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package javax.naming.spi;
import javax.naming.*;
import javax.naming.directory.Attributes;
import java.util.Hashtable;
/**
* This interface represents a factory for obtaining the state of an
* object and corresponding attributes for binding.
*<p>
* The JNDI framework allows for object implementations to
* be loaded in dynamically via {@code object factories}.
* <p>
* A {@code DirStateFactory} extends {@code StateFactory}
* by allowing an {@code Attributes} instance
* to be supplied to and be returned by the {@code getStateToBind()} method.
* {@code DirStateFactory} implementations are intended to be used by
* {@code DirContext} service providers.
* When a caller binds an object using {@code DirContext.bind()},
* he might also specify a set of attributes to be bound with the object.
* The object and attributes to be bound are passed to
* the {@code getStateToBind()} method of a factory.
* If the factory processes the object and attributes, it returns
* a corresponding pair of object and attributes to be bound.
* If the factory does not process the object, it must return null.
*<p>
* For example, a caller might bind a printer object with some printer-related
* attributes.
*<blockquote><pre>
* ctx.rebind("inky", printer, printerAttrs);
*</pre></blockquote>
* An LDAP service provider for {@code ctx} uses a {@code DirStateFactory}
* (indirectly via {@code DirectoryManager.getStateToBind()})
* and gives it {@code printer} and {@code printerAttrs}. A factory for
* an LDAP directory might turn {@code printer} into a set of attributes
* and merge that with {@code printerAttrs}. The service provider then
* uses the resulting attributes to create an LDAP entry and updates
* the directory.
*
* <p> Since {@code DirStateFactory} extends {@code StateFactory}, it
* has two {@code getStateToBind()} methods, where one
* differs from the other by the attributes
* argument. {@code DirectoryManager.getStateToBind()} will only use
* the form that accepts the attributes argument, while
* {@code NamingManager.getStateToBind()} will only use the form that
* does not accept the attributes argument.
*
* <p> Either form of the {@code getStateToBind()} method of a
* DirStateFactory may be invoked multiple times, possibly using different
* parameters. The implementation is thread-safe.
*
* @author Rosanna Lee
* @author Scott Seligman
*
* @see DirectoryManager#getStateToBind
* @see DirObjectFactory
* @since 1.3
*/
public interface DirStateFactory extends StateFactory {
/**
* Retrieves the state of an object for binding given the object and attributes
* to be transformed.
*<p>
* {@code DirectoryManager.getStateToBind()}
* successively loads in state factories. If a factory implements
* {@code DirStateFactory}, {@code DirectoryManager} invokes this method;
* otherwise, it invokes {@code StateFactory.getStateToBind()}.
* It does this until a factory produces a non-null answer.
*<p>
* When an exception is thrown by a factory,
* the exception is passed on to the caller
* of {@code 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.
* <p>
* The {@code name} and {@code 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 {@code nameCtx} it should synchronize its use
* against concurrent access, since context implementations are not
* guaranteed to be thread-safe.
*<p>
* The {@code name}, {@code inAttrs}, and {@code 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.
* The object returned by this method is owned by the caller.
* The implementation will not subsequently modify it.
* It will contain either a new {@code Attributes} object that is
* likewise owned by the caller, or a reference to the original
* {@code inAttrs} parameter.
*
* @param obj A possibly null object whose state is to be retrieved.
* @param name The name of this object relative to {@code nameCtx},
* or null if no name is specified.
* @param nameCtx The context relative to which the {@code name}
* parameter is specified, or null if {@code 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.
* @param inAttrs The possibly null attributes to be bound with the object.
* The factory must not modify {@code inAttrs}.
* @return A {@code Result} containing the object's state for binding
* and the corresponding
* attributes to be bound; null if the object don't use this factory.
* @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 DirectoryManager#getStateToBind
*/
public Result getStateToBind(Object obj, Name name, Context nameCtx,
Hashtable<?,?> environment,
Attributes inAttrs)
throws NamingException;
/**
* An object/attributes pair for returning the result of
* DirStateFactory.getStateToBind().
*/
public static class Result {
/**
* The possibly null object to be bound.
*/
private Object obj;
/**
* The possibly null attributes to be bound.
*/
private Attributes attrs;
/**
* Constructs an instance of Result.
*
* @param obj The possibly null object to be bound.
* @param outAttrs The possibly null attributes to be bound.
*/
public Result(Object obj, Attributes outAttrs) {
this.obj = obj;
this.attrs = outAttrs;
}
/**
* Retrieves the object to be bound.
* @return The possibly null object to be bound.
*/
public Object getObject() { return obj; };
/**
* Retrieves the attributes to be bound.
* @return The possibly null attributes to be bound.
*/
public Attributes getAttributes() { return attrs; };
}
}