io.grpc.ServerInterceptor Maven / Gradle / Ivy
/*
* Copyright 2014 The 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.
*/
package io.grpc;
import javax.annotation.concurrent.ThreadSafe;
/**
* Interface for intercepting incoming calls before they are dispatched by
* {@link ServerCallHandler}.
*
* Implementers use this mechanism to add cross-cutting behavior to server-side calls. Common
* example of such behavior include:
*
* - Enforcing valid authentication credentials
* - Logging and monitoring call behavior
* - Delegating calls to other servers
*
*
* The interceptor may be called for multiple {@link ServerCall calls} by one or more threads
* without completing the previous ones first. Refer to the
* {@link io.grpc.ServerCall.Listener ServerCall.Listener} docs for more details regarding thread
* safety of the returned listener.
*/
@ThreadSafe
public interface ServerInterceptor {
/**
* Intercept {@link ServerCall} dispatch by the {@code next} {@link ServerCallHandler}. General
* semantics of {@link ServerCallHandler#startCall} apply and the returned
* {@link io.grpc.ServerCall.Listener} must not be {@code null}.
*
*
If the implementation throws an exception, {@code call} will be closed with an error.
* Implementations must not throw an exception if they started processing that may use {@code
* call} on another thread.
*
* @param call object to receive response messages
* @param headers which can contain extra call metadata from {@link ClientCall#start},
* e.g. authentication credentials.
* @param next next processor in the interceptor chain
* @return listener for processing incoming messages for {@code call}, never {@code null}.
*/
ServerCall.Listener interceptCall(
ServerCall call,
Metadata headers,
ServerCallHandler next);
}