org.apache.sling.commons.osgi

Class RankedServices<T>

java.lang.Object

org.apache.sling.commons.osgi.RankedServices<T>

Type Parameters:

T - Service type

All Implemented Interfaces:

Iterable<T>

@ProviderType
public final class RankedServices<T>
extends Object
implements Iterable<T>

Helper class that collects all services registered via OSGi bind/unbind methods. The services are ordered by service ranking and can be iterated directly using this object instance. Implementation is thread-safe.

Usage example:

1. Define a dynamic reference with cardinality OPTIONAL_MULTIPLE in your service:

 @Reference(name = "myService", referenceInterface = MyService.class,
     cardinality = ReferenceCardinality.OPTIONAL_MULTIPLE, policy = ReferencePolicy.DYNAMIC)
 private final RankedServices<MyService> myServices = new RankedServices<MyService>();
 

2. Define bind/unbind methods that delegate to the RankedServices instance:

 void bindMyService(MyService service, Map<String, Object> props) {
   myServices.bind(service, props);
 }
 void unbindMyService(MyService service, Map<String, Object> props) {
   myServices.unbind(service, props);
 }
 

To access the list of referenced services you can access them in a thread-safe manner:

 for (MyService service : myServices) {
   // your code...
 }
 

Optionally you can pass in a RankedServices.ChangeListener instance to get notified when the list of referenced services has changed.

Since:

2.3

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	RankedServices.ChangeListener Notification for changes on services list.

Constructor Summary

Constructors

Constructor and Description
RankedServices() Instantiate without change listener.
RankedServices(RankedServices.ChangeListener changeListener) Instantiate with change listener.

Method Summary

Modifier and Type	Method and Description
void	bind(T service, Map<String,Object> props) Handle bind service event.
Collection<T>	get() Lists all services registered in OSGi, sorted by service ranking.
Iterator<T>	iterator() Iterates all services registered in OSGi, sorted by service ranking.
void	unbind(T service, Map<String,Object> props) Handle unbind service event.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

RankedServices

public RankedServices()

Instantiate without change listener.

RankedServices

public RankedServices(RankedServices.ChangeListener changeListener)

Instantiate with change listener.

Parameters:

changeListener - Change listener

Method Detail

bind

public void bind(T service,
                 Map<String,Object> props)

Handle bind service event.

Parameters:

service - Service instance

props - Service reference properties

unbind

public void unbind(T service,
                   Map<String,Object> props)

Handle unbind service event.

Parameters:

service - Service instance

props - Service reference properties

get

public Collection<T> get()

Lists all services registered in OSGi, sorted by service ranking.

Returns:

Collection of service instances

iterator

public Iterator<T> iterator()

Iterates all services registered in OSGi, sorted by service ranking.

Specified by:

iterator in interface Iterable<T>

Returns:

Iterator with service instances.