org.osgi.service.cm

Interface ManagedServiceFactory

@ConsumerType
public interface ManagedServiceFactory

Manage multiple service instances. Bundles registering this interface are giving the Configuration Admin service the ability to create and configure a number of instances of a service that the implementing bundle can provide. For example, a bundle implementing a DHCP server could be instantiated multiple times for different interfaces using a factory.

Each of these service instances is represented, in the persistent storage of the Configuration Admin service, by a factory Configuration object that has a PID. When such a Configuration is updated, the Configuration Admin service calls the ManagedServiceFactory updated method with the new properties. When updated is called with a new PID, the Managed Service Factory should create a new factory instance based on these configuration properties. When called with a PID that it has seen before, it should update that existing service instance with the new configuration information.

In general it is expected that the implementation of this interface will maintain a data structure that maps PIDs to the factory instances that it has created. The semantics of a factory instance are defined by the Managed Service Factory. However, if the factory instance is registered as a service object with the service registry, its PID should match the PID of the corresponding Configuration object (but it should not be registered as a Managed Service!).

An example that demonstrates the use of a factory. It will create serial ports under command of the Configuration Admin service.

   class SerialPortFactory
     implements ManagedServiceFactory {
     ServiceRegistration registration;
     Hashtable ports;
     void start(BundleContext context) {
       Hashtable properties = new Hashtable();
       properties.put( Constants.SERVICE_PID,
         "com.acme.serialportfactory" );
       registration = context.registerService(
         ManagedServiceFactory.class.getName(),
         this,
         properties
       );
     }
     public void updated( String pid,
       Dictionary properties  ) {
       String portName = (String) properties.get("port");
       SerialPortService port =
         (SerialPort) ports.get( pid );
       if ( port == null ) {
         port = new SerialPortService();
         ports.put( pid, port );
         port.open();
       }
       if ( port.getPortName().equals(portName) )
         return;
       port.setPortName( portName );
     }
     public void deleted( String pid ) {
       SerialPortService port =
         (SerialPort) ports.get( pid );
       port.close();
       ports.remove( pid );
     }
     ...
   }
 

If a ManagedServiceFactory is registered without the service.pid property, it will be ignored.

"ThreadSafe"

Method Summary

Modifier and Type	Method and Description
void	deleted(String pid) Remove a factory instance.
String	getName() Return a descriptive name of this factory.
void	updated(String pid, Dictionary<String,?> properties) Create a new instance, or update the configuration of an existing instance.

Method Detail

getName

String getName()

Return a descriptive name of this factory.

Returns:

the name for the factory, which might be localized

updated

void updated(String pid,
             Dictionary<String,?> properties)
      throws ConfigurationException

Create a new instance, or update the configuration of an existing instance. If the PID of the Configuration object is new for the Managed Service Factory, then create a new factory instance, using the configuration properties provided. Else, update the service instance with the provided properties.

If the factory instance is registered with the Framework, then the configuration properties should be copied to its registry properties. This is not mandatory and security sensitive properties should obviously not be copied.

If this method throws any Exception, the Configuration Admin service must catch it and should log it.

When the implementation of updated detects any kind of error in the configuration properties, it should create a new ConfigurationException which describes the problem.

The Configuration Admin service must call this method asynchronously. This implies that implementors of the ManagedServiceFactory class can be assured that the callback will not take place during registration when they execute the registration in a synchronized method.

If the security allows multiple managed service factories to be called back for a single configuration then the callbacks must occur in service ranking order.

It is valid to create multiple factory instances that are bound to different locations. Managed Service Factory services must only be updated with configurations that are bound to their location or that start with the ? prefix and for which they have permission. Changes in the location must be reflected by deleting the corresponding configuration if the configuration is no longer visible or updating when it becomes visible.

Parameters:

pid - The PID for this configuration.

properties - A copy of the configuration properties. This argument must not contain the service.bundleLocation" property. The value of this property may be obtained from the Configuration.getBundleLocation method.

Throws:

ConfigurationException - when the configuration properties are invalid.

"Required Permissions"

ConfigurationPermission[c.location,TARGET] Required by the bundle that registered this service

deleted

void deleted(String pid)

Remove a factory instance. Remove the factory instance associated with the PID. If the instance was registered with the service registry, it should be unregistered. The Configuration Admin must call deleted for each instance it received in updated(String, Dictionary).

If this method throws any Exception, the Configuration Admin service must catch it and should log it.

The Configuration Admin service must call this method asynchronously.

Parameters:

pid - the PID of the service to be removed