SEBA-89 Framework for fabric-crossconnect service

Change-Id: I65d8199b50703feaf828ca9bc251558ac2878fae
diff --git a/xos/synchronizer/model_policies/model_policy_fabriccrossconnectserviceinstance.py b/xos/synchronizer/model_policies/model_policy_fabriccrossconnectserviceinstance.py
new file mode 100644
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+++ b/xos/synchronizer/model_policies/model_policy_fabriccrossconnectserviceinstance.py
@@ -0,0 +1,45 @@
+
+# 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 synchronizers.new_base.modelaccessor import FabricCrossconnectServiceInstance, model_accessor
+from synchronizers.new_base.policy import Policy
+from synchronizers.new_base.exceptions import *
+
+from xosconfig import Config
+from multistructlog import create_logger
+
+log = create_logger(Config().get('logging'))
+
+class FabricCrossconnectServiceInstancePolicy(Policy):
+    model_name = "FabricCrossconnectServiceInstance"
+
+    def handle_create(self, service_instance):
+        return self.handle_update(service_instance)
+
+    def handle_update(self, service_instance):
+        log.info("Handle_update Fabric Crossconnect Service Instance", service_instance=service_instance)
+
+        if (service_instance.link_deleted_count > 0) and (not service_instance.provided_links.exists()):
+            # If this instance has no links pointing to it, delete
+            self.handle_delete(service_instance)
+            if FabricCrossconnectServiceInstance.objects.filter(id=service_instance.id).exists():
+                service_instance.delete()
+            return
+
+    def handle_delete(self, service_instance):
+        log.info("Handle_delete Fabric-Crossconnect Service Instance", service_instance=service_instance)
+
+