server/clientinterface/CorbaControlHandlerServant.java

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

//---IMPORTS---
import uk.ac.ukc.iscream.util.*;
import uk.ac.ukc.iscream.componentmanager.*;
import uk.ac.ukc.iscream.core.*;
import uk.ac.ukc.iscream.client.*;


/**
 * Acts as a Handler to a CORBA based client.
 *
 * !!! FUNDAMENTAL DESIGN PROBLEM !!!
 * !!! Need a way to "shutdown" this class !!!
 *
 * @author  $Author$
 * @version $Id$
 */
class CorbaHandlerServant extends Thread implements CorbaHandlerOperations {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public final String REVISION = "$Revision: 1.1 $";
    
//---STATIC METHODS---

//---CONSTRUCTORS---
    
    /**
     * Construct a new CorbaHandlerServant.
     *
     * @param packetSorter A reference to the PacketSorter in the component
     * @param name The name of the client
     * @param client A reference to the "servant" part of the connecting client.
     */
    public CorbaHandlerServant(PacketSorter packetSorter, String name, Client client) {
        _packetSorter = packetSorter;
        _clientName = name;
        _hostList = "";
        _queue = new Queue();
        _client = client;
        _logger.write(toString(), Logger.SYSINIT, "created");
    }
    
//---PUBLIC METHODS---
    
    /**
     * This method loops round until we "shutdown" (not implemented yet). Inside
     * the main loop we will first wait until the startData() method is called,
     * then we'll send data constantly until stopData() is called.
     */
    public void run() {
        // get a queue
        _queueID = _queue.getQueue();
        // we'll keep going until someone implements a "shutdown" :)
        run = true;
        while(run) {
            // initially lock until someone tells us to start
            synchronized(this) {
                try { wait(); } catch(Exception e) {}
            }
            // loop sending data
            while(_sendingData) {
                try {
                    String xml = (String) _queue.get(_queueID);
                    // if it's not null (which could happen if we're "released")
                    // send it on to the client that we're connected to.
                    if(xml != null) {
                        _client.receiveXML(xml);
                    }
                }
                catch(InvalidQueueException e) {
                    // lets stop sending - maybe stop altogether ?
                    stopData();
                    _logger.write(toString(), Logger.ERROR, "Queue failure: "+e);
                }
            }
            // now, we've obviously been stopped, so we'll head back round this
            // while loop until someone starts us again.
        }
        // if we get here we've been told to stop
        _logger.write(toString(), Logger.SYSMSG, "Shutting Down");
        // remove ourselves from the queue
        _queue.removeQueue(_queueID);
    }
    
    /**
     * Start sending data to the client.
     *
     * @return a boolean stating whether the attempt to start succeeded
     */
    public boolean startData() {
        if(!_sendingData) {
            // register the Queue
            _packetSorter.register(_queue, _hostList);
            // mark the running flag
            _sendingData = true;
            // bump the loop
            synchronized(this) {
                try { notifyAll(); } catch(Exception e) {}
            }
            return true;
        }
        else {
            return false;
        }
    }
    
    /**
     * Stop sending data to the client.
     *
     * @return a boolean stating whether the attempt to stop succeeded
     */
    public boolean stopData() {
        if(_sendingData) {
            // deregister the Queue
            _packetSorter.deregister(_queue, _hostList);
            // stop ourselves running
            _sendingData = false;
            // if the main loop is waiting for data it won't notice the
            // above flag to stop. This bumps it out of the blocked get().
            _queue.releaseQueue(_queueID);
            return true;
        }
        else {
            return false;
        }
    }
    
    /**
     * Sets the host list for the Client to the requested semi-colon separated
     * list of hostnames. This will only succeed if we are not sending data.
     *
     * @param hostList A semi-colon separated list of hostnames to use.
     * @return Whether the request succeeded.
     */
    public boolean setHostList(String hostList) {
        if(!_sendingData) {
            _hostList = hostList;
            return true;
        }
        else {
            return false;
        }
    }
    
    /**
     * 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 = ClientInterfaceMain.NAME;
    
    /**
     * This holds a reference to the
     * system logger that is being used.
     */
    private Logger _logger = ReferenceManager.getInstance().getLogger();
    
    /**
     * A reference to the Configuration Manager the system is using
     */
    private ConfigurationManager _configManager = ReferenceManager.getInstance().getCM();
    
    /**
         * A reference to the PacketSorter.
         */
    private PacketSorter _packetSorter;
    
    /**
     * The host list the Client has requested
     */
    private String _hostList;
    
    /**
     * The name of the connected client.
     */
    private String _clientName;
    
    /**
     * Whether we are active and sending data.
     */
    private boolean _sendingData;
    
    /**
     * The Queue we'll use for buffering data to the client.
     */
    private Queue _queue;
    
    /**
     * The "servant" part of the client we're connected to.
     */
    private Client _client;
    
    /**
     * Our queue number within our Queue
     */
    private int _queueID;
    
    /**
     * The flag that dictates whether the main loop should *completely* exit
     */
    private boolean run;
    
//---STATIC ATTRIBUTES---

}
Revision:	1.1
Committed:	Sat Feb 3 00:42:54 2001 UTC (23 years, 3 months ago) by tdb
Branch:	MAIN
Log Message:	Initial checkins of the two files that handle connections from CORBA based clients (most likely local clients). The Listener is essentially a "factory" for the Handler class. There is a single Handler associated with each connected client.
#	User	Rev	Content
1	tdb	1.1	//---PACKAGE DECLARATION---
2			package uk.ac.ukc.iscream.clientinterface;
3
4			//---IMPORTS---
5			import uk.ac.ukc.iscream.util.*;
6			import uk.ac.ukc.iscream.componentmanager.*;
7			import uk.ac.ukc.iscream.core.*;
8			import uk.ac.ukc.iscream.client.*;
9
10
11			/**
12			* Acts as a Handler to a CORBA based client.
13			*
14			* !!! FUNDAMENTAL DESIGN PROBLEM !!!
15			* !!! Need a way to "shutdown" this class !!!
16			*
17			* @author $Author$
18			* @version $Id$
19			*/
20			class CorbaHandlerServant extends Thread implements CorbaHandlerOperations {
21
22			//---FINAL ATTRIBUTES---
23
24			/**
25			* The current CVS revision of this class
26			*/
27			public final String REVISION = "$Revision: 1.1 $";
28
29			//---STATIC METHODS---
30
31			//---CONSTRUCTORS---
32
33			/**
34			* Construct a new CorbaHandlerServant.
35			*
36			* @param packetSorter A reference to the PacketSorter in the component
37			* @param name The name of the client
38			* @param client A reference to the "servant" part of the connecting client.
39			*/
40			public CorbaHandlerServant(PacketSorter packetSorter, String name, Client client) {
41			_packetSorter = packetSorter;
42			_clientName = name;
43			_hostList = "";
44			_queue = new Queue();
45			_client = client;
46			_logger.write(toString(), Logger.SYSINIT, "created");
47			}
48
49			//---PUBLIC METHODS---
50
51			/**
52			* This method loops round until we "shutdown" (not implemented yet). Inside
53			* the main loop we will first wait until the startData() method is called,
54			* then we'll send data constantly until stopData() is called.
55			*/
56			public void run() {
57			// get a queue
58			_queueID = _queue.getQueue();
59			// we'll keep going until someone implements a "shutdown" :)
60			run = true;
61			while(run) {
62			// initially lock until someone tells us to start
63			synchronized(this) {
64			try { wait(); } catch(Exception e) {}
65			}
66			// loop sending data
67			while(_sendingData) {
68			try {
69			String xml = (String) _queue.get(_queueID);
70			// if it's not null (which could happen if we're "released")
71			// send it on to the client that we're connected to.
72			if(xml != null) {
73			_client.receiveXML(xml);
74			}
75			}
76			catch(InvalidQueueException e) {
77			// lets stop sending - maybe stop altogether ?
78			stopData();
79			_logger.write(toString(), Logger.ERROR, "Queue failure: "+e);
80			}
81			}
82			// now, we've obviously been stopped, so we'll head back round this
83			// while loop until someone starts us again.
84			}
85			// if we get here we've been told to stop
86			_logger.write(toString(), Logger.SYSMSG, "Shutting Down");
87			// remove ourselves from the queue
88			_queue.removeQueue(_queueID);
89			}
90
91			/**
92			* Start sending data to the client.
93			*
94			* @return a boolean stating whether the attempt to start succeeded
95			*/
96			public boolean startData() {
97			if(!_sendingData) {
98			// register the Queue
99			_packetSorter.register(_queue, _hostList);
100			// mark the running flag
101			_sendingData = true;
102			// bump the loop
103			synchronized(this) {
104			try { notifyAll(); } catch(Exception e) {}
105			}
106			return true;
107			}
108			else {
109			return false;
110			}
111			}
112
113			/**
114			* Stop sending data to the client.
115			*
116			* @return a boolean stating whether the attempt to stop succeeded
117			*/
118			public boolean stopData() {
119			if(_sendingData) {
120			// deregister the Queue
121			_packetSorter.deregister(_queue, _hostList);
122			// stop ourselves running
123			_sendingData = false;
124			// if the main loop is waiting for data it won't notice the
125			// above flag to stop. This bumps it out of the blocked get().
126			_queue.releaseQueue(_queueID);
127			return true;
128			}
129			else {
130			return false;
131			}
132			}
133
134			/**
135			* Sets the host list for the Client to the requested semi-colon separated
136			* list of hostnames. This will only succeed if we are not sending data.
137			*
138			* @param hostList A semi-colon separated list of hostnames to use.
139			* @return Whether the request succeeded.
140			*/
141			public boolean setHostList(String hostList) {
142			if(!_sendingData) {
143			_hostList = hostList;
144			return true;
145			}
146			else {
147			return false;
148			}
149			}
150
151			/**
152			* Overrides the {@link java.lang.Object#toString() Object.toString()}
153			* method to provide clean logging (every class should have this).
154			*
155			* This uses the uk.ac.ukc.iscream.util.NameFormat class
156			* to format the toString()
157			*
158			* @return the name of this class and its CVS revision
159			*/
160			public String toString() {
161			return FormatName.getName(
162			_name,
163			getClass().getName(),
164			REVISION);
165			}
166
167			//---PRIVATE METHODS---
168
169			//---ACCESSOR/MUTATOR METHODS---
170
171			//---ATTRIBUTES---
172
173			/**
174			* This is the friendly identifier of the
175			* component this class is running in.
176			* eg, a Filter may be called "filter1",
177			* If this class does not have an owning
178			* component, a name from the configuration
179			* can be placed here. This name could also
180			* be changed to null for utility classes.
181			*/
182			private String _name = ClientInterfaceMain.NAME;
183
184			/**
185			* This holds a reference to the
186			* system logger that is being used.
187			*/
188			private Logger _logger = ReferenceManager.getInstance().getLogger();
189
190			/**
191			* A reference to the Configuration Manager the system is using
192			*/
193			private ConfigurationManager _configManager = ReferenceManager.getInstance().getCM();
194
195			/**
196			* A reference to the PacketSorter.
197			*/
198			private PacketSorter _packetSorter;
199
200			/**
201			* The host list the Client has requested
202			*/
203			private String _hostList;
204
205			/**
206			* The name of the connected client.
207			*/
208			private String _clientName;
209
210			/**
211			* Whether we are active and sending data.
212			*/
213			private boolean _sendingData;
214
215			/**
216			* The Queue we'll use for buffering data to the client.
217			*/
218			private Queue _queue;
219
220			/**
221			* The "servant" part of the client we're connected to.
222			*/
223			private Client _client;
224
225			/**
226			* Our queue number within our Queue
227			*/
228			private int _queueID;
229
230			/**
231			* The flag that dictates whether the main loop should completely exit
232			*/
233			private boolean run;
234
235			//---STATIC ATTRIBUTES---
236
237			}