Event driven architecture refactored.

1. Renamed Message to Event and Event to AbstractEvent
2. Generified Event and Handler
3. Updated EventDispatcher to make unsafe configuration impossible
4. Updated UML diagram accordingly

event-driven-architecture/src/main/java/com/iluwatar/eda/event/AbstractEvent.java

@@ -0,0 +1,49 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.eda.event;
+
+import com.iluwatar.eda.framework.EventDispatcher;
+import com.iluwatar.eda.framework.Event;
+
+/**
+ * The {@link AbstractEvent} class serves as a base class for defining custom events happening with your
+ * system. In this example we have two types of events defined.
+ * <ul>
+ *   <li>{@link UserCreatedEvent} - used when a user is created</li>
+ *   <li>{@link UserUpdatedEvent} - used when a user is updated</li>
+ * </ul>
+ * Events can be distinguished using the {@link #getType() getType} method.
+ */
+public abstract class AbstractEvent implements Event {
+
+  /**
+   * Returns the event type as a {@link Class} object
+   * In this example, this method is used by the {@link EventDispatcher} to
+   * dispatch events depending on their type.
+   *
+   * @return the AbstractEvent type as a {@link Class}.
+   */
+  public Class<? extends Event> getType() {
+    return getClass();
+  }
+}