Added more event and listener interface definitions.
diff --git a/net/api/src/main/java/org/onlab/onos/net/DeviceId.java b/net/api/src/main/java/org/onlab/onos/net/DeviceId.java
index ebb3fb7..45528a4 100644
--- a/net/api/src/main/java/org/onlab/onos/net/DeviceId.java
+++ b/net/api/src/main/java/org/onlab/onos/net/DeviceId.java
@@ -1,9 +1,12 @@
 package org.onlab.onos.net;
 
 import java.net.URI;
+import java.util.Objects;
+
+import static com.google.common.base.Objects.toStringHelper;
 
 /**
- * Immutable representaion of a device identity.
+ * Immutable representation of a device identity.
  */
 public class DeviceId {
 
@@ -22,4 +25,25 @@
         return uri;
     }
 
+    @Override
+    public int hashCode() {
+        return Objects.hash(uri);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null || getClass() != obj.getClass()) {
+            return false;
+        }
+        final DeviceId other = (DeviceId) obj;
+        return Objects.equals(this.uri, other.uri);
+    }
+    @Override
+    public String toString() {
+        return toStringHelper(this).add("uri", uri).toString();
+    }
+
 }