OSGI working example

[Suresh Khant]

Hi All,

I have started learning OSGI and I want working example for that(already tested )..

Anyone can help me ?

by the way I have tried several examples but I was unable to run them correctly.

[Tim Moores]

What, exactly, have you tried, and how, exactly, did that not work?

Also, which implementation are you using? Apache Felix, for example, has numerous examples readily available online: http://felix.apache.org/site/apache-felix-osgi-tutorial.html and http://felix.apache.org/site/apache-felix-application-demonstration.html

[Suresh Khant]

Thanks Moores for your reply ,

I have tried this example http://www.javaworld.com/javaworld/jw-03-2008/jw-03-osgi1.html?page=2

and i have got this error

   1. osgi> !SESSION 2011-08-15 23:52:42.245 -----------------------------------------------  
   2. eclipse.buildId=unknown  
   3. java.version=1.6.0_26  
   4. java.vendor=Sun Microsystems Inc.  
   5. BootLoader constants: OS=linux, ARCH=x86, WS=gtk, NL=en_US  
   6. Command-line arguments:  -dev file:/data/Applications/eclipse-helios/workspace/.metadata/.plugins/org.eclipse.pde.core/OSGi Framework/dev.properties -os linux -ws gtk -arch x86 -consoleLog -console  
   7.   
   8. !ENTRY org.drools.eclipse 4 0 2011-08-15 23:52:44.134  
   9. !MESSAGE   
  10. !STACK 0  
  11. org.osgi.framework.BundleException: The bundle "org.drools.eclipse_5.2.0.v20110116-0638-H14 [46]" could not be resolved. Reason: Missing Constraint: Require-Bundle: org.eclipse.jdt.junit; bundle-version="0.0.0"  
  12.     at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolverError(AbstractBundle.java:1317)  
  13.     at org.eclipse.osgi.framework.internal.core.AbstractBundle.getResolutionFailureException(AbstractBundle.java:1301)  
  14.     at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:319)  
  15.     at org.eclipse.osgi.framework.internal.core.AbstractBundle.resume(AbstractBundle.java:374)  
  16.     at org.eclipse.osgi.framework.internal.core.Framework.resumeBundle(Framework.java:1067)  
  17.     at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:561)  
  18.     at org.eclipse.osgi.framework.internal.core.StartLevelManager.resumeBundles(StartLevelManager.java:546)  
  19.     at org.eclipse.osgi.framework.internal.core.StartLevelManager.incFWSL(StartLevelManager.java:459)  
  20.     at org.eclipse.osgi.framework.internal.core.StartLevelManager.doSetStartLevel(StartLevelManager.java:243)  
  21.     at org.eclipse.osgi.framework.internal.core.StartLevelManager.dispatchEvent(StartLevelManager.java:440)  
  22.     at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:227)  
  23.     at org.eclipse.osgi.framework.eventmgr.EventManager$EventThread.run(EventManager.java:337)  

[Tim Moores]

If you're a beginner with OSGI I wouldn't start by mucking around with as complex an application as Eclipse. Start with a simple example instead that doesn't have any other external dependencies. The Felix examples I pointed you to accomplish that nicely.

[Suresh Khant]

Thanks Moores for your reply,


I have did the following steps
1. create Activator.java file
2. generate the jar file "BundleExample1.jar"
3. start it using the command
start file:/home/test/Desktop/BundleExample1.jar

but am getting the following error

g! start file:/home/test/Desktop/BundleExample1.jar
org.osgi.framework.BundleException: Activator start error in bundle [5].
	at org.apache.felix.framework.Felix.activateBundle(Felix.java:2027)
	at org.apache.felix.framework.Felix.startBundle(Felix.java:1895)
	at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:944)
	at org.apache.felix.gogo.command.Basic.start(Basic.java:729)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:585)
	at org.apache.felix.gogo.runtime.Reflective.invoke(Reflective.java:137)
	at org.apache.felix.gogo.runtime.CommandProxy.execute(CommandProxy.java:82)
	at org.apache.felix.gogo.runtime.Closure.executeCmd(Closure.java:477)
	at org.apache.felix.gogo.runtime.Closure.executeStatement(Closure.java:403)
	at org.apache.felix.gogo.runtime.Pipe.run(Pipe.java:108)
	at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:183)
	at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:120)
	at org.apache.felix.gogo.runtime.CommandSessionImpl.execute(CommandSessionImpl.java:89)
	at org.apache.felix.gogo.shell.Console.run(Console.java:62)
	at org.apache.felix.gogo.shell.Shell.console(Shell.java:203)
	at org.apache.felix.gogo.shell.Shell.gosh(Shell.java:128)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:585)
	at org.apache.felix.gogo.runtime.Reflective.invoke(Reflective.java:137)
	at org.apache.felix.gogo.runtime.CommandProxy.execute(CommandProxy.java:82)
	at org.apache.felix.gogo.runtime.Closure.executeCmd(Closure.java:477)
	at org.apache.felix.gogo.runtime.Closure.executeStatement(Closure.java:403)
	at org.apache.felix.gogo.runtime.Pipe.run(Pipe.java:108)
	at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:183)
	at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:120)
	at org.apache.felix.gogo.runtime.CommandSessionImpl.execute(CommandSessionImpl.java:89)
	at org.apache.felix.gogo.shell.Activator.run(Activator.java:75)
	at java.lang.Thread.run(Thread.java:595)
Caused by: java.lang.UnsupportedClassVersionError: Bad version number in .class file
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
	at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.findClass(BundleWiringImpl.java:2128)
	at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1432)
	at org.apache.felix.framework.BundleWiringImpl.access$400(BundleWiringImpl.java:72)
	at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1843)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at org.apache.felix.framework.BundleWiringImpl.getClassByDelegation(BundleWiringImpl.java:1317)
	at org.apache.felix.framework.Felix.createBundleActivator(Felix.java:4154)
	at org.apache.felix.framework.Felix.activateBundle(Felix.java:1972)
	... 32 more
java.lang.UnsupportedClassVersionError: Bad version number in .class file

manifest.mf

Manifest-Version: 1.0
Bundle-Name: Service listener example
Bundle-Description: A bundle that displays messages at startup and when service events occur
Bundle-Vendor: Apache Felix
Bundle-Version: 1.0.0
Bundle-Activator: tutorial.example1.Activator
Import-Package: org.osgi.framework

Activator.java

/*
 * Apache Felix OSGi tutorial.
**/

package tutorial.example1;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceEvent;

/**
 * This class implements a simple bundle that utilizes the OSGi
 * framework's event mechanism to listen for service events. Upon
 * receiving a service event, it prints out the event's details.
**/
public class Activator implements BundleActivator, ServiceListener
{
    /**
     * Implements BundleActivator.start(). Prints
     * a message and adds itself to the bundle context as a service
     * listener.
     * @param context the framework context for the bundle.
    **/
    public void start(BundleContext context)
    {
        System.out.println("Starting to listen for service events.");
        context.addServiceListener(this);
    }

    /**
     * Implements BundleActivator.stop(). Prints
     * a message and removes itself from the bundle context as a
     * service listener.
     * @param context the framework context for the bundle.
    **/
    public void stop(BundleContext context)
    {
        context.removeServiceListener(this);
        System.out.println("Stopped listening for service events.");

        // Note: It is not required that we remove the listener here,
        // since the framework will do it automatically anyway.
    }

    /**
     * Implements ServiceListener.serviceChanged().
     * Prints the details of any service event from the framework.
     * @param event the fired service event.
    **/
    public void serviceChanged(ServiceEvent event)
    {
        String[] objectClass = (String[])
            event.getServiceReference().getProperty("objectClass");

        if (event.getType() == ServiceEvent.REGISTERED)
        {
            System.out.println(
                "Ex1: Service of type " + objectClass[0] + " registered.");
        }
        else if (event.getType() == ServiceEvent.UNREGISTERING)
        {
            System.out.println(
                "Ex1: Service of type " + objectClass[0] + " unregistered.");
        }
        else if (event.getType() == ServiceEvent.MODIFIED)
        {
            System.out.println(
                "Ex1: Service of type " + objectClass[0] + " modified.");
        }
    }
}

[Tim Moores]

Looks like you're using an old JRE version. Recompile the sources with the JDK/JRE with which you intend to run them.