JADE agents - Exception message: Dispatcher error - Caused by: DispatcherException in remote site. No skeleton for object-id

Question

I'm attempting setup 2 agents(DFSearchAgent) and another agent that registers a service by type (DFRegisterAgent).

However, I cannot launch "peripheral container" or an extra container that hosts a 2nd agent.

Assumptions:

• Both containers are on the same machine therefore same IP & same port.
• JADE version 4.5.0
• Running virtualized Ubuntu on WSL (Windows)
• References: https://jade.tilab.com/documentation/examples/yellow-pages/ and https://jade.tilab.com/doc/tutorials/JADEAdmin/startJade.html

Initially, I launch DFSearchAgent and DFRegisterAgent in the same "MainController" using the JADE GUI options with steps: , right click, MainContainer, chose "Start New Agent", then selected DFSearchedAgent from the pre-packaged examples:

Console output:

INFO: ----------------------------------
    This is JADE 4.5.0 - revision 6825 of 23-05-2017 10:06:04
    downloaded in Open Source, under LGPL restrictions,
    at http://jade.tilab.com/
----------------------------------------
May 28, 2021 2:01:59 PM jade.imtp.leap.LEAPIMTPManager initialize
INFO: Listening for intra-platform commands on address:
- jicp://137.79.225.104:1099

May 28, 2021 2:02:00 PM jade.core.BaseService init
INFO: Service jade.core.management.AgentManagement initialized
May 28, 2021 2:02:00 PM jade.core.BaseService init
INFO: Service jade.core.messaging.Messaging initialized
May 28, 2021 2:02:00 PM jade.core.BaseService init
INFO: Service jade.core.resource.ResourceManagement initialized
May 28, 2021 2:02:00 PM jade.core.BaseService init
INFO: Service jade.core.mobility.AgentMobility initialized
May 28, 2021 2:02:00 PM jade.core.BaseService init
INFO: Service jade.core.event.Notification initialized
May 28, 2021 2:02:00 PM jade.mtp.http.HTTPServer <init>
INFO: HTTP-MTP Using XML parser com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser
May 28, 2021 2:02:00 PM jade.core.messaging.MessagingService boot
INFO: MTP addresses:
http://XYZ-064067.xyz.abc.gov:7778/acc
May 28, 2021 2:02:00 PM jade.core.AgentContainerImpl joinPlatform
INFO: --------------------------------------
Agent container Main-Container@137.79.225.104 is ready.
--------------------------------------------

Agent DFRegisterAgent registering service "unknown" of type "weather-forecast

I repeated the same steps for adding the DFSearchAgent , to the same MainContainer .

Console output (Search agent was able to find a registered agent. All is good):

Agent DFSearchAgent found the following weather-forecast services:
Service "unknown" provided by agent DFRegisterAgent@137.79.225.104:1099/JADE

Now to the problem...

If I re-attempt the above steps, however with two different containers 1 MainContainer and 1 peripheral, then I get an exception (DispatcherException in remote site. No skeleton for object-id).

Attempt #1 (Using 1 Main-Container, 1 Peripheral Container, same machine) Steps:

1. Remove DFSearchAgent & DFRegisterAgent from already running Main-Container

OR

Shut down old container & launch a new Main-Container via java jade.Boot -gui

2. Launch 2nd peripheral container via command line run:

   java jade.Boot -gui -container

OR provide agent at startup

java jade.Boot -gui -container provider:examples.yellowPages.DFRegisterAgent my-forecast

Exception from console:

Exception message: Dispatcher error - Caused by:  DispatcherException in remote site. No skeleton for object-id 15724561

Attempt 2 steps (using 2 Main-Containers, same machine, GUI commands):

Steps:

1. Using 2 different shell/command windows, run

Run in shell #1 java jade.Boot -gui

Snippet of 1st console out:

May 28, 2021 2:50:27 PM jade.core.Runtime beginContainer
INFO: ----------------------------------
    This is JADE 4.5.0 - revision 6825 of 23-05-2017 10:06:04
    downloaded in Open Source, under LGPL restrictions,
    at http://jade.tilab.com/
----------------------------------------
May 28, 2021 2:50:27 PM jade.imtp.leap.LEAPIMTPManager initialize
INFO: Listening for intra-platform commands on address:
- jicp://137.79.225.104:1099

Run in shell #2 java jade.Boot -gui

Snippet of 2st console out:

May 28, 2021 2:50:40 PM jade.core.Runtime beginContainer
INFO: ----------------------------------
    This is JADE 4.5.0 - revision 6825 of 23-05-2017 10:06:04
    downloaded in Open Source, under LGPL restrictions,
    at http://jade.tilab.com/
----------------------------------------
May 28, 2021 2:50:40 PM jade.imtp.leap.LEAPIMTPManager initialize
INFO: Listening for intra-platform commands on address:
- jicp://137.79.225.104:1099

Two GUIs were launched, and there are 2 main containers.

2. Using GUI add first DFRegisterAgent, then register DFSearchAgent.

1st Console:

Agent DFRegisterAgent registering service "unknown" of type "weather-forecast"

2nd Console:

Agent DFSearchAgent searching for services of type "weather-forecast" Agent DFSearchAgent did not find any weather-forecast service

Issue/Problem: Although there were not any exceptions, the search agent could not find a registered agent.

Attempt 3 steps (using 1 Main-Container & 1 peripheral container, same machine, shell commands):

Steps:

1. Launch the 1st Main-Container

   java jade.Boot -gui

Console ouput:

May 28, 2021 3:02:15 PM jade.core.Runtime beginContainer
INFO: ----------------------------------
    This is JADE 4.5.0 - revision 6825 of 23-05-2017 10:06:04
    downloaded in Open Source, under LGPL restrictions,
    at http://jade.tilab.com/
----------------------------------------
May 28, 2021 3:02:15 PM jade.imtp.leap.LEAPIMTPManager initialize
INFO: Listening for intra-platform commands on address:
- jicp://137.79.225.104:1099

2. In a new shell,attempt to launch 2nd peripheral container

   java jade.Boot -gui -container

Console output:

jade.core.IMTPException: jade.core.IMTPException occurred in remote container [Main container cannot reach newly starting node [Container-1, 179334, jicp://137.79.225.104:1099]: Dispatcher error - Caused by:  DispatcherException in remote site. No skeleton for object-id 179334]

Attempt 4 (via code):

I also attempt the same steps by setting up Java projects and instantiating the DFRegisterAgent and register (DFRegisterAgent in 1 MainContainer & instantiating the DFSearchAgent and register DFSearchAgent in 2 MainContainer.

Register the DFRegisterAgent:

package com.example.yellowpages;
import jade.util.leap.*; 
import jade.core.Profile;
import jade.core.ProfileImpl;
import jade.wrapper.*;
/**
 * Hello world!
 */
public final class App {
    private App() {
    }

    /**
     * Says hello to the world.
     * @param args The arguments of the program.
     */
    public static void main(String[] args) {
        System.out.println( "Start test..." );
        Properties pp = new Properties();
        pp.setProperty(Profile.GUI, Boolean.TRUE.toString());
        Profile p = new ProfileImpl(pp);
        jade.wrapper.AgentContainer ac = jade.core.Runtime.instance().createMainContainer(p);
        try {
            ac.acceptNewAgent("DFRegisterAgent",new DFRegisterAgent()).start();
            
        } catch (StaleProxyException e) {
            throw new Error(e);
        }
        System.out.println( "Test is complete..." );
    }
}

Register DFSearchAgent:

    package com.example.yellowpages;
    import jade.util.leap.*; 
    import jade.core.Profile;
    import jade.core.ProfileImpl;
    import jade.wrapper.*;
    /**
     * Hello world!
     */
    public final class App {
        private App() {
        }
    
        /**
         * Says hello to the world.
         * @param args The arguments of the program.
         */
        public static void main(String[] args) {
            System.out.println( "Start test..." );
            Properties pp = new Properties();
            pp.setProperty(Profile.GUI, Boolean.TRUE.toString());
            Profile p = new ProfileImpl(pp);
            jade.wrapper.AgentContainer ac = jade.core.Runtime.instance().createMainContainer(p);
            try {
                ac.acceptNewAgent("DFSearchAgent",new DFSearchAgent()).start();
                ac.acceptNewAgent("DFSubscribeAgent",new DFSubscribeAgent()).start();
                
            } catch (StaleProxyException e) {
                throw new Error(e);
            }
            System.out.println( "Test is complete..." );
        
}
}

I ran 2 programs, in 2 separate shell windows (1st ran the DFRegisterAgent, then the DFSearchAgent) using:

java -cp target/demo-1.jar com.example.yellowpages.App

1st console output snippet:

Agent container Main-Container@137.79.225.104 is ready.
--------------------------------------------
Test is complete...
Agent DFRegisterAgent registering service "unknown" of type "weather-forecast"

2nd console output snippet:

INFO: --------------------------------------
Agent container Main-Container@137.79.225.104 is ready.
--------------------------------------------
Agent DFSearchAgent searching for services of type "weather-forecast"
Test is complete...
Agent DFSearchAgent did not find any weather-forecast service

Looking at the GUI, both agents were registered.

The agents cannot see each other, when the agents are registered in separate containers & I cannot launch a peripheral container as a workaround.

How can I fix the search agent to find a registered agent?

Appreciated.

Answer 1

The error you report occurs when you launch a peripheral container without a main already active. Be sure your main is up and running before starting the peripheral container with the search agent on top.

Bye,

Giovanni