JADE ContractNet and GUI problems

Question

I have some problems with use of ContractNet (Interaction Protocol) and GUI with the use of JADE multiagent framework.

In particular, in the override of handlePropose method. I know that my problem comes from the use of a GUI. Let me explain:

My agent (Initiator) uses a first GUI and, after a click, the conversation begins with a second agent (Responder). According to the Protocol, the Initiator has thus sent a CFP to Responder. The agent Responder responds with a PROPOSE that contains different data.

Since here, everything ok. Now...

I wish that the agent Initiator, BEFORE returning a reply, may examine the data ... ie publish them on a JTable, for the user! The user will examine the proposal via GUI and will choose if to accept or not, by click on a button.

• If accept, the Initiator send ACCEPT_PROPOSAL.
• If not accept, the Initiator send REJECT_PROPOSAL.

This should be done in the method handleProposal. This is my code:

@Override
protected void handlePropose(final ACLMessage propose, final Vector acceptances) {
    try {
        System.out.println("Agent "+getLocalName()
            +": receive PROPOSE from "+propose.getSender().getLocalName());

        final ACLMessage reply = propose.createReply();

        Vector<Goods> goods = (Vector<Goods>) propose.getContentObject();

        // the JTable's GUI for visualize the list of data:
        final GoodsChoiceBox gcb = new GoodsChoiceBox(propose.getSender().getName(), goods);

        // the problem:
        gcb.getExecuteJButton().addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
               reply.setPerformative(ACLMessage.ACCEPT_PROPOSAL);
               System.out.println("Agent "+getLocalName()+": send ACCEPT PROPOSAL ");
               acceptances.addElement(reply);
            }
        });

        // similar case, but for REJECT:
        // gcb.getAbortJButton().addActionListener(... bla bla

        gcb.setVisible(true);

    } catch (UnreadableException e){
        e.printStackTrace();
    }
}

..... But, obviously, does not work.

In the Initiator agent, the ContractNet behaviour is aborted... so also handleInform, handleRefuse and handleFailure (for handle the answers) do not work. The Initiator's principal GUI is blocked. And other problems...

Instead, if I do this (WITHOUT JButton, another GUI and ActionListener):

@Override
protected void handlePropose(final ACLMessage propose, final Vector acceptances) {
    try {
        System.out.println("Agent "+getLocalName()
            +": received PROPOSE from "+propose.getSender().getLocalName());
        final ACLMessage reply = propose.createReply();

        Vector<Goods> goods = (Vector<Goods>) propose.getContentObject();

        // the JTable's GUI for visualize the list of data:
        final GoodsChoiceBox gcb = new GoodsChoiceBox(propose.getSender().getName(), goods);

        reply.setPerformative(ACLMessage.ACCEPT_PROPOSAL);
        System.out.println("Agente "+getLocalName()+": ACCEPT PROPOSAL di "+propose.getSender().getLocalName());
        acceptances.addElement(reply);

    } catch (UnreadableException e){
        e.printStackTrace();
    }
}

.... works.

I know that the problem is the ActionListener and its multithread nature. But I need the GUI there.

How can I fix?

Answer 1

I try to answer myself. I'm not sure it's the best solution, but certainly works.

Note that before coming to this solution I am well documented with the guides and tutorials found (on http://jade.tilab.com/), and confronting myself with other JADE developers (in mailing lists http://jade.tilab.com/pipermail/jade-develop/)

The answer is complicated, so I'll try to be exhaustive.

In my project I have to deal with two different types of agents.

• The ShipperAgent, which represents one shipper: it keeps track of the vehicles owned by the shipper, those available, and the goods "reserved" from it.

• The BuyerAgent, which represents customers (or buyers): each customer has a list of goods that want to move from point A to point B.

The two agents are registered to the yellow pages service.

In ShipperAgent, clicking on the "SEARCH" button you start a search: start a Contract Net Interaction Protocol.

---

Explain the Contract Net Interaction Protocol and my case

In the standard FIPA: http://www.fipa.org/specs/fipa00029/SC00029H.html

In JADE guide can be found here: http://jade.tilab.com/doc/programmersguide.pdf (p. 35)

Further on you will notice the changes that I had to take.

1. The ShipperAgent sends CFP each BuyerAgent.

2. Each BuyerAgent:

   2.1 if he has goods, send a PROPOSE to ShipperAgent.

   2.2 if does not have the goods, send a REFUSE to ShipperAgent. And for buyer, the protocol ends.

Since here is easy. With the sniffer, we can observe:

Now:

3. The ShipperAgent:

   3.1 receives one or more PROPOSE by buyers, and displays (see image below).

   3.2 if it receives the REFUSE (or does not receive anything after a certain time), ending communication with those buyer.

Here's how the Shipper graphically displays the proposals:

Now it's up to the user to choose which goods wants and what not.

To achieve this, I had to create some kind of "internal communication" to the agent himself: the GUI (in 3.1), once clicked Execute, sends a message to the agent. It may seem inelegant, but it seems to be the only way to not crash the protocol side ShipperAgent.

4. The ShipperAgent:

    4.1 if the user has selected one or more goods proposals (and click Execute), sends to the corresponding BuyerAgent an ACCEPT_PROPOSAL, where specific goods that want to (a subset of the previous proposal).

    4.2 if the user does not select any good (or click on Cancel), sends to the corresponding BuyerAgent an REJECT_PROPOSAL. Ends communication to that buyer.

5. The BuyerAgent:

    5.1 if receives an ACCEPT_PROPOSAL, check that the goods are still available (any other shippers could have them "reserved" in the meanwhile) and, if so, sends an INFORM.

   5.2 if receives an ACCEPT_PROPOSAL ma one or more goods are no longer available, sends FAILURE.

    5.3 if it receives an REJECT_PROPOSAL, ends communication with the ShipperAgent.

In brief this (for example):

---

The code

BuyerAgent.java I create a dispatcher who is always ready to receive the CFP. As soon as it receives and start protocol, buyer-side: start SearchJobResponder.

/*
 * ...
 */

final MessageTemplate template = MessageTemplate.and(
    MessageTemplate.MatchProtocol(FIPANames.InteractionProtocol.FIPA_CONTRACT_NET),
    MessageTemplate.MatchPerformative(ACLMessage.CFP) );

// SSResponderDispatcher:
SSResponderDispatcher dispatcher = new SSResponderDispatcher(this, template) {
    BuyerAgent b = (BuyerAgent) this.myAgent;
    protected Behaviour createResponder(ACLMessage initiationMsg) {
        // SearchJobResponder for single cfp:
        return new SearchJobResponder(b, initiationMsg);
    }
};

addBehaviour(dispatcher);

/*
 * ...
 */

ShipperAgent.java Search all buyer, creates a CFP and start the protocol, shipper-side: start SearchJobInitiator.

/*
 * ...
 */

ACLMessage cfp = new ACLMessage(ACLMessage.CFP);
AID[] buyerAgents = searchBuyers(); // search all buyerAgents
for (AID buyer : buyerAgents)
    cfp.addReceiver(buyer);
addBehaviour(new SearchJobInitiator(this, cfp));

/*
 * ...
 */

SearchJobInitiator.java This was the hard part...

/*
 * ...
 */

public class SearchJobInitiator extends ContractNetInitiator {
    ShipperAgent shipperAgent;

    public SearchJobInitiator(ShipperAgent a, ACLMessage cfp) {
        super(a, cfp);
        shipperAgent=a;
        // Very important:
        registerHandleAllResponses(new HandleProposes());
    }

    @Override
    protected Vector<?> prepareCfps(ACLMessage cfp) {

        long now = System.currentTimeMillis();

        cfp.setConversationId("contractNet-by-"
                +shipperAgent.getAID().getLocalName()+now);

        cfp.setContent("Fammi delle proposte di lavoro");

        /* 
         * filtering... 
         */

        cfp.setProtocol(FIPANames.InteractionProtocol.FIPA_CONTRACT_NET);

        cfp.setReplyByDate(new Date(now+10000));

        //cfp.setReplyWith("cfp"+System.currentTimeMillis()) //useless, is overwrited at the end

        return super.prepareCfps(cfp);
    }

    //inner class for handling a single proposal
    public class HandleProposes extends Behaviour {
        private static final long serialVersionUID = 1L;
        private Vector<ACLMessage> proposes;
        private Vector<ACLMessage> acceptances;
        private int numberOfProposes;

        public void onStart() {
            proposes = (Vector<ACLMessage>) getDataStore().get(ALL_RESPONSES_KEY);
            acceptances = (Vector<ACLMessage>) getDataStore().get(ALL_ACCEPTANCES_KEY);

            numberOfProposes=proposes.size();

            for (Iterator I=proposes.iterator(); I.hasNext();) {
                ACLMessage propose = (ACLMessage) I.next();

                // Very important:
                if (propose.getPerformative()==ACLMessage.PROPOSE)
                    myAgent.addBehaviour(new HandleSinglePropose(propose, acceptances));
                else
                    numberOfProposes--;
            }

        }

        public void action() {
            if (!done())
                block();
        }

        public boolean done() {
            return (acceptances.size()==numberOfProposes);
        }


        /*
         * Inner class for handle a single proposal and display it:
         */
        public class HandleSinglePropose extends Behaviour {
            private ACLMessage propose;
            private Vector<ACLMessage> acceptances;
            private boolean finish=false;

            public HandleSinglePropose (ACLMessage propose, Vector<ACLMessage> acceptances) {
                this.propose=propose;
                this.acceptances=acceptances;

                // This is GUI in 3.1 point
                GoodsChoiceBox gcb = new GoodsChoiceBox(shipperAgent, this, propose); // fill the JTable
                gcb.setVisible(true);
            }

            @Override
            public void action() {
                MessageTemplate mt = MessageTemplate.and(
                        MessageTemplate.MatchSender(shipperAgent.getAID()),
                        MessageTemplate.and(
                            MessageTemplate.MatchReplyWith("response"+propose.getReplyWith()),
                            MessageTemplate.or(
                                MessageTemplate.MatchPerformative(ACLMessage.ACCEPT_PROPOSAL),
                                MessageTemplate.MatchPerformative(ACLMessage.REJECT_PROPOSAL)
                ) ) ) ;

                // Read data from GUI. The user accept or reject:
                ACLMessage decisionFromGUI = shipperAgent.receive(mt);
                if (decisionFromGUI != null) {
                    ACLMessage reply = propose.createReply();
                    // bla bla...
                    finish=true;
                    HandleProposes.this.restart();
                } else {
                    block();
                }
            }

            public boolean done() {
                return finish;
            }


            public void handleChoice(ACLMessage propose, boolean bool, Vector<Goods> selectedGoods) {
                ACLMessage reply;
                if (bool){
                    reply = new ACLMessage(ACLMessage.ACCEPT_PROPOSAL);
                    //...
                } else {
                    reply = new ACLMessage(ACLMessage.REJECT_PROPOSAL);
                    //...
                }
                reply.addReceiver(shipperAgent.getAID());
                reply.setReplyWith("response"+propose.getReplyWith());
                shipperAgent.send(reply);
            }

        } // closes HandleSinglePropose

    } // closes HandleProposes

}

SearchJobResponder.java The responder is simple. The only thing of note: I extends SSContractNetResponder, don't extends ContractNetResponder.

public class SearchJobResponder extends SSContractNetResponder {
    BuyerAgent buyerAgent;

    public SearchJobResponder(BuyerAgent a, ACLMessage cfp) {
        super(a, cfp);
        buyerAgent = a;
    }

    /*
     * override methods...
     */
}

GoodsChoiceBox.java The GUI for show the proposals...

public GoodsChoiceBox(final Agent agent, final HandleSinglePropose behaviour, final ACLMessage propose){
    /*
     * graphics stuff
     */

    // if goods selected and press Execute
    behaviour.handleChoice(propose,true,selectedGoods);
    //else
    behaviour.handleChoice(propose,false,null); 

    /*
     * bla bla
     */
}

I know, I have dwelt much, but I did not know how else to explain. However, now my project work. But I'm open to any suggestions.

Answer 2

I often run into this problems of this sort. These are Finite State machine behaviours so you should be able to pause and resume a behavior but I'm not sure how. What I do is create two separate Interaction behaviors on the initiator side and one on the responder side.

Initiator                      Responder
|                                |
|                                |
| First behaviour                |The responder only has 1 behaviour
||        CFP->                 ||
||        <-Proposal            ||
|                               ||
| Second behaviour              ||
||        Accept prop->         ||
||        <-Response            ||
|                                |

Two points to remember

(1)

Make sure that you save the conversationID

msgRecieved.getConversationID

from the first behaviour and use it in the second Behaviour.

msg.setConversationID().

(2) The second behavior is another Contract net initiator but in prepareCFPs method set MESSAGE performative to accept proposal

class ContractServiceList extends ContractNetInitiator {

    protected Vector prepareCfps(ACLMessage cfp) {

        ACLmessage AP= new ACLmessage(ACLmessage.ACCEPT_PROPOSAL)
.....

These things are hard to explain so I tried to attached a picture but have 2 little rep points.

I now have enough rep points to attach the picture which I am doing.

Answer 3

I just realized that there is another solution to this problem. The second solution involves using ChildBehaviours and data stores. A child behaviour can be initiated pausing the parent behaviour. The parent behaviour must then be resumed one the child is complete.

I'm attaching a pic to better explain this interaction.

So at point A in your CNI (ContractNetInitiator) parent behaviour you want to initiate the Child behaviour. You would do this by using the CNI.registerHandlePropose(new Childbehaviour).

This is what the setup() method should look like:

 protected void setup()
{
  ContractNetInitiator parentBehave= new ContractNetInitiator (null, null, GlobDataStore);
  ContractNetInitiator.registerHandlePropose(new ChildBehavoiur (GlobDataStore));
  addBehaviour(CNI);    
}

In you Child behaviour you will have to check the data from the parent (GlobDataStore) and return a message to be passed back. Code to follow:

class ChildBehaviour extends OneShotBehaviour{

    @Override
    public void action() {
        //evaluate globalestore here;
        ACLMessage CNIresponse=new ACLMessage();

        if(true)
        {
            storeNotification(ACLMessage.ACCEPT_PROPOSAL, CNIresponse);
        }
        else
        {
            storeNotification(ACLMessage.REJECT_PROPOSAL, CNIresponse);
        }
    }



           public void storeNotification(int performative, ACLMessage original) 
      {                         
         // Retrieve the incoming request from the DataStore
         String incomingCFPkey = (String) ((ContractNetResponder) parent).CFP_KEY;
          incomingCFPkey = (String) ((ContractNetResponder) parent).CFP_KEY;

         ACLMessage incomingCFP = (ACLMessage) getDataStore().get(incomingCFPkey);
         // Prepare the notification to the request originator and store it in the DataStore
         ACLMessage notification = incomingCFP.createReply();
         notification.setPerformative(performative);
         notification.setContent(original.getContent());
         String notificationkey = (String) ((ContractNetResponder) parent).PROPOSE_KEY;
         getDataStore().put(notificationkey, notification);
      } 

    }