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1# Copyright 2020 The gRPC Authors
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14"""Abstract base classes for server-side classes."""
16import abc
17from typing import Generic, Iterable, Mapping, NoReturn, Optional, Sequence
19import grpc
21from ._metadata import Metadata # pylint: disable=unused-import
22from ._typing import DoneCallbackType
23from ._typing import MetadataType
24from ._typing import RequestType
25from ._typing import ResponseType
28class Server(abc.ABC):
29 """Serves RPCs."""
31 @abc.abstractmethod
32 def add_generic_rpc_handlers(
33 self, generic_rpc_handlers: Sequence[grpc.GenericRpcHandler]
34 ) -> None:
35 """Registers GenericRpcHandlers with this Server.
37 This method is only safe to call before the server is started.
39 Args:
40 generic_rpc_handlers: A sequence of GenericRpcHandlers that will be
41 used to service RPCs.
42 """
44 @abc.abstractmethod
45 def add_insecure_port(self, address: str) -> int:
46 """Opens an insecure port for accepting RPCs.
48 A port is a communication endpoint that used by networking protocols,
49 like TCP and UDP. To date, we only support TCP.
51 This method may only be called before starting the server.
53 Args:
54 address: The address for which to open a port. If the port is 0,
55 or not specified in the address, then the gRPC runtime will choose a port.
57 Returns:
58 An integer port on which the server will accept RPC requests.
59 """
61 @abc.abstractmethod
62 def add_secure_port(
63 self, address: str, server_credentials: grpc.ServerCredentials
64 ) -> int:
65 """Opens a secure port for accepting RPCs.
67 A port is a communication endpoint that used by networking protocols,
68 like TCP and UDP. To date, we only support TCP.
70 This method may only be called before starting the server.
72 Args:
73 address: The address for which to open a port.
74 if the port is 0, or not specified in the address, then the gRPC
75 runtime will choose a port.
76 server_credentials: A ServerCredentials object.
78 Returns:
79 An integer port on which the server will accept RPC requests.
80 """
82 @abc.abstractmethod
83 async def start(self) -> None:
84 """Starts this Server.
86 This method may only be called once. (i.e. it is not idempotent).
87 """
89 @abc.abstractmethod
90 async def stop(self, grace: Optional[float]) -> None:
91 """Stops this Server.
93 This method immediately stops the server from servicing new RPCs in
94 all cases.
96 If a grace period is specified, this method waits until all active
97 RPCs are finished or until the grace period is reached. RPCs that haven't
98 been terminated within the grace period are aborted.
99 If a grace period is not specified (by passing None for grace), all
100 existing RPCs are aborted immediately and this method blocks until
101 the last RPC handler terminates.
103 This method is idempotent and may be called at any time. Passing a
104 smaller grace value in a subsequent call will have the effect of
105 stopping the Server sooner (passing None will have the effect of
106 stopping the server immediately). Passing a larger grace value in a
107 subsequent call will not have the effect of stopping the server later
108 (i.e. the most restrictive grace value is used).
110 Args:
111 grace: A duration of time in seconds or None.
112 """
114 @abc.abstractmethod
115 async def wait_for_termination(
116 self, timeout: Optional[float] = None
117 ) -> bool:
118 """Continues current coroutine once the server stops.
120 This is an EXPERIMENTAL API.
122 The wait will not consume computational resources during blocking, and
123 it will block until one of the two following conditions are met:
125 1) The server is stopped or terminated;
126 2) A timeout occurs if timeout is not `None`.
128 The timeout argument works in the same way as `threading.Event.wait()`.
129 https://docs.python.org/3/library/threading.html#threading.Event.wait
131 Args:
132 timeout: A floating point number specifying a timeout for the
133 operation in seconds.
135 Returns:
136 A bool indicates if the operation times out.
137 """
139 def add_registered_method_handlers(self, service_name, method_handlers):
140 """Registers GenericRpcHandlers with this Server.
142 This method is only safe to call before the server is started.
144 Args:
145 service_name: The service name.
146 method_handlers: A dictionary that maps method names to corresponding
147 RpcMethodHandler.
148 """
151# pylint: disable=too-many-public-methods
152class ServicerContext(Generic[RequestType, ResponseType], abc.ABC):
153 """A context object passed to method implementations."""
155 @abc.abstractmethod
156 async def read(self) -> RequestType:
157 """Reads one message from the RPC.
159 Only one read operation is allowed simultaneously.
161 Returns:
162 A response message of the RPC.
164 Raises:
165 An RpcError exception if the read failed.
166 """
168 @abc.abstractmethod
169 async def write(self, message: ResponseType) -> None:
170 """Writes one message to the RPC.
172 Only one write operation is allowed simultaneously.
174 Raises:
175 An RpcError exception if the write failed.
176 """
178 @abc.abstractmethod
179 async def send_initial_metadata(
180 self, initial_metadata: MetadataType
181 ) -> None:
182 """Sends the initial metadata value to the client.
184 This method need not be called by implementations if they have no
185 metadata to add to what the gRPC runtime will transmit.
187 Args:
188 initial_metadata: The initial :term:`metadata`.
189 """
191 @abc.abstractmethod
192 async def abort(
193 self,
194 code: grpc.StatusCode,
195 details: str = "",
196 trailing_metadata: MetadataType = tuple(),
197 ) -> NoReturn:
198 """Raises an exception to terminate the RPC with a non-OK status.
200 The code and details passed as arguments will supersede any existing
201 ones.
203 Args:
204 code: A StatusCode object to be sent to the client.
205 It must not be StatusCode.OK.
206 details: A UTF-8-encodable string to be sent to the client upon
207 termination of the RPC.
208 trailing_metadata: A sequence of tuple represents the trailing
209 :term:`metadata`.
211 Raises:
212 Exception: An exception is always raised to signal the abortion the
213 RPC to the gRPC runtime.
214 """
216 @abc.abstractmethod
217 def set_trailing_metadata(self, trailing_metadata: MetadataType) -> None:
218 """Sends the trailing metadata for the RPC.
220 This method need not be called by implementations if they have no
221 metadata to add to what the gRPC runtime will transmit.
223 Args:
224 trailing_metadata: The trailing :term:`metadata`.
225 """
227 @abc.abstractmethod
228 def invocation_metadata(self) -> Optional[MetadataType]:
229 """Accesses the metadata sent by the client.
231 Returns:
232 The invocation :term:`metadata`.
233 """
235 @abc.abstractmethod
236 def set_code(self, code: grpc.StatusCode) -> None:
237 """Sets the value to be used as status code upon RPC completion.
239 This method need not be called by method implementations if they wish
240 the gRPC runtime to determine the status code of the RPC.
242 Args:
243 code: A StatusCode object to be sent to the client.
244 """
246 @abc.abstractmethod
247 def set_details(self, details: str) -> None:
248 """Sets the value to be used the as detail string upon RPC completion.
250 This method need not be called by method implementations if they have
251 no details to transmit.
253 Args:
254 details: A UTF-8-encodable string to be sent to the client upon
255 termination of the RPC.
256 """
258 @abc.abstractmethod
259 def set_compression(self, compression: grpc.Compression) -> None:
260 """Set the compression algorithm to be used for the entire call.
262 Args:
263 compression: An element of grpc.compression, e.g.
264 grpc.compression.Gzip.
265 """
267 @abc.abstractmethod
268 def disable_next_message_compression(self) -> None:
269 """Disables compression for the next response message.
271 This method will override any compression configuration set during
272 server creation or set on the call.
273 """
275 @abc.abstractmethod
276 def peer(self) -> str:
277 """Identifies the peer that invoked the RPC being serviced.
279 Returns:
280 A string identifying the peer that invoked the RPC being serviced.
281 The string format is determined by gRPC runtime.
282 """
284 @abc.abstractmethod
285 def peer_identities(self) -> Optional[Iterable[bytes]]:
286 """Gets one or more peer identity(s).
288 Equivalent to
289 servicer_context.auth_context().get(servicer_context.peer_identity_key())
291 Returns:
292 An iterable of the identities, or None if the call is not
293 authenticated. Each identity is returned as a raw bytes type.
294 """
296 @abc.abstractmethod
297 def peer_identity_key(self) -> Optional[str]:
298 """The auth property used to identify the peer.
300 For example, "x509_common_name" or "x509_subject_alternative_name" are
301 used to identify an SSL peer.
303 Returns:
304 The auth property (string) that indicates the
305 peer identity, or None if the call is not authenticated.
306 """
308 @abc.abstractmethod
309 def auth_context(self) -> Mapping[str, Iterable[bytes]]:
310 """Gets the auth context for the call.
312 Returns:
313 A map of strings to an iterable of bytes for each auth property.
314 """
316 def time_remaining(self) -> float:
317 """Describes the length of allowed time remaining for the RPC.
319 Returns:
320 A nonnegative float indicating the length of allowed time in seconds
321 remaining for the RPC to complete before it is considered to have
322 timed out, or None if no deadline was specified for the RPC.
323 """
325 def trailing_metadata(self):
326 """Access value to be used as trailing metadata upon RPC completion.
328 This is an EXPERIMENTAL API.
330 Returns:
331 The trailing :term:`metadata` for the RPC.
332 """
333 raise NotImplementedError()
335 def code(self):
336 """Accesses the value to be used as status code upon RPC completion.
338 This is an EXPERIMENTAL API.
340 Returns:
341 The StatusCode value for the RPC.
342 """
343 raise NotImplementedError()
345 def details(self):
346 """Accesses the value to be used as detail string upon RPC completion.
348 This is an EXPERIMENTAL API.
350 Returns:
351 The details string of the RPC.
352 """
353 raise NotImplementedError()
355 def add_done_callback(self, callback: DoneCallbackType) -> None:
356 """Registers a callback to be called on RPC termination.
358 This is an EXPERIMENTAL API.
360 Args:
361 callback: A callable object will be called with the servicer context
362 object as its only argument.
363 """
365 def cancelled(self) -> bool:
366 """Return True if the RPC is cancelled.
368 The RPC is cancelled when the cancellation was requested with cancel().
370 This is an EXPERIMENTAL API.
372 Returns:
373 A bool indicates whether the RPC is cancelled or not.
374 """
376 def done(self) -> bool:
377 """Return True if the RPC is done.
379 An RPC is done if the RPC is completed, cancelled or aborted.
381 This is an EXPERIMENTAL API.
383 Returns:
384 A bool indicates if the RPC is done.
385 """