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 1.13 2001/01/18 23:16:21 tdb1 Exp $
 */
public class UDPReader extends Thread{

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.13 $";

    /**
     * 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){
        _port = port;
        _queue = queue;
    }

//---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:	1.14
Committed:	Sun Jan 28 05:34:38 2001 UTC (23 years, 4 months ago) by tdb
Branch:	MAIN
Changes since 1.13:	+16 -8 lines
Log Message:	Some tidying up.
#	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	1.14	* @version $Id: UDPReader.java,v 1.13 2001/01/18 23:16:21 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	1.14	public final String REVISION = "$Revision: 1.13 $";
28	ajm	1.11
29			/**
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	1.8	_port = port;
46	tdb	1.12	_queue = queue;
47	pjm2	1.1	}
48
49	tdb	1.6	//---PUBLIC METHODS---
50	tdb	1.14
51			/**
52			* The main method in the class. Reads and queues XML sent
53			* over UDP.
54			*/
55	pjm2	1.1	public void run() {
56	tdb	1.14
57			// setup a Datagram socket
58	pjm2	1.1	DatagramSocket socket = null;
59			try {
60	tdb	1.8	socket = new DatagramSocket(_port);
61	pjm2	1.1	}
62			catch (BindException e){
63	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.");
64	pjm2	1.1	return;
65			}
66			catch (Exception e){
67	tdb	1.8	_logger.write(this.toString(), Logger.FATAL, "Could not start the UDPReader thread on port "+_port+".");
68	pjm2	1.1	return;
69			}
70
71	tdb	1.8	_logger.write(this.toString(), Logger.SYSMSG, "UDPReader thread ready and listening for UDP packets on port "+_port);
72	pjm2	1.1
73			byte[] buf;
74
75	tdb	1.14	// read UDP packets and queue them
76	pjm2	1.1	boolean running = true;
77			while (running){
78			try {
79	pjm2	1.3
80	tdb	1.12	// receive request and put it in the Queue
81	pjm2	1.1	buf = new byte[packetSizeLimit];
82			DatagramPacket packet = new DatagramPacket(buf, buf.length);
83			socket.receive(packet);
84	tdb	1.12	String xml = new String(packet.getData());
85			_queue.add(xml);
86	pjm2	1.1	}
87			catch (IOException e) {
88	tdb	1.8	_logger.write(this.toString(), Logger.WARNING, "This UDPReader thread has been shut down as an exception occured: "+e);
89	tdb	1.14	running = false;
90	pjm2	1.1	}
91			}
92			socket.close();
93			}
94	tdb	1.6
95			/**
96			* Overrides the {@link java.lang.Object#toString() Object.toString()}
97			* method to provide clean logging (every class should have this).
98			*
99	ajm	1.11	* This uses the uk.ac.ukc.iscream.util.NameFormat class
100			* to format the toString()
101			*
102	tdb	1.6	* @return the name of this class and its CVS revision
103			*/
104			public String toString() {
105	ajm	1.11	return FormatName.getName(
106			_name,
107			getClass().getName(),
108			REVISION);
109	tdb	1.6	}
110
111			//---PRIVATE METHODS---
112
113			//---ACCESSOR/MUTATOR METHODS---
114
115			//---ATTRIBUTES---
116
117	ajm	1.11	/**
118			* This is the friendly identifier of the
119			* component this class is running in.
120			* eg, a Filter may be called "filter1",
121			* If this class does not have an owning
122			* component, a name from the configuration
123			* can be placed here. This name could also
124			* be changed to null for utility classes.
125			*/
126			private String _name = FilterMain.NAME;
127
128			/**
129			* This holds a reference to the
130			* system logger that is being used.
131			*/
132			private Logger _logger = ReferenceManager.getInstance().getLogger();
133
134			/**
135			* The port that this reader is using
136			*/
137	tdb	1.8	int _port;
138	ajm	1.11
139			/**
140	tdb	1.12	* The Queue object
141	ajm	1.11	*/
142	tdb	1.12	Queue _queue;
143	tdb	1.6
144			//---STATIC ATTRIBUTES---
145
146	pjm2	1.1	}