Package com.ibm.wsspi.kernel.service.utils

Class AtomicServiceReference<T>

java.lang.Object
com.ibm.wsspi.kernel.service.utils.AtomicServiceReference<T>
public class AtomicServiceReference<T> extends Object
Small class performing atomic operations to find/retrieve/cache the instance of a DeclarativeServices component reference from service registry via the service reference.

Use this to maintain a lazy-resolved reference of cardinality one (single service reference associated with a single, lazily-resolved service instance).

Usage (following OSGi DS naming conventions/patterns): 

 private final AtomicServiceReference&ltT&gt serviceRef = new AtomicServiceReference&ltT&gt("referenceName");
 
 protected void activate(ComponentContext ctx) {
  serviceRef.activate(ctx);
 }
 
 protected void deactivate(ComponentContext ctx) {
  serviceRef.deactivate(ctx);
 }
 
 protected void setReferenceName(ServiceReference&ltT&gt ref) {
  serviceRef.setReference(ref);
 }
 
 protected void unsetReferenceName(ServiceReference&ltT&gt ref) {
  serviceRef.unsetReference(ref);
 }
 
 private T getReferenceName() {
  return serviceRef.getService();
 }

  • Constructor Details

    • AtomicServiceReference

      public AtomicServiceReference(String name)
      Create a new AtomicServiceReference for the named service. e.g. from bnd.bnd: referenceName=.... or from component.xml: <reference name="referenceName".... >
      Parameters:
      name - Name of DS reference

  • Method Details

    • activate

      public void activate(org.osgi.service.component.ComponentContext context)

    • deactivate

      public void deactivate(org.osgi.service.component.ComponentContext context)

    • setReference

      public boolean setReference(org.osgi.framework.ServiceReference<T> reference)
      Update service reference associated with this service.
      Parameters:
      referenceName - ServiceReference for the target service. Service references are equal if they point to the same service registration, and are ordered by increasing service.ranking and decreasing service.id. ServiceReferences hold no service properties: requests/queries for properties are forwarded onto the backing service registration.
      Returns:
      true if this is replacing a previous (non-null) service reference

    • unsetReference

      public boolean unsetReference(org.osgi.framework.ServiceReference<T> reference)
      Clear the service reference associated with this service. This first checks to see whether or not the reference being unset matches the current reference. For Declarative Services dynamic components: if a replacement is available for a dynamic reference, DS will call set with the new reference before calling unset to clear the old one.
      Parameters:
      reference - ServiceReference associated with service to be unset.
      Returns:
      true if a non-null value was replaced

    • getReference

      public org.osgi.framework.ServiceReference<T> getReference()
      Returns:
      ServiceReference for the target service. Service references are equal if they point to the same service registration, and are ordered by increasing service.ranking and decreasing service.id. ServiceReferences hold no service properties: requests/queries for properties are forwarded onto the backing service registration.

    • getService

      public T getService()
      Returns:
      T or null if unavailable

    • getServiceWithException

      public T getServiceWithException()
      Returns:
      T
      Throws:
      IllegalStateException - if the internal state is such that locating the service is not possible or if the service is not retrievable

    • toString

      public String toString()
      Overrides:
      toString in class Object