server/XMLReader/UDPReader.java

import java.io.*;
import java.net.*;
import java.util.*;

// This class contains the main method to be run by
// the filter children.  It harvests UDP traffic
//
//
public class UDPReader {

    public static void main(String[] args) throws IOException {

        // default UDP listening port.
        int port = 4589;
        final int packetSizeLimit = 8192;

        // Allow the user to choose their own port number.
        if (args.length == 1){
            try {
                port = new Integer(args[0]).intValue();
            }
            catch (Exception e){
                // If something went wrong, use the default again.
                port = 4589;
            }
        }

        DatagramSocket socket = null;
        try {
            socket = new DatagramSocket(port);
        }
        catch (BindException e){
            System.out.println("Some other process is already listening on port "+port+".");
            System.out.println("Please specify another port number on the command line.");
            System.exit(0);
        }
        
        System.out.println("UDPReader ready and listening for UDP packets on port "+port);

        byte[] buf;
        UDPReaderThread t = new UDPReaderThread();
        
        boolean running = true;
        while (running){
            System.gc();
            try {
                buf = new byte[packetSizeLimit];
                // receive request
                DatagramPacket packet = new DatagramPacket(buf, buf.length);
                socket.receive(packet);
                t.run(packet);
            }
            catch (IOException e) {
                System.out.println("An exception occured in the UDPReader!");
                e.printStackTrace();
            }
        }
        socket.close();
    }
}
Revision:	1.4
Committed:	Fri Nov 17 20:44:31 2000 UTC (24 years ago) by pjm2
Branch:	MAIN
Changes since 1.3:	+6 -3 lines
Log Message:	UDPReader and UDPReaderThread have been altered to prevent a serious problem whereby the system ran out of free memory after a certain amount of UDP packets had been received. Testing with XMLSender2 has revealed that this problem has been solved. There is now little chance of the UDPReader rejecting packets as it queues each arrival straight to the UDPReaderThread, thus making "event storms" managable. In fact, the queuing nature may even assist in quenching such problems.
#	User	Rev	Content
1	pjm2	1.1	import java.io.*;
2			import java.net.*;
3			import java.util.*;
4
5			// This class contains the main method to be run by
6			// the filter children. It harvests UDP traffic
7			//
8			//
9			public class UDPReader {
10
11			public static void main(String[] args) throws IOException {
12
13	pjm2	1.2	// default UDP listening port.
14			int port = 4589;
15			final int packetSizeLimit = 8192;
16	pjm2	1.1
17	pjm2	1.2	// Allow the user to choose their own port number.
18			if (args.length == 1){
19			try {
20			port = new Integer(args[0]).intValue();
21			}
22			catch (Exception e){
23			// If something went wrong, use the default again.
24			port = 4589;
25			}
26			}
27
28	pjm2	1.3	DatagramSocket socket = null;
29			try {
30			socket = new DatagramSocket(port);
31			}
32			catch (BindException e){
33			System.out.println("Some other process is already listening on port "+port+".");
34			System.out.println("Please specify another port number on the command line.");
35			System.exit(0);
36			}
37
38	pjm2	1.2	System.out.println("UDPReader ready and listening for UDP packets on port "+port);
39
40	pjm2	1.4	byte[] buf;
41			UDPReaderThread t = new UDPReaderThread();
42
43	pjm2	1.2	boolean running = true;
44			while (running){
45	pjm2	1.4	System.gc();
46	pjm2	1.2	try {
47	pjm2	1.4	buf = new byte[packetSizeLimit];
48	pjm2	1.1	// receive request
49	pjm2	1.2	DatagramPacket packet = new DatagramPacket(buf, buf.length);
50			socket.receive(packet);
51	pjm2	1.4	t.run(packet);
52	pjm2	1.2	}
53			catch (IOException e) {
54			System.out.println("An exception occured in the UDPReader!");
55			e.printStackTrace();
56			}
57	pjm2	1.1	}
58			socket.close();
59			}
60			}