/*
* Copyright (c) 1996 Sun Microsystems, Inc. All Rights Reserved.
*
* Sun grants you ("Licensee") a non-exclusive, royalty free, license to use,
* modify and redistribute this software in source and binary code form,
* provided that i) this copyright notice and license appear on all copies of
* the software; and ii) Licensee does not utilize the software in a manner
* which is disparaging to Sun.
*
* 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 AND ITS LICENSORS SHALL NOT BE
* LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THE 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 SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* This software is not designed or intended for use in on-line control of
* aircraft, air traffic, aircraft navigation or aircraft communications; or in
* the design, construction, operation or maintenance of any nuclear
* facility. Licensee represents and warrants that it will not use or
* redistribute the Software for such purposes.
*/
package examples.stock;
import java.rmi.*;
import java.rmi.server.*;
import java.rmi.registry.LocateRegistry;
import java.util.*;
public class StockServer extends UnicastRemoteObject
implements StockWatch, Runnable
{
/** table that maps StockNotify objects to a vector of stocks */
private Hashtable notifyTable = new Hashtable();
/** table that maps stock names to stock update info */
private Hashtable stockTable = new Hashtable();
/** thread for notifying watchers of stock updates */
private Thread notifier = null;
private static String name[] = { "Sun", "HP", "Microsoft", "DEC","Novell",
"IBM","Apple","Netscape","Borland","SGI"};
/**
* Construct the stock server
* @exception RemoteException if remote object cannot be exported
*/
public StockServer() throws RemoteException
{
for (int i=0; i<name.length; i++) {
stockTable.put(name[i], new Stock(name[i]));
}
}
/**
* Request notification of stock updates.
* @param stock the stock name
* @param obj the remote object to be notified
* @return the latest update of the stock
* @exception StockNotFoundException if stock is not known
*/
public synchronized Stock watch (String stock, StockNotify obj)
throws StockNotFoundException
{
System.out.println("StockServer.watch: " + stock );
if (!stockTable.containsKey(stock))
throw new StockNotFoundException(stock);
Vector stocks = (Vector)notifyTable.get(obj);
// register intereted party...
if (stocks == null) {
stocks = new Vector();
notifyTable.put(obj, stocks);
}
// add stock to list
if (!stocks.contains(stock)) {
stocks.addElement(stock);
}
// start thread to notify watchers...
if (notifier == null) {
notifier = new Thread(this, "StockNotifier");
notifier.start();
}
return (Stock)stockTable.get(stock);
}
/**
* Cancel request for stock updates for a particular stock.
* @param stock the stock name
* @param obj the remote object canceling the notification
*/
public void cancel(String stock, StockNotify obj)
{
Vector stocks = (Vector)notifyTable.get(obj);
stocks.removeElement(stock);
}
/**
* Returns an array of stock update information for the stocks
* already registered by the remote object.
* @param obj the remote object
* @return the list of stocks, or null if obj is not watching any
* stocks
* @exception RemoteException if some communication failure occurs
*/
public Stock[] list(StockNotify obj)
{
Vector stocks = (Vector)notifyTable.get(obj);
Stock[] stockList = null;
if (stocks != null) {
Enumeration enum = stocks.elements();
stockList = new Stock[stocks.size()];
int i=0;
// collect updates to the stocks this watcher is
// interested in
while (enum.hasMoreElements()) {
String stockname = (String)enum.nextElement();
stockList[i++] = (Stock)stockTable.get(stockname);
}
}
return stockList;
}
/**
* Cancel all requests for stock updates for the remote object.
* @param obj the remote object canceling the request
* @exception RemoteException if some communication failure occurs
*/
public synchronized void cancelAll(StockNotify obj)
{
notifyTable.remove(obj);
if (notifyTable.isEmpty()) {
Thread thread = notifier; // in case current thread is notifier
notifier = null;
thread.stop();
}
}
/**
* Private method to generate random stock updates
*/
private void generateUpdates()
{
Enumeration enum = stockTable.elements();
while (enum.hasMoreElements()) {
Stock stock = (Stock)enum.nextElement();
stock.update();
}
}
/**
* The run method (called from the notifier thread) sends out stock
* updates periodically to those remote objects that have
* registered interest in being notified.
*/
public void run()
{
while (true) {
try {
// wait for a few seconds between updates
Thread.currentThread().sleep(2000);
} catch (InterruptedException e) {
}
Date date = new Date();
// update stocks in table
generateUpdates();
// enumerate through each watcher...
Enumeration enum = notifyTable.keys();
while (enum.hasMoreElements()) {
StockNotify obj = (StockNotify)enum.nextElement();
Stock[] stockList = list(obj);
if (stockList != null) {
// send update
try {
System.out.println("StockServer.run: sending update " +
date);
obj.update(date, stockList);
} catch (RemoteException e) {
// can't reach watcher; cancel notification request
System.out.println("StockServer.run: exception");
e.printStackTrace();
cancelAll(obj);
}
}
}
}
}
/**
* Start up the stock server; also creates a registry so that the
* StockApplet can lookup the server.
*/
public static void main(String args[])
{
// Create and install the security manager
System.setSecurityManager(new RMISecurityManager());
try {
System.out.println("StockServer.main: creating registry");
LocateRegistry.createRegistry(2005);
System.out.println("StockServer.main: creating server");
StockServer server = new StockServer();
System.out.println("StockServer.main: binding server ");
Naming.rebind("//:2005/example.stock.StockServer", server);
System.out.println("StockServer.main: done");
} catch (Exception e) {
System.out.println("StockServer.main: an exception occurred: " +
e.getMessage());
e.printStackTrace();
}
}
}
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