/**
* Logback: the reliable, generic, fast and flexible logging framework.
*
* Copyright (C) 1999-2006, QOS.ch
*
* This library is free software, you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation.
*/
package chapter7;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;
import java.util.Vector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.joran.JoranConfigurator;
import ch.qos.logback.core.joran.spi.JoranException;
/**
* A simple NumberCruncher implementation that logs its progress when
* factoring numbers. The purpose of the whole exercise is to show the
* use of mapped diagnostic contexts in order to distinguish the log
* output from different client requests.
* */
public class NumberCruncherServer extends UnicastRemoteObject
implements NumberCruncher {
private static final long serialVersionUID = 1L;
static Logger logger = LoggerFactory.getLogger(NumberCruncherServer.class);
public NumberCruncherServer() throws RemoteException {
}
public int[] factor(int number) throws RemoteException {
// The client's host is an important source of information.
try {
MDC.put("client", NumberCruncherServer.getClientHost());
} catch (java.rmi.server.ServerNotActiveException e) {
logger.warn("Caught unexpected ServerNotActiveException.", e);
}
// The information contained within the request is another source
// of distinctive information. It might reveal the users name,
// date of request, request ID etc. In servlet type environments,
// useful information is contained in the HttpRequest or in the
// HttpSession.
MDC.put("number", String.valueOf(number));
logger.info("Beginning to factor.");
if (number <= 0) {
throw new IllegalArgumentException(number +
" is not a positive integer.");
} else if (number == 1) {
return new int[] { 1 };
}
Vector<Integer> factors = new Vector<Integer>();
int n = number;
for (int i = 2; (i <= n) && ((i * i) <= number); i++) {
// It is bad practice to place log requests within tight loops.
// It is done here to show interleaved log output from
// different requests.
logger.debug("Trying " + i + " as a factor.");
if ((n % i) == 0) {
logger.info("Found factor " + i);
factors.addElement(new Integer(i));
do {
n /= i;
} while ((n % i) == 0);
}
// Placing artificial delays in tight-loops will also lead to
// sub-optimal resuts. :-)
delay(100);
}
if (n != 1) {
logger.info("Found factor " + n);
factors.addElement(new Integer(n));
}
int len = factors.size();
int[] result = new int[len];
for (int i = 0; i < len; i++) {
result[i] = ((Integer) factors.elementAt(i)).intValue();
}
// clean up
MDC.remove("client");
MDC.remove("number");
return result;
}
static void usage(String msg) {
System.err.println(msg);
System.err.println("Usage: java chapter7.NumberCruncherServer configFile\n" +
" where configFile is a logback configuration file.");
System.exit(1);
}
public static void delay(int millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
}
}
public static void main(String[] args) {
if (args.length != 1) {
usage("Wrong number of arguments.");
}
String configFile = args[0];
if (configFile.endsWith(".xml")) {
try {
LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();
JoranConfigurator configurator = new JoranConfigurator();
configurator.setContext(lc);
lc.shutdownAndReset();
configurator.doConfigure(args[0]);
} catch (JoranException je) {
je.printStackTrace();
}
}
NumberCruncherServer ncs;
try {
ncs = new NumberCruncherServer();
logger.info("Creating registry.");
Registry registry = LocateRegistry.createRegistry(Registry.REGISTRY_PORT);
registry.rebind("Factor", ncs);
logger.info("NumberCruncherServer bound and ready.");
} catch (Exception e) {
logger.error("Could not bind NumberCruncherServer.", e);
return;
}
}
}