Adding event sink & dispatcher abstractions.
Increased strength of the provider & service types.
diff --git a/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java b/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java
index b28df4e..b3d85ad 100644
--- a/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java
+++ b/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java
@@ -5,7 +5,7 @@
 /**
  * Means for injecting topology information into the core.
  */
-public interface TopologyProviderService extends ProviderService {
+public interface TopologyProviderService extends ProviderService<TopologyProvider> {
 
     // What can be conveyed in a topology that isn't by individual
     // providers?