Java example source code file (TransientNamingContext.java)

This example Java source code file (TransientNamingContext.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bindingtype, bound, corba, exception, hashtable, internalbindingkey, internalbindingvalue, list, log, logging, namecomponent, namingsystemexception, poa, root, there, transientnamingcontext, unbind, util

The TransientNamingContext.java Java example source code

/*
 * Copyright (c) 1996, 2003, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.corba.se.impl.naming.cosnaming;

// Import general CORBA classes
import org.omg.CORBA.SystemException;
import org.omg.CORBA.Object;
import org.omg.CORBA.INTERNAL;
import org.omg.CORBA.CompletionStatus;
import org.omg.CORBA.ORB;
import org.omg.PortableServer.POA;

// Import org.omg.CosNaming types
import org.omg.CosNaming.Binding;
import org.omg.CosNaming.BindingType;
import org.omg.CosNaming.BindingTypeHolder;
import org.omg.CosNaming.BindingListHolder;
import org.omg.CosNaming.BindingIteratorHolder;
import org.omg.CosNaming.NameComponent;
import org.omg.CosNaming.NamingContext;

import java.util.logging.Logger;
import java.util.logging.Level;

import java.util.Hashtable;
import com.sun.corba.se.impl.orbutil.LogKeywords;
import com.sun.corba.se.impl.logging.NamingSystemException;
import com.sun.corba.se.spi.logging.CORBALogDomains;

/**
 * Class TransientNamingContext implements the methods defined
 * by NamingContextDataStore, and extends the NamingContextImpl class to
 * provide a servant implementation of CosNaming::NamingContext.
 * The TransientNamingContext uses a hash table
 * to store the mappings between bindings and object references and the
 * hash table is not persistent; thereby the name "transient".
 * This class should not be used directly; instead, the class
 * TransientNameService should be instantiated.
 * <p>
 * The keys in the hash table are InternalBindingKey objects, containing
 * a single NameComponent and implementing the proper functions, i.e.,
 * equals() and hashCode() in an efficient manner. The values in the hash
 * table are InternalBindingValues and store a org.omg.CosNaming::Binding and
 * the object reference associated with the binding. For iteration,
 * TransientBindingIterator objects are created, which are passed a cloned
 * copy of the hashtable. Since elements are inserted and deleted and
 * never modified, this provides stable iterators at the cost of cloning
 * the hash table.
 * <p>
 * To create and destroy object references, the TransientNamingContext
 * uses the orb.connect() and orb.disconnect() methods.
 *
 * @see NamingContextImpl
 * @see NamingContextDataStore
 * @see TransientBindingIterator
 * @see TransientNameService
 */
public class TransientNamingContext extends NamingContextImpl implements NamingContextDataStore
{
    private Logger readLogger, updateLogger, lifecycleLogger;

    // XXX: the wrapper calls are all preceded by logger updates.
    // These can be combined, and then we simply use 3 NamingSystemException wrappers,
    // for read, update, and lifecycl.
    private NamingSystemException wrapper ;

    /**
     * Constructs a new TransientNamingContext object.
     * @param orb an orb object.
     * @param initial the initial naming context.
     * @exception Exception a Java exception thrown of the base class cannot
     * initialize.
     */
    public TransientNamingContext(com.sun.corba.se.spi.orb.ORB orb,
        org.omg.CORBA.Object initial,
        POA nsPOA )
        throws java.lang.Exception
    {
        super(orb, nsPOA );
        wrapper = NamingSystemException.get( orb, CORBALogDomains.NAMING ) ;

        this.localRoot = initial;
        readLogger = orb.getLogger( CORBALogDomains.NAMING_READ);
        updateLogger = orb.getLogger( CORBALogDomains.NAMING_UPDATE);
        lifecycleLogger = orb.getLogger(
            CORBALogDomains.NAMING_LIFECYCLE);
        lifecycleLogger.fine( "Root TransientNamingContext LIFECYCLE.CREATED" );
    }

    /**
     * Binds the object to the name component as the specified binding type.
     * It creates a InternalBindingKey object and a InternalBindingValue
     * object and inserts them in the hash table.
     * @param n A single org.omg.CosNaming::NameComponent under which the
     * object will be bound.
     * @param obj An object reference to be bound under the supplied name.
     * @param bt The type of the binding (i.e., as object or as context).
     * @exception org.omg.CORBA.SystemException One of a fixed set of CORBA
     * system exceptions.
     */
    public final void Bind(NameComponent n, org.omg.CORBA.Object obj,
                           BindingType bt)
        throws org.omg.CORBA.SystemException
    {
        // Create a key and a value
        InternalBindingKey key = new InternalBindingKey(n);
        NameComponent[] name = new NameComponent[1];
        name[0] = n;
        Binding b = new Binding(name,bt);
        InternalBindingValue value = new InternalBindingValue(b,null);
        value.theObjectRef = obj;
        // insert it
        InternalBindingValue oldValue =
            (InternalBindingValue)this.theHashtable.put(key,value);

        if (oldValue != null) {
            updateLogger.warning( LogKeywords.NAMING_BIND + "Name " +
                getName( n ) + " Was Already Bound" );
            throw wrapper.transNcBindAlreadyBound() ;
        }
        if( updateLogger.isLoggable( Level.FINE ) ) {
            updateLogger.fine( LogKeywords.NAMING_BIND_SUCCESS +
                "Name Component: " + n.id + "." + n.kind );
        }
    }

    /**
     * Resolves the supplied name to an object reference and returns
     * the type of the resolved binding. It creates a InternalBindingKey
     * and uses the key for looking up in the hash table. If nothing
     * is found an exception is thrown, otherwise the object reference
     * is returned and the binding type set.
     * @param n a NameComponent which is the name to be resolved.
     * @param bth the BindingType as an out parameter.
     * @return the object reference bound under the supplied name, null if not
     * found.
     * @exception org.omg.CORBA.SystemException One of a fixed set of CORBA
     * system exceptions.
     */
    public final org.omg.CORBA.Object Resolve(NameComponent n,
                                              BindingTypeHolder bth)
        throws org.omg.CORBA.SystemException
    {
        // Is the initial naming context requested?
        if ( (n.id.length() == 0)
           &&(n.kind.length() == 0 ) )
        {
            bth.value = BindingType.ncontext;
            return localRoot;
        }

        // Create a key and lookup the value
        InternalBindingKey key = new InternalBindingKey(n);

        InternalBindingValue value =
            (InternalBindingValue) this.theHashtable.get(key);
        if (value == null) return null;
        if( readLogger.isLoggable( Level.FINE ) ) {
            readLogger.fine( LogKeywords.NAMING_RESOLVE_SUCCESS
                + "Namecomponent :" + getName( n ) );
        }

        // Copy out binding type and object reference
        bth.value = value.theBinding.binding_type;
        return value.theObjectRef;
    }

    /**
     * Deletes the binding with the supplied name. It creates a
     * InternalBindingKey and uses it to remove the value associated
     * with the key. If nothing is found an exception is thrown, otherwise
     * the element is removed from the hash table.
     * @param n a NameComponent which is the name to unbind
     * @return the object reference bound to the name, or null if not found.
     * @exception org.omg.CORBA.SystemException One of a fixed set of CORBA
     * system exceptions.
     */
    public final org.omg.CORBA.Object Unbind(NameComponent n)
        throws org.omg.CORBA.SystemException
    {
        // Create a key and remove it from the hashtable
        InternalBindingKey key = new InternalBindingKey(n);
        InternalBindingValue value =
            (InternalBindingValue)this.theHashtable.remove(key);

        // Return what was found
        if (value == null) {
            if( updateLogger.isLoggable( Level.FINE ) ) {
                updateLogger.fine( LogKeywords.NAMING_UNBIND_FAILURE +
                    " There was no binding with the name " + getName( n ) +
                    " to Unbind " );
            }
            return null;
        } else {
            if( updateLogger.isLoggable( Level.FINE ) ) {
                updateLogger.fine( LogKeywords.NAMING_UNBIND_SUCCESS +
                    " NameComponent:  " + getName( n ) );
            }
            return value.theObjectRef;
       }
    }

    /**
     * List the contents of this NamingContext. It creates a new
     * TransientBindingIterator object and passes it a clone of the
     * hash table and an orb object. It then uses the
     * newly created object to return the required number of bindings.
     * @param how_many The number of requested bindings in the BindingList.
     * @param bl The BindingList as an out parameter.
     * @param bi The BindingIterator as an out parameter.
     * @exception org.omg.CORBA.SystemException One of a fixed set of CORBA
     * system exceptions.
     */
    public final void List(int how_many, BindingListHolder bl,
                           BindingIteratorHolder bi)
        throws org.omg.CORBA.SystemException
    {
        try {
            // Create a new binding iterator servant with a copy of this
            // hashtable. nsPOA is passed to the object so that it can
            // de-activate itself from the Active Object Map when
            // Binding Iterator.destroy is called.
            TransientBindingIterator bindingIterator =
                new TransientBindingIterator(this.orb,
                (Hashtable)this.theHashtable.clone(), nsPOA);
            // Have it set the binding list
            bindingIterator.list(how_many,bl);

            byte[] objectId = nsPOA.activate_object( bindingIterator );
            org.omg.CORBA.Object obj = nsPOA.id_to_reference( objectId );

            // Get the object reference for the binding iterator servant
            org.omg.CosNaming.BindingIterator bindingRef =
                org.omg.CosNaming.BindingIteratorHelper.narrow( obj );

            bi.value = bindingRef;
        } catch (org.omg.CORBA.SystemException e) {
            readLogger.warning( LogKeywords.NAMING_LIST_FAILURE + e );
            throw e;
        } catch (Exception e) {
            // Convert to a CORBA system exception
            readLogger.severe( LogKeywords.NAMING_LIST_FAILURE + e );
            throw wrapper.transNcListGotExc( e ) ;
        }
    }

    /**
     * Create a new NamingContext. It creates a new TransientNamingContext
     * object, passing it the orb object.
     * @return an object reference for a new NamingContext object implemented
     * by this Name Server.
     * @exception org.omg.CORBA.SystemException One of a fixed set of CORBA
     * system exceptions.
     */
    public final org.omg.CosNaming.NamingContext NewContext()
        throws org.omg.CORBA.SystemException
    {
        try {
            // Create a new servant
            TransientNamingContext transContext =
                new TransientNamingContext(
                (com.sun.corba.se.spi.orb.ORB) orb,localRoot, nsPOA);

            byte[] objectId = nsPOA.activate_object( transContext );
            org.omg.CORBA.Object obj = nsPOA.id_to_reference( objectId );
            lifecycleLogger.fine( "TransientNamingContext " +
                "LIFECYCLE.CREATE SUCCESSFUL" );
            return org.omg.CosNaming.NamingContextHelper.narrow( obj );

        } catch (org.omg.CORBA.SystemException e) {
            lifecycleLogger.log(
                Level.WARNING, LogKeywords.LIFECYCLE_CREATE_FAILURE, e );
            throw e;
        } catch (Exception e) {
            lifecycleLogger.log(
                Level.WARNING, LogKeywords.LIFECYCLE_CREATE_FAILURE, e );
            throw wrapper.transNcNewctxGotExc( e ) ;
        }
    }

    /**
     * Destroys this NamingContext by disconnecting from the ORB.
     * @exception org.omg.CORBA.SystemException One of a fixed set of CORBA
     * system exceptions.
     */
    public final void Destroy()
        throws org.omg.CORBA.SystemException
    {
        // Destroy the object reference by disconnecting from the ORB
        try {
            byte[] objectId = nsPOA.servant_to_id( this );
            if( objectId != null ) {
                nsPOA.deactivate_object( objectId );
            }
            if( lifecycleLogger.isLoggable( Level.FINE ) ) {
                lifecycleLogger.fine(
                    LogKeywords.LIFECYCLE_DESTROY_SUCCESS );
            }
        } catch (org.omg.CORBA.SystemException e) {
            lifecycleLogger.log( Level.WARNING,
                LogKeywords.LIFECYCLE_DESTROY_FAILURE, e );
            throw e;
        } catch (Exception e) {
            lifecycleLogger.log( Level.WARNING,
                LogKeywords.LIFECYCLE_DESTROY_FAILURE, e );
            throw wrapper.transNcDestroyGotExc( e ) ;
        }
    }

    /**
     * A Utility Method For Logging..
     */
    private String getName( NameComponent n ) {
        return n.id + "." + n.kind;
    }

    /**
     * Return whether this NamingContext contains any bindings. It forwards
     * this request to the hash table.
     * @return true if this NamingContext contains no bindings.
     */
    public final boolean IsEmpty()
    {
        return this.theHashtable.isEmpty();
    }

    // A hashtable to store the bindings
    private final Hashtable  theHashtable = new Hashtable();

    /**
     * The local root naming context.
     */
    public org.omg.CORBA.Object localRoot;
}