CodeReview - Initial Commit for Kafka Integration Application

1. Partial REST API implementation
2. Partial Event Manager backend implementation

Change-Id: Ieaf703f7a3f6e296aea8ffcf155c7a1b603236ca
diff --git a/apps/kafka-integration/src/main/java/org/onosproject/kafkaintegration/api/dto/EventSubscriber.java b/apps/kafka-integration/src/main/java/org/onosproject/kafkaintegration/api/dto/EventSubscriber.java
new file mode 100644
index 0000000..95647e7
--- /dev/null
+++ b/apps/kafka-integration/src/main/java/org/onosproject/kafkaintegration/api/dto/EventSubscriber.java
@@ -0,0 +1,99 @@
+/**
+ * Copyright 2016-present Open Networking Laboratory
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.kafkaintegration.api.dto;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.Objects;
+
+import org.onosproject.kafkaintegration.api.dto.OnosEvent.Type;
+
+/**
+ * Representation of a subscription to an event type.
+ *
+ */
+public final class EventSubscriber {
+    private final String appName;
+    private final EventSubscriberGroupId subscriberGroupId;
+    private final Type eventType;
+
+    /**
+     * Creates a new Event Subscriber.
+     *
+     * @param name Application Name
+     * @param groupId Subscriber group id of the application
+     * @param eventType ONOS event type
+     */
+    public EventSubscriber(String name, EventSubscriberGroupId groupId,
+                           Type eventType) {
+        this.appName = checkNotNull(name);
+        this.subscriberGroupId = checkNotNull(groupId);
+        this.eventType = checkNotNull(eventType);
+    }
+
+    /**
+     * Returns the Application Name.
+     *
+     * @return application name
+     */
+    public String appName() {
+        return appName;
+    }
+
+    /**
+     * Returns the Subscriber Group Id.
+     *
+     * @return Subscriber Group Id
+     */
+    public EventSubscriberGroupId subscriberGroupId() {
+        return subscriberGroupId;
+    }
+
+    /**
+     * Returns the Event type.
+     *
+     * @return ONOS Event Type
+     */
+    public Type eventType() {
+        return eventType;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(appName, subscriberGroupId, eventType);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (o instanceof EventSubscriber) {
+            EventSubscriber sub = (EventSubscriber) o;
+            if (sub.appName.equals(appName)
+                    && sub.subscriberGroupId.equals(subscriberGroupId)
+                    && sub.eventType.equals(eventType)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this).add("appName", appName)
+                .addValue(subscriberGroupId.toString())
+                .add("eventType", eventType).toString();
+    }
+}