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import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Map;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTracker;
import org.touge.osgiutil.OSGiUtil;
import org.touge.osgiutil.OSGiUtil.OSGiServiceException;
import org.touge.osgiutil.OSGiUtil.ServiceFollower;
import org.touge.osgiutil.OSGiUtil.ServiceVisitor;
import org.touge.osgiutil.OSGiUtil.TrackingCollection;

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OSGiUtil Examples

public class Examples {

	public static void main(String[] args) {
		
		BundleContext context = null;

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Service binding patterns.

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You want to get a single reference to a specific service.

You expect only one and you want the operation to fail if the service is not available for some reason.

		
		try {
			Service1 service = 
					(Service1) OSGiUtil.getServiceInstance(context, Service1.class.getName());
		} catch (OSGiServiceException e) {

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Service was not available. Panic.

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You want to do something once a set of services is available.

You only want to know when the complete set exists. First define the services you want

		String [] services = { 
				Service1.class.getName(),
				Service2.class.getName(),
				Service3.class.getName()};

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Then call .withServices() and define a ServiceFollower.

		OSGiUtil.withServices(context, Arrays.asList(services) , new ServiceFollower() {

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			@Override
			public void unavailable(Object service) {

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Shutdown whatever needs to be shutdown, complete set of services no longer available.

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			@Override
			public void allAvailable(Map<String, Object> services, Map<String, ServiceReference> references) {

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The services map contains the complete set of services. The key is the service name, the value is a reference to the service. The map of references can be used to access the properties associated with the services.

			}
		});

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You want to act upon a set of instances that all implement the same service interface.

This is common with whiteboard-style services.

		OSGiUtil.onServices(context, Service2.class.getName(), null, new ServiceVisitor<Service2>() {

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			@Override
			public void apply(ServiceReference sr, Service2 service) {

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This method is called on all instances of Service2 in the registry at the time of call.

			}
			
		});

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You want to maintain a collection of services that may be referenced at any time.

The collection also allows to isolate dependent code from the OSGi APIs.

		TrackingCollection<Service3> serviceCollection = OSGiUtil.trackingCollection(context, Service3.class.getName());

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A TrackingCollection adds close() to the Collection interface to stop the collection from actively tracking services.

		if (!serviceCollection.isEmpty()) {

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Do something with the services.

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Finished with the services

		serviceCollection.close();

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Similar to the TrackingCollection but allows the client to define the collection to be populated.

		Collection<Service3> svcs = new ArrayList<Service3>();
		ServiceTracker tracker = OSGiUtil.collectServices(context, Service3.class.getName(), svcs);

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Do something with the services

		for (Service3 s : svcs)
			System.out.println(s.toString());

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Close the service tracker

		tracker.close();
	}

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Example service 1

	interface Service1 {
		
	}

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Example service 2

	interface Service2 {
		
	}

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Example service 3