server/filter/UDPReader.java

//---PACKAGE DECLARATION---
package uk.ac.ukc.iscream.filter;

//---IMPORTS---
import java.io.*;
import java.net.*;
import java.util.*;
import uk.ac.ukc.iscream.core.*;
import uk.ac.ukc.iscream.componentmanager.*;
import uk.ac.ukc.iscream.filter.*;
import uk.ac.ukc.iscream.util.*;

/**
 * This class contains the main method to be run by
 * the filterd.  It harvests UDP traffic, and queues it.
 *
 * @author  $Author: tdb1 $
 * @version $Id: UDPReader.java,v 1.15 2001/02/01 00:18:42 tdb1 Exp $
 */
public class UDPReader extends Thread{

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.15 $";
    
    /**
     * The maximum size of a packet
     */
    private final int packetSizeLimit = 8192;   
    
//---STATIC METHODS---

//---CONSTRUCTORS---

    /**
     * Constructs a new UDPReader.
     *
     * @param port The port on which we listen for UDP data
     * @param queue The queue which we are using
     */
    public UDPReader(int port, Queue queue){
        // set the Thread name
        setName("filter.UDPReader");
        
        _port = port;
        _queue = queue;
        _logger.write(toString(), Logger.SYSINIT, "started");
    }

//---PUBLIC METHODS---
    
    /**
     * The main method in the class. Reads and queues XML sent
     * over UDP.
     */
    public void run() {
        
        // setup a Datagram socket
        DatagramSocket socket = null;
        try {
            socket = new DatagramSocket(_port);
        }
        catch (BindException e){
            _logger.write(this.toString(), Logger.FATAL, "Could not start the UDPReader thread on port "+_port+" as this port was already in use.");
            return;
        }
        catch (Exception e){
            _logger.write(this.toString(), Logger.FATAL, "Could not start the UDPReader thread on port "+_port+".");
            return;
        }
        
        _logger.write(this.toString(), Logger.SYSMSG, "UDPReader thread ready and listening for UDP packets on port "+_port);
        
        byte[] buf;
        
        // read UDP packets and queue them
        boolean running = true;
        while (running){
            try {
                
                // receive request and put it in the Queue               
                buf = new byte[packetSizeLimit];
                DatagramPacket packet = new DatagramPacket(buf, buf.length);
                socket.receive(packet);
                String xml = new String(packet.getData());
                _queue.add(xml);
            }
            catch (IOException e) {
                _logger.write(this.toString(), Logger.WARNING, "This UDPReader thread has been shut down as an exception occured: "+e);
                running = false;
            }
        }
        socket.close();
    }
    
    /**
     * Overrides the {@link java.lang.Object#toString() Object.toString()}
     * method to provide clean logging (every class should have this).
     *
     * This uses the uk.ac.ukc.iscream.util.NameFormat class
     * to format the toString()
     *
     * @return the name of this class and its CVS revision
     */
    public String toString() {
        return FormatName.getName(
            _name,
            getClass().getName(),
            REVISION);
    }

//---PRIVATE METHODS---

//---ACCESSOR/MUTATOR METHODS---

//---ATTRIBUTES---

    /**
     * This is the friendly identifier of the
     * component this class is running in.
     * eg, a Filter may be called "filter1",
     * If this class does not have an owning
     * component,  a name from the configuration
     * can be placed here.  This name could also
     * be changed to null for utility classes.
     */
    private String _name = FilterMain.NAME;
    
    /**
     * This holds a reference to the
     * system logger that is being used.
     */
    private Logger _logger = ReferenceManager.getInstance().getLogger();
    
    /**
     * The port that this reader is using
     */
    int _port;
    
    /**
     * The Queue object
     */
    Queue _queue;

//---STATIC ATTRIBUTES---

}
Revision:	1.16
Committed:	Tue Mar 13 02:19:46 2001 UTC (23 years, 2 months ago) by tdb
Branch:	MAIN
Changes since 1.15:	+5 -2 lines
Log Message:	Given all the classes that extend Thread a name using Thread.setName(). It is only representative as far as it will tell us which class the Thread is, but this will go some way to aiding debugging. If time permitted, more effort could be taken to name each thread according to what it was dealing with.
#	User	Rev	Content
1	tdb	1.6	//---PACKAGE DECLARATION---
2			package uk.ac.ukc.iscream.filter;
3
4			//---IMPORTS---
5	pjm2	1.1	import java.io.*;
6			import java.net.*;
7			import java.util.*;
8	tdb	1.2	import uk.ac.ukc.iscream.core.*;
9	tdb	1.13	import uk.ac.ukc.iscream.componentmanager.*;
10	tdb	1.2	import uk.ac.ukc.iscream.filter.*;
11	ajm	1.9	import uk.ac.ukc.iscream.util.*;
12	pjm2	1.1
13	tdb	1.6	/**
14			* This class contains the main method to be run by
15	tdb	1.14	* the filterd. It harvests UDP traffic, and queues it.
16	tdb	1.6	*
17	tdb	1.13	* @author $Author: tdb1 $
18	tdb	1.16	* @version $Id: UDPReader.java,v 1.15 2001/02/01 00:18:42 tdb1 Exp $
19	tdb	1.6	*/
20	pjm2	1.1	public class UDPReader extends Thread{
21
22	tdb	1.6	//---FINAL ATTRIBUTES---
23
24			/**
25			* The current CVS revision of this class
26			*/
27	tdb	1.16	public final String REVISION = "$Revision: 1.15 $";
28	tdb	1.15
29	ajm	1.11	/**
30			* The maximum size of a packet
31			*/
32			private final int packetSizeLimit = 8192;
33	tdb	1.6
34			//---STATIC METHODS---
35
36			//---CONSTRUCTORS---
37
38	ajm	1.10	/**
39	tdb	1.14	* Constructs a new UDPReader.
40			*
41			* @param port The port on which we listen for UDP data
42			* @param queue The queue which we are using
43	ajm	1.10	*/
44	tdb	1.12	public UDPReader(int port, Queue queue){
45	tdb	1.16	// set the Thread name
46			setName("filter.UDPReader");
47
48	tdb	1.8	_port = port;
49	tdb	1.12	_queue = queue;
50	tdb	1.15	_logger.write(toString(), Logger.SYSINIT, "started");
51	pjm2	1.1	}
52
53	tdb	1.6	//---PUBLIC METHODS---
54	tdb	1.14
55			/**
56			* The main method in the class. Reads and queues XML sent
57			* over UDP.
58			*/
59	pjm2	1.1	public void run() {
60	tdb	1.14
61			// setup a Datagram socket
62	pjm2	1.1	DatagramSocket socket = null;
63			try {
64	tdb	1.8	socket = new DatagramSocket(_port);
65	pjm2	1.1	}
66			catch (BindException e){
67	tdb	1.8	_logger.write(this.toString(), Logger.FATAL, "Could not start the UDPReader thread on port "+_port+" as this port was already in use.");
68	pjm2	1.1	return;
69			}
70			catch (Exception e){
71	tdb	1.8	_logger.write(this.toString(), Logger.FATAL, "Could not start the UDPReader thread on port "+_port+".");
72	pjm2	1.1	return;
73			}
74
75	tdb	1.8	_logger.write(this.toString(), Logger.SYSMSG, "UDPReader thread ready and listening for UDP packets on port "+_port);
76	tdb	1.15
77	pjm2	1.1	byte[] buf;
78
79	tdb	1.14	// read UDP packets and queue them
80	pjm2	1.1	boolean running = true;
81			while (running){
82			try {
83	tdb	1.15
84			// receive request and put it in the Queue
85	pjm2	1.1	buf = new byte[packetSizeLimit];
86			DatagramPacket packet = new DatagramPacket(buf, buf.length);
87			socket.receive(packet);
88	tdb	1.12	String xml = new String(packet.getData());
89			_queue.add(xml);
90	pjm2	1.1	}
91			catch (IOException e) {
92	tdb	1.8	_logger.write(this.toString(), Logger.WARNING, "This UDPReader thread has been shut down as an exception occured: "+e);
93	tdb	1.14	running = false;
94	pjm2	1.1	}
95			}
96			socket.close();
97			}
98	tdb	1.15
99	tdb	1.6	/**
100			* Overrides the {@link java.lang.Object#toString() Object.toString()}
101			* method to provide clean logging (every class should have this).
102			*
103	ajm	1.11	* This uses the uk.ac.ukc.iscream.util.NameFormat class
104			* to format the toString()
105			*
106	tdb	1.6	* @return the name of this class and its CVS revision
107			*/
108			public String toString() {
109	ajm	1.11	return FormatName.getName(
110			_name,
111			getClass().getName(),
112			REVISION);
113	tdb	1.6	}
114
115			//---PRIVATE METHODS---
116
117			//---ACCESSOR/MUTATOR METHODS---
118
119			//---ATTRIBUTES---
120
121	ajm	1.11	/**
122			* This is the friendly identifier of the
123			* component this class is running in.
124			* eg, a Filter may be called "filter1",
125			* If this class does not have an owning
126			* component, a name from the configuration
127			* can be placed here. This name could also
128			* be changed to null for utility classes.
129			*/
130			private String _name = FilterMain.NAME;
131	tdb	1.15
132	ajm	1.11	/**
133			* This holds a reference to the
134			* system logger that is being used.
135			*/
136			private Logger _logger = ReferenceManager.getInstance().getLogger();
137
138			/**
139			* The port that this reader is using
140			*/
141	tdb	1.8	int _port;
142	ajm	1.11
143			/**
144	tdb	1.12	* The Queue object
145	ajm	1.11	*/
146	tdb	1.15	Queue _queue;
147	tdb	1.6
148			//---STATIC ATTRIBUTES---
149
150	pjm2	1.1	}