diff --git a/src/main/java/net/onrc/onos/core/topology/MastershipEvent.java b/src/main/java/net/onrc/onos/core/topology/MastershipEvent.java
new file mode 100644
index 0000000..01323ba
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/topology/MastershipEvent.java
@@ -0,0 +1,145 @@
+package net.onrc.onos.core.topology;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+
+import net.floodlightcontroller.core.IFloodlightProviderService.Role;
+import net.onrc.onos.core.topology.web.serializers.MastershipEventSerializer;
+import net.onrc.onos.core.util.Dpid;
+
+import org.apache.commons.lang.Validate;
+import org.codehaus.jackson.map.annotate.JsonSerialize;
+
+/**
+ * Self-contained Switch Mastership event Object.
+ * <p/>
+ * TODO: Rename to match what it is. (Switch/Port/Link/Host)Snapshot?
+ * FIXME: Current implementation directly use this object as
+ *        Replication message, but should be sending update operation info.
+ */
+@JsonSerialize(using = MastershipEventSerializer.class)
+public class MastershipEvent extends TopologyElement<MastershipEvent> {
+
+    private final Dpid dpid;
+    private final String onosInstanceId;
+    private final Role role;
+
+    /**
+     * Default constructor for Serializer to use.
+     */
+    @Deprecated
+    protected MastershipEvent() {
+        dpid = null;
+        onosInstanceId = null;
+        role = Role.SLAVE;              // Default role is SLAVE
+    }
+
+    /**
+     * Creates the Switch Mastership object.
+     *
+     * @param dpid the Switch DPID
+     * @param onosInstanceId the ONOS Instance ID
+     * @param role the ONOS instance role for the switch.
+     */
+    public MastershipEvent(Dpid dpid, String onosInstanceId, Role role) {
+        Validate.notNull(dpid);
+        Validate.notNull(onosInstanceId);
+
+        this.dpid = dpid;
+        this.onosInstanceId = onosInstanceId;
+        this.role = role;
+    }
+
+    /**
+     * Creates an unfrozen copy of given Object.
+     *
+     * @param original to make copy of.
+     */
+    public MastershipEvent(MastershipEvent original) {
+        super(original);
+        this.dpid = original.dpid;
+        this.onosInstanceId = original.onosInstanceId;
+        this.role = original.role;
+    }
+
+    /**
+     * Gets the Switch DPID.
+     *
+     * @return the Switch DPID.
+     */
+    public Dpid getDpid() {
+        return dpid;
+    }
+
+    /**
+     * Gets the ONOS Instance ID.
+     *
+     * @return the ONOS Instance ID.
+     */
+    public String getOnosInstanceId() {
+        return onosInstanceId;
+    }
+
+    /**
+     * Gets the ONOS Controller Role for the Switch.
+     *
+     * @return the ONOS Controller Role for the Switch.
+     */
+    public Role getRole() {
+        return role;
+    }
+
+    @Override
+    public String toString() {
+        return "[MastershipEvent " + getDpid() + "@" + getOnosInstanceId() +
+            "->" + getRole() + "]";
+    }
+
+    public byte[] getID() {
+        String keyStr = "M" + getDpid() + "@" + getOnosInstanceId();
+        return keyStr.getBytes(StandardCharsets.UTF_8);
+    }
+
+    public ByteBuffer getIDasByteBuffer() {
+        ByteBuffer buf = ByteBuffer.wrap(getID());
+        return buf;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(dpid, onosInstanceId);
+    }
+
+    /**
+     * Compares two MastershipEvent objects.
+     * MastershipEvent objects are equal if they have same DPID and same
+     * ONOS Instance ID.
+     *
+     * @param obj another object to compare to this
+     * @returns true if equal, false otherwise false.
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (obj == null) {
+            return false;
+        }
+
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+
+        // compare attributes
+        if (!super.equals(obj)) {
+            return false;
+        }
+
+        MastershipEvent other = (MastershipEvent) obj;
+        return dpid.equals(other.dpid) &&
+            onosInstanceId.equals(other.onosInstanceId);
+    }
+}