Apache ServiceMix 4.0 / interconnect OSGi bundles

Contents 1 Prerequisites 2 Introduction 3 Starting Apache ServiceMix 4.0 4 Create the core project 5 Modify the Manifest 6 Create a JAR-File an deploy your core bundle 7 Create a service bundle 8 Implement the interface 9 Modify the activator class 10 Deploy and start the service 11 Create a consumer for the service 12 Deploy the consumer

Prerequisites

• knowledge about the OSGi Service Plattform [1]
• Apache ServiceMix 4.0 installed [2]
• Eclipse Galileo [3]
• basic knowledge about programming with Java

Introduction

This tutorial shows how to connect OSGi bundles via an interface.

Starting Apache ServiceMix 4.0

• If you don't know how to start Apache ServiceMix follow the instructions on this page: [4]
• When the application is correctly up and runnig you'll see the ServiceMix prompt

Create the core project

• this project just offers the interface
• select: File > New > Project > Plug-in Project
• choose a name for your project: e.g. de.btu.dbis.InterfaceCore
• choose Target Plattform: OSGi Framework "Standard" and click next
• afterwards click finish
• Then you can delete the bundle activator class. We don't need it anymore.
• Now we want to create an Interface. right click on your project and choose New > Interface
• choose the package and a name for your interface then click finisch

• add some methods in your interface

package de.btu.dbis.interfacecore;

public interface IBundleInfo {

	public String getString();
	
	public String getString(String aString);
	
}

Modify the Manifest

• open the Manifest file
• delete the activator class from the Manifest
• click the runtime tab
• add your package to the Exported Packages
• Now your package is public and can be seen by other bundles.

Create a JAR-File an deploy your core bundle

• right click the project explorer choose: Export > Deployable plug-ins and fragments > Next
• choose your project and a destination afterwards click finish
• to deploy the jar file open the Apache ServiceMix prompt
• type: osgi/install file:///<path to your bundle>.jar
• or just put your bundle into the Apache ServiceMix deploy folder
• afterwards you can see the new bundle id
• start your bundle with: osgi/start <bundle id>

Create a service bundle

• create a new project
• open the Manifest and choose the Dependencies tab
• add to the Required Plug-ins the core package from the other bundle
• just click add and type the package name

Implement the interface

• create a new class and implement the interface
• the interface is visible to the project because we added it to the Required plug-ins
• if it isn't visible to your package be sure that your Manifest is stored

package de.btu.dbis.servicenoone;

import de.btu.dbis.interfacecore.IBundleInfo;

public class ServiceOne implements IBundleInfo {

	public String getString() {
		return "Bundle number one";
	}

	public String getString(String aString) {
		return "Bunlde number one: " + aString;
	}
}

Modify the activator class

• now we want to register this bundle as a service
• open the activator class an use the method registerService form the bunlde context

package de.btu.dbis.servicenoone;

import java.util.Hashtable;

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

import de.btu.dbis.interfacecore.IBundleInfo;

public class Activator implements BundleActivator {

	public void start(BundleContext context) throws Exception {
		context.registerService(IBundleInfo.class.getName(), 
					new ServiceOne(), new Hashtable());
		System.out.println("Service No One is registered");
	}

	public void stop(BundleContext context) throws Exception {
	}

}

Deploy and start the service

• like before deploy your service
• you should see the new bundle id
• use osgi/start <bundle id> to start your bundle

Create a consumer for the service

• now you can create a consumer for your service bundle
• create a new project
• in the Manifest choose the Dependencies tab and add the core interface to the Required Plug-ins
• afterwards you can implement the bundle activator

package de.btu.dbis.consumer;

import java.util.Scanner;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;

import de.btu.dbis.interfacecore.IBundleInfo;

public class Activator implements BundleActivator {

	public void start(BundleContext context) throws Exception {

		ServiceReference[] references =
			context.getAllServiceReferences(IBundleInfo.class.getName(), null);
		
		//just eye candy
		int i = -1;
		Scanner in = new Scanner(System.in);
		while(i!=0) {
			printMenu();
			i=in.nextInt();
			
			switch (i) {
			case 1:
				for(ServiceReference sr : references) {
					System.out.println(">> " + ((IBundleInfo)context.getService(sr)).getString());
				}
				break;
				
			case 2:
				for(ServiceReference sr : references) {
					System.out.println(">> " + ((IBundleInfo)context.getService(sr)).getString("test"));
				}
				break;

			case 3:
				for(ServiceReference sr : references) {
					System.out.println(">> " + sr.getBundle().getBundleId());
				}
				break;

			case 4:
				for(ServiceReference sr : references) {
					System.out.println(">> " + sr.getBundle().getSymbolicName());
				}
				break;
				
			case 5:
				System.out.println(">> bundle count: " + references.length);
			}
		}
	}
	
	private void printMenu() {
		System.out.println("\n=== Menu ===");
		System.out.println("0: quit");
		System.out.println("1: list all bundles / getString()");
		System.out.println("2: list all bundles / getString(aString)");
		System.out.println("3: list all bundles / id");
		System.out.println("4: list all bundles / name");
		System.out.println("5: bundle count");
		System.out.println("\n");
	}

	public void stop(BundleContext context) throws Exception {
	}
}

Deploy the consumer

• deploy the consumer like before the service
• test the implementation
• implement and test a few more services