Simple Log server with java SocketHandler and centralization of log records

A common requirement for all enterprise systems is the centralization of log records.

This systems simply use the SocketHandlers to store/display ongoing event logs.

SocketHandler is a subclasses of StreamHandler. Others classes are consoleHandler, FileHandler and SocketHandler.

In a distributed system nobody can perform a healty monitoring activity on the whole system without a centraliazed log system.

Let's have look at SocketHandler.

The following class will produce logs and sent to LogServer.

package socketLogger;

import java.io.*;
import java.util.logging.*;

public class LogTest {
    private static Logger logger = Logger.getAnonymousLogger ();
   
    public static void main (String argv[]) throws IOException {
        Handler handler = new SocketHandler ("localhost", 5000);
        //set handler log level
        handler.setLevel (Level.FINEST);
        //set logger log level
        logger.setLevel(Level.FINEST);
        //add socket handler to sent our logs to log server..
        logger.addHandler (handler);

        //lets make some noice
        logger.log (Level.SEVERE, "Hello, World");
        logger.log (Level.INFO, "Welcome Home");
        logger.log (Level.CONFIG, "Config ....");
        logger.log (Level.FINE, "Fine ....");
        logger.log (Level.FINEST, "Finest ....");
        logger.log (Level.WARNING, "Warning ....");
    }
}

And our log server which listens incoming logs and prints them to console.You can build your own log server with a nice gui and filtering/searching capabilities by enhancing this.

package socketLogger;

import javax.net.ssl.*;
import javax.net.*;
import java.io.*;
import java.net.*;

public class LogServer {
    private static final int PORT_NUM = 5000;
    private static ServerSocket serverSocket;
   
    public static void main (String args[]) {
        serverSocket = createServerSocket ();
        listenAndPrintLogMessages ();
    }

    private static void listenAndPrintLogMessages () {
        while (true) {
            Socket socket = null;
            try {
                System.out.println (" >> Server waiting for log messages...");
                socket = serverSocket.accept ();

                InputStream is = socket.getInputStream ();
                BufferedReader br = new BufferedReader (new InputStreamReader (is, "US-ASCII"));
                String line = null;
                while ((line = br.readLine ()) != null) {
                    System.out.println (line);
                }
            } catch (Exception e) {
                e.printStackTrace ();
            } finally {
                if (socket != null) {
                    try {
                        socket.close ();
                    } catch (IOException ignored) {
                    }
                }
            }
        }
    }

    private static ServerSocket createServerSocket () {
        ServerSocketFactory serverSocketFactory = ServerSocketFactory.getDefault ();
        try {
            serverSocket = serverSocketFactory.createServerSocket (PORT_NUM);
        } catch (IOException ioEx) {
            System.err.println ("Unable to create server");
            ioEx.printStackTrace();
            System.exit ( -1);
        }
        return serverSocket;
    }
}

see in action

And here is our logs which is captured from ServerSocket and printed to console in. By default the XMLFormatter class is used for formatting in the socket handler.So we have very nice log records now :)

 >> Server waiting for log messages...
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE log SYSTEM "logger.dtd">
<log>
<record>
  <date>2010-09-06T23:01:02</date>
  <millis>1283803262382</millis>
  <sequence>0</sequence>
  <level>SEVERE</level>
  <class>socketLogger.LogTest</class>
  <method>main</method>
  <thread>10</thread>
  <message>Hello, World</message>
</record>
<record>
  <date>2010-09-06T23:01:03</date>
  <millis>1283803263161</millis>
  <sequence>1</sequence>
  <level>INFO</level>
  <class>socketLogger.LogTest</class>
  <method>main</method>
  <thread>10</thread>
  <message>Welcome Home</message>
</record>
<record>
  <date>2010-09-06T23:01:03</date>
  <millis>1283803263162</millis>
  <sequence>2</sequence>
  <level>CONFIG</level>
  <class>socketLogger.LogTest</class>
  <method>main</method>
  <thread>10</thread>
  <message>Config ....</message>
</record>
<record>
  <date>2010-09-06T23:01:03</date>
  <millis>1283803263162</millis>
  <sequence>3</sequence>
  <level>FINE</level>
  <class>socketLogger.LogTest</class>
  <method>main</method>
  <thread>10</thread>
  <message>Fine ....</message>
</record>
<record>
  <date>2010-09-06T23:01:03</date>
  <millis>1283803263172</millis>
  <sequence>4</sequence>
  <level>FINEST</level>
  <class>socketLogger.LogTest</class>
  <method>main</method>
  <thread>10</thread>
  <message>Finest ....</message>
</record>
<record>
  <date>2010-09-06T23:01:03</date>
  <millis>1283803263172</millis>
  <sequence>5</sequence>
  <level>WARNING</level>
  <class>socketLogger.LogTest</class>
  <method>main</method>
  <thread>10</thread>
  <message>Warning ....</message>
</record>
 >> Server waiting for log messages...