Develop Reference

Can't get a working reference to an OSGi service

I'm trying to embed apache felix into a simple hello world java project with maven, but I can't find a way to get a reference to a service of a bundle. I've installed org.apache.felix.bundlerepository bundle into OSGi from a jar and also added it as a maven dependency to my project. After that I'm starting the bundle, getting BundleContext from it and then calling getServiceReference(RepositoryAdmin.class.getName()) on that bundle context. The first thing I'm unhappy with is that I have to use BundleContext from the installed bundle, if I'd use BundleContext of the Framework the ServiceReference will be always null. This is not convinient.
The second, more important issue, is that when I finally receiving a reference to RepositoryAdmin service from bundlerepository bundle I can't cast it to org.apache.felix.bundlerepository.RepositoryAdmin, executing the following code:
(RepositoryAdmin)admin.getBundleContext().getService(ref)
will throw this exception:
java.lang.ClassCastException: org.apache.felix.bundlerepository.impl.RepositoryAdminImpl cannot be cast to org.apache.felix.bundlerepository.RepositoryAdmin
I know this is a kind of classpath issue and may be caused by incompatibility of interfaces, but I'm using a bundle jar of the same version (2.0.2) as a maven dependency of my project.
I'm also aware of Constants.FRAMEWORK_SYSTEMPACKAGES_EXTRA osgi configuration option which should force a bundle to use a package from the host application, but it didnt help me.
Here is the main class of my project https://github.com/ArtemZ/osgi-study/blob/master/src/main/java/com/artemz/demo/Main.java which is messy because I was trying different things on it in order to get a reference to a service, but none actually worked for me.
Hope someone will help me, because I'm really desperate with this issue.

Thanks for giving some more details about what you are doing. I already followed the mails on the felix list.
Now I think I understand what happens. The reason why you can not get the service from outside the RepositoryAdmin bundle is that the package you define in
FRAMEWORK_SYSTEMPACKAGES_EXTRA is "org.apache.felix.bundlerepository; version=2.0.2"
is not the same version as the package from the RepositoryAdmin bundle. I downloaded the bundle and looked into the Manifest:
Export-Package: org.osgi.service.repository;version="1.0";uses:="org.osg
i.resource",org.apache.felix.bundlerepository;version="2.1";uses:="org.
osgi.framework"
So as you see the version you should export from the system bundle is 2.1 not 2.0.2.
In OSGi the versions are defined per package not on the bundle level. So while most times they are the same this is not always true. Espcecially for OSGi spec packages.
So when the package version are different you have two effects:
1. You will not be able to find a service with a different package
2. If you get a service object in some other way like you did then you will have a class cast exception as they are loaded by different classloaders.
So can you try the 2.1 version and report if it works?

NoSuchMethodError - Calling Class/Method from Class in Same Package

We are integrating an internal framework into our weblogic application and we are running into deployment problems.
Technologies Used
Weblogic 10.3.6 application
Spring 3.0
Maven 2
Eclipse J2EE
The Problem
On startup of the weblogic application, we receive the following NoSuchMethodError while initializing one of the beans. This error is occuring when calling classes in the org.joda.time (2.0) jar.
Caused By: java.lang.NoSuchMethodError: org.joda.time.DateTimeZone.convertLocalToUTC(JZ)J
at org.joda.time.LocalDate.toDateTimeAtStartOfDay(LocalDate.java:715)
at org.joda.time.LocalDate.toDateTimeAtStartOfDay(LocalDate.java:690)
. . . excluded . . .
Things We Have Tried
After Googling "NoSuchMethodError spring", many of the problems seem to be incompatible Spring versions. After printing the dependency tree, the only Spring version in use is 3.0.
Googling "NoSuchMethodError" usually gave JAR hell solutions.
Multiple versions of the same dependency. After doing some maven dependency management, the only joda-time jar in use is 2.0. Additionally, the local repository was purged of any unnecessary jars.
.war / runtime may not have the correct jars included in the lib directory. After looking into the WEB_INF/lib directory, the only joda-time jar is version 2.0, which contains all of the appropriate class files
One mysterious thing is that the DateTimeZone.convertLocalToUTC(JZ)J has been a part of the org.joda.time project since 1.0, so even if we have incompatible versions, the method should still be found, especially if the class and package are able to be found.
Finally there are no other DateTimeZone classes in the project (ctrl+shift+T search in eclipse) so I'm confused as to which class is being loaded if the org.joda.DateTimeZone class is not being loaded.
Questions:
Can anyone explain why the method could not be found?
Are there more places to check for existing or conflicting jars?
Is there a way to check the DateTimeZone class that the LocalDate class is using during runtime via Eclipse debug?

Here's some interesting reading:
prefer-web-inf-classes Element
The weblogic.xml Web application deployment descriptor contains a
element (a sub-element of the
element). By default, this element is set to
False. Setting this element to True subverts the classloader
delegation model so that class definitions from the Web application
are loaded in preference to class definitions in higher-level
classloaders. This allows a Web application to use its own version of
a third-party class, which might also be part of WebLogic Server. See
“weblogic.xml Deployment Descriptor Elements.”
taken from: http://docs.oracle.com/cd/E15051_01/wls/docs103/programming/classloading.html
Other troubleshooting tips:
You can try: -verbose:class and check your managed server's logs to check if the class is being loaded properly.
An efficient way to confirm which intrusive jar might be getting loaded is by running a whereis.jsp within the same webcontext (i.e., JVM instance) of this app.
--whereis.jsp --
<%# page import="java.security.*" %>
<%# page import="java.net.URL" %>
<%
Class cls = org.joda.time.DateTimeZone.class;
ProtectionDomain pDomain = cls.getProtectionDomain();
CodeSource cSource = pDomain.getCodeSource();
URL loc = cSource.getLocation();
out.println(loc);
// it should print something like "c:/jars/MyJar.jar"
%>
You can also try jarscan on your $WEBLOGIC_HOME folder to see if you can find the jar that contains this class: https://java.net/projects/jarscan/pages/Tutorial

A NoSuchMethodError is almost always due to conflicting library versions. In this case I'm guessing there are multiple versions of joda libraries in the two projects.
Weblogic is pulling the org.joda jar.
Tryu adding this in your weblogic.xml to exclude the jar that weblogic is pulling, and instead use your appllication jar.
The below is from my application, you can have a look what all we have to removed for our application.
<wls:container-descriptor>
<wls:prefer-application-packages>
<wls:package-name>antlr.*</wls:package-name>
<wls:package-name>org.slf4j.*</wls:package-name>
<wls:package-name>org.slf4j.helpers.*</wls:package-name>
<wls:package-name>org.slf4j.impl.*</wls:package-name>
<wls:package-name>org.slf4j.spi.*</wls:package-name>
<wls:package-name>org.hibernate.*</wls:package-name>
<wls:package-name>org.springframework.*</wls:package-name>
<wls:package-name>javax.persistence.*</wls:package-name>
<wls:package-name>org.apache.commons.*</wls:package-name>
<wls:package-name>org.apache.xmlbeans.*</wls:package-name>
<wls:package-name>javassist.*</wls:package-name>
<wls:package-name>org.joda.*</wls:package-name>
<wls:package-name>javax.xml.bind.*</wls:package-name>
<wls:package-name>com.sun.xml.bind.*</wls:package-name>
<wls:package-name>org.eclipse.persistence.*</wls:package-name>
</wls:prefer-application-packages>
<wls:show-archived-real-path-enabled>true</wls:show-archived-real-path-enabled>
</wls:container-descriptor>

LogConfigurationException when using HttpClient

When my code executes this line:
DefaultHttpClient httpclient = new DefaultHttpClient();
I'm getting this Exception:
org.apache.commons.logging.LogConfigurationException: Class org.apache.commons.logging.impl.Log4JLogger does not implement Log
does somebody know how can I solve that?
Maybe is not important (or maybe it is), but the app is a plugin for Jira, and is using Maven for the dependencies.
Thanks !
EDIT:
EDIT 2:
Could this be related with OSGi from Jira?
How can I use commons-logging in an OSGi environment?
From here:
http://wiki.apache.org/commons/Logging/FrequentlyAskedQuestions
Commons-logging was not designed with OSGi in mind. This is why it is
difficult to get commons-logging working in OSGi environments:
LogFactory loads Log implementations by name (see
Class.forName(String)). This is usually not possible in OSGi since
every bundle classloader can only see the classes a bundle defines
imports for. The bundle class loader that loads the commons-logging
bundle will not have access to user provided
commons-logging.properties files. commons-logging-api.jar contains
classes that are also included in commons-logging.jar. This is
contrary to traditional OSGi application architectures where one
bundle defines an API and other bundles provide implementations for
that API. There alternatives to using commons-logging directly in OSGi
are:
Rebundled versions that contain proper OSGi meta data are available
from Apache Felix, SpringSource and Eclipse Orbit. Using Pax logging.
Further information about this topic is available in the archives of
the commons dev ML and the felix dev ML and in Jira.
and when I try to access to the OSGi tab from Jira (going to JIRASERVER/plugins/servlet/upm/osgi#osgi) I can see an exception:
classNotFoundException: org.apache.commons.logging.impl.SLF4JLogFactory
And also I can see from the IDE (when searching for Log4JLogger class) that I have two definitions:
package org.apache.commons.logging.impl.Log4JLogger
public class Log4JLogger implements Log, Serializable {
and
package com.atlassian.extras.common.log;
class Log4jLogger implements com.atlassian.extras.common.log.Logger.Log {
this is really confusing....

I'm not sure, but could it be that the logger you configured does not correspond to the logger in your pom dependencies? Perhaps a different version?

REST client inside of OSGi application

I need to integrate a REST client into an existing OSGi application implemented using Apache Felix. The REST service is based on RESTeasy implementation (version 2.3.2.Final) of JAX-RS. I created a separate bundle with clients' dependencies, exporting required RESTeasy packages and importing them in the bundle where the client is used, but unfortunately I cannot get it working inside of the OSGi context.
I tried two different approaches. First one using the generic ClientRequest:
ClientRequest request = new ClientRequest(MyService.URL_TEST+"/stats");
request.body(javax.ws.rs.core.MediaType.APPLICATION_XML, stats);
ClientResponse<String> response = request.post(String.class);
The error that I get in this case is pretty weird:
[java] java.lang.RuntimeException: java.lang.ClassCastException:
org.jboss.resteasy.client.core.executors.ApacheHttpClient4Executor cannot be cast to
org.jboss.resteasy.client.ClientExecutor
where I it is known for sure that ApacheHttpClient4Executor implements the ClientExecutor interface.
When I try to use my own REST client wrapper around RESTeasy like this:
MyService myService = MyServiceClient.getInstance();
myService.saveStatistics(stats);
I get a different exception:
[java] java.lang.LinkageError: ClassCastException: attempting to
castjar:file:/D:/Development/Eclipses/eclipse_4.2_j2ee_x64/lib/jaxrs-api-2.3.2.Final.jar
!/javax/ws/rs/ext/RuntimeDelegate.classtobundle:
//78.0:1/javax/ws/rs/ext/RuntimeDelegate.class
As far as I understand, the LinkageError most probably has to do with the way RESTeasy initializes the RuntimeDelegate using some classloader tricks, which probably fall under the restrictions of OSGi framework. I get the suspicion that the java.lang.ClassCastException mentioned first has the same source.
Is there any way to get RESTeasy working inside of OSGi?
PS: discussion about a similar issue with RESTeasy, but outside of OSGi: java.lang.LinkageError: ClassCastException
Update:
these are the libraries included into restclient bundle:
activation-1.1.jar commons-codec-1.2.jar commons-httpclient-3.1.jar commons-io-2.1.jar commons-logging-1.0.4.jar flexjson-2.1.jar httpclient-4.1.2.jar httpcore-4.1.2.jar javassist-3.12.1.GA.jar jaxb-api-2.2.3.jar jaxb-impl-2.2.4.jar jaxrs-api-2.3.2.Final.jar jcip-annotations-1.0.jar jettison-1.3.1.jar jsr250-api-1.0.jar junit-4.10.jar log4j-1.2.14.jar resteasy-jaxb-provider-2.3.2.Final.jar resteasy-jaxrs-2.3.2.Final.jar resteasy-jettison-provider-2.3.2.Final.jar scannotation-1.0.3.jar slf4j-api-1.6.4.jar slf4j-log4j12-1.6.4.jar myservice-common-0.1.0.3.jar my-service-client-0.1.0.3-SNAPSHOT.jar stax-api-1.0-2.jar xmlpull-1.1.3.1.jar xpp3_min-1.1.4c.jar xstream-1.4.2.jar
These are the exports from the restclient bundle: javax.ws.rs, javax.ws.rs.ext, javax.ws.rs.core, org.jboss.resteasy.client, org.jboss.resteasy.client.cache, org.jboss.resteasy.client.extractors, org.jboss.resteasy.client.marshallers, org.jboss.resteasy.client.core.executors, javax.xml.bind.annotation, org.jboss.resteasy.plugins.providers, org.jboss.resteasy.plugins.providers.jaxb, org.jboss.resteasy.spi

Have a look at the SpringSource Bundle Repo, it's got some very useful pre-built bundles of common libraries including the Apache HTTP Client which we are using (in conjunction with gson) to do our RESTful comms.

(unfortunately a legacy module of my project still uses OSGi, but using RESTeasy 3.0.16 now)
When I need to OSGify a dependency my preferred solution now is to wrap it using the excellent Apache Ops4j Pax Tipi project.
The project provides a preconfigured Maven setup (parent POM handles the bundling) and you just have to adapt the GAV coordinates of the original project in a Tipi sub module with a org.apache.ops4j.pax.tipi prefix and build the new bundle project which draws in the original dependency, unpacks and wraps it as OSGi bundle.
You can start from an existing Tipi sub project that best matches your project setup (dependencies, etc.) and adapt any OSGi imports/exports missing (most often, these are created automatically by the maven-bundle-plugin anyway).
This worked quite well for me as long as the original project did not contain too many exotic or malformed dependencies.
However you may run into snags like transitive dependencies using the root package, as I currently experience, which can be a real show stopper (finding out which library is a real nightmare).
Unfortunately, RESTeasy seems to be affected by this, as I get exactly the same error (default package , even after declaring non-test and non-provided dependencies as optional:
The default package '.' is not permitted by the Import-Package syntax.
Upgrading the maven-bundle-plugin to the latest release 3.0.1 yields a different error (even less helpful):
[ERROR] Bundle org.ops4j.pax.tipi:org.ops4j.pax.tipi.resteasy-jaxrs:bundle:3.0.16.Final.1 : Can not parse name from bundle native code header:
[ERROR] Error(s) found in bundle configuration
Update seems to be solved by upping Tipi version in POM to 1.4.0, testing...

Is RESTEasy mandatory ?
I personally use jersey in OSGi and it is working perfectly, both as client and server.

This problem isn't limited to RESTeasy. It also occurs with Jersey.
It is occurring because you have two copies of the JAX-RS classes on the classpath.
You can see this in the LinkageError:
[java] java.lang.LinkageError: ClassCastException: attempting to cast jar:file:/D:/Development/Eclipses/eclipse_4.2_j2ee_x64/lib/jaxrs-api-2.3.2.Final.jar!/javax/ws/rs/ext/RuntimeDelegate.class to bundle://78.0:1/javax/ws/rs/ext/RuntimeDelegate.class
i.e. one copy is coming from:
D:/Development/Eclipses/eclipse_4.2_j2ee_x64/lib/jaxrs-api-2.3.2.Final.jar
and the other from the OSGI bundle.
This causes problems for the RuntimeDelegate class, which by default uses the system class loader to create the RuntimeDelegate implementation (see javax.ws.rs.ext.FactoryFinder).
The problem can also occur if the same jar is loaded via two different class loaders.
There are a couple of workarounds:
remove the jaxrs-api-2.3.2.Final.jar from the system class path
set the thread context class loader to that of your bundle, prior to making any JAX-RS calls.
The FactoryFinder will use this to load the RuntimeDelegate.
To avoid polluting your code with calls to Thread.currentThread().setContextClassLoader(myBundleClassLoader), you can wrap your JAX-RS client using a Proxy. e.g. see the Thread context classloader section of https://puredanger.github.io/tech.puredanger.com/2007/06/15/classloaders/

java.util.logging, ResourceBundles, SAAJ: exception on loading Glassfish OSGi webapp bundle

I'm being driven out of my mind by the following exception:
java.lang.IllegalArgumentException:
com.sun.xml.messaging.saaj.soap.LocalStrings != com.sun.xml.internal.messaging.saaj.soap.LocalStrings
at java.util.logging.Logger.getLogger(Logger.java:357)
at com.sun.xml.internal.messaging.saaj.soap.SAAJMetaFactoryImpl.<clinit>(SAAJMetaFactoryImpl.java:41)
It's occurring when I try to deploy a WAB (web application OSGi bundle) to Glassfish (3.1.1).
I'm trying to use an up-to-date version of SAAJ (com.sun.xml.messaging.saaj...) rather than the old JDK one (which is the com.sun.xml.internal.saaj... one), by putting the string com.sun.xml.messaging.saaj.soap.ver1_1.SOAPMessageFactory1_1Impl in the file META-INF/services/javax.xml.soap.MessageFactory.
It appears there is some logging going on before the OSGi classloading kicks in, and therefore the 'wrong' ResourceBundle is being returned during initialization of the static log field of com.sun.xml.messaging.saaj.soap.MessageFactoryImpl (SAAJ's implementation of javax.xml.soap.MessageFactory).
Anyone seen this / any workarounds on offer?

Never got to the bottom of this, but manifest voodoo eventually made it go away (with all of the javax.xml.ws / javax.ws.rs packages in Import-Package rather than on the bundle classpath WEB-INF/lib).
It was also possible to work around it by using
-Djavax.xml.soap.MessageFactory=com.sun.xml.messaging.saaj.soap.ver1_1.SOAPMessageFactory1_1Impl
on Glassfish startup, though obviously this forces that implementation on all users of MessageFactory.

See: JDK-6741342 : Logger.getLogger() throws java.lang.IllegalArgumentException on saaj classes.
Instead, it's related to the introduction of saaj into JDK 6.....and the workaround involved re-ordering jars.