org.osgi.service.cm

Interface ManagedService

public interface ManagedService

A service that can receive configuration data from a Configuration Admin service.

A Managed Service is a service that needs configuration data. Such an object should be registered with the Framework registry with the service.pid property set to some unique identifier called a PID.

If the Configuration Admin service has a Configuration object corresponding to this PID, it will callback the updated() method of the ManagedService object, passing the properties of that Configuration object.

If it has no such Configuration object, then it calls back with a null properties argument. Registering a Managed Service will always result in a callback to the updated() method provided the Configuration Admin service is, or becomes active. This callback must always be done asynchronously.

Else, every time that either of the updated() methods is called on that Configuration object, the ManagedService.updated() method with the new properties is called. If the delete() method is called on that Configuration object, ManagedService.updated() is called with a null for the properties parameter. All these callbacks must be done asynchronously.

The following example shows the code of a serial port that will create a port depending on configuration information.

  
   class SerialPort implements ManagedService {
  
     ServiceRegistration registration;
     Hashtable configuration;
     CommPortIdentifier id;
  
     synchronized void open(CommPortIdentifier id,
     BundleContext context) {
       this.id = id;
       registration = context.registerService(
         ManagedService.class.getName(),
         this,
         getDefaults()
       );
     }
  
     Hashtable getDefaults() {
       Hashtable defaults = new Hashtable();
       defaults.put( "port", id.getName() );
       defaults.put( "product", "unknown" );
       defaults.put( "baud", "9600" );
       defaults.put( Constants.SERVICE_PID,
         "com.acme.serialport." + id.getName() );
       return defaults;
     }
  
     public synchronized void updated(
       Dictionary configuration  ) {
       if ( configuration == 
 
 null
 
   )
         registration.setProperties( getDefaults() );
       else {
         setSpeed( configuration.get("baud") );
         registration.setProperties( configuration );
       }
     }
     ...
   }
   
 

As a convention, it is recommended that when a Managed Service is updated, it should copy all the properties it does not recognize into the service registration properties. This will allow the Configuration Admin service to set properties on services which can then be used by other applications.

Version:

$Revision: 1.4 $

Method Summary

Modifier and Type	Method and Description
void	updated(java.util.Dictionary properties) Update the configuration for a Managed Service.

Method Detail

updated

void updated(java.util.Dictionary properties)
      throws ConfigurationException

Update the configuration for a Managed Service.

When the implementation of updated(Dictionary) detects any kind of error in the configuration properties, it should create a new ConfigurationException which describes the problem. This can allow a management system to provide useful information to a human administrator.

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

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

Parameters:

properties - A copy of the Configuration properties, or null. 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 update fails