org.jgroups.demos.QuoteServer Maven / Gradle / Ivy

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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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package org.jgroups.demos;


import org.jgroups.JChannel;
import org.jgroups.JChannel;
import org.jgroups.ReceiverAdapter;
import org.jgroups.View;
import org.jgroups.blocks.RpcDispatcher;
import org.jgroups.logging.Log;
import org.jgroups.logging.LogFactory;
import org.jgroups.util.Util;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.*;


/**
 * Example of a replicated quote server. The server maintains state which consists of a list
 * of quotes and their corresponding values. When it is started, it tries to reach other
 * quote servers to get its initial state. If it does not receive any response after 5
 * seconds, it assumes it is the first server and starts processing requests.
 * Any updates are multicast across the cluster
 * @author Bela Ban
 */

public class QuoteServer extends ReceiverAdapter {
    final Map stocks=new HashMap<>();
    JChannel channel;
    RpcDispatcher          disp;
    static final String    channel_name="Quotes";
    protected Log           log=LogFactory.getLog(getClass());

    static final String props=null; // default stack from JChannel

    private void integrate(HashMap state) {
        if(state != null)
            state.keySet().forEach(key -> stocks.put(key, state.get(key)));
    }

    public void viewAccepted(View new_view) {
        System.out.println("Accepted view (" + new_view.size() + new_view.getMembers() + ')');
    }



    public void start() {
        try {
            channel=new JChannel(props);
            disp=(RpcDispatcher)new RpcDispatcher(channel, this)
              .setMembershipListener(this).setStateListener(this);
            channel.connect(channel_name);
            System.out.println("\nQuote Server started at " + new Date());
            System.out.println("Joined channel '" + channel_name + "' (" + channel.getView().size() + " members)");
            channel.getState(null, 0);
            System.out.println("Ready to serve requests");
        }
        catch(Exception e) {
            log.error("QuoteServer.start() : " + e);
            System.exit(-1);
        }
    }

    /* Quote methods: */

    public float getQuote(String stock_name) throws Exception {
        System.out.print("Getting quote for " + stock_name + ": ");
        Float retval=stocks.get(stock_name);
        if(retval == null) {
            System.out.println("not found");
            throw new Exception("Stock " + stock_name + " not found");
        }
        System.out.println(retval.floatValue());
        return retval;
    }

    public void setQuote(String stock_name, Float value) {
        System.out.println("Setting quote for " + stock_name + ": " + value);
        stocks.put(stock_name, value);
    }

    public Map getAllStocks() {
        System.out.print("getAllStocks: ");
        printAllStocks();
        return stocks;
    }

    public void printAllStocks() {
        System.out.println(stocks);
    }

    public void getState(OutputStream ostream) throws Exception {
        Util.objectToStream(stocks, new DataOutputStream(ostream));
    }

    public void setState(InputStream istream) throws Exception {
        integrate((HashMap)Util.objectFromStream(new DataInputStream(istream)));
    }


    public static void main(String args[]) {
        try {
            QuoteServer server=new QuoteServer();
            server.start();
            while(true) {
                Util.sleep(10000);
            }
        }
        catch(Throwable t) {
            t.printStackTrace();
        }
    }

}