/*
 * Copyright 2004 Sun Microsystems, Inc. All  Rights Reserved.
 *  
 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met:
 * 
 * -Redistributions of source code must retain the above copyright  
 *  notice, this list of conditions and the following disclaimer.
 * 
 * -Redistribution in binary form must reproduce the above copyright 
 *  notice, this list of conditions and the following disclaimer in 
 *  the documentation and/or other materials provided with the 
 *  distribution.
 *  
 * Neither the name of Sun Microsystems, Inc. or the names of 
 * contributors may be used to endorse or promote products derived 
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT,
 * SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF
 * THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *  
 * You acknowledge that Software is not designed, licensed or 
 * intended for use in the design, construction, operation or 
 * maintenance of any nuclear facility.
 */
package example.inetd;

import java.io.IOException;
import java.io.File;
import java.io.FileOutputStream;
import java.io.PrintStream;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;


/**
 * Used to launch a server from <code>inetd</code>.  The <code>main</code>
 * method of this server implementation exports the service object (an
 * instance of <code>ServiceInterface</code>) and then uses the utility
 * method <code>InitializeRegistry.initializeWithInheritedChannel</code> to
 * create and export a registry using an inherited channel (if any) and
 * to bind a name to the service proxy in that registry for clients to look
 * up.
 *
 * <p>This program, when configured to be started from <code>inetd</code>,
 * will start the server when a client attempts to look up the server by
 * name in the registry on the port configured with <code>inetd</code>.
 *
 * <p>To configure <code>inetd</code> to launch this program, the following
 * entry should be added to the configuration file
 * <code>/etc/inetd.conf</code>:
 *
 * <pre>
 *    example-server stream tcp wait nobody <b><i>jrehome</i></b>/bin/java \
 *	  java -classpath <b><i>classpath</i></b> example.inetd.Server
 * </pre>
 * where <b><i>jrehome</i></b> is the path to the installed JRE, and 
 * <b><i>classpath</i></b> is the class path for the example.
 *
 * <p>Additionally, the <code>example-server</code> name needs to be
 * configured as a service in the <code>/etc/services</code> file as
 * follows:
 *
 * <pre>
 *    example-server    <b><i>port</i></b>/tcp
 * </pre>
 * where <b><i>port</i></b> is the port the registry will accept requests
 * on.  Note that the service name--
 * here we used <code>example-server</code>-- can be another name, as long
 * as the chosen name it is not already configured in /etc/services.
 *
 * <p>This program also supports being run from the command line.  In this
 * case, there is no inherited channel, and the program will simply
 * create/export a remote service, create/export a registry on the port
 * number supplied as the command line argument, and then bind the
 * service's proxy in the registry for clients to look up.

 * <p>This program can be run from the command line as follows:
 *
 * <pre>
 *     java example.inetd.Server <b><i>port</i></b>
 * </pre>
 * where <b><i>port</i></b> is a nonzero port that the registry accepts
 * requests on.
 **/
public class Server implements ServiceInterface {

    public Server() {}

    public String sendMessage(String message) {
	System.out.println(message);
	return "received message: " + message;
    }

    public static void main(String[] args) {

	/*
	 * Redirect System.err output to a file.
	 */
	redirectErrorOutput();
	
	/*
	 * Parse port argument.
	 */
	int port = 0;
	if (args.length > 0) {
	    try {
		port = Integer.parseInt(args[0]);
		
	    } catch (NumberFormatException e) {
		goodbye("malformed port argument", e);
	    }
	}
	
	/*
	 * Create and export service, and then bind in local registry using 
	 * inherited channel, if any.
	 */
	ServiceInterface server = new Server();
	Remote proxy = null;
	try {
	    /*
	     * Use two argument exportObject method to make sure that
	     * dynamic proxy can be used.
	     */
	    proxy = UnicastRemoteObject.exportObject(server, 0);
	    
	} catch (RemoteException e) {
	    goodbye("exception exporting service", e);
	}
	
	try {
	    InitializeRegistry.initializeWithInheritedChannel(
		proxy, "ServiceInterface", port);
	    
	} catch (IllegalArgumentException e) {
	    goodbye("invalid port argument", e);
	} catch (Exception e) {
	    goodbye("exception occurred", e);
	}

	System.err.println("ready");
	
	/*
	 * Wait forever.
	 */
	try {
	    Thread.sleep(Long.MAX_VALUE);
	} catch (InterruptedException e) {
	    throw new AssertionError(e);
	}
    }

    /**
     * Redirects System.err output to a file.
     */
    private static void redirectErrorOutput() {
	try {
	    File file = File.createTempFile("example-server-err", null, null);
	    PrintStream errStream =
		new PrintStream(new FileOutputStream(file));
	    System.setErr(errStream);
	    
	} catch (IOException e) {
	    goodbye("exception setting up error output file", e);
	}
    }
    
    /**
     * Prints message and exception, then exits.
     */
    private static void goodbye(String message, Exception e) {
	System.err.println("Server: " + message + ": ");
	e.printStackTrace();
	System.exit(1);
    }
}