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A generic command shell with a client and server part.
There is a newer version: 3.3.2
/*
 * Copyright (c) 2002-2016 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.shell.impl;

import java.net.MalformedURLException;
import java.net.UnknownHostException;
import java.rmi.Naming;
import java.rmi.NotBoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;

/**
 * Class for specifying a location of an RMI object
 * Consists of host, port and name, as in. "rmi://:/"
 */
public class RmiLocation
{
    private final String host;
    private final int port;
    private final String name;

    private RmiLocation( String host, int port, String name )
    {
        this.host = host;
        this.port = port;
        this.name = name;
    }

    /**
     * Creates a new RMI location instance.
     * @param host the RMI host, f.ex. "localhost".
     * @param port the RMI port.
     * @param name the RMI name, f.ex. "shell".
     * @return a new {@link RmiLocation} instance.
     */
    public static RmiLocation location( String host, int port, String name )
    {
        return new RmiLocation( host, port, name );
    }

    /**
     * @return the host of this RMI location.
     */
    public String getHost()
    {
        return this.host;
    }

    /**
     * @return the port of this RMI location.
     */
    public int getPort()
    {
        return this.port;
    }

    /**
     * @return the name of this RMI location.
     */
    public String getName()
    {
        return this.name;
    }

    private static String getProtocol()
    {
        return "rmi://";
    }

    /**
     * @return "short" URL, consisting of protocol, host and port, f.ex.
     * "rmi://localhost:8080".
     */
    public String toShortUrl()
    {
        return getProtocol() + getHost() + ":" + getPort();
    }

    /**
     * @return the full RMI URL, f.ex.
     * "rmi://localhost:8080/the/shellname".
     */
    public String toUrl()
    {
        return getProtocol() + getHost() + ":" + getPort() + "/" + getName();
    }

    /**
     * Ensures that the RMI registry is created for this JVM instance and port,
     * see {@link #getPort()}.
     * @return the registry for the port.
     * @throws RemoteException RMI error.
     */
    public Registry ensureRegistryCreated()
        throws RemoteException
    {
        try
        {
            Naming.list( toShortUrl() );
            return LocateRegistry.getRegistry( getHost(), getPort() );
        }
        catch ( RemoteException e )
        {
            try
            {
                return LocateRegistry.createRegistry( getPort(), null, new HostBoundSocketFactory( host ) );
            }
            catch ( UnknownHostException hostException )
            {
                throw new RemoteException( "Unable to bind to '"+host+"', unknown hostname.", hostException );
            }
        }
        catch ( java.net.MalformedURLException e )
        {
            throw new RemoteException( "Malformed URL", e );
        }
    }

    /**
     * Binds an object to the RMI location defined by this instance.
     * @param object the object to bind.
     * @throws RemoteException RMI error.
     */
    public void bind( Remote object ) throws RemoteException
    {
        ensureRegistryCreated();
        try
        {
            Naming.rebind( toUrl(), object );
        }
        catch ( MalformedURLException e )
        {
            throw new RemoteException( "Malformed URL", e );
        }
    }

    /**
     * @return whether or not there's an object bound to the RMI location
     * defined by this instance.
     */
    public boolean isBound()
    {
        try
        {
            getBoundObject();
            return true;
        }
        catch ( RemoteException e )
        {
            return false;
        }
    }

    /**
     * @return the bound object for the RMI location defined by this instance.
     * @throws RemoteException if there's no object bound for the RMI location.
     */
    public Remote getBoundObject() throws RemoteException
    {
        try
        {
            return Naming.lookup( toUrl() );
        }
        catch ( NotBoundException e )
        {
            throw new RemoteException( "Not bound", e );
        }
        catch ( MalformedURLException e )
        {
            throw new RemoteException( "Malformed URL", e );
        }
    }
}