Contents of /experimental/agents/PeerHandler.java

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Revision 1.2 - (show annotations)
Sun May 6 19:01:48 2001 UTC (9 years, 4 months ago) by ajm
Branch: MAIN
CVS Tags: HEAD
Changes since 1.1: +62 -58 lines 
Now has some VERY crude byte code passing mechanisms in place.

Currently it does it a very silly and non standard way, this will change.  But hey, it works ;p
1 //---PACKAGE DECLARATION---
2
3 //---IMPORTS---
4 import java.io.ObjectInputStream;
5 import java.io.ObjectOutputStream;
6 import java.io.PrintWriter;
7 import java.io.BufferedReader;
8 import java.io.InputStreamReader;
9 import java.io.IOException;
10 import java.net.Socket;
11
12 /**
13 * Handles communication between this agent station and a peer
14 * agent stations.
15 *
16 * @author $Author: ajm $
17 * @version $Id: PeerHandler.java,v 1.2 2001/05/06 19:01:48 ajm Exp $
18 */
19 class PeerHandler extends Handler {
20
21 //---FINAL / FINAL STATIC ATTRIBUTES---
22
23 /**
24 * The current CVS revision of this class
25 */
26 public static final String REVISION = "$Revision: 1.2 $";
27
28 //---STATIC METHODS---
29
30 //---CONSTRUCTORS---
31
32 public PeerHandler(Socket socket) throws IOException {
33 super(socket);
34 // setup reader & writer
35 _objectOut = new ObjectOutputStream(_socket.getOutputStream());
36 _objectIn = new ObjectInputStream(_socket.getInputStream());
37 _logger.write(toString(), Logger.SYSINIT, "created");
38 }
39
40 //---PUBLIC METHODS---
41
42 public void run() {
43 _logger.write(toString(), Logger.SYSINIT, "started");
44 try {
45
46 while(_running) {
47 // VERY basic protocol, only allow sending of agents ;-)
48 try {
49 String message = (String) _objectIn.readObject();
50 if (message.equals("SENDAGENT")) {
51 receiveAgent();
52 } else {
53 _logger.write(toString(), Logger.ERROR, "protocol error expected: SENDAGENT got: " + message);
54 }
55 } catch (ClassNotFoundException e) {
56 _logger.write(toString(), Logger.ERROR, "object protocol error expected: a String got: a " + e.getMessage());
57 }
58 }
59
60 } catch (IOException e) {
61 _logger.write(toString(), Logger.ERROR, "I/O ERROR - " + e);
62 }
63
64 shutdownSocket();
65 AgentStation.getInstance().removePeer(this);
66 _logger.write(toString(), Logger.SYSMSG, "finished");
67 }
68
69 public boolean sendAgent(Agent agent) {
70 boolean result = false;
71 _logger.write(toString(), Logger.SYSMSG, "starting agent transfer - outbound");
72 try {
73 // VERY basic protocol, only allow sending of agents ;-)
74
75 // INCOMPLETE - infact it needs to create a second socket as I don't believe multiple
76 // stream types (ie, objectstream and printwriter) can be used together
77 // needs investigating
78
79 _objectOut.writeObject("SENDAGENT");
80 _objectOut.flush();
81
82 // send agent bytecode
83
84 // TODO - very dodgy and crude at the moment.
85 AgentClassLoader cl = new AgentClassLoader(ClassLoader.getSystemClassLoader());
86
87 // send the super class
88 byte[] byteCode = cl.getBytecode(agent.getClass().getSuperclass().getName());
89 _objectOut.writeInt(byteCode.length);
90 _objectOut.flush();
91 _objectOut.write(byteCode);
92 _objectOut.flush();
93
94 // send the agent
95 byteCode = cl.getBytecode(agent.getClass().getName());
96 _objectOut.writeInt(byteCode.length);
97 _objectOut.flush();
98 _objectOut.write(byteCode);
99 _objectOut.flush();
100
101 // send agent state (serialized object)
102
103 AgentStation.getInstance().removeAgent(agent);
104 _objectOut.writeObject(agent);
105 _objectOut.flush();
106
107 _logger.write(toString(), Logger.SYSMSG, "agent sent");
108 result = true;
109 } catch (IOException e) {
110 _logger.write(toString(), Logger.ERROR, "I/O ERROR - " + e);
111 }
112 return result;
113 }
114
115 /**
116 * Used to shutdown this thread
117 */
118 public void shutdown() {
119 _running = false;
120 }
121
122 /**
123 * Overrides the {@link java.lang.Object#toString() Object.toString()}
124 * method to provide clean logging (every class should have this).
125 *
126 * This uses the uk.ac.ukc.iscream.util.FormatName class
127 * to format the toString()
128 *
129 * @return the name of this class and its CVS revision
130 */
131 public String toString() {
132 return FormatName.getName(
133 _name,
134 getClass().getName(),
135 REVISION);
136 }
137
138 //---PRIVATE/PROTECTED METHODS---
139
140 /**
141 * Carry out functions to receive an Agent
142 * NOTE - duplicated code in DirectAgentHandler, solution? -
143 *
144 * @throws IOException on I/O error
145 */
146 private void receiveAgent() throws IOException {
147 _logger.write(toString(), Logger.SYSMSG, "starting agent transfer - inbound");
148 try {
149 // TODO - very crude
150 // receive agent bytecode
151 AgentClassLoader cl = new AgentClassLoader(ClassLoader.getSystemClassLoader());
152
153 // first the super class
154 int givenLength = _objectIn.readInt();
155 byte[] byteCode = new byte[givenLength];
156 _objectIn.readFully(byteCode);
157 cl.defineAgentClass(byteCode);
158
159 // then the agent
160
161 givenLength = _objectIn.readInt();
162 byteCode = new byte[givenLength];
163 _objectIn.readFully(byteCode);
164 cl.defineAgentClass(byteCode);
165
166
167 // receive agent state (serialized object)
168 Agent agent = (Agent) _objectIn.readObject();
169 AgentStation.getInstance().addAgent(agent);
170
171 _logger.write(toString(), Logger.DEBUG, "Agent state received");
172 _logger.write(toString(), Logger.SYSMSG, "Agent name - " + agent.getName());
173 _logger.write(toString(), Logger.DEBUG, agent.getName() + "'s transmission count - " + agent.getTransmissionCount());
174
175 _logger.write(toString(), Logger.SYSMSG, "Welcoming agent");
176 agent.onArrival(AgentStation.getInstance());
177
178 _logger.write(toString(), Logger.SYSMSG, "Starting agent thread");
179
180 Thread thread = new Thread(agent);
181 thread.start();
182
183 _logger.write(toString(), Logger.SYSMSG, "agent received");
184
185 } catch (ClassNotFoundException e) {
186 _logger.write(toString(), Logger.ERROR, "ERROR - possible error transferring agent bytecode - " + e);
187 }
188 }
189
190 //---ACCESSOR/MUTATOR METHODS---
191
192 //---ATTRIBUTES---
193
194 /**
195 * This is the friendly identifier of the
196 * component this class is running in.
197 * eg, a Filter may be called "filter1",
198 * If this class does not have an owning
199 * component, a name from the configuration
200 * can be placed here. This name could also
201 * be changed to null for utility classes.
202 */
203 private String _name = "PeerHandler";
204
205 /**
206 * This holds a reference to the
207 * system logger that is being used.
208 */
209 private Logger _logger = Logger.getInstance();
210
211 /**
212 * A "running" used by the main loop in the run() method to determine if
213 * it should continue running this thread.
214 */
215 private boolean _running = true;
216
217 /**
218 * Used for the input stream of this socket
219 */
220 private ObjectInputStream _objectIn;
221
222 /**
223 * Used for the output stream of this socket
224 */
225 private ObjectOutputStream _objectOut;
226
227 //---STATIC ATTRIBUTES---
228
229 }
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