Package org.apache.felix.dm

Interface Component

All Known Subinterfaces:
AdapterComponent, AspectComponent, BundleComponent, ComponentContext, FactoryComponent, ResourceComponent
@ProviderType public interface Component
Component interface. Components are the main building blocks for OSGi applications. They can publish themselves as a service, and they can have dependencies. These dependencies will influence their life cycle as component will only be activated when all required dependencies are available.
Author:
Felix Project Team

  • Method Details

    • setScope

      Component setScope(Component.ServiceScope scope)
      Sets the component scope.
      Parameters:
      scope - the component scope (default=SINGLETON)
      Returns:
      this component

    • setImplementation

      Component setImplementation(Object implementation)
      Sets the implementation for this component. You can actually specify an instance you have instantiated manually, or a Class that will be instantiated using its default constructor when the required dependencies are resolved, effectively giving you a lazy instantiation mechanism. There are four special methods that are called when found through reflection to give you life cycle management options:
      1. init() is invoked after the instance has been created and dependencies have been resolved, and can be used to initialize the internal state of the instance or even to add more dependencies based on runtime state
      2. start() is invoked right before the service is registered
      3. stop() is invoked right after the service is unregistered
      4. destroy() is invoked after all dependencies are removed
      In short, this allows you to initialize your instance before it is registered, perform some post-initialization and pre-destruction code as well as final cleanup. If a method is not defined, it simply is not called, so you can decide which one(s) you need. If you need even more fine-grained control, you can register as a service state listener too.
      Parameters:
      implementation - the implementation
      Returns:
      this component
      See Also:

    • add

      Component add(Dependency... dependencies)
      Adds dependency(ies) to this component, atomically. If the component is already active or if you add dependencies from the init method, then you should add all the dependencies in one single add method call (using the varargs argument), because this method may trigger component activation (like the ServiceTracker.open() method does).
      Parameters:
      dependencies - the dependencies to add.
      Returns:
      this component

    • remove

      Component remove(Dependency d)
      Removes a dependency from the component.
      Parameters:
      d - the dependency to remove
      Returns:
      this component

    • add

      Component add(ComponentStateListener listener)
      Adds a component state listener to this component.
      Parameters:
      listener - the state listener

    • remove

      Component remove(ComponentStateListener listener)
      Removes a component state listener from this component.
      Parameters:
      listener - the state listener

    • setInterface

      Component setInterface(String serviceName, Dictionary<?,?> properties)
      Sets the public interface under which this component should be registered in the OSGi service registry.
      Parameters:
      serviceName - the name of the service interface
      properties - the properties for this service
      Returns:
      this component

    • setInterface

      Component setInterface(String[] serviceNames, Dictionary<?,?> properties)
      Sets the public interfaces under which this component should be registered in the OSGi service registry.
      Parameters:
      serviceNames - the names of the service interface
      properties - the properties for these services
      Returns:
      this component

    • setInterface

      Component setInterface(Class<?> serviceName, Dictionary<?,?> properties)
      Sets the public interface under which this component should be registered in the OSGi service registry.
      Parameters:
      serviceName - the name of the service interface
      properties - the properties for this service
      Returns:
      this component

    • setInterface

      Component setInterface(Class<?>[] serviceNames, Dictionary<?,?> properties)
      Sets the public interfaces under which this component should be registered in the OSGi service registry.
      Parameters:
      serviceNames - the names of the service interface
      properties - the properties for these services
      Returns:
      this component

    • setAutoConfig

      Component setAutoConfig(Class<?> clazz, boolean autoConfig)
      Configures auto configuration of injected classes in the component instance. The following injections are currently performed, unless you explicitly turn them off:
      BundleContext
      the bundle context of the bundle
      ServiceRegistration
      the service registration used to register your service
      DependencyManager
      the dependency manager instance
      Component
      the component instance of the dependency manager
      Parameters:
      clazz - the class (from the list above)
      autoConfig - false to turn off auto configuration

    • setAutoConfig

      Component setAutoConfig(Class<?> clazz, String instanceName)
      Configures auto configuration of injected classes in the component instance.
      Parameters:
      clazz - the class (from the list above)
      instanceName - the name of the instance to inject the class into
      See Also:

    • setServiceProperties

      Component setServiceProperties(Dictionary<?,?> serviceProperties)
      Sets the service properties associated with the component. If the service was already registered, it will be updated.
      Parameters:
      serviceProperties - the properties

    • setCallbacks

      Component setCallbacks(String init, String start, String stop, String destroy)
      Sets the names of the methods used as callbacks. These methods, when found, are invoked as part of the life cycle management of the component implementation. The dependency manager will look for a method of this name with the following signatures, in this order:
      1. method(Component component)
      2. method()
      Parameters:
      init - the name of the init method
      start - the name of the start method
      stop - the name of the stop method
      destroy - the name of the destroy method
      Returns:
      the component

    • setCallbacks

      Component setCallbacks(Object instance, String init, String start, String stop, String destroy)
      Sets the names of the methods used as callbacks. These methods, when found, are invoked on the specified instance as part of the life cycle management of the component implementation.

      See setCallbacks(String init, String start, String stop, String destroy) for more information on the signatures. Specifying an instance means you can create a manager that will be invoked whenever the life cycle of a component changes and this manager can then decide how to expose this life cycle to the actual component, offering an important indirection when developing your own component models.

      Returns:
      this component

    • setFactory

      Component setFactory(Object factory, String createMethod)
      Sets the factory to use to create the implementation. You can specify both the factory class and method to invoke. The method should return the implementation, and can use any method to create it. Actually, this can be used together with setComposition to create a composition of instances that work together to implement a component. The factory itself can also be instantiated lazily by not specifying an instance, but a Class.
      Parameters:
      factory - the factory instance or class
      createMethod - the name of the create method
      Returns:
      this component

    • setFactory

      Component setFactory(String createMethod)
      Sets the factory to use to create the implementation. You specify the method to invoke. The method should return the implementation, and can use any method to create it. Actually, this can be used together with setComposition to create a composition of instances that work together to implement a component.

      Note that currently, there is no default for the factory, so please use setFactory(factory, createMethod) instead.

      Parameters:
      createMethod - the name of the create method
      Returns:
      this component

    • setComposition

      Component setComposition(Object instance, String getMethod)
      Sets the instance and method to invoke to get back all instances that are part of a composition and need dependencies injected. All of them will be searched for any of the dependencies. The method that is invoked must return an Object[].
      Parameters:
      instance - the instance that has the method
      getMethod - the method to invoke
      Returns:
      this component

    • setComposition

      Component setComposition(String getMethod)
      Sets the method to invoke on the service implementation to get back all instances that are part of a composition and need dependencies injected. All of them will be searched for any of the dependencies. The method that is invoked must return an Object[].
      Parameters:
      getMethod - the method to invoke
      Returns:
      this component

    • setDebug

      Component setDebug(String label)
      Activate debug for this component. Informations related to dependency processing will be displayed using osgi log service, our to standard output if no log service is currently available.
      Parameters:
      label -

    • getServiceRegistration

      org.osgi.framework.ServiceRegistration getServiceRegistration()
      Returns the service registration for this component. The method will return null if no service registration is available, for example if this component is not registered as a service at all.
      Returns:
      the service registration

    • getInstance

      <U> U getInstance()
      Returns the instance that make up this component. If the component has a composition of instances, then the first instance of the composition is returned. Null is returned if the component has not even been instantiated.
      Returns:
      the component instances

    • getInstances

      Object[] getInstances()
      Returns the composition instances that make up this component, or just the component instance if it does not have a composition, or an empty array if the component has not even been instantiated.
      Returns:
      the component instances

    • getServiceProperties

      <K, V> Dictionary<K,V> getServiceProperties()
      Returns the component service properties. The returned dictionary is either empty if no service properties were defined for this component, or copy of the existing service properties associated with this component.
      Returns:
      a copy of the service properties associated to this component or an empty dictionary if no service properties were defined for this component.

    • getDependencyManager

      DependencyManager getDependencyManager()
      Returns the dependency manager associated with this component.
      Returns:
      the dependency manager associated with this component.

    • getComponentDeclaration

      ComponentDeclaration getComponentDeclaration()
      Returns the component description (dependencies, service provided, etc ...).
      Returns:
      the component description (dependencies, service provided, etc ...).