SEBA-405 Convert synchronizer framework to library

Change-Id: If8562f23dc15c7d18d7a8b040b33756708b3c5ec
diff --git a/lib/xos-synchronizer/xossynchronizer/backend_modelpolicy.py b/lib/xos-synchronizer/xossynchronizer/backend_modelpolicy.py
new file mode 100644
index 0000000..a8e826b
--- /dev/null
+++ b/lib/xos-synchronizer/xossynchronizer/backend_modelpolicy.py
@@ -0,0 +1,51 @@
+# 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 __future__ import print_function
+import os
+import inspect
+import imp
+import sys
+import threading
+import time
+from syncstep import SyncStep
+from synchronizers.new_base.event_loop import XOSObserver
+
+from xosconfig import Config
+from multistructlog import create_logger
+
+log = create_logger(Config().get("logging"))
+
+
+class Backend:
+    def run(self):
+        # start model policies thread
+        policies_dir = Config("model_policies_dir")
+        if policies_dir:
+            from synchronizers.model_policy import run_policy
+
+            model_policy_thread = threading.Thread(target=run_policy)
+            model_policy_thread.start()
+        else:
+            model_policy_thread = None
+            log.info("Skipping model policies thread due to no model_policies dir.")
+
+        while True:
+            try:
+                time.sleep(1000)
+            except KeyboardInterrupt:
+                print("exiting due to keyboard interrupt")
+                if model_policy_thread:
+                    model_policy_thread._Thread__stop()
+                sys.exit(1)