add ydb deps

7 files changed, 1652 insertions, 0 deletions

diff --git a/contrib/python/grpcio/py3/grpc/framework/interfaces/__init__.py b/contrib/python/grpcio/py3/grpc/framework/interfaces/__init__.py
new file mode 100644
index 00000000000..5fb4f3c3cfd
--- /dev/null
+++ b/contrib/python/grpcio/py3/grpc/framework/interfaces/__init__.py
@@ -0,0 +1,13 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
diff --git a/contrib/python/grpcio/py3/grpc/framework/interfaces/base/__init__.py b/contrib/python/grpcio/py3/grpc/framework/interfaces/base/__init__.py
new file mode 100644
index 00000000000..5fb4f3c3cfd
--- /dev/null
+++ b/contrib/python/grpcio/py3/grpc/framework/interfaces/base/__init__.py
@@ -0,0 +1,13 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
diff --git a/contrib/python/grpcio/py3/grpc/framework/interfaces/base/base.py b/contrib/python/grpcio/py3/grpc/framework/interfaces/base/base.py
new file mode 100644
index 00000000000..8caee325c2c
--- /dev/null
+++ b/contrib/python/grpcio/py3/grpc/framework/interfaces/base/base.py
@@ -0,0 +1,325 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
+"""The base interface of RPC Framework.
+
+Implementations of this interface support the conduct of "operations":
+exchanges between two distinct ends of an arbitrary number of data payloads
+and metadata such as a name for the operation, initial and terminal metadata
+in each direction, and flow control. These operations may be used for transfers
+of data, remote procedure calls, status indication, or anything else
+applications choose.
+"""
+
+# threading is referenced from specification in this module.
+import abc
+import enum
+import threading  # pylint: disable=unused-import
+
+# pylint: disable=too-many-arguments
+
+
+class NoSuchMethodError(Exception):
+    """Indicates that an unrecognized operation has been called.
+
+    Attributes:
+      code: A code value to communicate to the other side of the operation
+        along with indication of operation termination. May be None.
+      details: A details value to communicate to the other side of the
+        operation along with indication of operation termination. May be None.
+    """
+
+    def __init__(self, code, details):
+        """Constructor.
+
+        Args:
+          code: A code value to communicate to the other side of the operation
+            along with indication of operation termination. May be None.
+          details: A details value to communicate to the other side of the
+            operation along with indication of operation termination. May be None.
+        """
+        super(NoSuchMethodError, self).__init__()
+        self.code = code
+        self.details = details
+
+
+class Outcome(object):
+    """The outcome of an operation.
+
+  Attributes:
+    kind: A Kind value coarsely identifying how the operation terminated.
+    code: An application-specific code value or None if no such value was
+      provided.
+    details: An application-specific details value or None if no such value was
+      provided.
+  """
+
+    @enum.unique
+    class Kind(enum.Enum):
+        """Ways in which an operation can terminate."""
+
+        COMPLETED = 'completed'
+        CANCELLED = 'cancelled'
+        EXPIRED = 'expired'
+        LOCAL_SHUTDOWN = 'local shutdown'
+        REMOTE_SHUTDOWN = 'remote shutdown'
+        RECEPTION_FAILURE = 'reception failure'
+        TRANSMISSION_FAILURE = 'transmission failure'
+        LOCAL_FAILURE = 'local failure'
+        REMOTE_FAILURE = 'remote failure'
+
+
+class Completion(abc.ABC):
+    """An aggregate of the values exchanged upon operation completion.
+
+  Attributes:
+    terminal_metadata: A terminal metadata value for the operaton.
+    code: A code value for the operation.
+    message: A message value for the operation.
+  """
+
+
+class OperationContext(abc.ABC):
+    """Provides operation-related information and action."""
+
+    @abc.abstractmethod
+    def outcome(self):
+        """Indicates the operation's outcome (or that the operation is ongoing).
+
+    Returns:
+      None if the operation is still active or the Outcome value for the
+        operation if it has terminated.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def add_termination_callback(self, callback):
+        """Adds a function to be called upon operation termination.
+
+    Args:
+      callback: A callable to be passed an Outcome value on operation
+        termination.
+
+    Returns:
+      None if the operation has not yet terminated and the passed callback will
+        later be called when it does terminate, or if the operation has already
+        terminated an Outcome value describing the operation termination and the
+        passed callback will not be called as a result of this method call.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def time_remaining(self):
+        """Describes the length of allowed time remaining for the operation.
+
+    Returns:
+      A nonnegative float indicating the length of allowed time in seconds
+      remaining for the operation to complete before it is considered to have
+      timed out. Zero is returned if the operation has terminated.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def cancel(self):
+        """Cancels the operation if the operation has not yet terminated."""
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def fail(self, exception):
+        """Indicates that the operation has failed.
+
+    Args:
+      exception: An exception germane to the operation failure. May be None.
+    """
+        raise NotImplementedError()
+
+
+class Operator(abc.ABC):
+    """An interface through which to participate in an operation."""
+
+    @abc.abstractmethod
+    def advance(self,
+                initial_metadata=None,
+                payload=None,
+                completion=None,
+                allowance=None):
+        """Progresses the operation.
+
+    Args:
+      initial_metadata: An initial metadata value. Only one may ever be
+        communicated in each direction for an operation, and they must be
+        communicated no later than either the first payload or the completion.
+      payload: A payload value.
+      completion: A Completion value. May only ever be non-None once in either
+        direction, and no payloads may be passed after it has been communicated.
+      allowance: A positive integer communicating the number of additional
+        payloads allowed to be passed by the remote side of the operation.
+    """
+        raise NotImplementedError()
+
+
+class ProtocolReceiver(abc.ABC):
+    """A means of receiving protocol values during an operation."""
+
+    @abc.abstractmethod
+    def context(self, protocol_context):
+        """Accepts the protocol context object for the operation.
+
+    Args:
+      protocol_context: The protocol context object for the operation.
+    """
+        raise NotImplementedError()
+
+
+class Subscription(abc.ABC):
+    """Describes customer code's interest in values from the other side.
+
+  Attributes:
+    kind: A Kind value describing the overall kind of this value.
+    termination_callback: A callable to be passed the Outcome associated with
+      the operation after it has terminated. Must be non-None if kind is
+      Kind.TERMINATION_ONLY. Must be None otherwise.
+    allowance: A callable behavior that accepts positive integers representing
+      the number of additional payloads allowed to be passed to the other side
+      of the operation. Must be None if kind is Kind.FULL. Must not be None
+      otherwise.
+    operator: An Operator to be passed values from the other side of the
+      operation. Must be non-None if kind is Kind.FULL. Must be None otherwise.
+    protocol_receiver: A ProtocolReceiver to be passed protocol objects as they
+      become available during the operation. Must be non-None if kind is
+      Kind.FULL.
+  """
+
+    @enum.unique
+    class Kind(enum.Enum):
+
+        NONE = 'none'
+        TERMINATION_ONLY = 'termination only'
+        FULL = 'full'
+
+
+class Servicer(abc.ABC):
+    """Interface for service implementations."""
+
+    @abc.abstractmethod
+    def service(self, group, method, context, output_operator):
+        """Services an operation.
+
+    Args:
+      group: The group identifier of the operation to be serviced.
+      method: The method identifier of the operation to be serviced.
+      context: An OperationContext object affording contextual information and
+        actions.
+      output_operator: An Operator that will accept output values of the
+        operation.
+
+    Returns:
+      A Subscription via which this object may or may not accept more values of
+        the operation.
+
+    Raises:
+      NoSuchMethodError: If this Servicer does not handle operations with the
+        given group and method.
+      abandonment.Abandoned: If the operation has been aborted and there no
+        longer is any reason to service the operation.
+    """
+        raise NotImplementedError()
+
+
+class End(abc.ABC):
+    """Common type for entry-point objects on both sides of an operation."""
+
+    @abc.abstractmethod
+    def start(self):
+        """Starts this object's service of operations."""
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def stop(self, grace):
+        """Stops this object's service of operations.
+
+    This object will refuse service of new operations as soon as this method is
+    called but operations under way at the time of the call may be given a
+    grace period during which they are allowed to finish.
+
+    Args:
+      grace: A duration of time in seconds to allow ongoing operations to
+        terminate before being forcefully terminated by the stopping of this
+        End. May be zero to terminate all ongoing operations and immediately
+        stop.
+
+    Returns:
+      A threading.Event that will be set to indicate all operations having
+        terminated and this End having completely stopped. The returned event
+        may not be set until after the full grace period (if some ongoing
+        operation continues for the full length of the period) or it may be set
+        much sooner (if for example this End had no operations in progress at
+        the time its stop method was called).
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def operate(self,
+                group,
+                method,
+                subscription,
+                timeout,
+                initial_metadata=None,
+                payload=None,
+                completion=None,
+                protocol_options=None):
+        """Commences an operation.
+
+    Args:
+      group: The group identifier of the invoked operation.
+      method: The method identifier of the invoked operation.
+      subscription: A Subscription to which the results of the operation will be
+        passed.
+      timeout: A length of time in seconds to allow for the operation.
+      initial_metadata: An initial metadata value to be sent to the other side
+        of the operation. May be None if the initial metadata will be later
+        passed via the returned operator or if there will be no initial metadata
+        passed at all.
+      payload: An initial payload for the operation.
+      completion: A Completion value indicating the end of transmission to the
+        other side of the operation.
+      protocol_options: A value specified by the provider of a Base interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A pair of objects affording information about the operation and action
+        continuing the operation. The first element of the returned pair is an
+        OperationContext for the operation and the second element of the
+        returned pair is an Operator to which operation values not passed in
+        this call should later be passed.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def operation_stats(self):
+        """Reports the number of terminated operations broken down by outcome.
+
+    Returns:
+      A dictionary from Outcome.Kind value to an integer identifying the number
+        of operations that terminated with that outcome kind.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def add_idle_action(self, action):
+        """Adds an action to be called when this End has no ongoing operations.
+
+    Args:
+      action: A callable that accepts no arguments.
+    """
+        raise NotImplementedError()
diff --git a/contrib/python/grpcio/py3/grpc/framework/interfaces/base/utilities.py b/contrib/python/grpcio/py3/grpc/framework/interfaces/base/utilities.py
new file mode 100644
index 00000000000..281db62b5d4
--- /dev/null
+++ b/contrib/python/grpcio/py3/grpc/framework/interfaces/base/utilities.py
@@ -0,0 +1,71 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
+"""Utilities for use with the base interface of RPC Framework."""
+
+import collections
+
+from grpc.framework.interfaces.base import base
+
+
+class _Completion(base.Completion,
+                  collections.namedtuple('_Completion', (
+                      'terminal_metadata',
+                      'code',
+                      'message',
+                  ))):
+    """A trivial implementation of base.Completion."""
+
+
+class _Subscription(base.Subscription,
+                    collections.namedtuple('_Subscription', (
+                        'kind',
+                        'termination_callback',
+                        'allowance',
+                        'operator',
+                        'protocol_receiver',
+                    ))):
+    """A trivial implementation of base.Subscription."""
+
+
+_NONE_SUBSCRIPTION = _Subscription(base.Subscription.Kind.NONE, None, None,
+                                   None, None)
+
+
+def completion(terminal_metadata, code, message):
+    """Creates a base.Completion aggregating the given operation values.
+
+  Args:
+    terminal_metadata: A terminal metadata value for an operaton.
+    code: A code value for an operation.
+    message: A message value for an operation.
+
+  Returns:
+    A base.Completion aggregating the given operation values.
+  """
+    return _Completion(terminal_metadata, code, message)
+
+
+def full_subscription(operator, protocol_receiver):
+    """Creates a "full" base.Subscription for the given base.Operator.
+
+  Args:
+    operator: A base.Operator to be used in an operation.
+    protocol_receiver: A base.ProtocolReceiver to be used in an operation.
+
+  Returns:
+    A base.Subscription of kind base.Subscription.Kind.FULL wrapping the given
+      base.Operator and base.ProtocolReceiver.
+  """
+    return _Subscription(base.Subscription.Kind.FULL, None, None, operator,
+                         protocol_receiver)
diff --git a/contrib/python/grpcio/py3/grpc/framework/interfaces/face/__init__.py b/contrib/python/grpcio/py3/grpc/framework/interfaces/face/__init__.py
new file mode 100644
index 00000000000..5fb4f3c3cfd
--- /dev/null
+++ b/contrib/python/grpcio/py3/grpc/framework/interfaces/face/__init__.py
@@ -0,0 +1,13 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
diff --git a/contrib/python/grpcio/py3/grpc/framework/interfaces/face/face.py b/contrib/python/grpcio/py3/grpc/framework/interfaces/face/face.py
new file mode 100644
index 00000000000..ed0de6a7de2
--- /dev/null
+++ b/contrib/python/grpcio/py3/grpc/framework/interfaces/face/face.py
@@ -0,0 +1,1049 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
+"""Interfaces defining the Face layer of RPC Framework."""
+
+import abc
+import collections
+import enum
+
+# cardinality, style, abandonment, future, and stream are
+# referenced from specification in this 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 future  # pylint: disable=unused-import
+from grpc.framework.foundation import stream  # pylint: disable=unused-import
+
+# pylint: disable=too-many-arguments
+
+
+class NoSuchMethodError(Exception):
+    """Raised by customer code to indicate an unrecognized method.
+
+  Attributes:
+    group: The group of the unrecognized method.
+    name: The name of the unrecognized method.
+  """
+
+    def __init__(self, group, method):
+        """Constructor.
+
+    Args:
+      group: The group identifier of the unrecognized RPC name.
+      method: The method identifier of the unrecognized RPC name.
+    """
+        super(NoSuchMethodError, self).__init__()
+        self.group = group
+        self.method = method
+
+    def __repr__(self):
+        return 'face.NoSuchMethodError(%s, %s)' % (
+            self.group,
+            self.method,
+        )
+
+
+class Abortion(
+        collections.namedtuple('Abortion', (
+            'kind',
+            'initial_metadata',
+            'terminal_metadata',
+            'code',
+            'details',
+        ))):
+    """A value describing RPC abortion.
+
+  Attributes:
+    kind: A Kind value identifying how the RPC failed.
+    initial_metadata: The initial metadata from the other side of the RPC or
+      None if no initial metadata value was received.
+    terminal_metadata: The terminal metadata from the other side of the RPC or
+      None if no terminal metadata value was received.
+    code: The code value from the other side of the RPC or None if no code value
+      was received.
+    details: The details value from the other side of the RPC or None if no
+      details value was received.
+  """
+
+    @enum.unique
+    class Kind(enum.Enum):
+        """Types of RPC abortion."""
+
+        CANCELLED = 'cancelled'
+        EXPIRED = 'expired'
+        LOCAL_SHUTDOWN = 'local shutdown'
+        REMOTE_SHUTDOWN = 'remote shutdown'
+        NETWORK_FAILURE = 'network failure'
+        LOCAL_FAILURE = 'local failure'
+        REMOTE_FAILURE = 'remote failure'
+
+
+class AbortionError(Exception, metaclass=abc.ABCMeta):
+    """Common super type for exceptions indicating RPC abortion.
+
+    initial_metadata: The initial metadata from the other side of the RPC or
+      None if no initial metadata value was received.
+    terminal_metadata: The terminal metadata from the other side of the RPC or
+      None if no terminal metadata value was received.
+    code: The code value from the other side of the RPC or None if no code value
+      was received.
+    details: The details value from the other side of the RPC or None if no
+      details value was received.
+  """
+
+    def __init__(self, initial_metadata, terminal_metadata, code, details):
+        super(AbortionError, self).__init__()
+        self.initial_metadata = initial_metadata
+        self.terminal_metadata = terminal_metadata
+        self.code = code
+        self.details = details
+
+    def __str__(self):
+        return '%s(code=%s, details="%s")' % (self.__class__.__name__,
+                                              self.code, self.details)
+
+
+class CancellationError(AbortionError):
+    """Indicates that an RPC has been cancelled."""
+
+
+class ExpirationError(AbortionError):
+    """Indicates that an RPC has expired ("timed out")."""
+
+
+class LocalShutdownError(AbortionError):
+    """Indicates that an RPC has terminated due to local shutdown of RPCs."""
+
+
+class RemoteShutdownError(AbortionError):
+    """Indicates that an RPC has terminated due to remote shutdown of RPCs."""
+
+
+class NetworkError(AbortionError):
+    """Indicates that some error occurred on the network."""
+
+
+class LocalError(AbortionError):
+    """Indicates that an RPC has terminated due to a local defect."""
+
+
+class RemoteError(AbortionError):
+    """Indicates that an RPC has terminated due to a remote defect."""
+
+
+class RpcContext(abc.ABC):
+    """Provides RPC-related information and action."""
+
+    @abc.abstractmethod
+    def is_active(self):
+        """Describes whether the RPC is active or has terminated."""
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def time_remaining(self):
+        """Describes the length of allowed time remaining for the RPC.
+
+    Returns:
+      A nonnegative float indicating the length of allowed time in seconds
+      remaining for the RPC to complete before it is considered to have timed
+      out.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def add_abortion_callback(self, abortion_callback):
+        """Registers a callback to be called if the RPC is aborted.
+
+    Args:
+      abortion_callback: A callable to be called and passed an Abortion value
+        in the event of RPC abortion.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def cancel(self):
+        """Cancels the RPC.
+
+    Idempotent and has no effect if the RPC has already terminated.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def protocol_context(self):
+        """Accesses a custom object specified by an implementation provider.
+
+    Returns:
+      A value specified by the provider of a Face interface implementation
+        affording custom state and behavior.
+    """
+        raise NotImplementedError()
+
+
+class Call(RpcContext, metaclass=abc.ABCMeta):
+    """Invocation-side utility object for an RPC."""
+
+    @abc.abstractmethod
+    def initial_metadata(self):
+        """Accesses the initial metadata from the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The initial metadata object emitted by the service-side of the RPC, or
+        None if there was no such value.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def terminal_metadata(self):
+        """Accesses the terminal metadata from the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The terminal metadata object emitted by the service-side of the RPC, or
+        None if there was no such value.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def code(self):
+        """Accesses the code emitted by the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The code object emitted by the service-side of the RPC, or None if there
+        was no such value.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def details(self):
+        """Accesses the details value emitted by the service-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the service-side of the RPC.
+
+    Returns:
+      The details value emitted by the service-side of the RPC, or None if there
+        was no such value.
+    """
+        raise NotImplementedError()
+
+
+class ServicerContext(RpcContext, metaclass=abc.ABCMeta):
+    """A context object passed to method implementations."""
+
+    @abc.abstractmethod
+    def invocation_metadata(self):
+        """Accesses the metadata from the invocation-side of the RPC.
+
+    This method blocks until the value is available or is known not to have been
+    emitted from the invocation-side of the RPC.
+
+    Returns:
+      The metadata object emitted by the invocation-side of the RPC, or None if
+        there was no such value.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def initial_metadata(self, initial_metadata):
+        """Accepts the service-side initial metadata value of the RPC.
+
+    This method need not be called by method implementations if they have no
+    service-side initial metadata to transmit.
+
+    Args:
+      initial_metadata: The service-side initial metadata value of the RPC to
+        be transmitted to the invocation side of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def terminal_metadata(self, terminal_metadata):
+        """Accepts the service-side terminal metadata value of the RPC.
+
+    This method need not be called by method implementations if they have no
+    service-side terminal metadata to transmit.
+
+    Args:
+      terminal_metadata: The service-side terminal metadata value of the RPC to
+        be transmitted to the invocation side of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def code(self, code):
+        """Accepts the service-side code of the RPC.
+
+    This method need not be called by method implementations if they have no
+    code to transmit.
+
+    Args:
+      code: The code of the RPC to be transmitted to the invocation side of the
+        RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def details(self, details):
+        """Accepts the service-side details of the RPC.
+
+    This method need not be called by method implementations if they have no
+    service-side details to transmit.
+
+    Args:
+      details: The service-side details value of the RPC to be transmitted to
+        the invocation side of the RPC.
+    """
+        raise NotImplementedError()
+
+
+class ResponseReceiver(abc.ABC):
+    """Invocation-side object used to accept the output of an RPC."""
+
+    @abc.abstractmethod
+    def initial_metadata(self, initial_metadata):
+        """Receives the initial metadata from the service-side of the RPC.
+
+    Args:
+      initial_metadata: The initial metadata object emitted from the
+        service-side of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def response(self, response):
+        """Receives a response from the service-side of the RPC.
+
+    Args:
+      response: A response object emitted from the service-side of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def complete(self, terminal_metadata, code, details):
+        """Receives the completion values emitted from the service-side of the RPC.
+
+    Args:
+      terminal_metadata: The terminal metadata object emitted from the
+        service-side of the RPC.
+      code: The code object emitted from the service-side of the RPC.
+      details: The details object emitted from the service-side of the RPC.
+    """
+        raise NotImplementedError()
+
+
+class UnaryUnaryMultiCallable(abc.ABC):
+    """Affords invoking a unary-unary RPC in any call style."""
+
+    @abc.abstractmethod
+    def __call__(self,
+                 request,
+                 timeout,
+                 metadata=None,
+                 with_call=False,
+                 protocol_options=None):
+        """Synchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the response.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def future(self, request, timeout, metadata=None, protocol_options=None):
+        """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event(self,
+              request,
+              receiver,
+              abortion_callback,
+              timeout,
+              metadata=None,
+              protocol_options=None):
+        """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A Call for the RPC.
+    """
+        raise NotImplementedError()
+
+
+class UnaryStreamMultiCallable(abc.ABC):
+    """Affords invoking a unary-stream RPC in any call style."""
+
+    @abc.abstractmethod
+    def __call__(self, request, timeout, metadata=None, protocol_options=None):
+        """Invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event(self,
+              request,
+              receiver,
+              abortion_callback,
+              timeout,
+              metadata=None,
+              protocol_options=None):
+        """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A Call object for the RPC.
+    """
+        raise NotImplementedError()
+
+
+class StreamUnaryMultiCallable(abc.ABC):
+    """Affords invoking a stream-unary RPC in any call style."""
+
+    @abc.abstractmethod
+    def __call__(self,
+                 request_iterator,
+                 timeout,
+                 metadata=None,
+                 with_call=False,
+                 protocol_options=None):
+        """Synchronously invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the response.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def future(self,
+               request_iterator,
+               timeout,
+               metadata=None,
+               protocol_options=None):
+        """Asynchronously invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event(self,
+              receiver,
+              abortion_callback,
+              timeout,
+              metadata=None,
+              protocol_options=None):
+        """Asynchronously invokes the underlying RPC.
+
+    Args:
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A single object that is both a Call object for the RPC and a
+        stream.Consumer to which the request values of the RPC should be passed.
+    """
+        raise NotImplementedError()
+
+
+class StreamStreamMultiCallable(abc.ABC):
+    """Affords invoking a stream-stream RPC in any call style."""
+
+    @abc.abstractmethod
+    def __call__(self,
+                 request_iterator,
+                 timeout,
+                 metadata=None,
+                 protocol_options=None):
+        """Invokes the underlying RPC.
+
+    Args:
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event(self,
+              receiver,
+              abortion_callback,
+              timeout,
+              metadata=None,
+              protocol_options=None):
+        """Asynchronously invokes the underlying RPC.
+
+    Args:
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of
+        the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A single object that is both a Call object for the RPC and a
+        stream.Consumer to which the request values of the RPC should be passed.
+    """
+        raise NotImplementedError()
+
+
+class MethodImplementation(abc.ABC):
+    """A sum type that describes a method implementation.
+
+  Attributes:
+    cardinality: A cardinality.Cardinality value.
+    style: A style.Service value.
+    unary_unary_inline: The implementation of the method as a callable value
+      that takes a request value and a ServicerContext object and returns a
+      response value. Only non-None if cardinality is
+      cardinality.Cardinality.UNARY_UNARY and style is style.Service.INLINE.
+    unary_stream_inline: The implementation of the method as a callable value
+      that takes a request value and a ServicerContext object and returns an
+      iterator of response values. Only non-None if cardinality is
+      cardinality.Cardinality.UNARY_STREAM and style is style.Service.INLINE.
+    stream_unary_inline: The implementation of the method as a callable value
+      that takes an iterator of request values and a ServicerContext object and
+      returns a response value. Only non-None if cardinality is
+      cardinality.Cardinality.STREAM_UNARY and style is style.Service.INLINE.
+    stream_stream_inline: The implementation of the method as a callable value
+      that takes an iterator of request values and a ServicerContext object and
+      returns an iterator of response values. Only non-None if cardinality is
+      cardinality.Cardinality.STREAM_STREAM and style is style.Service.INLINE.
+    unary_unary_event: The implementation of the method as a callable value that
+      takes a request value, a response callback to which to pass the response
+      value of the RPC, and a ServicerContext. Only non-None if cardinality is
+      cardinality.Cardinality.UNARY_UNARY and style is style.Service.EVENT.
+    unary_stream_event: The implementation of the method as a callable value
+      that takes a request value, a stream.Consumer to which to pass the
+      response values of the RPC, and a ServicerContext. Only non-None if
+      cardinality is cardinality.Cardinality.UNARY_STREAM and style is
+      style.Service.EVENT.
+    stream_unary_event: The implementation of the method as a callable value
+      that takes a response callback to which to pass the response value of the
+      RPC and a ServicerContext and returns a stream.Consumer to which the
+      request values of the RPC should be passed. Only non-None if cardinality
+      is cardinality.Cardinality.STREAM_UNARY and style is style.Service.EVENT.
+    stream_stream_event: The implementation of the method as a callable value
+      that takes a stream.Consumer to which to pass the response values of the
+      RPC and a ServicerContext and returns a stream.Consumer to which the
+      request values of the RPC should be passed. Only non-None if cardinality
+      is cardinality.Cardinality.STREAM_STREAM and style is
+      style.Service.EVENT.
+  """
+
+
+class MultiMethodImplementation(abc.ABC):
+    """A general type able to service many methods."""
+
+    @abc.abstractmethod
+    def service(self, group, method, response_consumer, context):
+        """Services an RPC.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      response_consumer: A stream.Consumer to be called to accept the response
+        values of the RPC.
+      context: a ServicerContext object.
+
+    Returns:
+      A stream.Consumer with which to accept the request values of the RPC. The
+        consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing values to this object. Implementations must not assume that this
+        object will be called to completion of the request stream or even called
+        at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+      NoSuchMethodError: If this MultiMethod does not recognize the given group
+        and name for the RPC and is not able to service the RPC.
+    """
+        raise NotImplementedError()
+
+
+class GenericStub(abc.ABC):
+    """Affords RPC invocation via generic methods."""
+
+    @abc.abstractmethod
+    def blocking_unary_unary(self,
+                             group,
+                             method,
+                             request,
+                             timeout,
+                             metadata=None,
+                             with_call=False,
+                             protocol_options=None):
+        """Invokes a unary-request-unary-response method.
+
+    This method blocks until either returning the response value of the RPC
+    (in the event of RPC completion) or raising an exception (in the event of
+    RPC abortion).
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the response.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def future_unary_unary(self,
+                           group,
+                           method,
+                           request,
+                           timeout,
+                           metadata=None,
+                           protocol_options=None):
+        """Invokes a unary-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def inline_unary_stream(self,
+                            group,
+                            method,
+                            request,
+                            timeout,
+                            metadata=None,
+                            protocol_options=None):
+        """Invokes a unary-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def blocking_stream_unary(self,
+                              group,
+                              method,
+                              request_iterator,
+                              timeout,
+                              metadata=None,
+                              with_call=False,
+                              protocol_options=None):
+        """Invokes a stream-request-unary-response method.
+
+    This method blocks until either returning the response value of the RPC
+    (in the event of RPC completion) or raising an exception (in the event of
+    RPC abortion).
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      with_call: Whether or not to include return a Call for the RPC in addition
+        to the response.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      The response value for the RPC, and a Call for the RPC if with_call was
+        set to True at invocation.
+
+    Raises:
+      AbortionError: Indicating that the RPC was aborted.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def future_stream_unary(self,
+                            group,
+                            method,
+                            request_iterator,
+                            timeout,
+                            metadata=None,
+                            protocol_options=None):
+        """Invokes a stream-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and a future.Future. In the
+        event of RPC completion, the return Future's result value will be the
+        response value of the RPC. In the event of RPC abortion, the returned
+        Future's exception value will be an AbortionError.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def inline_stream_stream(self,
+                             group,
+                             method,
+                             request_iterator,
+                             timeout,
+                             metadata=None,
+                             protocol_options=None):
+        """Invokes a stream-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request_iterator: An iterator that yields request values for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      An object that is both a Call for the RPC and an iterator of response
+        values. Drawing response values from the returned iterator may raise
+        AbortionError indicating abortion of the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event_unary_unary(self,
+                          group,
+                          method,
+                          request,
+                          receiver,
+                          abortion_callback,
+                          timeout,
+                          metadata=None,
+                          protocol_options=None):
+        """Event-driven invocation of a unary-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A Call for the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event_unary_stream(self,
+                           group,
+                           method,
+                           request,
+                           receiver,
+                           abortion_callback,
+                           timeout,
+                           metadata=None,
+                           protocol_options=None):
+        """Event-driven invocation of a unary-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      request: The request value for the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A Call for the RPC.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event_stream_unary(self,
+                           group,
+                           method,
+                           receiver,
+                           abortion_callback,
+                           timeout,
+                           metadata=None,
+                           protocol_options=None):
+        """Event-driven invocation of a unary-request-unary-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A pair of a Call object for the RPC and a stream.Consumer to which the
+        request values of the RPC should be passed.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def event_stream_stream(self,
+                            group,
+                            method,
+                            receiver,
+                            abortion_callback,
+                            timeout,
+                            metadata=None,
+                            protocol_options=None):
+        """Event-driven invocation of a unary-request-stream-response method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+      receiver: A ResponseReceiver to be passed the response data of the RPC.
+      abortion_callback: A callback to be called and passed an Abortion value
+        in the event of RPC abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+      metadata: A metadata value to be passed to the service-side of the RPC.
+      protocol_options: A value specified by the provider of a Face interface
+        implementation affording custom state and behavior.
+
+    Returns:
+      A pair of a Call object for the RPC and a stream.Consumer to which the
+        request values of the RPC should be passed.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def unary_unary(self, group, method):
+        """Creates a UnaryUnaryMultiCallable for a unary-unary method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A UnaryUnaryMultiCallable value for the named unary-unary method.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def unary_stream(self, group, method):
+        """Creates a UnaryStreamMultiCallable for a unary-stream method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A UnaryStreamMultiCallable value for the name unary-stream method.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def stream_unary(self, group, method):
+        """Creates a StreamUnaryMultiCallable for a stream-unary method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A StreamUnaryMultiCallable value for the named stream-unary method.
+    """
+        raise NotImplementedError()
+
+    @abc.abstractmethod
+    def stream_stream(self, group, method):
+        """Creates a StreamStreamMultiCallable for a stream-stream method.
+
+    Args:
+      group: The group identifier of the RPC.
+      method: The method identifier of the RPC.
+
+    Returns:
+      A StreamStreamMultiCallable value for the named stream-stream method.
+    """
+        raise NotImplementedError()
+
+
+class DynamicStub(abc.ABC):
+    """Affords RPC invocation via attributes corresponding to afforded methods.
+
+  Instances of this type may be scoped to a single group so that attribute
+  access is unambiguous.
+
+  Instances of this type respond to attribute access as follows: if the
+  requested attribute is the name of a unary-unary method, the value of the
+  attribute will be a UnaryUnaryMultiCallable with which to invoke an RPC; if
+  the requested attribute is the name of a unary-stream method, the value of the
+  attribute will be a UnaryStreamMultiCallable with which to invoke an RPC; if
+  the requested attribute is the name of a stream-unary method, the value of the
+  attribute will be a StreamUnaryMultiCallable with which to invoke an RPC; and
+  if the requested attribute is the name of a stream-stream method, the value of
+  the attribute will be a StreamStreamMultiCallable with which to invoke an RPC.
+  """
diff --git a/contrib/python/grpcio/py3/grpc/framework/interfaces/face/utilities.py b/contrib/python/grpcio/py3/grpc/framework/interfaces/face/utilities.py
new file mode 100644
index 00000000000..f27bd676155
--- /dev/null
+++ b/contrib/python/grpcio/py3/grpc/framework/interfaces/face/utilities.py
@@ -0,0 +1,168 @@
+# Copyright 2015 gRPC authors.
+#
+# 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.
+"""Utilities for RPC Framework's Face interface."""
+
+import collections
+
+# stream is referenced from specification in this module.
+from grpc.framework.common import cardinality
+from grpc.framework.common import style
+from grpc.framework.foundation import stream  # pylint: disable=unused-import
+from grpc.framework.interfaces.face import face
+
+
+class _MethodImplementation(face.MethodImplementation,
+                            collections.namedtuple('_MethodImplementation', [
+                                'cardinality',
+                                'style',
+                                'unary_unary_inline',
+                                'unary_stream_inline',
+                                'stream_unary_inline',
+                                'stream_stream_inline',
+                                'unary_unary_event',
+                                'unary_stream_event',
+                                'stream_unary_event',
+                                'stream_stream_event',
+                            ])):
+    pass
+
+
+def unary_unary_inline(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-unary RPC method as a callable value
+      that takes a request value and an face.ServicerContext object and
+      returns a response value.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.UNARY_UNARY,
+                                 style.Service.INLINE, behavior, None, None,
+                                 None, None, None, None, None)
+
+
+def unary_stream_inline(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-stream RPC method as a callable
+      value that takes a request value and an face.ServicerContext object and
+      returns an iterator of response values.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.UNARY_STREAM,
+                                 style.Service.INLINE, None, behavior, None,
+                                 None, None, None, None, None)
+
+
+def stream_unary_inline(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-unary RPC method as a callable
+      value that takes an iterator of request values and an
+      face.ServicerContext object and returns a response value.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.STREAM_UNARY,
+                                 style.Service.INLINE, None, None, behavior,
+                                 None, None, None, None, None)
+
+
+def stream_stream_inline(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-stream RPC method as a callable
+      value that takes an iterator of request values and an
+      face.ServicerContext object and returns an iterator of response values.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.STREAM_STREAM,
+                                 style.Service.INLINE, None, None, None,
+                                 behavior, None, None, None, None)
+
+
+def unary_unary_event(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-unary RPC method as a callable
+      value that takes a request value, a response callback to which to pass
+      the response value of the RPC, and an face.ServicerContext.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.UNARY_UNARY,
+                                 style.Service.EVENT, None, None, None, None,
+                                 behavior, None, None, None)
+
+
+def unary_stream_event(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a unary-stream RPC method as a callable
+      value that takes a request value, a stream.Consumer to which to pass the
+      the response values of the RPC, and an face.ServicerContext.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.UNARY_STREAM,
+                                 style.Service.EVENT, None, None, None, None,
+                                 None, behavior, None, None)
+
+
+def stream_unary_event(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-unary RPC method as a callable
+      value that takes a response callback to which to pass the response value
+      of the RPC and an face.ServicerContext and returns a stream.Consumer to
+      which the request values of the RPC should be passed.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.STREAM_UNARY,
+                                 style.Service.EVENT, None, None, None, None,
+                                 None, None, behavior, None)
+
+
+def stream_stream_event(behavior):
+    """Creates an face.MethodImplementation for the given behavior.
+
+  Args:
+    behavior: The implementation of a stream-stream RPC method as a callable
+      value that takes a stream.Consumer to which to pass the response values
+      of the RPC and an face.ServicerContext and returns a stream.Consumer to
+      which the request values of the RPC should be passed.
+
+  Returns:
+    An face.MethodImplementation derived from the given behavior.
+  """
+    return _MethodImplementation(cardinality.Cardinality.STREAM_STREAM,
+                                 style.Service.EVENT, None, None, None, None,
+                                 None, None, None, behavior)