Injecting Service Dependencies into Other Services

Property

Default Value

Description

String Required. A unique identifier for this service reference. The specified id must not be in conflict with any other implicit or explicit @Service annotation name attribute value.

interfaces

{}

String List Required if the filter property is not specified, otherwise it is optional. The interfaces that the service reference proxy should implement when it is wired in from the service registry. A service that implements these interfaces must be available in the registry. At least one interface or class name must be specified for this service reference.

filter

String Required if the interfaces property is not specified, otherwise it is optional. An OSGi filter expression that constrains the service registry lookup to only those services that match the given filter. The filter string is in the following format: (property-name = value). For example, (asynchronous-delivery=true) restricts the service lookup to those services that have a property with name asynchronous-delivery that is set to true.

timeout

5000 ms

Integer Optional. The amount of time (in milliseconds) to wait for a backing service to become available when an operation is invoked. If no matching service becomes available within this timeout period, an unchecked ServiceUnavailableException is thrown.

componentName

String Optional. A convenient shortcut for specifying a filter expression that matches the property named org.eclipse.gemini.blueprint.bean.name that is automatically advertised for beans, published with the @Service annotation.

dependsOn

String Optional. Specifies that the service reference should not be looked up in the service registry until the named dependent bean has been instantiated.

availability

Availability. OPTIONAL

ServiceReference.Availability Optional. Indicates the requirement for the availability of this service reference. By default, the reference is treated as an optional requirement. If set to MANDATORY, then the @Service registration will only succeed if the referenced service is already available.

Important:

Do not declare a mandatory reference to a service that is also exported by the same bundle. This can cause application context creation to fail through either deadlock or timeout.

@Service(name = “greeter-impl”, interfaces =
{ “com.example.osgi.greet.api.IGreeter”,
                      “org.osgi.service.cm.ManagedService” }, properties =
{ @Property(key = “service.pid”, values = “com.example.osgi.greet”) })

public class GreeterImpl implements IGreeter, ManagedService {
              public static final String KEY_HELLO = “hello”;
              private String key = KEY_HELLO;

             @ServiceReference(id = “resourceUtilRef”, interfaces =
{“com.example.osgi.greet.impl.ResourceUtil”})
                ResourceUtil resUtil;

                public void setResUtil(ResourceUtil resUtil) {
                             this.resUtil = resUtil;
                }

                ...
}

@Service
public class ResourceUtil {
             ...
}