diff --git a/src/main/java/net/onrc/onos/core/topology/NetworkGraphDiscoveryInterface.java b/src/main/java/net/onrc/onos/core/topology/NetworkGraphDiscoveryInterface.java
new file mode 100644
index 0000000..14ef0ea
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/topology/NetworkGraphDiscoveryInterface.java
@@ -0,0 +1,67 @@
+package net.onrc.onos.core.topology;
+
+import java.util.Collection;
+
+/**
+ * Interface used by the Topology Discovery module to write topology-related
+ * events.
+ */
+public interface NetworkGraphDiscoveryInterface {
+    /**
+     * Switch discovered event.
+     *
+     * @param switchEvent the switch event.
+     * @param portEvents the corresponding port events for the switch.
+     */
+    public void putSwitchDiscoveryEvent(SwitchEvent switchEvent,
+					Collection<PortEvent> portEvents);
+
+    /**
+     * Switch removed event.
+     *
+     * @param switchEvent the switch event.
+     */
+    public void removeSwitchDiscoveryEvent(SwitchEvent switchEvent);
+
+    /**
+     * Port discovered event.
+     *
+     * @param portEvent the port event.
+     */
+    public void putPortDiscoveryEvent(PortEvent portEvent);
+
+    /**
+     * Port removed event.
+     *
+     * @param portEvent the port event.
+     */
+    public void removePortDiscoveryEvent(PortEvent portEvent);
+
+    /**
+     * Link discovered event.
+     *
+     * @param linkEvent the link event.
+     */
+    public void putLinkDiscoveryEvent(LinkEvent linkEvent);
+
+    /**
+     * Link removed event.
+     *
+     * @param linkEvent the link event.
+     */
+    public void removeLinkDiscoveryEvent(LinkEvent linkEvent);
+
+    /**
+     * Device discovered event.
+     *
+     * @param deviceEvent the device event.
+     */
+    public void putDeviceDiscoveryEvent(DeviceEvent deviceEvent);
+
+    /**
+     * Device removed event.
+     *
+     * @param deviceEvent the device event.
+     */
+    public void removeDeviceDiscoveryEvent(DeviceEvent deviceEvent);
+}