Add a port method to assembly-level servers.

src/python/src/grpc/framework/assembly/implementations.py

@@ -195,7 +195,7 @@ def _servicer(implementations, pool):
       event_stream_in_stream_out_methods=event_stream_in_stream_out_methods)
 
 
-class _ServiceAssembly(activated.Activated):
+class _ServiceAssembly(interfaces.Server):
 
   def __init__(self, implementations, fore_link):
     self._implementations = implementations
@@ -237,6 +237,10 @@ class _ServiceAssembly(activated.Activated):
   def stop(self):
     self._stop()
 
+  def port(self):
+    with self._lock:
+      return self._fore_link.port()
+
 
 def assemble_face_stub(activated_rear_link):
   """Assembles a face_interfaces.Stub.
@@ -300,6 +304,6 @@ def assemble_service(implementations, activated_fore_link):
       when passed to this method.
 
   Returns:
-    An activated.Activated value encapsulating RPC service.
+    An interfaces.Server encapsulating RPC service.
   """
   return _ServiceAssembly(implementations, activated_fore_link)

src/python/src/grpc/framework/assembly/interfaces.py

@@ -37,6 +37,7 @@ import abc
 # module.
 from grpc.framework.common import cardinality  # pylint: disable=unused-import
 from grpc.framework.common import style  # pylint: disable=unused-import
+from grpc.framework.foundation import activated
 from grpc.framework.foundation import stream  # pylint: disable=unused-import
 
 
@@ -89,3 +90,25 @@ class MethodImplementation(object):
       style.Service.EVENT.
   """
   __metaclass__ = abc.ABCMeta
+
+
+class Server(activated.Activated):
+  """The server interface.
+
+  Aside from being able to be activated and deactivated, objects of this type
+  are able to report the port on which they are servicing RPCs.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  # TODO(issue 726): This is an abstraction violation; not every Server is
+  # necessarily serving over a network at all.
+  @abc.abstractmethod
+  def port(self):
+    """Identifies the port on which this Server is servicing RPCs.
+
+    This method may only be called while the server is active.
+
+    Returns:
+      The number of the port on which this Server is servicing RPCs.
+    """
+    raise NotImplementedError()