Started to work on topology abstraction.
Added more unit tests.
Changed mastership application to be synchronous.
diff --git a/net/api/src/main/java/org/onlab/onos/net/topology/TopoEdge.java b/net/api/src/main/java/org/onlab/onos/net/topology/TopoEdge.java
new file mode 100644
index 0000000..ef94eca
--- /dev/null
+++ b/net/api/src/main/java/org/onlab/onos/net/topology/TopoEdge.java
@@ -0,0 +1,18 @@
+package org.onlab.onos.net.topology;
+
+import org.onlab.graph.Edge;
+import org.onlab.onos.net.Link;
+
+/**
+ * Represents an edge in the topology graph.
+ */
+public interface TopoEdge extends Edge<TopoVertex> {
+
+ /**
+ * Returns the associated infrastructure link.
+ *
+ * @return backing infrastructure link
+ */
+ Link link();
+
+}