Refactored pseudowire code.

This refactoring is needed in order to be able to further
refactor the sr application in api / app / web, where api contains
the interfaces, used by other modules, app contains the implementations
and web contains rest related code.

Change-Id: I147442e5d1248941a6c3c4df2715b01e72c40b3f
diff --git a/src/main/java/org/onosproject/segmentrouting/pwaas/L2Tunnel.java b/src/main/java/org/onosproject/segmentrouting/pwaas/L2Tunnel.java
new file mode 100644
index 0000000..3e98480
--- /dev/null
+++ b/src/main/java/org/onosproject/segmentrouting/pwaas/L2Tunnel.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2016-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.segmentrouting.pwaas;
+
+import org.onlab.packet.MplsLabel;
+import org.onlab.packet.VlanId;
+import org.onosproject.net.Link;
+
+import java.util.List;
+
+public interface L2Tunnel {
+
+    /**
+     * Return the mode of the l2 tunnel.
+     *
+     * @return The pw mode.
+     */
+    L2Mode pwMode();
+
+    /**
+     * Returns the service delimiting tag.
+     *
+     * @return the sd tag
+     */
+    VlanId sdTag();
+
+    /**
+     * Returns the id of the tunnel.
+     *
+     * @return the tunnel id
+     */
+    long tunnelId();
+
+    /**
+     * Return the label of the pseudowire.
+     *
+     * @return the pw label.
+     */
+    MplsLabel pwLabel();
+
+    /**
+     * Returns the path used by the pseudowire.
+     *
+     * @return The path that is used
+     */
+    List<Link> pathUsed();
+
+    /**
+     * Returns the transport vlan used by the pseudowire.
+     *
+     * @return The transport vlan
+     */
+    VlanId transportVlan();
+
+    /**
+     * Returns the inter-co label used by the pseudowire.
+     *
+     * @return The inter CO label.
+     */
+    MplsLabel interCoLabel();
+
+    /**
+     * Sets the path that this pw uses.
+     *
+     * @param path The apth to use
+     */
+    void setPath(List<Link> path);
+
+    /**
+     * Set the transport vlan that this pw will use.
+     *
+     * @param vlan The vlan to use.
+     */
+    void setTransportVlan(VlanId vlan);
+}