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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( # noqa: B027
140 self, service_name, method_handlers
141 ):
142 """Registers GenericRpcHandlers with this Server.
144 This method is only safe to call before the server is started.
146 Args:
147 service_name: The service name.
148 method_handlers: A dictionary that maps method names to corresponding
149 RpcMethodHandler.
150 """
153# pylint: disable=too-many-public-methods
154class ServicerContext(Generic[RequestType, ResponseType], abc.ABC):
155 """A context object passed to method implementations."""
157 @abc.abstractmethod
158 async def read(self) -> RequestType:
159 """Reads one message from the RPC.
161 Only one read operation is allowed simultaneously.
163 Returns:
164 A response message of the RPC.
166 Raises:
167 An RpcError exception if the read failed.
168 """
170 @abc.abstractmethod
171 async def write(self, message: ResponseType) -> None:
172 """Writes one message to the RPC.
174 Only one write operation is allowed simultaneously.
176 Raises:
177 An RpcError exception if the write failed.
178 """
180 @abc.abstractmethod
181 async def send_initial_metadata(
182 self, initial_metadata: MetadataType
183 ) -> None:
184 """Sends the initial metadata value to the client.
186 This method need not be called by implementations if they have no
187 metadata to add to what the gRPC runtime will transmit.
189 Args:
190 initial_metadata: The initial :term:`metadata`.
191 """
193 @abc.abstractmethod
194 async def abort(
195 self,
196 code: grpc.StatusCode,
197 details: str = "",
198 trailing_metadata: MetadataType = (),
199 ) -> NoReturn:
200 """Raises an exception to terminate the RPC with a non-OK status.
202 The code and details passed as arguments will supersede any existing
203 ones.
205 Args:
206 code: A StatusCode object to be sent to the client.
207 It must not be StatusCode.OK.
208 details: A UTF-8-encodable string to be sent to the client upon
209 termination of the RPC.
210 trailing_metadata: A sequence of tuple represents the trailing
211 :term:`metadata`.
213 Raises:
214 Exception: An exception is always raised to signal the abortion the
215 RPC to the gRPC runtime.
216 """
217 raise NotImplementedError()
219 @abc.abstractmethod
220 async def abort_with_status(self, status: grpc.Status) -> NoReturn:
221 """Raises an exception to terminate the RPC with a non-OK status.
223 The status passed as argument will supersede any existing status code,
224 status message and trailing metadata.
226 This is an EXPERIMENTAL API.
228 Args:
229 status: A grpc.Status object. The status code in it must not be
230 StatusCode.OK.
232 Raises:
233 Exception: An exception is always raised to signal the abortion of the
234 RPC to the gRPC runtime.
235 """
236 raise NotImplementedError()
238 @abc.abstractmethod
239 def set_trailing_metadata(self, trailing_metadata: MetadataType) -> None:
240 """Sends the trailing metadata for the RPC.
242 This method need not be called by implementations if they have no
243 metadata to add to what the gRPC runtime will transmit.
245 Args:
246 trailing_metadata: The trailing :term:`metadata`.
247 """
249 @abc.abstractmethod
250 def invocation_metadata(self) -> Optional[MetadataType]:
251 """Accesses the metadata sent by the client.
253 Returns:
254 The invocation :term:`metadata`.
255 """
257 @abc.abstractmethod
258 def set_code(self, code: grpc.StatusCode) -> None:
259 """Sets the value to be used as status code upon RPC completion.
261 This method need not be called by method implementations if they wish
262 the gRPC runtime to determine the status code of the RPC.
264 Args:
265 code: A StatusCode object to be sent to the client.
266 """
268 @abc.abstractmethod
269 def set_details(self, details: str) -> None:
270 """Sets the value to be used the as detail string upon RPC completion.
272 This method need not be called by method implementations if they have
273 no details to transmit.
275 Args:
276 details: A UTF-8-encodable string to be sent to the client upon
277 termination of the RPC.
278 """
280 @abc.abstractmethod
281 def set_compression(self, compression: grpc.Compression) -> None:
282 """Set the compression algorithm to be used for the entire call.
284 Args:
285 compression: An element of grpc.compression, e.g.
286 grpc.compression.Gzip.
287 """
289 @abc.abstractmethod
290 def disable_next_message_compression(self) -> None:
291 """Disables compression for the next response message.
293 This method will override any compression configuration set during
294 server creation or set on the call.
295 """
297 @abc.abstractmethod
298 def peer(self) -> str:
299 """Identifies the peer that invoked the RPC being serviced.
301 Returns:
302 A string identifying the peer that invoked the RPC being serviced.
303 The string format is determined by gRPC runtime.
304 """
306 @abc.abstractmethod
307 def peer_identities(self) -> Optional[Iterable[bytes]]:
308 """Gets one or more peer identity(s).
310 Equivalent to
311 servicer_context.auth_context().get(servicer_context.peer_identity_key())
313 Returns:
314 An iterable of the identities, or None if the call is not
315 authenticated. Each identity is returned as a raw bytes type.
316 """
318 @abc.abstractmethod
319 def peer_identity_key(self) -> Optional[str]:
320 """The auth property used to identify the peer.
322 For example, "x509_common_name" or "x509_subject_alternative_name" are
323 used to identify an SSL peer.
325 Returns:
326 The auth property (string) that indicates the
327 peer identity, or None if the call is not authenticated.
328 """
330 @abc.abstractmethod
331 def auth_context(self) -> Mapping[str, Iterable[bytes]]:
332 """Gets the auth context for the call.
334 Returns:
335 A map of strings to an iterable of bytes for each auth property.
336 """
338 def time_remaining(self) -> float:
339 """Describes the length of allowed time remaining for the RPC.
341 Returns:
342 A nonnegative float indicating the length of allowed time in seconds
343 remaining for the RPC to complete before it is considered to have
344 timed out, or None if no deadline was specified for the RPC.
345 """
346 raise NotImplementedError()
348 def trailing_metadata(self):
349 """Access value to be used as trailing metadata upon RPC completion.
351 This is an EXPERIMENTAL API.
353 Returns:
354 The trailing :term:`metadata` for the RPC.
355 """
356 raise NotImplementedError()
358 def code(self):
359 """Accesses the value to be used as status code upon RPC completion.
361 This is an EXPERIMENTAL API.
363 Returns:
364 The StatusCode value for the RPC.
365 """
366 raise NotImplementedError()
368 def details(self):
369 """Accesses the value to be used as detail string upon RPC completion.
371 This is an EXPERIMENTAL API.
373 Returns:
374 The details string of the RPC.
375 """
376 raise NotImplementedError()
378 def add_done_callback(self, callback: DoneCallbackType) -> None:
379 """Registers a callback to be called on RPC termination.
381 This is an EXPERIMENTAL API.
383 Args:
384 callback: A callable object will be called with the servicer context
385 object as its only argument.
386 """
388 def cancelled(self) -> bool:
389 """Return True if the RPC is cancelled.
391 The RPC is cancelled when the cancellation was requested with cancel().
393 This is an EXPERIMENTAL API.
395 Returns:
396 A bool indicates whether the RPC is cancelled or not.
397 """
398 raise NotImplementedError()
400 def done(self) -> bool:
401 """Return True if the RPC is done.
403 An RPC is done if the RPC is completed, cancelled or aborted.
405 This is an EXPERIMENTAL API.
407 Returns:
408 A bool indicates if the RPC is done.
409 """
410 raise NotImplementedError()