org.apache.felix.dm

Interface AspectComponent

All Superinterfaces:

AbstractComponent, Component<AspectComponent>

public interface AspectComponent
extends Component<AspectComponent>

Interface used to configure the various parameters needed when defining a Dependency Manager aspect component. Aspects allow you to define an interceptor, or chain of interceptors for a service (to add features like caching or logging, etc ...). The dependency manager intercepts the original service, and allows you to execute some code before invoking the original service ... The aspect will be applied to any service that matches the specified interface and filter and will be registered with the same interface and properties as the original service, plus any extra properties you supply here. If you declare the original service as a member it will be injected.

Usage Examples

Here is a sample showing a DatabaseCache aspect which is created each time a Database interface is registered in the registry.

 
 public class Activator extends DependencyActivatorBase {
     &Override
     public void init(BundleContext context, DependencyManager dm) throws Exception {
         Component aspectComponent = createAspectComponent()
             .setAspect(Database.class, null, 10)
             .setImplementation(DatabaseCache.class);
         dm.add(aspectComponent);
     }
 }
 
 interface Database {
     String get(String key);
 }
 
 class DatabaseCache implements Database {
     volatile Database originalDatabase; // injected
     
     String get(String key) {
         String value = cache.get(key);
         if (value == null) {
             value = this.originalDatabase.get(key);
             store(key, value);
         }
         return value;
     }
     ... 
 }
  

For "add", "change", "remove" callbacks, the following method signatures are supported:

 (Component comp, ServiceReference ref, Service service)
 (Component comp, ServiceReference ref, Object service)
 (Component comp, ServiceReference ref)
 (Component comp, Service service)
 (Component comp, Object service)
 (Component comp)
 (Component comp, Map properties, Service service)
 (ServiceReference ref, Service service)
 (ServiceReference ref, Object service)
 (ServiceReference ref)
 (Service service)
 (Service service, Map propeerties)
 (Map properties, Service, service)
 (Service service, Dictionary properties)
 (Dictionary properties, Service service)
 (Object service)
 

For "swap" callbacks, the following method signatures are supported:

 (Service old, Service replace)
 (Object old, Object replace)
 (ServiceReference old, Service old, ServiceReference replace, Service replace)
 (ServiceReference old, Object old, ServiceReference replace, Object replace)
 (Component comp, Service old, Service replace)
 (Component comp, Object old, Object replace)
 (Component comp, ServiceReference old, Service old, ServiceReference replace, Service replace)
 (Component comp, ServiceReference old, Object old, ServiceReference replace, Object replace)
 (ServiceReference old, ServiceReference replace)
 (Component comp, ServiceReference old, ServiceReference replace)
 

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.felix.dm.Component

Component.ServiceScope

Method Summary

Modifier and Type	Method and Description
AspectComponent	setAspect(java.lang.Class<?> service, java.lang.String filter, int ranking) Sets the service interface to apply the aspect to (required parameter)
AspectComponent	setAspectCallbackInstance(java.lang.Object callbackInstance) Sets the instance to invoke the callbacks on (optional parameter).
AspectComponent	setAspectCallbacks(java.lang.String add, java.lang.String change, java.lang.String remove, java.lang.String swap) Sets name of the callbacks method to invoke on add,change,remove, or swap callbacks (optional parameter).
AspectComponent	setAspectField(java.lang.String autoConfig) Sets the aspect implementation field name where to inject original service (optional parameter).

Methods inherited from interface org.apache.felix.dm.Component

add, add, getServiceRegistration, remove, remove, setAutoConfig, setAutoConfig, setCallbacks, setCallbacks, setComposition, setComposition, setDebug, setFactory, setFactory, setImplementation, setInterface, setInterface, setInterface, setInterface, setScope, setServiceProperties

Methods inherited from interface org.apache.felix.dm.AbstractComponent

getComponentDeclaration, getDependencyManager, getInstance, getInstances, getServiceProperties

Method Detail

setAspect

AspectComponent setAspect(java.lang.Class<?> service,
                          java.lang.String filter,
                          int ranking)

Sets the service interface to apply the aspect to (required parameter)

Parameters:

service - the service interface to apply the aspect to

filter - the filter condition to use with the service aspect interface (null if no filter)

ranking - the level used to organize the aspect chain ordering

Returns:

this aspect parameter instance

setAspectField

AspectComponent setAspectField(java.lang.String autoConfig)

Sets the aspect implementation field name where to inject original service (optional parameter). If not set or null, any field matching the original service will be injected.

Parameters:

autoConfig - the aspect implementation field name where to inject original service

Returns:

this aspect parameter instance

setAspectCallbacks

AspectComponent setAspectCallbacks(java.lang.String add,
                                   java.lang.String change,
                                   java.lang.String remove,
                                   java.lang.String swap)

Sets name of the callbacks method to invoke on add,change,remove, or swap callbacks (optional parameter).

Parameters:

add - name of the callback method to invoke on add

change - name of the callback method to invoke on change

remove - name of the callback method to invoke on remove

swap - name of the callback method to invoke on swap

Returns:

this aspect parameter instance

setAspectCallbackInstance

AspectComponent setAspectCallbackInstance(java.lang.Object callbackInstance)

Sets the instance to invoke the callbacks on (optional parameter). null means the callbacks will be invoked on the aspect implementation object.

Parameters:

callbackInstance - the instance to invoke the callbacks on

Returns:

this aspect parameter instance