jxta远程教学p2p技术

package server; import java.util.*; import java.io.*; import net.jxta.id.IDFactory; import net.jxta.pipe.InputPipe; import net.jxta.pipe.PipeMsgEvent; import net.jxta.pipe.PipeMsgListener; import net.jxta.credential.AuthenticationCredential; import net.jxta.document.StructuredDocument; import net.jxta.document.Document; import net.jxta.document.StructuredTextDocument; import net.jxta.document.MimeMediaType; import net.jxta.membership.Authenticator; import net.jxta.membership.MembershipService; import net.jxta.peergroup.PeerGroup; import net.jxta.peergroup.PeerGroupFactory; import net.jxta.exception.PeerGroupException; import net.jxta.exception.ProtocolNotSupportedException; import net.jxta.document.AdvertisementFactory; import net.jxta.document.MimeMediaType; import net.jxta.discovery.DiscoveryService; import net.jxta.discovery.DiscoveryListener; import net.jxta.discovery.DiscoveryEvent; import net.jxta.pipe.PipeService; import net.jxta.pipe.OutputPipe; import net.jxta.pipe.OutputPipeListener; import net.jxta.pipe.OutputPipeEvent; import net.jxta.protocol.DiscoveryResponseMsg; import net.jxta.protocol.PipeAdvertisement; import net.jxta.protocol.PeerGroupAdvertisement; import net.jxta.protocol.ModuleImplAdvertisement; import net.jxta.protocol.PeerAdvertisement; import net.jxta.protocol.ResolverQueryMsg; import net.jxta.protocol.ResolverResponseMsg; import net.jxta.resolver.ResolverService; import net.jxta.resolver.QueryHandler; import net.jxta.endpoint.Message; import net.jxta.endpoint.MessageElement; import net.jxta.document.Advertisement; import net.jxta.id.ID; import net.jxta.impl.protocol.ResolverResponse; import net.jxta.impl.protocol.ResolverQuery; /** * Encapsulates an Agent framework that handles communication between many * Student peers. Sends a series of questions to Student peers, and * processes their answers. Once completed, this Teacher peer will * recommend additional resources to the student for improvement * depending on the exam result. */ public class Teacher { public static final String DISTANCE_LEARNING = "DL:"; public static final String TEACHER_PIPE = "teacher_pipe"; public static final String ACTION_TAG = "tag"; public static final String CLIENT_NAME = "client"; public static final String COURSE_NAME = "course"; private PeerGroup netPeerGroup; private DiscoveryService discoverySvc; private PipeAdvertisement pipeAdv; private InputPipe inputPipe; private AgentFactory agentFactory = AgentFactory.getInstance(); // This Hashtable is used to store the agents used for individual students. private Hashtable agentTable = new Hashtable(); private void sendMessage(String clientName, Map map) throws IOException { for (;;) { Enumeration enum = discoverySvc.getLocalAdvertisements( DiscoveryService.ADV, "Name", Teacher.DISTANCE_LEARNING + clientName); while (enum.hasMoreElements()) { PipeAdvertisement pipeAdv = (PipeAdvertisement) enum.nextElement(); PipeService pipeSvc = netPeerGroup.getPipeService(); OutputPipe outputPipe = null; try { outputPipe = pipeSvc.createOutputPipe(pipeAdv, 1000); Message message = pipeSvc.createMessage(); Set keySet = map.keySet(); Iterator iterator = keySet.iterator(); while (iterator.hasNext()) { String key = (String) iterator.next(); String value = (String) map.get(key); MessageElement element = message.newMessageElement(key, new MimeMediaType( "text/plain"), new ByteArrayInputStream( value.getBytes())); message.addElement(element); } outputPipe.send(message); System.out.println("Sent message"); return; } catch (IOException io) { io.printStackTrace(); } finally { if (outputPipe != null) { outputPipe.close(); } } } // Need to look remotely. discoverySvc.getRemoteAdvertisements(null, DiscoveryService.ADV, "Name", Teacher.DISTANCE_LEARNING + clientName, 10, null); try { Thread.sleep(5 * 1000); // 5 sec too short if this is truly distant System.out.print("."); } catch (Exception ignore) { } } } /** * Publish our pipe advertisement. */ public void publishPipeAdv() throws IOException { PipeAdvertisement pipeAdv = null; String advType = PipeAdvertisement.getAdvertisementType(); pipeAdv = (PipeAdvertisement) AdvertisementFactory.newAdvertisement( advType); pipeAdv.setPipeID(IDFactory.newPipeID(netPeerGroup.getPeerGroupID())); pipeAdv.setName(DISTANCE_LEARNING + TEACHER_PIPE); pipeAdv.setType(PipeService.UnicastType); discoverySvc.publish(pipeAdv, DiscoveryService.ADV); discoverySvc.remotePublish(pipeAdv, DiscoveryService.ADV); this.pipeAdv = pipeAdv; } /** * Create an input pipe for inbound messages. */ public void createInputPipe() throws IOException { PipeService pipeSvc = netPeerGroup.getPipeService(); PipeMsgListener listener = new InputPipeMsgListener(); this.inputPipe = pipeSvc.createInputPipe(this.pipeAdv, listener); } /** * Start up the Net Peer group & get the Discovery Service for that group. */ public void startJxta() throws PeerGroupException, IOException { this.netPeerGroup = PeerGroupFactory.newNetPeerGroup(); this.discoverySvc = netPeerGroup.getDiscoveryService(); // Flush all local cache information. We want to start from scratch. discoverySvc.flushAdvertisements(null, DiscoveryService.ADV); discoverySvc.flushAdvertisements(null, DiscoveryService.PEER); discoverySvc.flushAdvertisements(null, DiscoveryService.GROUP); } /** * Create the Teacher and initiate the JXTA services. */ public static void main(String[] argc) throws Exception { Teacher teacher = new Teacher(); teacher.startJxta(); teacher.publishPipeAdv(); teacher.createInputPipe(); System.out.println("Ready to teach"); } /** * Handles the Student Teacher interactions. */ class InputPipeMsgListener implements PipeMsgListener { /** * Utility method to extract the value of a provided key * * @param message The Message to parse. * @param key The key to search for. */ private String getElementValue(Message message, String key) { if (!message.hasElement(key)) { return null; } MessageElement element = message.getElement(key); InputStream stream = element.getStream(); try { byte[] bytes = new byte[stre