import org.zeromq.ZContext;
import org.zeromq.ZFrame;
import org.zeromq.ZMQ;
import org.zeromq.ZMQ.Socket;
import org.zeromq.ZThread;
import org.zeromq.ZThread.IAttachedRunnable;
import java.util.Random;
// Espresso Pattern
// This shows how to capture data using a pub-sub proxy
public class espresso
{
// The subscriber thread requests messages starting with
// A and B, then reads and counts incoming messages.
private static class Subscriber implements IAttachedRunnable
{
@Override
public void run(Object[] args, ZContext ctx, Socket pipe)
{
// Subscribe to "A" and "B"
Socket subscriber = ctx.createSocket(ZMQ.SUB);
subscriber.connect("tcp://localhost:6001");
subscriber.subscribe("A".getBytes());
subscriber.subscribe("B".getBytes());
int count = 0;
while (count < 5) {
String string = subscriber.recvStr();
if (string == null)
break; // Interrupted
count++;
}
ctx.destroySocket(subscriber);
}
}
// .split publisher thread
// The publisher sends random messages starting with A-J:
private static class Publisher implements IAttachedRunnable
{
@Override
public void run(Object[] args, ZContext ctx, Socket pipe)
{
Socket publisher = ctx.createSocket(ZMQ.PUB);
publisher.bind("tcp://*:6000");
Random rand = new Random(System.currentTimeMillis());
while (!Thread.currentThread().isInterrupted()) {
String string = String.format("%c-%05d", 'A' + rand.nextInt(10), rand.nextInt(100000));
if (!publisher.send(string))
break; // Interrupted
try {
Thread.sleep(100); // Wait for 1/10th second
} catch (InterruptedException e) {
}
}
ctx.destroySocket(publisher);
}
}
// .split listener thread
// The listener receives all messages flowing through the proxy, on its
// pipe. In CZMQ, the pipe is a pair of ZMQ_PAIR sockets that connect
// attached child threads. In other languages your mileage may vary:
private static class Listener implements IAttachedRunnable
{
@Override
public void run(Object[] args, ZContext ctx, Socket pipe)
{
// Print everything that arrives on pipe
while (true) {
ZFrame frame = ZFrame.recvFrame(pipe);
if (frame == null)
break; // Interrupted
frame.print(null);
frame.destroy();
}
}
}
// .split main thread
// The main task starts the subscriber and publisher, and then sets
// itself up as a listening proxy. The listener runs as a child thread:
public static void main(String[] argv)
{
// Start child threads
ZContext ctx = new ZContext();
ZThread.fork(ctx, new Publisher());
ZThread.fork(ctx, new Subscriber());
Socket subscriber = ctx.createSocket(ZMQ.XSUB);
subscriber.connect("tcp://localhost:6000");
Socket publisher = ctx.createSocket(ZMQ.XPUB);
publisher.bind("tcp://*:6001");
Socket listener = ZThread.fork(ctx, new Listener());
ZMQ.proxy (subscriber, publisher, listener);
System.out.println(" interrupted");
// Tell attached threads to exit
ctx.destroy();
}
}