CORD-1849 Split XOS code out of OLT and VTN repos

Change-Id: I307b2a9a54fdcdab14e6bf96d9a9b060ff421a77
diff --git a/xos/tosca/resources/accessdevice.py b/xos/tosca/resources/accessdevice.py
new file mode 100644
index 0000000..a9fd999
--- /dev/null
+++ b/xos/tosca/resources/accessdevice.py
@@ -0,0 +1,49 @@
+
+# Copyright 2017-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.
+
+
+from services.volt.models import AccessDevice, VOLTDevice
+from xosresource import XOSResource
+
+class XOSAccessDevice(XOSResource):
+    provides = "tosca.nodes.AccessDevice"
+    xos_model = AccessDevice
+    copyin_props = ["uplink", "vlan"]
+    name_field = None
+
+    def get_xos_args(self, throw_exception=True):
+        args = super(XOSAccessDevice, self).get_xos_args()
+
+        volt_device_name = self.get_requirement("tosca.relationships.MemberOfDevice", throw_exception=throw_exception)
+        if volt_device_name:
+            args["volt_device"] = self.get_xos_object(VOLTDevice, throw_exception=throw_exception, name=volt_device_name)
+
+        return args
+
+    # AccessDevice has no name field, so we rely on matching the keys. We assume
+    # the for a given VOLTDevice, there is only one AccessDevice per (uplink, vlan)
+    # pair.
+
+    def get_existing_objs(self):
+        args = self.get_xos_args(throw_exception=False)
+        volt_device = args.get("volt_device", None)
+        uplink = args.get("uplink", None)
+        vlan = args.get("vlan", None)
+        if (volt_device is not None) and (uplink is not None) and (vlan is not None):
+            existing_obj = self.get_xos_object(AccessDevice, volt_device=volt_device, uplink=uplink, vlan=vlan, throw_exception=False)
+            if existing_obj:
+                return [ existing_obj ]
+        return []
+