preparing event bus

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

bus/src/main/java/de/srsoftware/umbrella/messagebus/MessageBus.java

@@ -0,0 +1,27 @@
+package de.srsoftware.umbrella.messagebus;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class MessageBus {
+	private static MessageBus SINGLETON = new MessageBus();
+	private Set<EventListener> listeners = new HashSet<>();
+
+	private MessageBus(){}
+
+	public void dispatch(Event event){
+		listeners.parallelStream().forEach(l -> l.onEvent(event));
+	}
+
+	public void drop(EventListener listener){
+		listeners.remove(listener);
+	}
+
+	public static MessageBus messageBus(){
+		return SINGLETON;
+	}
+
+	public void register(EventListener listener){
+		listeners.add(listener);
+	}
+}