Added more event and listener interface definitions.
diff --git a/net/api/src/main/java/org/onlab/onos/net/link/LinkEvent.java b/net/api/src/main/java/org/onlab/onos/net/link/LinkEvent.java
new file mode 100644
index 0000000..18987ea
--- /dev/null
+++ b/net/api/src/main/java/org/onlab/onos/net/link/LinkEvent.java
@@ -0,0 +1,48 @@
+package org.onlab.onos.net.link;
+
+import org.onlab.onos.event.AbstractEvent;
+import org.onlab.onos.net.Link;
+
+/**
+ * Describes infrastructure link event.
+ */
+public class LinkEvent extends AbstractEvent<LinkEvent.Type, Link> {
+
+ /**
+ * Type of link events.
+ */
+ public enum Type {
+ /**
+ * Signifies that a new link has been detected.
+ */
+ LINK_ADDED,
+
+ /**
+ * Signifies that a link has been removed.
+ */
+ LINK_REMOVED
+ }
+
+ /**
+ * Creates an event of a given type and for the specified link and the
+ * current time.
+ *
+ * @param type link event type
+ * @param link event link subject
+ */
+ public LinkEvent(Type type, Link link) {
+ super(type, link);
+ }
+
+ /**
+ * Creates an event of a given type and for the specified link and time.
+ *
+ * @param type link event type
+ * @param link event link subject
+ * @param time occurrence time
+ */
+ public LinkEvent(Type type, Link link, long time) {
+ super(type, link, time);
+ }
+
+}
diff --git a/net/api/src/main/java/org/onlab/onos/net/link/LinkListener.java b/net/api/src/main/java/org/onlab/onos/net/link/LinkListener.java
new file mode 100644
index 0000000..03039db
--- /dev/null
+++ b/net/api/src/main/java/org/onlab/onos/net/link/LinkListener.java
@@ -0,0 +1,9 @@
+package org.onlab.onos.net.link;
+
+import org.onlab.onos.event.EventListener;
+
+/**
+ * Entity capable of receiving infrastructure link related events.
+ */
+public interface LinkListener extends EventListener<LinkEvent> {
+}