api and manager for statistic service
Change-Id: If00b8b43a2bd780ae3c05321697896290fb0f415
diff --git a/core/api/src/main/java/org/onlab/onos/net/statistic/StatisticService.java b/core/api/src/main/java/org/onlab/onos/net/statistic/StatisticService.java
new file mode 100644
index 0000000..b1809d7
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/net/statistic/StatisticService.java
@@ -0,0 +1,51 @@
+package org.onlab.onos.net.statistic;
+
+import org.onlab.onos.net.ConnectPoint;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.flow.FlowRule;
+
+/**
+ * Service for obtaining statistic information about link in the system.
+ * Statistics are obtained from the FlowRuleService in order to minimize the
+ * amount of hammering occuring at the dataplane.
+ */
+public interface StatisticService {
+
+ /**
+ * Obtain the load for a the ingress to the given link.
+ * @param link the link to query.
+ * @return a {@link org.onlab.onos.net.statistic.Load Load}
+ */
+ Load load(Link link);
+
+ /**
+ * Obtain the load for the given port.
+ * @param connectPoint the port to query
+ * @return a {@link org.onlab.onos.net.statistic.Load}
+ */
+ Load load(ConnectPoint connectPoint);
+
+ /**
+ * Find the most loaded link along a path.
+ * @param path the path to search in
+ * @return the most loaded {@link org.onlab.onos.net.Link}.
+ */
+ Link max(Path path);
+
+ /**
+ * Find the least loaded link along a path.
+ * @param path the path to search in
+ * @return the least loaded {@link org.onlab.onos.net.Link}.
+ */
+ Link min(Path path);
+
+ /**
+ * Returns the highest hitter (a flow rule) of for a given port, ie. the
+ * flow rule which is generating the most load.
+ * @param connectPoint the port
+ * @return the flow rule
+ */
+ FlowRule highestHitter(ConnectPoint connectPoint);
+
+}