package org.jgroups.demos;
import org.jgroups.Global;
import org.jgroups.JChannel;
import org.jgroups.Message;
import org.jgroups.ReceiverAdapter;
import org.jgroups.conf.ConfiguratorFactory;
import org.jgroups.conf.ProtocolConfiguration;
import org.jgroups.conf.ProtocolStackConfigurator;
import org.jgroups.util.Util;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Simple pub-sub program using a shared transport: every topic creates a new channel
* @author bela
* @since 3.0
*/
public class PubSub {
final Map<String,JChannel> topics=new HashMap<String,JChannel>();
void start(String props) throws Exception {
System.out.println("\n========== PubSub instance started =========");
System.out.println("Valid commands are:");
System.out.println("subscribe <topic>");
System.out.println("unsubscribe <topic>");
System.out.println("exit");
System.out.println("print (prints all topics)");
System.out.println("<topic>: <message>\n\n");
System.out.println("Example");
System.out.println("subscribe one\nsubscribe two\none: hello world\n\n");
for(;;) {
System.out.print("> ");
String line=Util.readLine(System.in).trim();
if(line.startsWith("subscribe")) {
final String topic=line.substring("subscribe".length()).trim();
if(!topics.containsKey(topic)) {
// we need to make sure "singleton_name" is set in the transport
JChannel ch=createSharedChannel("pubsub", props);
ch.setReceiver(new ReceiverAdapter() {
public void receive(Message msg) {
System.out.println("[" + topic + "] << " + msg.getObject());
}
});
ch.connect(topic);
topics.put(topic, ch);
System.out.println("subscribed to topic \"" + topic + "\"; current subscriptions: " + topics.keySet());
}
continue;
}
if(line.startsWith("unsubscribe")) {
final String topic=line.substring("unsubscribe".length()).trim();
JChannel ch=topics.remove(topic);
if(ch == null) {
System.err.println("Topic \"" + topic + "\" not found");
continue;
}
Util.close(ch);
System.out.println("unsubscribed from topic \"" + topic + "\"; current subscriptions: " + topics.keySet());
continue;
}
if(line.startsWith("exit"))
break;
if(line.startsWith("print")) {
System.out.println("topics: " + topics.keySet());
continue;
}
int index=line.indexOf(":");
if(index == -1) {
// post to all topics
for(JChannel ch: topics.values()) {
Message msg=new Message(null, null, line);
ch.send(msg);
}
continue;
}
String topic=line.substring(0, index).trim();
String message=line.substring(index).trim();
JChannel ch=topics.get(topic);
if(ch == null) {
System.err.println("sending to topic \"" + topic + "\" failed as topic doesn't exist, subscribe first");
continue;
}
Message msg=new Message(null, null, message);
ch.send(msg);
}
for(JChannel ch: topics.values())
Util.close(ch);
}
private static JChannel createSharedChannel(String singleton_name, String props) throws Exception {
ProtocolStackConfigurator config=ConfiguratorFactory.getStackConfigurator(props);
List<ProtocolConfiguration> protocols=config.getProtocolStack();
ProtocolConfiguration transport=protocols.get(0);
transport.getProperties().put(Global.SINGLETON_NAME, singleton_name);
return new JChannel(config);
}
public static void main(final String[] args) throws Exception {
String props=null;
for(int i=0; i < args.length; i++) {
if(args[i].equals("-props")) {
props=args[++i];
continue;
}
help();
return;
}
new PubSub().start(props);
}
protected static void help() {
System.out.println("PubSub [-props props]");
System.out.println("Valid commands are:");
System.out.println("subscribe <topic>");
System.out.println("unsubscribe <topic>");
System.out.println("exit");
System.out.println("print (prints all topics)");
System.out.println("<topic>: <message>\n\n");
System.out.println("Example");
System.out.println("subscribe one\nsubscribe two\none: hello world");
}
}