* The JNDI framework allows for object implementations to * be loaded in dynamically via object factories. * For example, when looking up a printer bound in the name space, * if the print service binds printer names to References, the printer * Reference could be used to create a printer object, so that * the caller of lookup can directly operate on the printer object * after the lookup. *
An ObjectFactory is responsible * for creating objects of a specific type. In the above example, * you may have a PrinterObjectFactory for creating * Printer objects. *
* For the reverse process, when an object is bound into the namespace, * JNDI provides state factories. * Continuing with the printer example, suppose the printer object is * updated and rebound: *
* ctx.rebind("inky", printer);
* * A state factory must implement the StateFactory interface. * In addition, the factory class must be public and must have a * public constructor that accepts no parameters. *
* The getStateToBind() method of a state factory may * be invoked multiple times, possibly using different parameters. * The implementation is thread-safe. *
* StateFactory is intended for use with service providers * that implement only the Context interface. * DirStateFactory is intended for use with service providers * that implement the DirContext interface. * * @author Rosanna Lee * @author Scott Seligman * * @see NamingManager#getStateToBind * @see DirectoryManager#getStateToBind * @see ObjectFactory * @see DirStateFactory * @since 1.3 */ public interface StateFactory { /** * Retrieves the state of an object for binding. *
* NamingManager.getStateToBind() * successively loads in state factories and invokes this method * on them until one produces a non-null answer. * DirectoryManager.getStateToBind() * successively loads in state factories. If a factory implements * DirStateFactory, then DirectoryManager * invokes DirStateFactory.getStateToBind(); otherwise * it invokes StateFactory.getStateToBind(). *
When an exception * is thrown by a factory, the exception is passed on to the caller * of NamingManager.getStateToBind() and * DirectoryManager.getStateToBind(). * The search for other factories * that may produce a non-null answer is halted. * A factory should only throw an exception if it is sure that * it is the only intended factory and that no other factories * should be tried. * If this factory cannot create an object using the arguments supplied, * it should return null. *
* The name and nameCtx parameters may
* optionally be used to specify the name of the object being created.
* See the description of "Name and Context Parameters" in
* {@link ObjectFactory#getObjectInstance ObjectFactory.getObjectInstance()}
* for details.
* If a factory uses nameCtx it should synchronize its use
* against concurrent access, since context implementations are not
* guaranteed to be thread-safe.
*
* The name and environment parameters
* are owned by the caller.
* The implementation will not modify these objects or keep references
* to them, although it may keep references to clones or copies.
*
* @param obj A non-null object whose state is to be retrieved.
* @param name The name of this object relative to nameCtx,
* or null if no name is specified.
* @param nameCtx The context relative to which the name
* parameter is specified, or null if name is
* relative to the default initial context.
* @param environment The possibly null environment to
* be used in the creation of the object's state.
* @return The object's state for binding;
* null if the factory is not returning any changes.
* @exception NamingException if this factory encountered an exception
* while attempting to get the object's state, and no other factories are
* to be tried.
*
* @see NamingManager#getStateToBind
* @see DirectoryManager#getStateToBind
*/
public Object getStateToBind(Object obj, Name name, Context nameCtx,
Hashtable environment)
throws NamingException;
}