admin Console but have some sort of application level configuration e.g in deployment.xml etc which we can point to the name of that Shared Isolated Lib and use it . I have gone through SO and google but not found any thing doing that . I however know that there are commercial application doing it but do not know how . This question from How can I specify a shared library reference at the web module level in Websphere 6.1 deployment descriptors? is closely what I am after but I not want to specify version numbers or jar names as the answer states
I found a way by simply following what WAS Admin Console was actually doing.
Create a deployment.xml in your EAR file if you do not have one already .
You will find a reference to class loader like below
<classloader xmi:id="Classloader_1311552732281" mode="PARENT_FIRST">
Modify it and add reference to the shared Liberary created on server like below
<classloader xmi:id="Classloader_1311552732281" mode="PARENT_FIRST">
<libraries libraryName="JSF2_SHARED_LIB" sharedClassloader="true"/>
</classloader>
#dbreaux has also shown a way .Accpeting my own answer as fits my needs better but big thanks to dbreaux too for advice.
Is the issue just that you don't want to have to configure each application separately, or that you don't want to use the admin console at all? You can associate a shared library with an entire server, which might be preferable to doing it for each app.
The other way to create those application associations is in the WebSphere-specific .xmi deployment files. These are created when you deploy but can also be included in WAR/EAR files. I don't know if that would help you at all. If it would, the official way to create them ahead of time is using one of the Deployment Tools, but since they're just XML, you may feel comfortable creating them manually.
To append extra details to Shahzeb's answer:
My environment: Websphere 8.5; Windows 7;(Eclipse Luna to generate testing .war file)
I have installed the war file exported from eclipse on websphere server by websphere console.
Then exported it again and unpack it to see what websphere automatically add to it to generate EAR.
[folder]META-INF
[folder]ibmconfig
[file]application.xml
[file]ibm-application-bnd.xmi
[file]ibm-application-runtime.props
[file]MANIFEST.MF
[file]was.module
[file]was.policy
[file]was.webmodule
[file]myWAR.war
And the file deployment.xml is placed in
..\ibmconfig\cells\defaultCell\applications\defaultApp\deployments\defaultApp\
whose content in form of
<?xml version="1.0" encoding="UTF-8"?>
<appdeployment:Deployment xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:appdeployment="http://www.ibm.com/websphere/appserver/schemas/5.0/appdeployment.xmi" xmi:id="Deployment_1417052686904">
<deployedObject xmi:type="appdeployment:ApplicationDeployment" xmi:id="ApplicationDeployment_1417052686904" deploymentId="0" startingWeight="1" binariesURL="$(APP_INSTALL_ROOT)/[server service name]Cell/myWAR.ear" useMetadataFromBinaries="false" enableDistribution="true" createMBeansForResources="true" reloadEnabled="false" appContextIDForSecurity="href:[server service name]Cell/myWAR" filePermission=".*\.dll=755#.*\.so=755#.*\.a=755#.*\.sl=755" allowDispatchRemoteInclude="false" allowServiceRemoteInclude="false" asyncRequestDispatchType="DISABLED" standaloneModule="true" enableClientModule="false">
<targetMappings xmi:id="DeploymentTargetMapping_1417052686904" enable="true" target="ServerTarget_1417052686904"/>
<classloader xmi:id="Classloader_1417052686904" mode="PARENT_FIRST"/>
<modules xmi:type="appdeployment:WebModuleDeployment" xmi:id="WebModuleDeployment_1417052686904" deploymentId="1" startingWeight="10000" uri="myWAR.war" containsEJBContent="0">
<targetMappings xmi:id="DeploymentTargetMapping_1417052686905" target="ServerTarget_1417052686904"/>
<classloader xmi:id="Classloader_1417052686905"/>
</modules>
<properties xmi:id="Property_1417052686904" name="metadata.complete" value="true"/>
</deployedObject>
<deploymentTargets xmi:type="appdeployment:ServerTarget" xmi:id="ServerTarget_1417052686904" name="server1" nodeName="[server service name]"/>
</appdeployment:Deployment>
(Since I have no reputation, I have to do it all in text.. )

Can I set the classloader policy for WebSphere in the ibm-web-bnd.xmi file?

I have a JEE application that runs on WAS 6. It needs to have the class loader order setting to "Classes loaded with application class loader first", and the WAR class loader policy option set to "Single class loader for application".
Is it possible to specify these options inside the EAR file, whether in the ibm-web-bnd.xmi file or some other file, so the admin doesn't need to change these setting manually?
Since the app is deployed via an automated script, and the guy who is in charge of deployment is off site, and also for some other political reasons, this would greatly help!
Thanks to #Matthew Murdoch's answer, I was able to come up with a solution. Here it is, in case it helps someone else.
I created a deployment.xml like this:
<?xml version="1.0" encoding="UTF-8"?>
<appdeployment:Deployment xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:appdeployment="http://www.ibm.com/websphere/appserver/schemas/5.0/appdeployment.xmi" xmi:id="Deployment_1241112964096">
<deployedObject xmi:type="appdeployment:ApplicationDeployment" xmi:id="ApplicationDeployment_1241112964096" startingWeight="1" warClassLoaderPolicy="SINGLE">
<classloader xmi:id="Classloader_1241112964096" mode="PARENT_LAST"/>
<modules xmi:type="appdeployment:WebModuleDeployment" xmi:id="WebModuleDeployment_1241112964096" startingWeight="10000" uri="AGS.war">
<classloader xmi:id="Classloader_1241112964097"/>
</modules>
</deployedObject>
</appdeployment:Deployment>
Make sure to change the name of your WAR file(s) to match (mine is called AGS.war).
I also changed the numbers in the xmi:id attributes, to be sure they are unique, though I'm not sure it it really matters that they be unique across applications.
Then, I put the deployment.xml file in the root of my EAR file, via ANT:
<ear destfile="${artifactsDir}/${earName}.ear" appxml="${projectName}_EAR/application.xml">
<fileset dir="${artifactsDir}" includes="${warName}.war"/>
<fileset dir="${projectName}_EAR/" includes="deployment.xml"/>
</ear>
Edit (2): The WebSphere Application Server Toolkit (AST) is a tool you can use to enhance an EAR file with this information (see for example the 'Configure an Enhanced EAR' section in this document).
Edit (1): This post suggests that the 'Classes loaded with application class loader first' (the PARENT_LAST setting) can be set in the deployment.xml file within the EAR.
If you have control over the automated deployment scripts this can be done. Below is some wsadmin jython code for setting the web module class loader order to 'Classes loaded with application class loader first' (interestingly the setting is called PARENT_LAST which is what it was labelled in previous versions of the admin console...).
wsadmin example (jython):
def getWebModule(config, applicationName):
webModules = config.list('WebModuleDeployment').
split(system.getProperty('line.separator'))
for webModule in webModules:
if (webModule.find(applicationName) != -1):
return webModule
return None
applicationName = "<Your application name here>"
webModule = getWebModule(AdminConfig, applicationName)
if (webModule != None):
AdminConfig.modify(webModule, "[[classloaderMode PARENT_LAST]]")
AdminConfig.save()
else:
print "Error: Cannot find web module for application: " + applicationName
Check out this link. There are different ways to set class loader policy using Jython based on your server version -
http://pic.dhe.ibm.com/infocenter/wasinfo/v7r0/index.jsp?topic=%2Fcom.ibm.websphere.express.doc%2Finfo%2Fexp%2Fae%2Frxml_7libapp4.html
Similar to the answer from pkaeding, I discovered as follows, not specific to a particular .war by name, but useful when applying to whatever is the default .war in the .ear file. (.ear files with one .war file in them have only that .war, so naming the .war isn't necessary in the entry.) This approach may be good for situations where you may need to re-name of the .war project later for some reason, and so you wouldn't need to worry about updating the deployment.xml file. I found the deployment.xml file buried inside a cell reference directory trail; dunno if it's fine as shown when the file is placed at directory level META-INF and no deeper.
In my particular case, I found deployment.xml in my .ear project at:
<project_root>\META-INF\ibmconfig\cells\defaultCell\applications\defaultApp\deployments\defaultApp\
The content of the file looks a lot like:
<appdeployment:Deployment xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI"
xmlns:appdeployment="http://www.ibm.com/websphere/appserver/schemas/5.0/appdeployment.xmi" xmi:id="Deployment_1262775196208">
<deployedObject xmi:type="appdeployment:ApplicationDeployment"
xmi:id="ApplicationDeployment_1262775196208" startingWeight="10">
<classloader xmi:id="Classloader_1262775196208" mode="PARENT_LAST" />
</deployedObject>
</appdeployment:Deployment>
The line:
<classloader xmi:id="Classloader_1262775196208" mode="PARENT_LAST" />
originally read:
<classloader xmi:id="Classloader_1262775196208" mode="PARENT_FIRST" />
Note no reference to any .war is being made. As pkaeding mentioned, you shouldn't expect the various id numbers to be the same for you.

Controlling the classpath in a servlet

My servlet application includes a number of library .jars, some of which contain embedded log4j.xml or log4j.properties files. I'd like to ensure that log4j finds my log4j.xml first! I've tried searching for some specification of the priorities of the various classpath elements in a servlet (e.g. does WEB-INF/classes always precede WEB-INF/lib?), or some way to configure or tweak the servlet's classloader so that a given resource directory appears early in the classpath. So far, I've drawn a blank. Any suggestions on ensuring that a servlet .war file loads the correct log4j.xml via the classloader?
Tomcat 8.5
Ditto Tomcat 8.0.
See documentation: Class Loader HOW-TO.
Tomcat 8.0
The answer is simple, taken from the Tomcat documentation page, Class Loader HOW-TO. In particular notice the use of the /WEB-INF/ directory/folder.
Therefore, from the perspective of a web application, class or resource loading looks in the following repositories, in this order:
Bootstrap classes of your JVM
/WEB-INF/classes of your web application
/WEB-INF/lib/*.jar of your web application
System class loader classes (described above)
Common class loader classes (described above)
If the web application class loader is configured with <Loader delegate="true"/> then the order becomes:
Bootstrap classes of your JVM
System class loader classes (described above)
Common class loader classes (described above)
/WEB-INF/classes of your web application
/WEB-INF/lib/*.jar of your web application
Tomcat 6
Excerpted from Tomcat 6 page, Class Loader HOW-TO.
Therefore, from the perspective of a web application, class or resource loading looks in the following repositories, in this order:
Bootstrap classes of your JVM
System class loader classes (described above)
/WEB-INF/classes of your web application
/WEB-INF/lib/*.jar of your web application
$CATALINA_HOME/lib
$CATALINA_HOME/lib/*.jar
As far as I understand the resource selection from the classpath is non-deterministic (from the point of view of the app developer). Even if the same file is loaded consistently the behaviour could change:
1. When you upgrade the version of your current container.
2. If you switch containers.
The simplest solution will be to remove embedded log4j config files from library jars. It is almost never a good idea to embed log4j config's as it leads to the problem you are seeing here...
Are they third party jars or jars you developed?
We the Spring Log4jConfigListener in our web.xml file.
You can specify as a context parameter the location of the log4j config file, i.e. you could set it as /WEB-INF/log4j.xml
Would this be an option for you? If you're not using Spring I know that you can set the Log4j location programatically which might also work.
In my experience, WEB-INF/classes typically takes precedence over jars in WEB-INF/lib, however, that also depends on the servlet container you use (I could never figure out the behavior of JRun, for instance). It would help immensely if you could tell me which container you're using.
Also, are you certain that the offending log4j configuration is in a jar in WEB-INF/lib? Typically, when I've run into classpath problems in a servlet container situation, it's because of libraries that reside outside of the web app.
The servlet specs recommend that web app classloaders load their own classes before delegating to the container's classloader (SRV.9.7.2), but since this is counter to the Java spec, not all vendors do this by default (in fact Tomcat is the only container I've used that does this by default). With that said, it's always possible to configure your container's web app classloading behavior. If you tell me which container you're using, I may be able to help you (specifically, I have done this successfully before on WebLogic, WebSphere, Glassfish and JRun)).
If you're unable to control the classpath, since Tomcat is setting it for you, are you at least able to set a system property for log4j.configuration? I believe that location pointed to by that property can be set outside of the classpath.
If not, another approach, although an ugly one, would be to explicitly run one of the configurators yourself in your application code.
You need to have log4j.properties in your CLASSPATH. The best place is under WEB-INF/classes.
You also have to make sure that you use your version of log4j.jar. So, put it in WEB-INF/lib, just to make sure you are not using one from tomcat folders, since it may cause strange classloading issues.

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