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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 ._typing import DoneCallbackType
22from ._typing import MetadataType
23from ._typing import RequestType
24from ._typing import ResponseType
27class Server(abc.ABC):
28 """Serves RPCs."""
30 @abc.abstractmethod
31 def add_generic_rpc_handlers(
32 self, generic_rpc_handlers: Sequence[grpc.GenericRpcHandler]
33 ) -> None:
34 """Registers GenericRpcHandlers with this Server.
36 This method is only safe to call before the server is started.
38 Args:
39 generic_rpc_handlers: A sequence of GenericRpcHandlers that will be
40 used to service RPCs.
41 """
43 @abc.abstractmethod
44 def add_insecure_port(self, address: str) -> int:
45 """Opens an insecure port for accepting RPCs.
47 A port is a communication endpoint that used by networking protocols,
48 like TCP and UDP. To date, we only support TCP.
50 This method may only be called before starting the server.
52 Args:
53 address: The address for which to open a port. If the port is 0,
54 or not specified in the address, then the gRPC runtime will choose a port.
56 Returns:
57 An integer port on which the server will accept RPC requests.
58 """
60 @abc.abstractmethod
61 def add_secure_port(
62 self, address: str, server_credentials: grpc.ServerCredentials
63 ) -> int:
64 """Opens a secure port for accepting RPCs.
66 A port is a communication endpoint that used by networking protocols,
67 like TCP and UDP. To date, we only support TCP.
69 This method may only be called before starting the server.
71 Args:
72 address: The address for which to open a port.
73 if the port is 0, or not specified in the address, then the gRPC
74 runtime will choose a port.
75 server_credentials: A ServerCredentials object.
77 Returns:
78 An integer port on which the server will accept RPC requests.
79 """
81 @abc.abstractmethod
82 async def start(self) -> None:
83 """Starts this Server.
85 This method may only be called once. (i.e. it is not idempotent).
86 """
88 @abc.abstractmethod
89 async def stop(self, grace: Optional[float]) -> None:
90 """Stops this Server.
92 This method immediately stops the server from servicing new RPCs in
93 all cases.
95 If a grace period is specified, this method waits until all active
96 RPCs are finished or until the grace period is reached. RPCs that haven't
97 been terminated within the grace period are aborted.
98 If a grace period is not specified (by passing None for grace), all
99 existing RPCs are aborted immediately and this method blocks until
100 the last RPC handler terminates.
102 This method is idempotent and may be called at any time. Passing a
103 smaller grace value in a subsequent call will have the effect of
104 stopping the Server sooner (passing None will have the effect of
105 stopping the server immediately). Passing a larger grace value in a
106 subsequent call will not have the effect of stopping the server later
107 (i.e. the most restrictive grace value is used).
109 Args:
110 grace: A duration of time in seconds or None.
111 """
113 @abc.abstractmethod
114 async def wait_for_termination(
115 self, timeout: Optional[float] = None
116 ) -> bool:
117 """Continues current coroutine once the server stops.
119 This is an EXPERIMENTAL API.
121 The wait will not consume computational resources during blocking, and
122 it will block until one of the two following conditions are met:
124 1) The server is stopped or terminated;
125 2) A timeout occurs if timeout is not `None`.
127 The timeout argument works in the same way as `threading.Event.wait()`.
128 https://docs.python.org/3/library/threading.html#threading.Event.wait
130 Args:
131 timeout: A floating point number specifying a timeout for the
132 operation in seconds.
134 Returns:
135 A bool indicates if the operation times out.
136 """
138 # Suppressing pyright[reportUnknownParameterType, reportMissingParameterType]
139 # for type annotation of service_name and method_handlers as it will be
140 # taken up along with the sync stack changes.
141 def add_registered_method_handlers( # noqa: B027
142 self, service_name, method_handlers # pyright: ignore # noqa: PGH003
143 ) -> None:
144 """Registers GenericRpcHandlers with this Server.
146 This method is only safe to call before the server is started.
148 Args:
149 service_name: The service name.
150 method_handlers: A dictionary that maps method names to corresponding
151 RpcMethodHandler.
152 """
155# pylint: disable=too-many-public-methods
156class ServicerContext(Generic[RequestType, ResponseType], abc.ABC):
157 """A context object passed to method implementations."""
159 @abc.abstractmethod
160 async def read(self) -> RequestType:
161 """Reads one message from the RPC.
163 Only one read operation is allowed simultaneously.
165 Returns:
166 A response message of the RPC.
168 Raises:
169 An RpcError exception if the read failed.
170 """
172 @abc.abstractmethod
173 async def write(self, message: ResponseType) -> None:
174 """Writes one message to the RPC.
176 Only one write operation is allowed simultaneously.
178 Raises:
179 An RpcError exception if the write failed.
180 """
182 @abc.abstractmethod
183 async def send_initial_metadata(
184 self, initial_metadata: MetadataType
185 ) -> None:
186 """Sends the initial metadata value to the client.
188 This method need not be called by implementations if they have no
189 metadata to add to what the gRPC runtime will transmit.
191 Args:
192 initial_metadata: The initial :term:`metadata`.
193 """
195 @abc.abstractmethod
196 async def abort(
197 self,
198 code: grpc.StatusCode,
199 details: str = "",
200 trailing_metadata: MetadataType = (),
201 ) -> NoReturn:
202 """Raises an exception to terminate the RPC with a non-OK status.
204 The code and details passed as arguments will supersede any existing
205 ones.
207 Args:
208 code: A StatusCode object to be sent to the client.
209 It must not be StatusCode.OK.
210 details: A UTF-8-encodable string to be sent to the client upon
211 termination of the RPC.
212 trailing_metadata: A sequence of tuple represents the trailing
213 :term:`metadata`.
215 Raises:
216 Exception: An exception is always raised to signal the abortion the
217 RPC to the gRPC runtime.
218 """
219 raise NotImplementedError()
221 @abc.abstractmethod
222 async def abort_with_status(self, status: grpc.Status) -> NoReturn:
223 """Raises an exception to terminate the RPC with a non-OK status.
225 The status passed as argument will supersede any existing status code,
226 status message and trailing metadata.
228 This is an EXPERIMENTAL API.
230 Args:
231 status: A grpc.Status object. The status code in it must not be
232 StatusCode.OK.
234 Raises:
235 Exception: An exception is always raised to signal the abortion of the
236 RPC to the gRPC runtime.
237 """
238 raise NotImplementedError()
240 @abc.abstractmethod
241 def set_trailing_metadata(self, trailing_metadata: MetadataType) -> None:
242 """Sends the trailing metadata for the RPC.
244 This method need not be called by implementations if they have no
245 metadata to add to what the gRPC runtime will transmit.
247 Args:
248 trailing_metadata: The trailing :term:`metadata`.
249 """
251 @abc.abstractmethod
252 def invocation_metadata(self) -> Optional[MetadataType]:
253 """Accesses the metadata sent by the client.
255 Returns:
256 The invocation :term:`metadata`.
257 """
259 @abc.abstractmethod
260 def set_code(self, code: grpc.StatusCode) -> None:
261 """Sets the value to be used as status code upon RPC completion.
263 This method need not be called by method implementations if they wish
264 the gRPC runtime to determine the status code of the RPC.
266 Args:
267 code: A StatusCode object to be sent to the client.
268 """
270 @abc.abstractmethod
271 def set_details(self, details: str) -> None:
272 """Sets the value to be used the as detail string upon RPC completion.
274 This method need not be called by method implementations if they have
275 no details to transmit.
277 Args:
278 details: A UTF-8-encodable string to be sent to the client upon
279 termination of the RPC.
280 """
282 @abc.abstractmethod
283 def set_compression(self, compression: grpc.Compression) -> None:
284 """Set the compression algorithm to be used for the entire call.
286 Args:
287 compression: An element of grpc.compression, e.g.
288 grpc.compression.Gzip.
289 """
291 @abc.abstractmethod
292 def disable_next_message_compression(self) -> None:
293 """Disables compression for the next response message.
295 This method will override any compression configuration set during
296 server creation or set on the call.
297 """
299 @abc.abstractmethod
300 def peer(self) -> str:
301 """Identifies the peer that invoked the RPC being serviced.
303 Returns:
304 A string identifying the peer that invoked the RPC being serviced.
305 The string format is determined by gRPC runtime.
306 """
308 @abc.abstractmethod
309 def peer_identities(self) -> Optional[Iterable[bytes]]:
310 """Gets one or more peer identity(s).
312 Equivalent to
313 servicer_context.auth_context().get(servicer_context.peer_identity_key())
315 Returns:
316 An iterable of the identities, or None if the call is not
317 authenticated. Each identity is returned as a raw bytes type.
318 """
320 @abc.abstractmethod
321 def peer_identity_key(self) -> Optional[str]:
322 """The auth property used to identify the peer.
324 For example, "x509_common_name" or "x509_subject_alternative_name" are
325 used to identify an SSL peer.
327 Returns:
328 The auth property (string) that indicates the
329 peer identity, or None if the call is not authenticated.
330 """
332 @abc.abstractmethod
333 def auth_context(self) -> Mapping[str, Iterable[bytes]]:
334 """Gets the auth context for the call.
336 Returns:
337 A map of strings to an iterable of bytes for each auth property.
338 """
340 def time_remaining(self) -> float:
341 """Describes the length of allowed time remaining for the RPC.
343 Returns:
344 A nonnegative float indicating the length of allowed time in seconds
345 remaining for the RPC to complete before it is considered to have
346 timed out, or None if no deadline was specified for the RPC.
347 """
348 raise NotImplementedError()
350 def trailing_metadata(self) -> MetadataType:
351 """Access value to be used as trailing metadata upon RPC completion.
353 This is an EXPERIMENTAL API.
355 Returns:
356 The trailing :term:`metadata` for the RPC.
357 """
358 raise NotImplementedError()
360 def code(self) -> grpc.StatusCode:
361 """Accesses the value to be used as status code upon RPC completion.
363 This is an EXPERIMENTAL API.
365 Returns:
366 The StatusCode value for the RPC.
367 """
368 raise NotImplementedError()
370 def details(self): # pyright: ignore[reportUnknownParameterType]
371 """Accesses the value to be used as detail string upon RPC completion.
373 This is an EXPERIMENTAL API.
375 Returns:
376 The details string of the RPC.
377 """
378 raise NotImplementedError()
380 def add_done_callback(self, callback: DoneCallbackType) -> None:
381 """Registers a callback to be called on RPC termination.
383 This is an EXPERIMENTAL API.
385 Args:
386 callback: A callable object will be called with the servicer context
387 object as its only argument.
388 """
390 def cancelled(self) -> bool:
391 """Return True if the RPC is cancelled.
393 The RPC is cancelled when the cancellation was requested with cancel().
395 This is an EXPERIMENTAL API.
397 Returns:
398 A bool indicates whether the RPC is cancelled or not.
399 """
400 raise NotImplementedError()
402 def done(self) -> bool:
403 """Return True if the RPC is done.
405 An RPC is done if the RPC is completed, cancelled or aborted.
407 This is an EXPERIMENTAL API.
409 Returns:
410 A bool indicates if the RPC is done.
411 """
412 raise NotImplementedError()