Added initial pieces for topology related notifications.
diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyElement.java b/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyElement.java
new file mode 100644
index 0000000..6809125
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyElement.java
@@ -0,0 +1,90 @@
+package net.onrc.onos.ofcontroller.topology;
+
+/**
+ * Class for storing information about a Topology Element: Switch, Port or
+ * Link.
+ */
+public class TopologyElement {
+ /**
+ * The Element Type.
+ */
+ enum Type {
+ ELEMENT_SWITCH, // Network Switch
+ ELEMENT_PORT, // Switch Port
+ ELEMENT_LINK // Unidirectional Link between Switch Ports
+ }
+
+ private Type elementType; // The element type
+ private long fromSwitchDpid = 0; // The Switch DPID
+ private int fromSwitchPort = 0; // The Switch Port
+ private long toSwitchDpid = 0; // The Neighbor Switch DPID
+ private int toSwitchPort = 0; // The Neighbor Switch Port
+
+ /**
+ * Constructor to create a Topology Element for a Switch.
+ *
+ * @param switchDpid the Switch DPID.
+ */
+ public TopologyElement(long switchDpid) {
+ this.elementType = Type.ELEMENT_SWITCH;
+ this.fromSwitchDpid = switchDpid;
+ }
+
+ /**
+ * Constructor to create a Topology Element for a Switch Port.
+ *
+ * @param switchDpid the Switch DPID.
+ * @param switchPort the Switch Port.
+ */
+ public TopologyElement(long switchDpid, int switchPort) {
+ this.elementType = Type.ELEMENT_PORT;
+ this.fromSwitchDpid = switchDpid;
+ this.fromSwitchPort = switchPort;
+ }
+
+ /**
+ * Constructor to create a Topology Element for an unidirectional Link
+ * between Switch Ports.
+ *
+ * @param fromSwitchDpid the Switch DPID the Link begins from.
+ * @param fromSwitchPort the Switch Port the Link begins from.
+ * @param toSwitchDpid the Switch DPID the Link ends to.
+ * @param toSwitchPort the Switch Port the Link ends to.
+ */
+ public TopologyElement(long fromSwitchDpid, int fromSwitchPort,
+ long toSwitchDpid, int toSwitchPort) {
+ this.elementType = Type.ELEMENT_LINK;
+ this.fromSwitchDpid = fromSwitchDpid;
+ this.fromSwitchPort = fromSwitchPort;
+ this.toSwitchDpid = toSwitchDpid;
+ this.toSwitchPort = toSwitchPort;
+ }
+
+ /**
+ * Get the Topology Element ID.
+ *
+ * The Topology Element ID has the following format:
+ * - Switch: "Switch=<Dpid>"
+ * Example: "Switch=00:00:00:00:00:00:00:01"
+ * - Switch Port: "Port=<Dpid>/<PortId>"
+ * Example: "Port=00:00:00:00:00:00:00:01/1"
+ * - Link: "Link=<FromDpid>/<FromPortId>/<ToDpid>/<ToPortId>"
+ * Example: "Link=00:00:00:00:00:00:00:01/1/00:00:00:00:00:00:00:02/1"
+ *
+ * @return the Topology Element ID.
+ */
+ public String elementId() {
+ switch (elementType) {
+ case ELEMENT_SWITCH:
+ return "Switch=" + fromSwitchDpid;
+ case ELEMENT_PORT:
+ return "Port=" + fromSwitchDpid + "/" + fromSwitchPort;
+ case ELEMENT_LINK:
+ return "Link=" + fromSwitchDpid + "/" + fromSwitchPort +
+ toSwitchDpid + "/" + toSwitchPort;
+ }
+
+ assert(false);
+ return null;
+ }
+}