Ping Agent

import java.util.Date;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.OutputStreamWriter;

import jade.core.*;
import jade.core.behaviours.*;
import jade.lang.acl.ACLMessage;
import jade.domain.FIPAAgentManagement.ServiceDescription;
import jade.domain.FIPAAgentManagement.DFAgentDescription;
import jade.domain.DFService;
import jade.domain.FIPAException;

/**
   This agent implements a simple Ping Agent for the AgentCities project.
   First of all the agent registers itself with the DF of the platform and 
   then waits for ACLMessages.
   If  a QUERY_REF message arrives that contains the string "ping" within the content 
   then it replies with an INFORM message whose content will be the string "alive". 
   If it receives a NOT_UNDERSTOOD message no reply is sent. 
   For any other message received it replies with a NOT_UNDERSTOOD message.
   The exchanged message are written in a log file whose name is the local name of the agent.

   @author Tiziana Trucco - CSELT S.p.A.
   @version  $Date: 2002/01/31 09:58:40 $ $Revision: 1.4 $  
*/


public class PingAgent extends Agent {

  PrintWriter logFile;
  
  class WaitPingAndReplyBehaviour extends SimpleBehaviour {

    private boolean finished = false;
    
    public WaitPingAndReplyBehaviour(Agent a) {
      super(a);
    }

    public void action() {
      
      ACLMessage  msg = blockingReceive();
      
      if(msg != null){
        if(msg.getPerformative() == ACLMessage.NOT_UNDERSTOOD)
        {
          log("Received the following message: "+ msg.toString());
          log("No reply message sent.");
        }
        else{
          log("Received the following message: "+ msg.toString());
          ACLMessage reply = msg.createReply();
        
          //if((msg.getPerformative()== ACLMessage.QUERY_REF)||(msg.getPerformative()== ACLMessage.QUERY_IF))
          if(msg.getPerformative()== ACLMessage.QUERY_REF)
          {
            String content = msg.getContent();
            if ((content != null) && (content.indexOf("ping") != -1))
            {
              reply.setPerformative(ACLMessage.INFORM);
              //reply.setContent("(pong)");
              reply.setContent("alive");
            }
            else
            {
              reply.setPerformative(ACLMessage.NOT_UNDERSTOOD);
              reply.setContent("( UnexpectedContent (expected ping))");
            }
      
          }
          else
          {
            reply.setPerformative(ACLMessage.NOT_UNDERSTOOD);
            reply.setContent("( (Unexpected-act "+ACLMessage.getPerformative(msg.getPerformative())+") ( expected (query-ref :content ping)))");

          }
                  
          log("Replied with the following message: "+ reply.toString());
          send(reply);
        }
      }else{
        //System.out.println("No message received");
      }
    }
  
    public boolean done() {
      return finished;
    }
  } //End class WaitPingAndReplyBehaviour
    
  
  protected void setup() {
    
    /** Registration with the DF */
    DFAgentDescription dfd = new DFAgentDescription();
    ServiceDescription sd = new ServiceDescription();   
    sd.setType("AgentcitiesPingAgent"); 
    sd.setName(getName());
    sd.setOwnership("TILAB");
    //sd.addOntologies("PingAgent");
    dfd.setName(getAID());
    dfd.addServices(sd);
    try {
      DFService.register(this,dfd);
    } catch (FIPAException e) {
      System.err.println(getLocalName()+" registration with DF unsucceeded. Reason: "+e.getMessage());
      doDelete();
    }
      
    try{
      logFile = new PrintWriter(new FileWriter(getLocalName()+".txt",true));
      log("Agent: " + getName() + " born");
      WaitPingAndReplyBehaviour PingBehaviour = new  WaitPingAndReplyBehaviour(this);
      addBehaviour(PingBehaviour);
    }catch(IOException e){
      System.out.println("WARNING: The agent needs the "+ getLocalName()+".txt file.");
      e.printStackTrace();
    }
  }

  public synchronized void log(String str) {
        
    logFile.println((new Date()).toString()+ " - " + str);
    logFile.flush();
  }
    
}//end class PingAgent