Using an external java library in OSGI bundle

Question

I want to use this java library [1]enj-library in my OSGI bundle that will be executed under KURA eclipse platform.

I compiled the library as jar and then I created a new plugin project under eclipse "Plug-in from existing JAR archive"

then I tried to add it to my bundle, but it did not work: 1.I tried to import the bundle and I verified that the version is correct in both manifest files in the import and the export, but I gopt this error:

org.osgi.framework.BundleException: The bundle "org.eclipse.kura.binding.enocean_1.0.0.201506181418 [70]" could not be resolved. Reason: Missing Constraint: Import-Package: it.polito.elite.enocean.enj.communication; version="1.0.0"
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolverError(AbstractBundle.java:1332)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolutionFailureException(AbstractBundle.java:1316)
    at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:323)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:300)
    at org.tigris.mtoolkit.iagent.internal.rpc.RemoteBundleAdminImpl.startBundle(RemoteBundleAdminImpl.java:230)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.tigris.mtoolkit.iagent.internal.pmp.InvocationThread.run(InvocationThread.java:54)
    at org.tigris.mtoolkit.iagent.internal.utils.ThreadPool$Worker.run(ThreadPool.java:179)
    at java.lang.Thread.run(Thread.java:724)

2.I added it as a required bundle but the I got the same error:

org.osgi.framework.BundleException: The bundle "org.eclipse.kura.binding.enocean_1.0.0.201506181349 [70]" could not be resolved. Reason: Missing Constraint: Require-Bundle: EnOceanJavaLibraryplugIn; bundle-version="1.0.0"
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolverError(AbstractBundle.java:1332)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolutionFailureException(AbstractBundle.java:1316)
    at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:323)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:300)
    at org.tigris.mtoolkit.iagent.internal.rpc.RemoteBundleAdminImpl.startBundle(RemoteBundleAdminImpl.java:230)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.tigris.mtoolkit.iagent.internal.pmp.InvocationThread.run(InvocationThread.java:54)
    at org.tigris.mtoolkit.iagent.internal.utils.ThreadPool$Worker.run(ThreadPool.java:179)
    at java.lang.Thread.run(Thread.java:724)

3.I added in the class path and my bundle started but I got the class not found exception

java.lang.ClassNotFoundException: org.eclipse.kura.binding.enocean.EnOcean
    at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:501)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
    at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
    at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at org.eclipse.osgi.internal.loader.BundleLoader.loadClass(BundleLoader.java:340)
    at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:229)
    at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1212)
    at org.eclipse.equinox.internal.ds.model.ServiceComponent.createInstance(ServiceComponent.java:493)
    at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.createInstance(ServiceComponentProp.java:272)
    at org.eclipse.equinox.internal.ds.model.ServiceComponentProp.build(ServiceComponentProp.java:333)
    at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponent(InstanceProcess.java:620)
    at org.eclipse.equinox.internal.ds.InstanceProcess.buildComponents(InstanceProcess.java:197)
    at org.eclipse.equinox.internal.ds.Resolver.buildNewlySatisfied(Resolver.java:473)
    at org.eclipse.equinox.internal.ds.Resolver.enableComponents(Resolver.java:217)
    at org.eclipse.equinox.internal.ds.SCRManager.performWork(SCRManager.java:816)
    at org.eclipse.equinox.internal.ds.SCRManager$QueuedJob.dispatch(SCRManager.java:783)
    at org.eclipse.equinox.internal.ds.WorkThread.run(WorkThread.java:89)
    at org.eclipse.equinox.internal.util.impl.tpt.threadpool.Executor.run(Executor.java:70)

[1]https://github.com/dog-gateway/enj-library

how can I include this library on my OSGI bundle?

Thanks a lot for your help!

Answer 1

The enocean library seems to be an OSGi bundle. So you should add it to your target platform and use Import-Package in your own bundle to access the packages you need.

Answer 2

There is also the handy-dandy 'org.osgi.framework.system.packages.extra' property in the configuration, this comma separated list will allow the named packages from the system class loader to be present in the system bundle and thereby accessible to the plugins.

if you use apache felix, look at https://felix.apache.org/documentation/subprojects/apache-felix-framework/apache-felix-framework-configuration-properties.html

another great page is: https://moi.vonos.net/java/osgi-classloaders/ really technical but gives a very good understanding of the OSGi class loading process