diff --git a/src/dls_servbase_api/context_base.py b/src/dls_servbase_api/context_base.py
deleted file mode 100644
index b536781..0000000
--- a/src/dls_servbase_api/context_base.py
+++ /dev/null
@@ -1,35 +0,0 @@
-import logging
-
-logger = logging.getLogger(__name__)
-
-
-class ContextBase:
-    """ """
-
-    # ----------------------------------------------------------------------------------------
-    def __init__(self, specification):
-        self.__specification = specification
-        self.__interface = None
-
-    # ----------------------------------------------------------------------------------------
-    def get_interface(self):
-        return self.__interface
-
-    def set_interface(self, interface):
-        self.__interface = interface
-
-    interface = property(get_interface, set_interface)
-
-    # ----------------------------------------------------------------------------------------
-    async def __aenter__(self):
-        """ """
-
-        await self.aenter()
-
-        return self.interface
-
-    # ----------------------------------------------------------------------------------------
-    async def __aexit__(self, type, value, traceback):
-        """ """
-
-        await self.aexit()
diff --git a/src/dls_servbase_api/datafaces/context.py b/src/dls_servbase_api/datafaces/context.py
index 2f11209..f76fb86 100644
--- a/src/dls_servbase_api/datafaces/context.py
+++ b/src/dls_servbase_api/datafaces/context.py
@@ -1,5 +1,8 @@
 import logging
 
+# Base class.
+from dls_utilpack.client_context_base import ClientContextBase
+
 # Things created in the context.
 from dls_servbase_api.datafaces.datafaces import (
     Datafaces,
@@ -9,48 +12,39 @@
 logger = logging.getLogger(__name__)
 
 
-class Context:
+class Context(ClientContextBase):
     """
     Client context for a dls_servbase_dataface object.
     On entering, it creates the object according to the specification (a dict).
     On exiting, it closes client connection.
 
-    The aenter and aexit methods are exposed for use by an enclosing context.
+    The aenter and aexit methods are exposed for use by an enclosing context and the base class.
     """
 
     # ----------------------------------------------------------------------------------------
     def __init__(self, specification):
-        self.__specification = specification
-        self.__dls_servbase_dataface = None
-
-    # ----------------------------------------------------------------------------------------
-    async def __aenter__(self):
-        """ """
-
-        await self.aenter()
-
-    # ----------------------------------------------------------------------------------------
-    async def __aexit__(self, type, value, traceback):
-        """ """
-
-        await self.aexit()
+        ClientContextBase.__init__(self, specification)
 
     # ----------------------------------------------------------------------------------------
     async def aenter(self):
         """ """
 
         # Build the object according to the specification.
-        self.__dls_servbase_dataface = Datafaces().build_object(self.__specification)
+        self.interface = Datafaces().build_object(self.specification)
 
         # If there is more than one dataface, the last one defined will be the default.
-        dls_servbase_datafaces_set_default(self.__dls_servbase_dataface)
+        dls_servbase_datafaces_set_default(self.interface)
+
+        # Open client session to the service or direct connection.
+        await self.interface.open_client_session()
 
     # ----------------------------------------------------------------------------------------
     async def aexit(self):
         """ """
 
-        if self.__dls_servbase_dataface is not None:
-            await self.__dls_servbase_dataface.close_client_session()
+        if self.interface is not None:
+            # Close client session to the service or direct connection.
+            await self.interface.close_client_session()
 
             # Clear the global variable.  Important between pytests.
             dls_servbase_datafaces_set_default(None)
diff --git a/src/dls_servbase_api/guis/context.py b/src/dls_servbase_api/guis/context.py
index 12d97fb..58a1b19 100644
--- a/src/dls_servbase_api/guis/context.py
+++ b/src/dls_servbase_api/guis/context.py
@@ -1,7 +1,7 @@
 import logging
 
 # Base class.
-from dls_servbase_api.context_base import ContextBase
+from dls_utilpack.client_context_base import ClientContextBase
 
 # Things created in the context.
 from dls_servbase_api.guis.guis import Guis, dls_servbase_guis_set_default
@@ -9,25 +9,25 @@
 logger = logging.getLogger(__name__)
 
 
-class Context(ContextBase):
+class Context(ClientContextBase):
     """
     Client context for a dls_servbase_gui object.
     On entering, it creates the object according to the specification (a dict).
     On exiting, it closes client connection.
 
-    The aenter and aexit methods are exposed for use by an enclosing context.
+    The aenter and aexit methods are exposed for use by an enclosing context and the base class.
     """
 
     # ----------------------------------------------------------------------------------------
     def __init__(self, specification):
-        self.__specification = specification
+        ClientContextBase.__init__(self, specification)
 
     # ----------------------------------------------------------------------------------------
     async def aenter(self):
         """ """
 
         # Build the object according to the specification.
-        self.interface = Guis().build_object(self.__specification)
+        self.interface = Guis().build_object(self.specification)
 
         # If there is more than one gui, the last one defined will be the default.
         dls_servbase_guis_set_default(self.interface)