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.
#	Content
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	}