Package org.apache.felix.cm

Interface PersistenceManager

All Known Subinterfaces:
ExtPersistenceManager, NotCachablePersistenceManager
All Known Implementing Classes:
CachingPersistenceManagerProxy, FilePersistenceManager, MemoryPersistenceManager, PersistenceManagerProxy
@ConsumerType public interface PersistenceManager
The PersistenceManager interface defines the API to be implemented to support persisting configuration data. This interface may be implemented by bundles, which support storing configuration data in different locations.

The Apache Felix Configuration Admin Service bundles provides an implementation of this interface using the platform file system to store configuration data.

Implementations of this interface must support loading and storing java.util.Dictionary objects as defined in section 104.4.2, Configuration Properties, of the Configuration Admin Service Specification Version 1.2.

To make implementations of this interface available to the Configuration Admin Service they must be registered as service for this interface. The Configuration Admin Service will consider all registered services plus the default platform file system based implementation to load configuration data. To store new configuration data, the persistence manager service with the highest rank value - the service.ranking service property - is used. If no persistence manager service has been registered, the platform file system based implementation is used.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final String
    PROPERTY_NAME
    Service registration property to define a unique name for the persistence manager.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    delete(String pid)
    Removes the Dictionary for the given pid.
    boolean
    exists(String pid)
    Returns true if a persisted Dictionary exists for the given pid.
    Enumeration
    getDictionaries()
    Returns an enumeration of all Dictionary objects known to this persistence manager.
    Dictionary
    load(String pid)
    Returns the Dictionary for the given pid.
    void
    store(String pid, Dictionary properties)
    Stores the Dictionary under the given pid.

  • Field Details

    • PROPERTY_NAME

      static final String PROPERTY_NAME
      Service registration property to define a unique name for the persistence manager.
      Since:
      1.2
      See Also:

  • Method Details

    • exists

      boolean exists(String pid)
      Returns true if a persisted Dictionary exists for the given pid.
      Parameters:
      pid - The identifier for the dictionary to test.
      Returns:
      true if a persisted dictionary exists for the pid.

    • load

      Dictionary load(String pid) throws IOException
      Returns the Dictionary for the given pid.

      Implementations are expected to return dictionary instances which may be modified by the caller without affecting any underlying data or affecting future calls to this method with the same PID. In other words the reference equation load(pid) != load(pid) must hold true.

      Parameters:
      pid - The identifier for the dictionary to load.
      Returns:
      The dictionary for the identifier. This must not be null but may be empty.
      Throws:
      IOException - If an error occurs loading the dictionary. An IOException must also be thrown if no dictionary exists for the given identifier.

    • getDictionaries

      Enumeration getDictionaries() throws IOException
      Returns an enumeration of all Dictionary objects known to this persistence manager.

      Implementations of this method are allowed to return lazy enumerations. That is, it is allowable for the enumeration to not return a dictionary if loading it results in an error.

      Implementations are expected to return dictionary instances which may be modified by the caller without affecting any underlying data or affecting future calls to this method.

      The Enumeration returned from this method must be stable against concurrent calls to either of the load(String), store(String, Dictionary), and delete(String) methods.

      Returns:
      A possibly empty Enumeration of all dictionaries.
      Throws:
      IOException - If an error occurs getting the dictionaries.

    • store

      void store(String pid, Dictionary properties) throws IOException
      Stores the Dictionary under the given pid.

      The dictionary provided to this method must be considered private to the caller. Any modification by the caller after this method finishes must not influence any internal storage of the provided data. Implementations must not modify the dictionary.

      Parameters:
      pid - The identifier of the dictionary.
      properties - The Dictionary to store.
      Throws:
      IOException - If an error occurs storing the dictionary. If this exception is thrown, it is expected, that exists(pid returns false.

    • delete

      void delete(String pid) throws IOException
      Removes the Dictionary for the given pid. If such a dictionary does not exist, this method has no effect.
      Parameters:
      pid - The identifier of the dictionary to delete.
      Throws:
      IOException - If an error occurs deleting the dictionary. This exception must not be thrown if no dictionary with the given identifier exists.