1 files changed, 25 insertions, 0 deletions
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/listeners/NodeListener.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/listeners/NodeListener.java
new file mode 100644
index 00000000000..351b68b3b57
--- /dev/null
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/listeners/NodeListener.java
@@ -0,0 +1,25 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.vespa.clustercontroller.core.listeners;
+
+import com.yahoo.vdslib.state.Node;
+import com.yahoo.vdslib.state.NodeState;
+import com.yahoo.vespa.clustercontroller.core.NodeInfo;
+import com.yahoo.vespa.clustercontroller.core.hostinfo.HostInfo;
+
+/**
+ * Implemented by classes wanting events when there are node changes.
+ */
+public interface NodeListener {
+
+    default void handleNewNodeState(NodeInfo currentInfo, NodeState newState) {}
+    default void handleNewWantedNodeState(NodeInfo node, NodeState newState) {}
+
+    /** Invoked after NodeInfo has been removed from the content cluster. */
+    default void handleRemovedNode(Node node) {}
+
+    /**
+     * For every getnodestate RPC call, handleUpdatedHostInfo() will be called with the host info JSON string.
+     */
+    default void handleUpdatedHostInfo(NodeInfo node, HostInfo newHostInfo) {}
+
+}