Add getType to Topology interfaces.

Change-Id: If0726e99db224f790e66f0e8f8adca3864ff6f69
diff --git a/src/main/java/net/onrc/onos/core/topology/ITopologyElement.java b/src/main/java/net/onrc/onos/core/topology/ITopologyElement.java
new file mode 100644
index 0000000..b9ce0d3
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/topology/ITopologyElement.java
@@ -0,0 +1,16 @@
+package net.onrc.onos.core.topology;
+
+// TODO give me a better name.
+/**
+ * Interface common to Topology element interfaces.
+ */
+public interface ITopologyElement {
+
+    // TODO The term Type is a bit confusing, may rename to something like layer
+    /**
+     * Returns the type of topology element.
+     *
+     * @return the type of the topology element
+     */
+    public String getType();
+}