SW-705: Fix mising function

MAC/Services/src/observation_control_rpc.py

@@ -20,7 +20,8 @@
 
 
 import logging
-from lofar.messaging.rpc import RPCClient, RPCClientContextManagerMixin
+from lofar.messaging import RPCClient, RPCClientContextManagerMixin, DEFAULT_BUSNAME, \
+    DEFAULT_BROKER, DEFAULT_RPC_TIMEOUT
 from lofar.mac.config import DEFAULT_OBSERVATION_CONTROL_SERVICE_NAME
 
 ''' Simple RPC client for Service ObservationControl2
@@ -34,5 +35,12 @@ class ObservationControlRPCClient(RPCClientContextManagerMixin):
         super().__init__()
         self._rpc_client = rpc_client
 
+    @staticmethod
+    def create(exchange=DEFAULT_BUSNAME, broker=DEFAULT_BROKER, timeout=DEFAULT_RPC_TIMEOUT):
+        """Create a OTDBRPC connecting to the given exchange/broker on the default DEFAULT_OTDB_SERVICENAME service"""
+        return ObservationControlRPCClient(
+            RPCClient(service_name=DEFAULT_OBSERVATION_CONTROL_SERVICE_NAME,
+                      exchange=exchange, broker=broker, timeout=timeout))
+
     def abort_observation(self, sas_id):
         return self._rpc_client.execute('AbortObservation', sas_id=sas_id)