YuRu's Life

How to create a simple service for your bundle?

Environment information:
OS: Fedora core 5
IDE: Eclipse 3.2.0
JRE:1.6.0 update 7
Knopflerfish: Release 2.0.0 (Knopflerfish OSGi Desktop Version 2.0.1)

1. Create a manifest.mf file
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: FirstService
Bundle-SymbolicName: FirstService
Bundle-Version: 1.0.0
Bundle-Activator: firstservice.Activator
Bundle-Localization: plugin
Import-Package: org.osgi.framework;version="1.3.0"
Export-Package: firstservice

Note:attention the"Export-Package" it's in your source code's destination.

2. create the service interface
package firstservice;
import java.util.Date;

public interface FirstService {
    public String getFormatteDate(Date date);
}

3. create the service implementation
package firstservice;

import java.text.DateFormat;
import java.util.Date;

import firstservice.FirstService;

public class FirstServiceImpl implements FirstService {

    public String getFormattedDate( Date date ){
        return DateFormat.getDateInstance( DateFormat.SHORT ).format(date);
    }

    public String getFormatteDate(Date date) {
        return null;
    }
}

Note:In the KF documents the abstract is not exist, but in the java API, the DateFormat.getDateInstance() is need a abstract ,so I write two getFormatteDate() method, one for wok,another to return null.

4. create an Activator that Registers the Service
package firstservice;

import java.util.Hashtable;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.ServiceRegistration;

import firstservice.FirstService;

public class Activator implements BundleActivator {

    public static BundleContext bc = null;
   
    public void start(BundleContext bc) throws Exception {
        System.out.println( bc.getBundle().getHeaders().get( Constants.BUNDLE_NAME ) + " starting... " );
        Activator.bc = bc;
        FirstService service = new FirstServiceImpl();
        final ServiceRegistration registration =
            bc.registerService(FirstService.class.getName(), service, new Hashtable());
        System.out.println("Service registered: FirstServuce");
    }

    public void stop(BundleContext context) throws Exception {
        System.out.println(bc.getBundle().getHeaders().get( Constants.BUNDLE_NAME ) + " stopping... ");
        Activator.bc = null;
    }

}


Note:In the KF documents, the variable: registration doesn't declare for 'final',and went you compile the code, you will get a warnings because the registration is never read.
I'm not sure for this one. I will test it more and more.

5. Now, build it and run in KF Desktop.


Author: YuRu-Wei 2008/10/01 @ Shu-Te University CSIE Lab